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PC-SIG Diskette Library (Disk #159)
[PCjs Machine "ibm5150"]
Waiting for machine "ibm5150" to load....
Information about “PC FIRING LINE”
This is the first issue of the PC FIRING LINE NEWSLETTER. It has beena
positioned as the underground newspaper for the IBM user. You will be
presented with the untold tales and in-depth programming aids. Some of
the articles are about ADA, Assembly routines, and items not written
about by IBM. It also contains many sample program listings with
accompanying documentation.
Special Requirements: None.
How to Start: Type GO (press enter).
Suggested Registration: $12.00
File Descriptions:
0 BAT Batch file.
PATCH2 BAT Batch file.
8087 REV Information file.
ADA1CMP REV Information file.
BIGDEAL ASM Assembly source code.
GRABBAG ASM Assembly source code.
COLORFUL EXE Sub-program.
DEBUG PAT Patch for DEBUG.
GRABBAG EXE Sub-program.
LIST1 ADA Test the ADS compiler in ADA.
LIST1 ASM Test the ADS compiler in Assembley.
LIST1 C Test the ADS compiler in C.
LIST1 PAS Test the ADS compiler in Pascal.
PCFL EXE Main Program.
PRETTY1 COM Program embellisher
TXT ADS Advertisments
WRITERS GDE Text file.
???????? TXT Text file (20 files).
1-2-3.TXT
Copyright 1984 by ABComputing
╔═════════════════════════════════════════════════════════════════════════════╗
║ The 1-2-3 Advantage ║
║ ║
║ by ║
║ ║
║ Jerrold Benedict ║
╚═════════════════════════════════════════════════════════════════════════════╝
┌────────────────────────────┐
│ Introduction │
└────────────────────────────┘
Lotus Development Corporation's 1-2-3, the integrated
spreadsheet,database and graphing program, has received high
praise from reviewers and the marketplace. While much has
been written about its capabilities, little has been
documented on one of its most powerful features, its
programmability. 1-2-3 can be programmed to automatically
load or store files, calculate formulas, print or graph
data, or prompt for user input. 1-2-3 commands, or
combinations of 1-2-3 commands, can be used to simulate many
commands available in Microsoft Basic, or other high-level
programming languages. These stored command sequences, or
keystrokes, are called keyboard macros.
┌────────────────────────────┐
│ Executing Keyboard Macros │
└────────────────────────────┘
After being stored, 1-2-3 macros are invoked in either
of two ways. They are started automatically when loaded with
a /FILE retrieve operation, or, if already on the workspace,
are started by pressing the Alt key and the letter name of
the macro. Macros are named using the /RANGE name create
operation, and must begin with a backward slash
(symbolizing the Alt key ), followed by a zero or an
alphabetic character.
┌─────────────────────────────────────┐
│ Legal Names of Macros │
├──────────────────┬──────────────────┤
│ Automatic Macros │ Alt Macros │
├──────────────────┼──────────────────┤
│ \0 │ \A to \Z │
└──────────────────┴──────────────────┘
┌────────────────────────────┐
│ Where Are Macros Put? │
└────────────────────────────┘
Macros can be put anywhere on the 1-2-3 workspace,
provided they do not interfere with area occupied by
spreadsheet or database models. Because the 1-2-3 workspace
is so large (2048 rows by 256 columns), there is a large
area for macro programs. If memory constraints are a
problem, macros can be used to load other macros, to erase
portions of the workspace, or to load other models.
┌────────────────────────────┐
│ Storing Macro Keystrokes │
└────────────────────────────┘
Storing macro keystrokes is a simple task. The command
sequences ( or keystrokes ) are first entered in the 1-2-3
workspace in label form ( e.g. preceded by a label prefix).
They are then assigned a macro range name following the
rules described above. Macros used with other models can be
stored in a file and retrieved later.
┌────────────────────────────┐
│ Sample Macro Keystrokes │
└────────────────────────────┘
Macro keystrokes can consist of any 1-2-3 command and
function available with normal keystrokes, as well as
special programming commands. This wide variety of
keystrokes provides for a versatile programming language.
Many of the 1-2-3 macro keystrokes can be used to accomplish
the same tasks as Microsoft BASIC commands and functions,
while other are unique to 1-2-3.
┌────────────────────────────┐ ┌────────────────────────────┐
│ BASIC Commands & Functions │ │ Equivalent 1-2-3 Macro │
│ │ │ Keystrokes │
└────────────────────────────┘ └────────────────────────────┘
┌─────────────────────────┐
│ Program Control │
└─────────────────────────┘
IF-THEN-ELSE /XIFORMULA~
GOTO /XGLOCATION~
GOSUB /XCLOCATION~
RETURN /XR
INPUT {?}~
" /XNMESSAGE~LOCATION~
" /XLMESSAGE~LOCATION~
" /XNLOCATION~
ON N GOTO /XI(N)~/XGLOCATION~
ON N GOSUB /XI(N)~/XCLOCATION~
END /XQ~
SYSTEM /QY~
RUN {ALT}MACRO NAME (A-Z)
┌─────────────────────────┐
│ File Control │
└─────────────────────────┘
LOAD /FR
CHAIN /FC~
SAVE /FS
KILL /FE~
FILES /FL~
┌─────────────────────────┐
│ Output Control │
└─────────────────────────┘
TAB {RIGHT}
PRINT LABEL~
" NUMBER~
LPRINT LABEL~/PP~RANGE~GQ
" NUMBER~/PP~RANGE~GQ
LOCATE {GOTO}
CLS {HOME}/REA1.H20~
USING /RFFORMAT~
" /WCCOLUMN WIDTH~
BEEP {NAME}~
┌─────────────────────────┐
│ Program Editing │
└─────────────────────────┘
TRON, TROFF {ALT}{HELP}
EDIT {GOTO}LOCATION~{EDIT}
DELETE /REMACRO RANGE~
LIST {GOTO}MACRO LOCATION~
LLIST /PP~MACRO RANGE~GQ
NEW /WEY~
┌─────────────────────────┐
│ Program Documentation │
└─────────────────────────┘
REM LABEL~ (NEXT COLUMN)
┌─────────────────────────┐
│ Variables │
└─────────────────────────┘
LET /RNCVARIABLE~LOCATION~
┌─────────────────────────┐
│ Text/numeric Conversion │
└─────────────────────────┘
VAL {EDIT}{HOME}{DEL}~
STR$ {EDIT}{HOME}'~
Some BASIC commands and functions can only be
implemented in 1-2-3 with tricky macro keystroke sequences:
┌────────────────────────────────────────────────────────────┐
│ FOR-NEXT LOOP │
├──────────────────────────┬─────────────────────────────────┤
│ FOR-NEXT COLUMN │ Total no. of loops: 5 │
│ (FOR I = 1 TO 5) │ Current loop no.: 1 │
├──────────────────────────┴─────────────────────────────────┤
│ │
│ 1 - Start macro with cursor here │
│ 2 │
│ 3 │
│ 4 │
│ 5 │
│ │
│ /WGRM Recalculate manually │
│ /RNCNUMBER~LOCATION1~ Total no. of loops │
│ /RNCCOUNTER~LOCATION2~ Current loop number │
│ /RNCCOLUMN~ FOR-NEXT column │
│ {BS}.{END}{DOWN}~ " " │
│ {GOTO}NUMBER~ Calculate total loops │
│ @COUNT(COLUMN){CALC}~ " " │
│ {DOWN}+(COUNTER)+1~ Calculate current loop │
│ {GOTO}COLUMN Start FOR-NEXT loop │
│ {EDIT}{CALC}{DOWN}{CALC} Assign RANGE NAME "loop" │
│ {PGDN}{PGDN}THIS WORKS!~ Steps between loops │
│ {PGUP}{PGUP} " " │
│ /XI(COUNTER)<=(NUMBER)~/XGLOOP~ Loop or End MAcro │
│ /WGRA Recalculate automatically │
│ {GOTO}COLUMN~/XQ~ Return to column, quit │
└────────────────────────────────────────────────────────────┘
1-2-3 also has commands and functions not easily
implemented in BASIC.
┌────────────────────────────┐
│ Sample Macros │
└────────────────────────────┘
The following simple macros demonstrate the flexibility
and power of 1-2-3 keystrokes. These macros can be combined
with other customized macros to form a library of
subroutines.
┌─────────────────────────────────────────────────────┐
1. │ Convert formula to number │
└─────────────────────────────────────────────────────┘
{EDIT}{CALC}
┌─────────────────────────────────────────────────────┐
2. │ Insert one row or column │
└─────────────────────────────────────────────────────┘
ROW COLUMN
--- ------
/WIR~ /WIC~
┌─────────────────────────────────────────────────────┐
3. │ Center labels in row or column │
└─────────────────────────────────────────────────────┘
ROW COLUMN
--- ------
/RLC.{END}{RIGHT}~ /RLC.{END}{DOWN}~
┌─────────────────────────────────────────────────────┐
4. │ Display worksheet formulas │
└─────────────────────────────────────────────────────┘
/WGFT~/WGC30~
┌─────────────────────────────────────────────────────┐
5. │ Enter months as column headings across row │
└─────────────────────────────────────────────────────┘
^JAN{RIGHT}^FEB{RIGHT}^MAR{RIGHT}^APR{RIGHT}
^MAY{RIGHT}^JUN{RIGHT}^JUL{RIGHT}^AUG{RIGHT}
^SEP{RIGHT}^OCT{RIGHT}^NOV{RIGHT}^DEC{RIGHT}
{END}{LEFT}
┌─────────────────────────────────────────────────────┐
6. │ Save, print or graph worksheet │
└─────────────────────────────────────────────────────┘
/XMLOCATION~ SAVE PRINT GRAPH
FILE:CHART1 ENTIRE W/S BAR GRAPH
/FSCHART1~R~ /PPCA /GRG
RA1.H100~ TB
OML10~ XC13.C22~
MR140~ AF13.F22~
QGQ OSYFC0~Q
TFSALES~
QVQ
┌─────────────────────────────────────────────────────┐
7. │ Calculate year-to-date values │
└─────────────────────────────────────────────────────┘
CURRENT YTD
ENTER CURRENT PERIOD AMOUNT, THEN 100 468
GOTO YTD CELL - INVOKE MACRO 345 590
{EDIT}+{DOWN}{LEFT}{UP}~ - ASSIGN \Y HERE
{EDIT}{CALC}~{DOWN}
/RNCYTD~{LEFT}~
/XI(@COUNT(YTD)=1)~/RNDYTD~/XG\Y~
/RNDYTD~
┌─────────────────────────────────────────────────────┐
8. │ Enter numbers using numeric keypad │
└─────────────────────────────────────────────────────┘
/XMLOCATION~ DOWN RIGHT
SELECT SELECT INPUT DIRECTION
{?}~ {?}~ - ASSIGN \D, \R
{DOWN} {RIGHT}
/XG\D~ /XG\R~
┌─────────────────────────────────────────────────────┐
9. │ If current cell=0, branch to other macro, else quit │
└─────────────────────────────────────────────────────┘
/RNCHERE~~
/XIHERE=0~/RNDHERE~/XG\A~
/RNDHERE~/XQ~
OTHER MACRO - ASSIGN \A HERE
┌─────────────────────────────────────────────────────┐
10. │ Display various named and save graphs in succession │
└─────────────────────────────────────────────────────┘
/GNU{?}~ - ASSIGN \G HERE
Q/XG\G~
┌──────────────────────────────────┐
│ File Name: ██ 1-2-3.txt ██ │
└──────────────────────────────────┘
ADA1.TXT
Copyright 1984 by ABComputing
╔═════════════════════════════════════════════════════════════════════════════╗
║ Ada - New Language in Town ║
║ ║
║ by ║
║ ║
║ George Gordon Noel ║
╚═════════════════════════════════════════════════════════════════════════════╝
┌──────────────────────┐
│ Introduction │
└──────────────────────┘
I am a free lance writer, and have used Ada on a
full-time basis for over one year. I am also a member of
ADATEC, the professional society devoted to Ada.
As Ada has the full support of the U.S. government, it
is destined to become one of the most important programming
languages of the last part of this century. It is my purpose
to introduce you to this important language.
If you have questions about Ada (or comments on this
column), send them to PCFL and I will do my best to answer
them. Your feedback is needed.
This first column addresses the history and nature of
Ada. A full Ada tutorial begins in the next issue of PCFL.
Ada is a new language, and good tutorial literature is
difficult to find. Those seriously studying Ada should
subscribe to ADA LETTERS, the authoritative Ada journal.
They should also consider joining ADATEC. Send inquiries
regarding the ADA LETTERS or membership in ADATEC to the
Association for Computing Machinery, 11 West 42nd St., New
York, NY 10036.
Ada was created by the United States Department of
Defense ( DoD ) as a solution to a very costly problem. In
typical bureaucratic fashion, different branches of the
Pentagon used different computer languages to program
embedded systems ( computers that live inside and control
larger machines such as cruise missiles or space probes ).
Government analysts realized that adopting one language as a
common "tongue" could save the taxpayers a sizable amount of
money. A committee (of course) was formed to draft a list of
specifications for this common language.
Existing languages such as Pascal and PL/1 were
considered, but found inadequate. The Pentagon contracted a
large multinational corporation, CII Honeywell Bull, to
design a new language to their stringent specifications. The
result was Ada.
The name Ada is not an acronym like FORTRAN or BASIC.
Ada was a nineteenth century British noblewoman - Augusta
Ada, Countess of Lovelace. She assisted the pioneering
inventor Charles Babbage in the development of his
mechanical computer called the analytical engine.
┌──────────────────────┐
│ Design Goals of Ada │
└──────────────────────┘
The primary design goals of Ada were to provide a
structured language, a portable language, and a modular
language.
┌──────────────────────┐
│ Structured Language │
└──────────────────────┘
A structured language encourages well thought out,
highly formalized programs. The syntax of Ada is very rigid,
which restricts a programmer's freedom. This eliminates the
sort of sloppy, bug-filled programming that comes naturally
in non-structured languages such as BASIC or FORTRAN.
(EDITOR'S NOTE: them is fighting words! )
The formality of Ada's syntax is to be expected as Ada
has borrowed from another highly structured language:
Pascal. In future columns, we will consider features of Ada
that go far beyond anything in Pascal.
┌──────────────────────┐
│ Portability │
└──────────────────────┘
The second design goal was portability. As Ada is a
trademark of the DoD, any language calling itself Ada must
meet DoD standards. These standards are detailed in the "Ada
Language Reference Manual" - unfortunately, one of the worst
written documents in the English language. ( If you are
serious about Ada, though, you should own a copy. Order it
from ADATEC at the address given above.) There can be no
deviations from the standard - no subsets, supersets,
dialects, or variants. When a compiler meets the standard,
it is submitted to the DoD for "validation."
Ada programs written on one computer can be moved to
another machine without translation. This type of
standardization was one of the original advantages of
Pascal, although the weaknesses in that language have
spawned a number of dialects that are incompatible with each
other.
┌──────────────────────┐
│ Modularity │
└──────────────────────┘
The last major design goal of Ada is modularity - the
ability to break a large program into smaller, more easily
managed parts (top-down programming) or to assemble small,
pre-compiled modules into one large program (bottom-up
programming). Other languages have this ability. In FORTRAN,
independently compiled subroutines can be linked to form one
large module. But, modularity in Ada far exceeds anything I
have seen in other languages.
This is because Ada has a dual nature - it is part
compiler and part data base manager. When a program is
compiled, Ada places it in a data base called a "program
library" where it waits patiently until it is needed. Since
this is the part of Ada that excites me the most, we will
use it as a springboard for our first example.
┌──────────────────────┐
│ Example Program │
└──────────────────────┘
When an Ada compiler is purchased, a program library
containing several packages is included. One package is the
module TEXT_IO, which contains the tools for doing input and
output with text characters. ( I/O routines are not an
intrinsic part of Ada as they are in most languages.) If I/O
routines are needed, the TEXT_IO module must be retrieved
from the program library. This is done using an Ada command
called a "with clause," consisting of the word "with"
followed by the name of the module to be retrieved from the
program library.
Our first Ada program has a "with clause" as a heading.
It is an example of a "procedure," an Ada program unit
similar to the subroutines of PL/1, FORTRAN, and a host of
other languages.
with TEXT_IO;
procedure MESSAGE is
use TEXT_IO;
begin
put ("How are things going so far?");
end MESSAGE;
Ignoring the "with clause" and some syntactical
curiosities (such as the "use clause" in line three), this
could be Pascal or any number of modern languages. As we
have not begun our tutorial, do not be concerned with the
pieces of the language you don't understand.
When the program is compiled and run, it prints the
message:
How are things going so far?
The input/output of this program is done by the "put"
procedure in line five, which prints a string. Before the
"put" procedure can be used, it must be retrieved from the
TEXT_IO module in the program library. This is accomplished
by the "with clause." When the Ada compiler encounters "with
TEXT_IO" it acts like a data base manager, searching the
program library until TEXT_IO is found. Upon locating the
module, the compiler makes all the resources inside the
module (including the "put" procedure) available to the
MESSAGE program.
All compiled programs are placed in the program
library. The MESSAGE example program is there now, and can
be retrieved using the "with clause," just as we did for
TEXT_IO.
with TEXT_IO, MESSAGE;
procedure ADA_SENDS_HER_GREETINGS is
use TEXT_IO;
begin
put ("The Countess asks `");
MESSAGE;
put ("'");
end ADA_SENDS_HER_GREETINGS;
Compiling and running this program results in the
display:
The Countess asks `How are things going so far?'
I hope the answer is "Fine". This question from Lady
Lovelace brings us to the end of the first column.
┌──────────────────────┐
│ Conclusion │
└──────────────────────┘
Those hungry for more are invited to dine on the source
code in the "Ada Programs" section of this column. One
program is a sort program, and the other finds the greatest
common divisor of two integers. The latter routine is
intended as a demonstration of Ada's "package" facility.
The nitty-gritty details needed to understand Ada will
begin pouring in, in the next issue of PCFL.
┌──────────────────────────────────┐
│ File Name: ██ ada1.txt ██ │
└──────────────────────────────────┘
ASM1.TXT
Copyright 1984 by ABComputing
╔═════════════════════════════════════════════════════════════════════════════╗
║ Introduction to Assembly Language ║
║ ║
║ by ║
║ ║
║ Bill Salkin ║
╚═════════════════════════════════════════════════════════════════════════════╝
┌──────────────────────────────────┐
│ Introduction │
└──────────────────────────────────┘
Still looking for the needle in the haystack? Or has it
pricked you more than once? These are the sentiments of
beginning and experienced assembly language programmers.
This column is for beginners and you will get the
POINT! We remove the veil of secrecy from the clandestine
brotherhood of assembly language programmers, and reveal how
easy it is to use assembly language ( Gasp! ).
Our approach is to write programs implementing a
particular function ( such as clearing the screen ), and
examine them. Initially, no explanation of the technical
aspects of the program is given. After successfully creating
and running several such programs, you will have gained
considerable confidence in your assembly language ability.
The time is then ripe to "circle back" and explain the
omitted technical foundation.
Be patient, run all examples, and you will soon find
yourself bored with the monotony of the language - but
impressed with the power it affords you.
┌──────────────────────────────────┐
│ Assumptions │
└──────────────────────────────────┘
All source code, unless stated otherwise, should run
under any release of DOS.
You should be familiar with 1) the binary and
hexadecimal numbering systems; 2) the terms bits, bytes, and
"K."
┌──────────────────────────────────┐
│ Notation │
└──────────────────────────────────┘
The letter "H" is used to indicate a hexadecimal
number. Hence 24H = 36 decimal and 0BH = 11 decimal.
Binary numbers are terminated with the letter "B".
00000011B = 3 decimal and 00001111B = 15 decimal.
Unless we affix an "H" to a number, the number is
interpreted as a decimal number. 21 is regarded as 21
decimal, and 21H = 33 decimal.
┌──────────────────────────────────┐
│ Recommended Reading │
└──────────────────────────────────┘
You should purchase the following books:
1) INTRODUCTION to ASM-86, by Intel Corporation,
2) 8088 ASSEMBLER LANGUAGE PROGRAMMING the IBM PC,
by David Willen and Jeffrey Krantz. Howard
Sams Co.
I own both books and will testify to their high
tutorial content.
Intel's book is not written for the IBM PC explicitly
but the information applies to the PC. This book is a
beautiful expression of information difficult to find
elsewhere.
Dan Rollin's book "IBM PC: 8088 MACRO Assembler
Programming" should be available soon from Macmillan, and I
hope to add it to the above list. Dan is a good writer, and
very experienced in assembly language.
Scanlon's book will be of use when you can run simple
assembly language programs without difficulty.
┌──────────────────────────────────┐
│ ASM. vs. MASM │
└──────────────────────────────────┘
The assembler package as purchased from IBM is called
the MACRO ASSEMBLER. Actually, the MACRO ASSEMBLER diskette
contains both the assembler ( ASM.EXE ) and a macro
assembler (MASM.EXE ). These are distinct processors, with
MASM being a superset of ASM.
References to "the assembler" in this column apply to
both ASM and MASM unless specifically noted.
Using ASM, errors detected in source code are displayed
and an error code given. For the same program, MASM
additionally displays an explanation of the error.
(Sometimes these explanations are less clear than no
explanation. My favorite is #71 : "This message not
currently used." If the space is available, PCFL may want to
rent it.)
A macro is similar to a subroutine. MASM supports macro
processing, and occupies 67K bytes.
ASM does not support macro processing, and occupies 52K
bytes.
ASM can process small programs in a PC with 64K of RAM,
but I suggest a minimum of 128K RAM for use with either
assembler.
Neither assembler currently supports 8087 code. (Rumor:
this situation will change soon.)
When either assembler prompts for the filespec, if only
the filename is keyed, a file extension of ".asm" is
assumed. Accordingly, all assembly language source files in
this column use ".asm" as the file extension to minimize
typing.
┌──────────────────────────────────┐
│ Program Structure │
└──────────────────────────────────┘
In general, an assembly program contains a data
segment, stack segment, and a code segment.
A segment is a 64K contiguous area used for a specific
purpose. The data segment holds data ( constants and
variables), and the STACK segment is used as a
communications ground for subroutines. The CODE segment
contains the "guts" or what we loosely refer to as "the
program."
Declarations for the DATA, STACK, and CODE segments are
shown below.
┌──────────────────────┐
│ DATA SEGMENT │
└──────────────────────┘
DATA SEGMENT PARA
DATA ENDS
┌──────────────────────┐
│ STACK SEGMENT │
└──────────────────────┘
STACK SEGMENT PARA STACK 'STACK'
STACK ENDS
┌──────────────────────┐
│ CODE SEGMENT │
└──────────────────────┘
CODE SEGMENT PARA
CODE ENDS
A segment is indicated to the assembler by the statement
XXXXXX SEGMENT PARA
where XXXXXX is the name of the segment. In a later column
we delve into the meaning of PARA, and how the LINKER uses
the segment name.
A segment is closed or completed, by using
XXXXXX ENDS
where "XXXXXX" is the name used in the declaration of the
SEGMENT ( ENDS = END of Segment ).
┌──────────────────────────────────┐
│ Registers │
└──────────────────────────────────┘
The brain of the IBM PC is the 8088 chip. It contains
several registers, of which we mention only four.
AX register BX register CX register DX register
┌───────────┐ ┌───────────┐ ┌───────────┐ ┌───────────┐
│ AH │ AL │ │ BH │ BL │ │ CH │ CL │ │ DH │ DL │
└───────────┘ └───────────┘ └───────────┘ └───────────┘
Each register can hold a 16 bit ( 2 byte ) number. The
largest integer that can be contained in AX,BX,CX, or DX is
65535.
Each register is divided into an 8-bit "high" and 8-bit
"low" part. As shown above, AH represents the high order 8
bits of the AX register, and AL represents the low 8 bits.
The largest integer an 8-bit register can hold is 255.
The PC has every kind of register we could want -
except a cash register.
Certain instructions assume that their input can be
found in a given register. For example, the "loop"
instruction assumes the CX ( "count" ) register contains the
number of iterations; and 2) string related operations
assume the SI and DI registers act as "source" and
"destination" pointers.
Registers are also important because they are the
fastest area on the chip that the programmer can access.
To store or place the number 8 in the AH register use
the assembly instruction:
MOV AH,8
The MOV instruction moves the source operand (8) into
the destination operand (AH).
In assembly instructions, the source operand is always
the right operand,and the destination operand is the left
operand.
The following is an illegal MOV instruction:
MOV CL,3000 ;move 3000 decimal into the CL register
as an 8-bit register ( CL is an 8-bit register ) can not
hold an integer larger than 255.
┌──────────────────────────────────┐
│ Comment (;) │
└──────────────────────────────────┘
A semicolon (;) is used to indicate the beginning of a
comment. Any information from the semicolon to the end of
the line is disregarded by the assembler. ( Maybe if those
darn assemblers would stop ignoring comments and read them,
our code would work the way we want it to, not the way we
program it! Of course, considering the quality of source
code documentation, it may be best to ignore the comments.)
Comments can be placed in any column, and used to
explain individual source code statements or entire
sections.
┌──────────────────────────────────┐
│ Batch File │
└──────────────────────────────────┘
We are almost prepared to run our first assembly
language program. But first... the batch file, please.
Assembling source code for errors, linking, and running
the resultant module is a repetitive process. The batch file
0.bat (contained on this diskette) is simple to use but
adequate for our purposes:
ASM %1;
LINK %1;
%1
It will assemble, link and run the program with
filespec %1.
ASM in 0.bat refers to ASM.EXE, and LINK refers to
LINK.EXE ( the "linker" ). Both modules must be available to
use 0.bat.
To assemble,link, and run the program in file
BIGDEAL.ASM, type
A>0 BIGDEAL
and press the ENTER key. (Recall the assembler defaults to a
file extension of ".asm", so the name BIGDEAL used above is
regarded as a reference to BIGDEAL.ASM.)
Assuming that BIGDEAL.ASM has no errors, the output of
the batch file is:
A>ASM BIGDEAL;
The IBM Personal Computer Assembler
Version 1.00 (C)Copyright IBM Corp 1981
Warning Severe
Errors Errors
0 0
A>LINK BIGDEAL;
IBM Personal Computer Linker
Version 2.00 (C)Copyright IBM Corp 1981, 1982, 1983
A>BIGDEAL
A>
( NOTE: The linker is version 2.00, as I use DOS 2.0 ).
The source code for program BIGDEAL is contained in the
file BIGDEAL.ASM on this diskette.
Format a new diskette and copy these files to it:
ASM.EXE, LINK.EXE, BIGDEAL.ASM, 0.BAT. (Label this diskette
"Assembler Work Diskette.") Then apply 0.bat to BIGDEAL.ASM
and verify the above output. If the output is not as shown,
then YOU SCREWED UP! Continue trying until your output
agrees with that shown above.
┌──────────────────────────────────┐
│ Sample Program │
└──────────────────────────────────┘
When BIGDEAL.ASM was assembled,linked, and run, nothing
apparent occurred.
Try this: type BIGDEAL on the command line and press
the ENTER key. The screen looks as follows:
A>BIGDEAL
A>
Still no apparent reaction.
Actually, BIGDEAL.ASM contains the linkage conventions
needed to return to DOS. (We have gotten "in" and "out" of
the program successfully.)
This simple program is the foundation on which we build
future programs. Study its general structure carefully.
Routine BIGDEAL.ASM follows.
;COPYRIGHT 1984 BY ABComputing
;
; ┌───────────────────────────────────────────────────────────────────┐
; │ │
; │ THIS ROUTINE RETURNS TO THE CALLER WHEN INVOKED. │
; │ │
; └───────────────────────────────────────────────────────────────────┘
;
;------------------------------------------------------------------------
DATA SEGMENT PARA
DATA ENDS
;------------------------------------------------------------------------
;The above segment is called a data segment. We
;initialize and save variables or constants in this
;segment. Think of a segment as a section of memory
;capable of containing 64K of information.
;
;The above DATA segment does not actually contain any
;data. It is empty.
;
;( NOTE: This small discussion, is a series of comment
;statements as each line is preceded by a semicolon.)
;
;Further note that assembly language code is free format.
;There are no defined positions where instructions or
;directives must be placed. Develop a style of coding
;that appeals to you, and use it consistently.
;------------------------------------------------------------------------
STACK SEGMENT PARA STACK 'STACK'
DB 40H DUP('STCK')
STACK ENDS
;------------------------------------------------------------------------
;This is the stack segment. The stack is a common
;communication area for subroutines. Variables are
;"pushed" (saved) onto the stack by one routine to be
;"popped" ( retrieved ) and used by another.
;
;This stack segment is NOT empty.
;
;DB means "define byte." The information following DB is
;regarded as being consecutive bytes in memory.
;
;DUP means "duplicate." The stack contains 40H copies of
;the four bytes 'STCK'.
;
;In summary, as 40H = 64 decimal, the stack segment
;contains 64 copies of the four bytes 'STCK' and occupies
;256 bytes.
;
;If we could look into memory at the STACK segment we
;would see
;
; ... ... ... ... ...
;
; STCKSTCKSTCKSTCKSTCKSTCKSTCKSTCK
; STCKSTCKSTCKSTCKSTCKSTCKSTCKSTCK
; STCKSTCKSTCKSTCKSTCKSTCKSTCKSTCK
; STCKSTCKSTCKSTCKSTCKSTCKSTCKSTCK
; STCKSTCKSTCKSTCKSTCKSTCKSTCKSTCK
; STCKSTCKSTCKSTCKSTCKSTCKSTCKSTCK
; STCKSTCKSTCKSTCKSTCKSTCKSTCKSTCK
; STCKSTCKSTCKSTCKSTCKSTCKSTCKSTCK
; ... ... ... ... ...
;
;Later we show how to view memory using the program
;DEBUG. We won't have difficulty recognizing the STACK
;segment, will we?
;------------------------------------------------------------------------
CODE SEGMENT PARA
;This is the code segment where the "guts" of our program
;goes.
ASSUME CS:CODE, DS:DATA, SS:STACK
;The ASSUME statement in the code segment tells the
;assembler to make certain assumptions about the contents
;of certain registers ( Hint: CS = "code segment" and its
;value indicates the start of the code segment; DS points
;to the data segment, and SS points to the STACK segment.
;The assembler is told to assume that these settings are
;in effect.)
;
;It is the programmer's responsibility to adjust the
;contents of these registers ( CS,DS,SS ) to agree with
;the information supplied by the ASSUME statement.
;--STANDARD LINKAGE TO DOS
BIGDEAL PROC FAR ;DO
PUSH DS ;
SUB AX,AX ;
PUSH AX ; NOT
MOV AX,DATA ;
MOV DS,AX ; ALTER!
;We do not explain the standard linkage convention at this
;time, but will later.
;-- RETURN TO DOS
RET ;RETurn to DOS
;The RET statement normally RETurns to the program that
;called this program. Through a series of events we return
;to DOS.
BIGDEAL ENDP ;END of Procedure
CODE ENDS ;END of code Segment
;------------------------------------------------------------------------
END BIGDEAL ;END of routine BIGDEAL
┌──────────────────────────────────┐
│ Conclusion │
└──────────────────────────────────┘
It takes considerable effort to create the simplest
assembly language routines. This column has discussed the
most difficult aspect of assembly language for the novice -
writing your first routine. Future programs are essentially
exercises in filling in the data and code segments in the
above "shell." Assembly language IS that easy ( almost
anti-climactic). And they said you couldn't do it!
My next assembly column shows how to clear the display,
print a string on the display, and delete a file. These
operations invite a discussion of BIOS and DOS calls.
The source code for these functions can be viewed by
pressing the Esc key, followed by the F2 key. Run each
program, and write me if you have any difficulties.
P.S. It may be interesting to study the size of an ".EXE"
module ( use BIGDEAL.EXE ). Very small, and indicative of
the small space used by assembly language modules.
┌──────────────────────────────────┐
│ File Name: ██ asm1.txt ██ │
└──────────────────────────────────┘
BIGDEAL.ASM
;COPYRIGHT 1984 BY ABComputing
;
; ┌──────────────────────────────────┐
; │ File Name: ██ bigdeal.asm ██ │
; └──────────────────────────────────┘
;
; ┌───────────────────────────────────────────────────────────────────┐
; │ │
; │ THIS ROUTINE RETURNS TO THE CALLER WHEN INVOKED. │
; │ │
; └───────────────────────────────────────────────────────────────────┘
;
;------------------------------------------------------------------------
DATA SEGMENT PARA
DATA ENDS
;------------------------------------------------------------------------
;------------------------------------------------------------------------
STACK SEGMENT PARA STACK 'STACK'
DB 40H DUP('STCK')
STACK ENDS
;------------------------------------------------------------------------
;------------------------------------------------------------------------
CODE SEGMENT PARA
ASSUME CS:CODE, DS:DATA, SS:STACK
;--STANDARD LINKAGE TO DOS
BIGDEAL PROC FAR ;DO
PUSH DS ;
SUB AX,AX ;
PUSH AX ; NOT
MOV AX,DATA ;
MOV DS,AX ; ALTER!
;-- RETURN TO DOS
RET ;RETurn to DOS
BIGDEAL ENDP ;END of Procedure
CODE ENDS ;END of Segment
;------------------------------------------------------------------------
END BIGDEAL ;END of routine BIGDEAL
C1.TXT
Copyright (c) 1984 by Daniel L. Roady. All rights reserved.
╔═════════════════════════════════════════════════════════════════════════════╗
║ THE "STANDARD I/O LIBRARY" ║
║ ║
║ by ║
║ ║
║ Daniel L. Roady ║
╚═════════════════════════════════════════════════════════════════════════════╝
┌──────────────────────────────────┐
│ Introduction │
└──────────────────────────────────┘
This is the first in a series of articles describing a
"UNIX" compatible implementation of the "Standard I/O
Library." The library contains the members listed in the
following table and several standard macros for character
handling.
┌─────────────────────┬────────────────────┐
│ getchar │ putchar │
├─────────────────────┼────────────────────┤
│ printf │ scanf │
├─────────────────────┼────────────────────┤
│ fopen │ fclose │
├─────────────────────┼────────────────────┤
│ getc │ putc │
├─────────────────────┼────────────────────┤
│ ungetc │ calloc │
├─────────────────────┼────────────────────┤
│ cfree │ strlen │
├─────────────────────┼────────────────────┤
│ strcpy │ strcat │
├─────────────────────┼────────────────────┤
│ strcmp │ │
└─────────────────────┴────────────────────┘
This article discusses the printf function. The source
code for this function can be viewed by pressing the Esc
key, followed by the F2 key.
┌──────────────────────────────────┐
│ Printf Overview │
└──────────────────────────────────┘
Printf provides automatic formatting and type
conversions for output to the standard output channel
("stdout").
The printf calling sequence is:
printf(control-string, arg1, arg2 ....);
The parameter "control-string" is actually a character
pointer to a quoted string containing the text to be output.
"Control-string" may additionally contain formatting and
type conversion specifications.
The arguments ( arg1, arg2, etc ) correspond with the
conversion specifications in "control-string."
A fuller discussion of the printf function can be found
in "The C Programming Language" by Kernighan and Ritchie.
┌──────────────────────────────────┐
│ Printf Source Code package │
└──────────────────────────────────┘
The printf package consists of three externally
accessible routines: printf, fprintf, and sprintf. Each
routine performs the same formatting and conversion function
but the output destinations are different. Printf outputs to
stdout; fprintf outputs to a specified file; and sprintf
outputs to a memory buffer.
A typical call to each routine is shown below.
┌──────────────────────────────────────────────────────┐
│ #include <stdio.h> │
│ │
│ FILE *fopen(),*fp; │
│ char buffer[133]; │
│ │
│ main() │
│ { │
│ printf("It's a small world.\n"); │
│ │
│ fp = fopen("outfile.txt","w"); │
│ fprintf(fp,"It's a small world.\n"); │
│ fclose(fp); │
│ │
│ sprintf(buffer,"It's a small world.\n"); │
│ } │
└──────────────────────────────────────────────────────┘
The printf package is written as three entry points to
handle the details of the output selection. Each entry point
performs some specific setup on a few global variables and
calls the routine "outf."
"Outf" scans the control-string, searching for a "%"
character. If the character read is not a "%", it is passed
to the output routine "putchar." If the character is a "%",
the succeeding characters are examined and global variables
are initialized to indicate left or right justification, the
pad character, field width, precision, long or short, or the
conversion type. Once the conversion type is determined, the
appropriate parameter is passed to the routine that performs
the particular conversion.
The conversion routines create ASCII strings from their
input parameters. The strings are output, temporarily, to an
internal buffer. The routine "obstore" performs this
function. When conversion is complete, the routine "bfrout"
inserts any necessary padding for left or right
justification and outputs the entire converted field via
"putchar."
"Outf" continues to scan the control-string until the
entire control-string has been searched.
┌──────────────────────────────────┐
│ File Name: ██ c1.txt ██ │
└──────────────────────────────────┘
CPYRIGHT.TXT
╔═════════════════════════════════════════════════════════════════════════════╗
║ ║
║ ║
║ Copyright 1984 by ABComputing. ALL RIGHTS RESERVED ║
║ ║
║ ║
╚═════════════════════════════════════════════════════════════════════════════╝
PC Firing Line/PC Underground, or portions thereof, are
not to be sold or used in a product for sale without the
written consent of ABComputing. The only exception is that
small excerpts may be used for critical review.
Copies may be made for non-profit use.
If clarification is required contact ABComputing, at
P.O. Box 5503, North Hollywood, CA 91616-5503. Or phone
(818) 509-9002.
Associations that aid the handicapped are encouraged
to contact us if our material, in any form, can be of
value.
┌──────────────────────────────────┐
│ DisKclaimer │
└──────────────────────────────────┘
We cannot guarantee the accuracy of, or assume
responsibility for, information on a diskette. All source
code and text is used at your own risk.
┌──────────────────────────────────┐
│ File Name: ██ cpyright.txt ██ │
└──────────────────────────────────┘
DOS1.TXT
Copyright 1984 by ABComputing
╔═════════════════════════════════════════════════════════════════════════════╗
║ PC DOS and Firmware ║
║ ║
║ by ║
║ ║
║ Don Buresh ║
╚═════════════════════════════════════════════════════════════════════════════╝
┌──────────────────────────────────┐
│ Introduction │
└──────────────────────────────────┘
This column treats the IBM PC Disk Operating System (PC
DOS ) and firmware. I will discuss the technical features
(and undocumented bugs) in PC DOS using the PC DOS manual as
our functional specification.
I would like to thank Bill Salkin, the editor of PCFL,
for permitting me to write this column ( EDITOR'S NOTE:
Actually, I couldn't stop him.)
With each article appearing in PCFL I will attempt to
provide coding examples that illustrate the topic. These
examples are the functional equivalents of the PC DOS
commands. They will be distributed to PC user groups and
electronic bulletin boards across the country on a
FREEWARE(tm) basis. Ten years in data processing has
convinced me that there are relatively few good coding
examples in the public domain. I intend to provide
structured assembly language code for the benefit of all.
The schedule given below is tentative but indicates the
direction of this column.
┌──────────────────────────────────┐
│ Second Article │
└──────────────────────────────────┘
My next article is concerned with three topics. The
first topic is a summary of the birth and growth of PC DOS.
The second is a review of the commands of PC DOS and how
they have grown in function since their introduction two
years ago. Third, we investigate IBMBIO.COM (or its MS-DOS
equivalent IO.SYS) and COMMAND.COM, describing their
intimate relationship to IBMDOS.COM (Did you know that IBM
wrote IBMBIO.COM and COMMAND.COM and that Microsoft, Inc.,
is only responsible for DOS?)
┌──────────────────────────────────┐
│ Third Article │
└──────────────────────────────────┘
In the third article, we examine the PC DOS interrupts
listed in Appendix A of the DOS manual. The Program Segment
Prefix and the File Control Blocks (FCB) created by PC DOS
when executing a .COM or .EXE file are discussed. In
particular, we learn how assembly language programs can gain
access to the command line. Third, we consider how PC DOS
creates and maintains the disk directory file and the File
Allocation Table (FAT) of a disk.
┌──────────────────────────────────┐
│ Fourth Article │
└──────────────────────────────────┘
The fourth article concentrates on the PC DOS utility
DISKCOPY. This utility has the ability to access all the
available memory of your IBM Personal Computer. This is
extremely important because the micro code of the Intel 8088
processor chip divides memory into 64K segments ( areas ).
An assembly language program demonstrating how to access all
memory in your system (subject to the constraint that you do
not write over Video RAM ) will be presented. The assembly
language program FREECOPY, provided on a FREEWARE(tm) basis,
will further illustrate the concept.
┌──────────────────────────────────┐
│ Fifth Article │
└──────────────────────────────────┘
The fifth article is centered around the FORMAT
utility. I would like to develop a program that formats
either a diskette or a hard disk, but may settle on
formatting a diskette only. In the process we will analyze
the implications of writing the bit pattern 0F6H to a
diskette.(Did you know that this bit pattern does not stress
a diskette so that a defective formatted diskette will slip
through FORMAT.COM? What is the best bit pattern???? TRS-80
users know that 6DB6H is the most stressful bit pattern that
can be written on a diskette.) I intend to write the program
FREEFRMT, serving the same functions as FORMAT, but also
writing a 6DB6H bit pattern on a diskette. FREEFRMT will be
offered on a FREEWARE(tm) basis.
After the fifth article it may be an appropriate time
to discuss DISKCOMP and MODE. The interesting feature of
DISKCOMP is that the NEC 765 (or the Intel 8272 for owners
of the older versions of the IBM PC) floppy disk controller
chip can be programmed to SCAN the contents of memory
against the bit patterns on a diskette indicating any
differences. This program is straightforward and a real
gem.
The program FREEMODE demonstrates how to parse a
complicated command line and redirect the parallel printer
interrupt (INT 17H) to a serial line (INT 14H). The
implications to the operating system, in particular, Ctrl
PrtSc or INT 05H of the ROM, are discussed.
┌──────────────────────────────────┐
│ Change of Direction │
└──────────────────────────────────┘
We could continue to rewrite the various functions of
PC DOS, but it would be more useful to re-investigate
IBMDOS.COM, IBMBIO.COM, and COMMAND.COM and provide a
thorough analysis of the relationships among these programs.
They form a chain directly to the firmware.
Before discussing the firmware in the ROM, the subject
of device drivers and how they can be used with PC DOS 2.0
and 2.1 is explored. I am going to write a sample device
driver and invite you to submit assembly language device
drivers for public examination. Please place your source in
the public domain so that we can all learn from it.
┌──────────────────────────────────┐
│ Sixth Article │
└──────────────────────────────────┘
We are finally prepared to discuss the firmware. My
favorite ROM interrupt is the video interrupt or INT 10H ( I
have done considerable work with the display driver ).
Topics to be discussed are 1) why the IBM PC INT 10H is so
slow; 2) how to scroll up, down, and sideways; 3)how to
create graphic characters; etc.
┌──────────────────────────────────┐
│ Seventh Article │
└──────────────────────────────────┘
In this article we interrupt drive the RS-232-C ports
so a program can collect data over the serial port while a
concurrent process is executing in another part of the
program. In the process, we redirect INTerrupts 09H and 0CH
so characters can be sent and received concurrently.
Modified versions of these two interrupts, and INT 14H, are
provided.
┌──────────────────────────────────┐
│ Eighth Article │
└──────────────────────────────────┘
This article concentrates on the disk driver interrupt,
otherwise known as INT 13H. The three (3) chips that must be
programmed for INT 13H are the Intel 8237 Dynamic Memory
Access (DMA) chip, the Intel 8259 hardware interrupt chip
and the NEC 765 (or Intel 8272). INT 13H is one of the most
powerful and little understood software interrupts. We
demonstrate how companies use this interrupt to copy protect
their programs. The information given in this article is
published in the Intel Data Catalog which is sold over the
counter. Companies use the information contained in this
book to create proprietary copy-protection schemes.
Actually, software companies are merely specifying the
parameters to these three chips. As an example, I will show
how to format a diskette with odd sector sizes, such as 189
bytes per sector.
┌──────────────────────────────────┐
│ Ninth & Tenth articles │
└──────────────────────────────────┘
The next two articles consider the remaining interrupts
in the PC firmware and show how to use them effectively in
programs. Use of INTerrupts 1BH through 1FH are
demonstrated. (Interrupt 1B is used for "Ctrl Break"
processing; 1C points to code executed with every tick of
the clock; 1D is used for video initialization; 1E is used
to adjust the disk parameter table; and 1F offers
programmers the opportunity to create unique graphic
characters.)
┌──────────────────────────────────┐
│ Eleventh Article │
└──────────────────────────────────┘
With these tasks behind us, we return to PC DOS and
explain the file-handling interrupts. The reason for this
change in direction is that by this time I hope to release
(in the public domain) an assembly language terminal program
with the XMODEM file-transfer protocol. I also want the
program to contain a terminal routine with an ANSI parser as
well as an interrupt-driven conversational routine. This
program demonstrates how to use the PC DOS and ROM
interrupts in a significant manner.
┌──────────────────────────────────┐
│ Conclusion │
└──────────────────────────────────┘
In closing, I invite all of my readers to suggest other
topics to cover in this column.
You are further encouraged to send me assembly language
coding examples to discuss, and then be placed in the public
domain. Please do not send proprietary code which you have
written as an employee of a company. I will neither release
nor discuss proprietary code!
I hope your interest has been whetted by this
introductory article. Good programming!!!!
*XENIX(tm) is a trademark of Microsoft, Inc.
**FREEWARE(tm) is a trademark of Headlands Press, Inc.
┌──────────────────────────────────┐
│ File Name: ██ dos1.txt ██ │
└──────────────────────────────────┘
DOS2.TXT
Copyright 1984 by ABComputing
╔═════════════════════════════════════════════════════════════════════════════╗
║ A Bug in the DOS 2.0 Program Loader ║
║ ║
║ by ║
║ ║
║ Richard Levaro ║
╚═════════════════════════════════════════════════════════════════════════════╝
┌──────────────────────────────────┐
│ Introduction │
└──────────────────────────────────┘
One of the most powerful features of DOS 2.0 is the
ability to access the program loader via a DOS function call
(4B). Using the DOS loader is relatively easy from Assembly
Language, but is more difficult from high level languages
like Pascal and C. Some of the newer versions of C contain
function calls which make it easy to implement DOS function
calls, and there are utility packages for Pascal and C on
the market which can do this as well. Moreover, the
"infamous" SHELL command from BASIC uses the DOS loader
too.
┌──────────────────────────────────┐
│ Unmasking the Demon │
└──────────────────────────────────┘
Unfortunately, the 2.0 version of the loader has a bug.
Specifically, DOS assumes that the current value of the DS
register points to the Program Segment Prefix. This
assumption is correct for COM files, and for some EXE files,
but is never true for Pascal or C EXE files. Because DOS
uses the reserved area in the Program Segment Prefix for a
scratch area, the net result is that part of the program
data segment is overwritten. In a C program, this problem
can be avoided by reserving low memory in the data segment
(alter the initiator program whose source is provided in
most C compilers), but it is not possible in Pascal because
low memory is used by the heap.
┌──────────────────────────────────┐
│ Conclusion │
└──────────────────────────────────┘
DOS 2.0 can be patched so that DOS saves the data
segment and sets the DS register to point to the correct
area. To effect this correction, use the batch file
patch2.bat (on this diskette ) to patch COMMAND.COM. With
the patched version of COMMAND.COM, the BASICA SHELL command
will perform correctly. This bug has been fixed in DOS 2.1.
┌──────────────────────────────────┐
│ File Name: ██ dos2.txt ██ │
└──────────────────────────────────┘
DOS3.TXT
Copyright 1984 by Dan Rollins
╔═════════════════════════════════════════════════════════════════════════════╗
║ The Interrupt Phone Book ║
║ ║
║ by ║
║ ║
║ Dan Rollins ║
╚═════════════════════════════════════════════════════════════════════════════╝
EDITOR'S NOTE: Due to diskette space limitations this
article has been abridged. The remainder will appear in the
next issue of PCFL.
┌───────────────────────────────┬─────────────────────────────────────────────┐
│ Interrupt │ │
├──────┬─────────┬──────────────┤ NAME/Description │
│ Type │ Address │ Subfunctions │ │
├──────┴─────────┴──────────────┼─────────────────────────────────────────────┤
│ │ │
│ 0 0-3 none │ DIVIDE_BY_0/Automatically taken upon div- │
│ │ ision overflow │
│ │ │
│ 1 4-7 none │ SINGLE_STEP/taken after every instruction │
│ │ when CPU Trap Flag indicates single-step │
│ │ mode (bit 8 of FLAGS is 1) │
│ │ │
│ 2 8-B none │ NON_MASKABLE/vector not disabled via CLI │
│ │ │
│ 3 C-F none │ BREAKPOINT/taken when CPU executes the │
│ │ 1-byte INT 3 (0CCH) │
│ │ │
│ 4 10-13 none │ OVERFLOW/taken when OF=1 and INTO opcode │
│ │ is executed │
│ │ │
│ 5 14-17 none │ PRINT_SCREEN/service dumps the screen to │
│ │ the printer Invoked by KBD_INT for shifted │
│ │ key 55 (PrtSc) │
│ │ │
│ 6 18-1B none │ reserved │
│ │ │
│ 7 1C-1F none │ reserved │
│ │ │
│ 8 20-23 none │ TIMER_INT/55ms timer "tick" taken 18.2 │
│ │ times per second. Updates BIOS clock and │
│ │ turns off diskette drive motors after 2 │
│ │ seconds of inactivity. │
│ │ │
│ 9 24-27 none │ KBD_INT/taken whenever a key is pressed or │
│ │ released. Stores characters/scan-codes in │
│ │ buffer at [0040:001E]. Updates shift-key │
│ │ status at [0040:0017,18] │
│ │ │
│ A 28-2B none │ reserved │
│ │ │
│ B 2C-2F none │ reserved │
│ │ │
│ C 30-33 none │ reserved │
│ │ │
│ D 34-37 none │ reserved │
│ │ │
│ E 38-3B none │ DISKETTE_INT/indicates that a seek is in │
│ │ progress (sets bit-8 of 40:003E) │
│ │ │
│ F 3C-3F none │ reserved │
│ │ │
└───────────────────────────────┴─────────────────────────────────────────────┘
┌────────┬─────────┬──────────────────────────────────────────────────────────┐
│ Type │ Address │ │
├────────┼─────────┤ VIDEO_IO/services handle video output │
│ 10 │ 40-43 │ │
└────────┴─────────┴──────────────────────────────────────────────────────────┘
┌────┬────────────────────────────────────────────────────────────────────────┐
│ AH │ NAME/Description │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 0 │ SET_MODE/initializes for one of 7 text or graphics modes │
│ │ AL = 0: 40x25 BW │
│ │ AL = 1: 40x25 color │
│ │ AL = 2: 80x25 BW │
│ │ AL = 3: 80x25 color graphics │
│ │ AL = 4: 320x200 color graphics │
│ │ AL = 5: 320x200 BW graphics │
│ │ AL = 6: 640x200 BW graphics │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 1 │ SET_CUR_TYPE/set the size of the cursor or turn it off │
│ │ CH=start line (bit 5=no cursor), CL=end line │
│ │ CL=end line │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 2 │ SET_CUR_POS/re-position the cursor │
│ │ DH=row (0-24) │
│ │ DL=column (0-79 or 0-39) │
│ │ BH=video page │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 3 │ READ_CUR_POS/return the position of the cursor │
│ │ BH=video page │
│ │ returns: DH=row, DL=clm, CX=cursor size │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 4 │ READ_LIGHT_PEN/fetch light pen information │
│ │ returns: AH=0 light pen not triggered │
│ │ AH=1: DH,DL=character row,column │
│ │ CH,CL=graphics row,column │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 5 │ SELECT_ACTIVE_PAGE/set page number for services 6 and 7 │
│ │ AL = new page (0-7 for modes 0 & 1, 0-3 for modes 2 & 3) │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 6 │ SCROLL_PAGE_UP/scroll up or clear a display "window" │
│ │ AL=number of lines to scroll (0=blank entire window) │
│ │ CH,CL=row,column of top left corner of window │
│ │ DH,DL=row,column of lowest right corner of window │
│ │ BH=video attribute for blanked lines │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 7 │ SCROLL_PAGE_DOWN/scroll down or clear a display "window" │
│ │ (see sub-function 6 for parameters) │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 8 │ READ_CHAR_ATTR/fetch a character from the cursor position │
│ │ BH=page number │
│ │ returns: AL=character, AH=attribute │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 9 │ WRITE_CHAR_ATTR/display character(s) & attribute at cursor │
│ │ AL=character to display │
│ │ BH=display page, │
│ │ BL=attribute (graphics modes: BL=color (or 80H for XOR) │
│ │ CX=repeat count │
├────┼────────────────────────────────────────────────────────────────────────┤
│ A │ WRITE_CHAR/display character(s) only (use current attribute) │
│ │ (see sub-function 9 for parameters) │
├────┼────────────────────────────────────────────────────────────────────────┤
│ B │ SET_COLOR_PALETTE/set palette for graphics or text border │
│ │ BH=0: select border (text mode) │
│ │ BL=color (0-15, 16-31 for high-intensity chars. │
│ │ BH=1: select graphics palette │
│ │ BL=palette code (0=grn/red/yel, 1=cyan/mag/white) │
├────┼────────────────────────────────────────────────────────────────────────┤
│ C │ WRITE_DOT/plot one graphics pixel │
│ │ DX=row, │
│ │ CX=clm │
│ │ AL=color (bit 7 to XOR the dot) │
├────┼────────────────────────────────────────────────────────────────────────┤
│ D │ READ_DOT/determine the color of one graphics pixel │
│ │ DX=row, │
│ │ CX=clm, │
│ │ returns: AL=color of dot │
├────┼────────────────────────────────────────────────────────────────────────┤
│ E │ WRITE_TTY/write one character and update cursor. Also │
│ │ handles CR (0DH), beep (07H), and scrolls screen if │
│ │ needed. │
│ │ AL=char to write │
│ │ BL=foreground if in graphics mode │
├────┼────────────────────────────────────────────────────────────────────────┤
│ F │ VIDEO_STATE/fetch the mode and size of the screen │
│ │ returns: AL=mode (see sub-function 0), │
│ │ AH=size, │
│ │ BH=page │
└────┴────────────────────────────────────────────────────────────────────────┘
┌───────────────────────────────┬─────────────────────────────────────────────┐
│ Interrupt │ │
├──────┬─────────┬──────────────┤ NAME/Description │
│ Type │ Address │ Subfunctions │ │
├──────┴─────────┴──────────────┼─────────────────────────────────────────────┤
│ 11 44-47 none │ EQUIPMENT_CHECK/fetch a code describing │
│ │ active peripherals. │
│ │ returns: AX=equipment code bits: │
│ │ │
│ │ PP-JSSS-DDVVRR-I │
│ │ │
│ │ PP = number of printers │
│ │ J = joystick │
│ │ SSS = serial devices (RS-232 ports) │
│ │ DD = number of disk drives (00=1, 01=2, │
│ │ 10=3, 11=4) │
│ │ VV = video (11=BW card, 01 & 10 = color │
│ │ card) │
│ │ RR = RAM in mother-board ( 00=16K... │
│ │ 11=64K), │
│ │ I = disk-existance (0=no drives in │
│ │ system) │
│ │ │
│ 12 48-4B none │ MEMORY_SIZE/fetch AX=count of contiguous │
│ │ 1K RAM blocks │
└───────────────────────────────┴─────────────────────────────────────────────┘
┌────────┬─────────┬──────────────────────────────────────────────────────────┐
│ Type │ Address │ │
├────────┼─────────┤ DISKETTE_IO/access the 5-1/4 inch diskette drives │
│ 13 │ 4C-4F │ │
└────────┴─────────┴──────────────────────────────────────────────────────────┘
┌────┬────────────────────────────────────────────────────────────────────────┐
│ AH │ NAME/Description │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 0 │ RESET/reset the disk controller chip │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 1 │ GET_STATUS/fetch AL=status of most recent operation │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 2 │ READ_SECTORS/read one or more sectors from diskette │
│ │ DH = head DL = drive (0=A, 1=B, etc.) │
│ │ CH = track CL = sector (1-8 or 1-9 for DOS 2.0) │
│ │ AL = sectors to read │
│ │ ES:BX = address to store/fetch data │
│ │ [0000:0078] = doubleword pointer to diskette parms │
│ │ returns: Carry Flag = NC (0) for successful │
│ │ Carry Flag = CY (1) failure │
│ │ AH = disk status (error reason) │
│ │ 80H = timeout: disk failed to respond │
│ │ 40H = seek operation failure │
│ │ 20H = NEC disk drive controller failed │
│ │ 10H = bad Cyclical Redundancy Check (CRC) │
│ │ 09H = attempted access across 64K boundary │
│ │ 08H = DMA overrun │
│ │ 04H = record not found │
│ │ 03H = write protect error │
│ │ 02H = sector ID error (can't find address mark) │
│ │ 01H = unknown command │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 3 │ WRITE_SECTORS/write from memory to disk │
│ │ (parameters as with sub-function 2) │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 4 │ VERIFY/verify that a write operation was successful │
│ │ (parameters as with sub-function 2, but ES:BX not needed) │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 5 │ FORMAT_TRACK/write sector-ID bytes for 1 track │
│ │ ES:BX points to 8 (or 9) 4-byte sector ID marks: │
│ │ byte 0 = track number │
│ │ byte 1 = head number │
│ │ byte 2 = sector number │
│ │ byte 3 = bytes in sector (0=128, 1=256, 2=512, 3=1024) │
└────┴────────────────────────────────────────────────────────────────────────┘
┌────────┬─────────┬──────────────────────────────────────────────────────────┐
│ Type │ Address │ RS232_IO/initialize and access serial communications │
├────────┼─────────┤ port. │
│ 14 │ 50-53 │ │
└────────┴─────────┴──────────────────────────────────────────────────────────┘
┌────┬────────────────────────────────────────────────────────────────────────┐
│ AH │ NAME/Description │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 0 │ RS232_IO/initialize and access serial communications port │
│ │ INIT_COM/initialize port named by DX (0 or 1) │
│ │ initialization bit pattern: BBBPPSLL │
│ │ BBB = baud rate: 110,150,300,600,1200,2400,4800,9600 │
│ │ PP = parity: 01 = odd, 11 = even │
│ │ S = stop bits: 0 = 1, 1 = 2 │
│ │ LL = word length: 10 = 7-bits, 11 = 8-bits │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 1 │ SEND_CHAR/send character to comm port DX (0 or 1) │
│ │ AL = character │
│ │ returns: bit 7 of AH = 1 if error │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 2 │ AWAIT_COMM_CHAR/wait for a character from comm port DX │
│ │ returns: AL = character │
│ │ AH = error code (0 for no error) │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 3 │ COMM_STATUS/fetch the status of comm port DX (0 or 1) │
│ │ returns: comm-line status in AH, modem status in AL │
│ │ AH bit 7 = timeout │
│ │ bit 6 = empty transmit shift register │
│ │ bit 5 = empty transmit holding register │
│ │ bit 4 = break detected ("long-space") │
│ │ bit 3 = framing error │
│ │ bit 2 = parity error │
│ │ bit 1 = overrun error │
│ │ bit 0 = data ready │
│ │ AL bit 7 = received line signal detect │
│ │ bit 6 = ring indicator │
│ │ bit 5 = data set ready │
│ │ bit 4 = clear to send │
│ │ bit 3 = delta receive line signal detect │
│ │ bit 2 = trailing edge ring detector │
│ │ bit 1 = delta data set ready │
│ │ bit 0 = delta clear to send │
└────┴────────────────────────────────────────────────────────────────────────┘
┌────────┬─────────┬──────────────────────────────────────────────────────────┐
│ Type │ Address │ CASSETTE_IO/access cassette tape drive │
├────────┼─────────┤ (NOP for IBM-XT) │
│ 15 │ 54-57 │ │
└────────┴─────────┴──────────────────────────────────────────────────────────┘
┌────┬────────────────────────────────────────────────────────────────────────┐
│ AH │ NAME/Description │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 0 │ CASS_ON/start the motor │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 1 │ CASS_OFF/turn the motor off │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 2 │ CASS_READ/read CX bytes into ES:BX buffer │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 3 │ CASS_WRITE/write CX bytes from ES:BX buffer to tape │
└────┴────────────────────────────────────────────────────────────────────────┘
┌────────┬─────────┬──────────────────────────────────────────────────────────┐
│ Type │ Address │ │
├────────┼─────────┤ KBD_IO/access the keyboard buffer │
│ 16 │ 58-5B │ │
└────────┴─────────┴──────────────────────────────────────────────────────────┘
┌────┬────────────────────────────────────────────────────────────────────────┐
│ AH │ NAME/Description │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 0 │ AWAIT_CHAR/read the next character in keyboard buffer, │
│ │ If no key ready, wait for one. │
│ │ returns: AL = ASCII character, AH = scan-code │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 1 │ PREVIEW_KEY/see if key is ready │
│ │ returns: ZF = ZR (1) if no key ready, else │
│ │ ZF = NZ and AX=char/scan-code │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 2 │ SHIFT_STATUS/fetch bit flags indicating shift status │
│ │ returns: AL = bit codes (same as [0040:0017]) │
│ │ bit 7 = Insert state │
│ │ bit 6 = CapsLock state │
│ │ bit 5 = NumLock state │
│ │ bit 4 = ScrollLock state │
│ │ bit 3 = Alternate shift (Alt key) │
│ │ bit 2 = Control shift (Ctrl key) │
│ │ bit 1 = Left shift (left caps-shift key) │
│ │ bit 0 = Right shift (right caps-shift key) │
│ │ note: other codes found at [0040:0018] │
│ │ bit 7 = Insert shift (Ins key) │
│ │ bit 6 = Caps shift (CapsLock key) │
│ │ bit 5 = Num shift (NumLock key) │
│ │ bit 4 = Scroll shift (ScrollLock key) │
│ │ bit 3 = Hold state (Ctrl-NumLock is in effect) │
└────┴────────────────────────────────────────────────────────────────────────┘
┌────────┬─────────┬──────────────────────────────────────────────────────────┐
│ Type │ Address │ │
├────────┼─────────┤ PRINTER_IO/access the parallel printer(s) │
│ 17 │ 5C-5F │ │
└────────┴─────────┴──────────────────────────────────────────────────────────┘
┌────┬────────────────────────────────────────────────────────────────────────┐
│ AH │ NAME/Description │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 0 │ PRINT_CHAR/send AL to printer DX (0, 1, or 2) │
│ │ returns: AH=1 for timeout error, AL=status (see below) │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 1 │ INIT_PRINTER/set init line low, send 0CH to printer DX │
│ │ returns: status as below │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 2 │ PRINTER_STATUS/read status of printer DX into AH │
│ │ returns: bit flags: │
│ │ bit 7 = Printer is busy │
│ │ bit 6 = Acknowledge line state │
│ │ bit 5 = Out-of-paper line state │
│ │ bit 4 = printer selected line state │
│ │ bit 3 = I/O error │
│ │ bit 2 = unused │
│ │ bit 1 = unused │
│ │ bit 0 = Time-out error │
└────┴────────────────────────────────────────────────────────────────────────┘
┌───────────────────────────────┬─────────────────────────────────────────────┐
│ Interrupt │ │
├──────┬─────────┬──────────────┤ NAME/Description │
│ Type │ Address │ Subfunctions │ │
├──────┴─────────┴──────────────┼─────────────────────────────────────────────┤
│ │ │
│ 18 60-63 none │ ROM_BASIC/execute non-disk BASIC at │
│ │ F600:0000 │
│ │ │
│ 19 64-67 none │ BOOT_STRAP/read track 0, sector 1 into │
│ │ 0000:7C00, then transfer control to that │
│ │ address. If no diskette drive available, │
│ │ transfers to ROM-BASIC. │
└───────────────────────────────┴─────────────────────────────────────────────┘
┌────────┬─────────┬──────────────────────────────────────────────────────────┐
│ Type │ Address │ │
├────────┼─────────┤ TIME_OF_DAY/access the PC internal clock │
│ 1A │ 68-6B │ │
└────────┴─────────┴──────────────────────────────────────────────────────────┘
┌────┬────────────────────────────────────────────────────────────────────────┐
│ AH │ NAME/Description │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 0 │ READ_CLOCK/fetch count of 55ms "ticks" since power-on │
│ │ returns: CX = high word of count │
│ │ DX = low word of count │
│ │ AL = 0 when no 24-hour overflow since power-on │
├────┼────────────────────────────────────────────────────────────────────────┤
│ 1 │ SET_CLOCK/set number of 55ms in clock variable │
│ │ CX = high word of timer ticks │
│ │ DX = low word of timer ticks │
│ │ note: the clock ticks are incremented by TIMER_INT │
│ │ at about 18.2 times per second. Therefore: │
│ │ counts per second = 18 (12H) │
│ │ counts per minute = 1092 (444H) │
│ │ counts per hour = 65543 (10011H) │
│ │ counts per day = 1573040 (1800B0H) │
└────┴────────────────────────────────────────────────────────────────────────┘
┌───────────────────────────────┬─────────────────────────────────────────────┐
│ Interrupt │ │
├──────┬─────────┬──────────────┤ NAME/Description │
│ Type │ Address │ Subfunctions │ │
├──────┴─────────┴──────────────┼─────────────────────────────────────────────┤
│ 1B 6C-6F none │ KEYBOARD_BREAK/routine taken when KBD_INT │
│ │ senses Ctrl-Break. │
│ 1C 70-73 none │ │
│ │ USER_TIMER_INT/taken 18.2 times per │
│ │ second; invoked by the TIMER_INT; │
│ │ normally vectors to dummy IRET. │
└───────────────────────────────┴─────────────────────────────────────────────┘
┌────────┬─────────┬──────────────────────────────────────────────────────────┐
│ Type │ Address │ VIDEO_PARMS_PTR/vector of video initialization │
├────────┼─────────┤ parameters. │
│ 1D │ 74-77 │ │
└────────┴─────────┴──────────────────────────────────────────────────────────┘
┌─────────────────────────────────────────────────────────────────────────────┐
│ NAME/Description │
├─────────────────────────────────────────────────────────────────────────────┤
│ VIDEO_PARMS_PTR/vector of video initialization parameters │
│ │
│ This doubleword address points to 3 sets of 16-bytes │
│ containing data to initialize for video modes for video │
│ modes 0&1 (40 clm), 2&3 (80 clm), and 4,5&6 (graphics). │
│ Parm table format corresponds to the Motorola 6845 CRT │
│ controller registers: │
│ R0 : horiz. total (horiz. sync in characters) │
│ R1 : horiz. displayed (chars per line) │
│ R2 : horiz. sync position (move display left or right) │
│ R3 : sync width (vert. and horiz. pulse: 4-bits each) │
│ R4 : vertical total (total character lines) │
│ R5 : vertical adjust (adjust for 50 or 60 Hz refresh) │
│ R6 : vert. displayed (lines of chars displayed) │
│ R7 : Vert. sync position (lines shifted up or down) │
│ R8 : Interlace (bits 4 and 5) and skew (bits 6 and 7) │
│ R9 : Max scan line addr (scan lines per char row) │
│ R10: Cursor start (starting scan line of cursor) │
│ R11: Cursor stop (ending scan line of cursor) │
│ R12: vid-mem start address high byte (6-bits) │
│ R13: vid-mem start address low byte (8-bits) │
│ R14: cursor address high byte (6-bits) │
│ R15: cursor address low byte (8-bits) │
└─────────────────────────────────────────────────────────────────────────────┘
┌────────┬─────────┬──────────────────────────────────────────────────────────┐
│ Type │ Address │ │
├────────┼─────────┤ DISKETTE_PARMS_PTR/vector of diskette controller parms │
│ 1E │ 78-7B │ │
└────────┴─────────┴──────────────────────────────────────────────────────────┘
┌─────────────────────────────────────────────────────────────────────────────┐
│ NAME/Description │
├─────────────────────────────────────────────────────────────────────────────┤
│ DISKETTE_PARMS_PTR/vector of diskette controller parms: │
│ │
│ This doubleword address points to data that is used │
│ by DISKETTE_IO. 11-byte table format: │
│ byte 0 : 4-bit step rate, 4-bit head unload time │
│ byte 1 : 7-bit head load time, 1-bit DMA flag │
│ byte 2 : 55ms counts--delay till motor off │
│ byte 3 : sector size (0=128, 1=256, 2=512, 3=1024) │
│ byte 4 : last sector on track │
│ byte 5 : gap between sectors │
│ byte 6 : data length for DMA transfers │
│ byte 7 : gap length for format │
│ byte 8 : fill byte for format │
│ byte 9 : head settle time (in milliseconds) │
│ byte 10: motor start time (in 1/8 second intervals) │
└─────────────────────────────────────────────────────────────────────────────┘
┌────────┬─────────┬──────────────────────────────────────────────────────────┐
│ Type │ Address │ │
├────────┼─────────┤ DISKETTE_PARMS_PTR/vector of diskette controller parms │
│ 1F │ 7C-7F │ │
└────────┴─────────┴──────────────────────────────────────────────────────────┘
┌─────────────────────────────────────────────────────────────────────────────┐
│ NAME/Description │
├─────────────────────────────────────────────────────────────────────────────┤
│ GRAPHICS_TBL_PTR/vector of data used by VIDEO_IO to │
│ display characters above ASCII 127 in graphics modes. │
│ Doubleword address points to 1K table composed of 128 │
│ 8-byte character definition bit-patterns. First byte │
│ of each entry is top row, last byte is bottom row. │
└─────────────────────────────────────────────────────────────────────────────┘
┌──────────────────────────────────┐
│ File Name: ██ dos3.txt ██ │
└──────────────────────────────────┘
FILES159.TXT
Disk No: 159
Program Title: PC FIRING LINE
PC-SIG version: 1.1
This is the first issue of the PC FIRING LINE NEWSLETTER. It has beena
positioned as the underground newspaper for the IBM user. You will be
presented with the untold tales and in-depth programming aids. Some of
the articles are about ADA, Assembly routines, and items not written
about by IBM. It also contains many sample program listings with
accompanying documentation.
Usage: Reference.
Special Requirements: None.
How to Start: Type GO (press enter).
Suggested Registration: $12.00
File Descriptions:
0 BAT Batch file.
PATCH2 BAT Batch file.
8087 REV Information file.
ADA1CMP REV Information file.
BIGDEAL ASM Assembly source code.
GRABBAG ASM Assembly source code.
COLORFUL EXE Sub-program.
DEBUG PAT Patch for DEBUG.
GRABBAG EXE Sub-program.
LIST1 ADA Test the ADS compiler in ADA.
LIST1 ASM Test the ADS compiler in Assembley.
LIST1 C Test the ADS compiler in C.
LIST1 PAS Test the ADS compiler in Pascal.
PCFL EXE Main Program.
PRETTY1 COM Program embellisher
TXT ADS Advertisments
WRITERS GDE Text file.
???????? TXT Text file (20 files).
PC-SIG
1030D East Duane Avenue
Sunnyvale Ca. 94086
(408) 730-9291
(c) Copyright 1985,86,87,88,89 PC-SIG, Inc.
FORT1.TXT
Copyright 1984 by ABComputing
╔═════════════════════════════════════════════════════════════════════════════╗
║ Common Tangents to Two Ellipses ║
║ ║
║ by ║
║ ║
║ Bill Salkin ║
╚═════════════════════════════════════════════════════════════════════════════╝
┌──────────────────────────────────┐
│ Introduction │
└──────────────────────────────────┘
Visualize two ellipses as displayed on a graphics
screen. There are many lines tangent to both ellipses. To
specify which tangent line is desired, each ellipse is
selected with a light pen.
The point where the light pen "touches" an ellipse
indicates the side to which the tangent line will be drawn.
When both ellipses have been light pen selected, a unique
tangent line can be determined, and finally drawn on the
graphics screen.
This article outlines a method for finding common
tangents to two ellipses.
┌──────────────────────────────────┐
│ Terminology │
└──────────────────────────────────┘
ELLIPSE1 ELLIPSE2
.*°*. .*°*.
* * * *
* * P = (E,F) * *
* P1 ─ * ──────────────── *─ P2 *
* │ * * │ *
* * * *
°*.*° °*.*°
Q1(X1,Y1) ─────── Q2(X2,Y2) ───────
Q1' Q2'
Figure ( it-out ) #1
Description of nomenclature used in Figure 1:
┌──────────────────┬───────────────────┐
│ ELLIPSE1 │ ELLIPSE2 │
┌───────────────────────────────┼──────────────────┼───────────────────┤
│ center │ P1(XC1,YC1) │ P2(XC2,YC2) │
│ radius vector from center │ │ │
│ intersects ellipse at: │ Q1(X1,Y1) │ Q2(X2,Y2) │
│ tangent vector at QI │ Q1' │ Q2' │
├───────────────────────────────┴──────────────────┴───────────────────┤
│ The vector P = (E,F) joins the centers of the ellipses. │
└──────────────────────────────────────────────────────────────────────┘
All data associated with ELLIPSEI ( I = 1,2 ) has the
number "I" appended.
┌──────────────────────────────────┐
│ The Method │
└──────────────────────────────────┘
Consider a line tangent to ELLIPSE1 and ELLIPSE2 at
points Q1 and Q2, respectively. This line must be parallel
to the tangent vectors at Q1 and Q2. As the vector cross
product of parallel vectors is 0, this condition can be
formulated mathematically as:
( Q2 - Q1 ) X Q1' = 0 and ( Q2 - Q1 ) X Q2' = 0 (1)
Q1 is a point on ELLIPSE1. Q1' is the derivative of the
parametric equation of ELLIPSE1, evaluated at point Q1.
( Q2 - Q1) is a vector joining the perimeters of the
ellipses. It acts as an approximation to the tangent line.
If the above equations are satisfied, ( Q2 - Q1 ) is tangent
to both ellipses.
Two simultaneous non-linear equations are represented
by (1). The method used to solve these equations is the
"3-dimensional" Newton method. This method is discussed
next.
┌──────────────────────────────────┐
│ 3-d Newton Method │
└──────────────────────────────────┘
This is an iterative method for solving the equations
f(x,y) = 0, and g(x,y) = 0
An initial point ( x(0), y(0) ) is selected and
successive points (hopefully converging to an answer) are
found from the sequences:
x(n) = x(n-1) + h(n-1)
y(n) = y(n-1) + k(n-1)
where h and k satisfy
f ( x(n-1), y(n-1)) h(n-1)
x
+ f ( x(n-1), y(n-1)) k(n-1) = - f( x(n-1), y(n-1))
y
and
g ( x(n-1), y(n-1)) h(n-1)
x
+ g ( x(n-1), y(n-1)) k(n-1) = - g( x(n-1), y(n-1))
y
f denotes the partial derivative of f with respect to x.
x
These equations are derived by replacing the
multivariable Taylor series by its linear part.
┌──────────────────────────────────┐
│ Transformation 1 │
└──────────────────────────────────┘
The equations in (1) must be transformed into a form
that is suitable for Newton's method.
From vector algebra, Q1 and Q2 can be represented as:
Q1 = P1 +iX1 + jY1, Q2 = P2 + iX2 + jY2
where "i" and "j" are the orthogonal unit vectors forming
the standard basis for the complex plane. P1 and P2 are the
centers of the ellipses.
Substituting these expressions in (1), and using P =
(E,F) = Ei + Fj gives
[ ( E + X2 - X1 )i + ( F + Y2 - Y1)j ] X [ IX1' + jY1'] = 0
[ ( E + X2 - X1 )i + ( F + Y2 - Y1)j ] X [ IX2' + jY2'] = 0
Simplifying these equations gives
[ ( E + X2 - X1 ) Y1' - ( F + Y2 - Y1) X1' ] = 0
(2)
[ ( E + X2 - X1 ) Y2' - ( F + Y2 - Y1) X2' ] = 0
┌──────────────────────────────────┐
│ Transformation 2 │
└──────────────────────────────────┘
The parametric equation of an ellipse, with origin
(XC,YC), semimajor axis "a", semiminor axis "b", and rotated
@ radians ( with respect to the positive x-axis ) is:
X = XC + ( a cos@ ) cost - ( b sin@ ) sint
(3)
Y = YC + ( b cos@ ) sint + ( a sin@ ) cost
where 0 <= t <= Two Pi radians
┌──────────────────────────────────┐
│ The Grand Finale │
└──────────────────────────────────┘
Substitution of the equations (3) into (2) result in
two equations in two unknowns. This is the form needed by
Newton's method.
The equations resulting from this substitution are not
given in this article! The reader is encouraged to perform
the algebra and determine them.
I have applied Newton's method to these equations and
can report that the method has never failed in my experience
( undoubtedly owing to the infinite differentiability of the
ellipse parametric equations ).
┌──────────────────────────────────┐
│ Conclusion │
└──────────────────────────────────┘
It is difficult to present mathematical symbols and
diagrams on the IBM PC.
The tangent-line geometry in this article can be
"massaged" to address other geometrical problems such as
finding the projection of a point to an ellipse, or the
intersection of two splines.
┌──────────────────────────────────┐
│ File Name: ██ fort1.txt ██ │
└──────────────────────────────────┘
GO.TXT
╔═════════════════════════════════════════════════════════════════════════╗
║ <<<< Disk No: 159 PC Firing Line >>>> ║
╠═════════════════════════════════════════════════════════════════════════╣
║ ║
║ To start the disk, type: ║
║ ║
║ PCFL (press enter) ║
║ ║
╚═════════════════════════════════════════════════════════════════════════╝
GRABBAG.ASM
;COPYRIGHT 1984 BY ABComputing
;
; ┌───────────────────────────────────────────────────────────────────┐
; │ │
; │ "GRABBAG" CONTAINS AN UNANNOUNCED PROGRAM; IT CAN BE IN ANY │
; │ LANGUAGE, AND ON ANY SUBJECT. │
; │ │
; │ $25 AND LAURELS IF YOUR PROGRAM IS SELECTED! │
; │ │
; │ THIS GRABBAG WAS WRITTEN BY BILL SALKIN 1/5/83 │
; │ │
; │ THE EXECUTABLE VERSION OF THIS CODE IS IN GRABBAG.EXE ON THIS │
; │ DISKETTE. │
; │ │
; └───────────────────────────────────────────────────────────────────┘
;
; ┌───────────────────────────────────────────────────────────────────┐
; │ │
; │ THIS GRABBAG ALLOWS USERS OF A COLOR MONITOR TO CHANGE EITHER │
; │ THE FOREGROUND OR BACKGROUND COLOR OF THE DISPLAY BY PRESSING │
; │ THE F1 OR F2 FUNCTION KEYS, RESPECTIVELY. THE BORDER COLOR IS │
; │ SET TO EQUAL THE BACKGROUND COLOR. │
; │ │
; │ F10 IS PRESSED TO EXIT THIS PROGRAM AND RETURN TO DOS. │
; │ │
; │ THE FOREGROUND AND BACKGROUND COLORS ESTABLISHED IN THIS │
; │ ROUTINE ARE NOT RESET UPON EXIT TO DOS. THIS ALLOWS THE USER │
; │ TO DISCOVER PLEASANT COLOR COMBINATIONS AND USE THEM UNDER │
; │ DOS. │
; │ │
; │ THE ROUTINE COLORFUL.EXE, ON THIS DISKETTE, FEATURES ONE │
; │ ADDITIONAL OPTION: PRESSING F3 ALLOWS THE USER TO ADJUST THE │
; │ BORDER COLOR. ( THAT ROUTINE WAS AN AFTERTHOUGHT - DESIGNED │
; │ FOR THOSE NOT USING AN ASSEMBLER BUT WANTING FULL COLOR │
; │ CONTROL.) │
; │ │
; └───────────────────────────────────────────────────────────────────┘
;
; ┌───────────────────────────────────────────────────────────────────┐
; │ │
; │ THIS GRABBAG ACCESSES THE HARDWARE DIRECTLY! │
; │ │
; │ DESIGN DOCUMENTATION EXPLAINING THIS GRABBAG WILL APPEAR IN │
; │ THE NEXT ISSUE OF PCFL. │
; │ │
; └───────────────────────────────────────────────────────────────────┘
;
; ┌──────────────────────────────────┐
; │ File Name: ██ grabbag.txt ██ │
; └──────────────────────────────────┘
;
;------------------------------------------------------------------------------
F1 EQU 59 ;SCAN CODE FOR F1 KEY
F2 EQU 60 ;SCAN CODE FOR F2 KEY
F10 EQU 68 ;SCAN CODE FOR F10 KEY
NO EQU 0
YES EQU 1
;------------------------------------------------------------------------------
DATA SEGMENT PARA
ATTRIBUTE DB 7 ;COLOR ATTRIBUTE
BACKGROUND DB 0 ;BACKGROUND COLOR OF SCREEN
COLOR_CARD DB NO ;= "YES" IF COLOR ADAPTER FOUND; ELSE "NO"
CRT_MODE_SET DB 0 ;NEEDED TO TURN CRT BEAM ON
DISPLAY_ADDRESS DW 0B000H ;HOLDS ADDRESS OF DISPLAY RAM
EXIT DB NO ;EXIT = "YES" MEANS RETURN TO DOS
EXT_CODE DB NO ;= "YES" IF EXTENDED CODE KEY PRESSED
;= "NO" IF NON-EXTENDED CODE KEY PRESSED
FOREGROUND DB 0 ;FOREGROUND COLOR OF SCREEN
KEYIN DB 0 ;HOLDS SCAN CODE OF KEY PRESSED
;--THE PANEL "MSG" ID DISPLAYED ON THE SCREEN.
MSG DB 'Grabbag #1. Copyright 1984 by ABComputing'
DB 39 DUP(' ') ;LAZY MAN'S APPROACH TO MOVE
DB 80 DUP(' ') ; THE CURSOR.
DB ' Press F1 to modify the foreground color'
DB 36 DUP(' ') ;LAZY MAN'S APPROACH TO MOVE CURSOR
DB ' Press F2 to modify the background color'
DB 36 DUP(' ') ;LAZY MAN'S APPROACH TO MOVE CURSOR
DB ' Press F10 to exit this program','$'
;--MESSAGE DISPLAYED IF MONOCHROME CARD FOUND.
FARWELL DB 7 ;BEEP TO ALERT USER
DB 'This program needs the color adapter. Sorry!','$'
DATA ENDS
;------------------------------------------------------------------------------
;------------------------------------------------------------------------------
STACK SEGMENT PARA STACK 'STACK'
DB 40H DUP('STCK')
STACK ENDS
;------------------------------------------------------------------------------
;------------------------------------------------------------------------------
CODE SEGMENT PARA
ASSUME CS:CODE, DS:DATA, SS:STACK, ES:NOTHING
;--STANDARD LINKAGE TO DOS
MAIN PROC FAR ;STANDARD LINKAGE TO DOS
PUSH DS ; DO
MOV AX,0 ; NOT
PUSH AX ; ALTER!
MOV AX,DATA
MOV DS,AX
;--ROUTINE INIT CHECKS WHICH DISPLAY ADAPTER IS INSTALLED. IF
; MONOCHROME, THEN COLOR_CARD IS SET = NO. IF COLOR_CARD = YES, THEN
; DISPLAY_ADDRESS IS SET = 0B800H, AND THE SCREEN MODE IS SET FOR
; 80x25 ALPHANUMERIC COLOR MODE ( NOTE: SETTING THE SCREEN MODE AUTO-
; MATICALLY CLEARS THE SCREEN AND CAUSES THE CURSOR TO BE DISPLAYED.)
CALL INIT
CMP COLOR_CARD,YES ;IF COLOR_CARD = YES, THEN CONTINUE
JE MAI1 ; CONTINUE PROGRAM
CALL GOOD_BYE ;DISPLAY FARWELL MESSAGE
JMP MAI3 ; CLEAR SCREEN AND RETURN TO DOS
;--CLEAR THE SCREEN
MAI1: CALL CLEAR
;--ROUTINE CUR_OFF TURNS THE CURSOR DISPLAY OFF. IT IS CALLED AFTER
; ROUTINE INIT, AS SETTING THE MODE TURNS THE CURSOR DISPLAY ON.
CALL CUR_OFF
;--DISPLAY THE PANEL "MSG" ( Press F1 to modify the foreground
; color... )
CALL DISPLAY
;--GET_KEY RETURNS THE SCAN CODE OF THE PRESSED KEY IN KEYIN. ROUTINE
; KEYS CALLS THE SUBROUTINES THAT CHANGE THE FOREGROUND,BACKGROUND,
; AND BORDER COLORS.
MAI2: CALL GET_KEY
CALL KEYS ;HANDLE F1, F2, F10 KEY PRESSES
CALL CLEAR ;SET BACKGROUND OF SCREEN TO DESIRED
; COLOR
CALL DISPLAY ;DISPLAYS THE PANEL "MSG"
;--PRESSING F10 IN KEYS SETS EXIT = YES INDICATING THAT
; PROGRAM TERMINATION IS WANTED.
CMP EXIT,YES
JNE MAI2 ;IF EXIT = NO, THEN WAIT FOR NEXT KEY
;--RETURN TO DOS. PURPOSELY DO NOT RESET COLOR ATTRIBUTE. MAINTAIN
; COLORS USED FOR DOS.
CALL CUR_ON
CALL CLEAR ;CLEAR THE SCREEN
MAI3: RET
;------------------------------------------------------------------------------
;
; ┌───────────────────────────────────────────────────────────────────┐
; │ │
; │ FROM THIS PORTION ONWARD ALL ROUTINES ARE │
; │ LISTED ALPHABETICALLY BY NAME. │
; │ │
; └───────────────────────────────────────────────────────────────────┘
;
;------------------------------------------------------------------------------
;ROUTINE BACK_GROUND
;
; BRIEF:
; INCREMENTS `BACKGROUND' BY ONE. IF BACKGROUND IS NOT IN THE
; RANGE 0 <= BACKGROUND <= 7 , THEN BACKGROUND IS SET = 0.
;
; INPUT:
; VALUE OF BACKGROUND
;
; OUTPUT:
; ATTRIBUTE CORRESPONDING TO INCREMENTED VALUE OF BACKGROUND
;------------------------------------------------------------------------------
BACK_GROUND PROC NEAR
INC BACKGROUND
CMP BACKGROUND,7 ;7 IS MAX ALLOWED BACKGROUND COLOR
JBE BAC1
;--BACKGROUND IS > 7. RESET IT TO 0.
MOV BACKGROUND,0
BAC1: CALL SET_COLOR ;DETERMINES "ATTRIBUTE" VALUE FOR OLD
; FOREGROUND NEW BACKGROUND SETTINGS.
RET
BACK_GROUND ENDP
;------------------------------------------------------------------------------
;------------------------------------------------------------------------------
;ROUTINE CLEAR
;
; BRIEF:
; CLEARS THE SCREEN
;
; INPUT:
; ATTRIBUTE
;------------------------------------------------------------------------------
CLEAR PROC NEAR
MOV AH,6 ;REQUEST SCROLL SCREEN SERVICE
MOV AL,0 ;SCROLL ENTIRE SCREEN
MOV BH,ATTRIBUTE ;BACKGROUND ATTRIBUTE
MOV CX,0000H ;UPPER LEFT CORNER OF SCREEN (0,0 )
MOV DX,184FH ;LOWER RIGHT CORNER OF ( 24,79 )
INT 10H ;INVOKE SCROLL SCREEN SERVICE
RET
CLEAR ENDP
;------------------------------------------------------------------------------
;------------------------------------------------------------------------------
;ROUTINE CUR_OFF
;
; BRIEF:
; TURNS THE CURSOR DISPLAY OFF
;
;------------------------------------------------------------------------------
CUR_OFF PROC NEAR
PUSH AX
PUSH CX
;--SETTING BIT 5 TO 0 TURNS IN CH TURNS THE CURSOR OFF.
MOV CH,00100000B ;SET BIT 5 IN CURSOR START REGISTER TO 1
MOV AH,1 ;REQUEST "NON DISPLAY" SERVICE
INT 10H ;INVOKE "NON DISPLAY" SERVICE
POP CX
POP AX
RET
CUR_OFF ENDP
;------------------------------------------------------------------------------
;------------------------------------------------------------------------------
;ROUTINE CUR_ON
;
; BRIEF:
; TURNS THE CURSOR DISPLAY ON FOR COLOR MONITORS
;
;------------------------------------------------------------------------------
CUR_ON PROC NEAR
PUSH AX
PUSH CX
MOV AH,1 ;REQUEST "SET CURSOR TYPE" SERVICE
MOV CL,7 ;END SCAN LINE = 7 DECIMAL FOR COLOR
MOV CH,6 ;START SCAN LINE = 6 DECIMAL COLOR
INT 10H ;INVOKE "SET CURSOR TYPE" SERVICE
POP CX
POP AX
RET
CUR_ON ENDP
;------------------------------------------------------------------------------
;------------------------------------------------------------------------------
;ROUTINE DISPLAY
;
; BRIEF:
; DISPLAYS THE PANEL POINTED TO BY MSG ( `Press F1 to modify
; foreground color...Press F2....' ).
;
; INPUT:
; ATTRIBUTE, DISPLAY_ADDRESS
;
; OUTPUT:
; THE PANEL POINTED TO BY MSG IS DISPLAYED WITH THE FOREGROUND
; AND BACKGROUND GIVEN IN ATTRIBUTE.
;------------------------------------------------------------------------------
DISPLAY PROC NEAR
PUSH AX
PUSH BX
PUSH CX
PUSH DI
PUSH ES
PUSH SI
;--SET UP ES, DI, SI, AND AL FOR STOSB OPERATION TO MOVE "MSG" INTO
; THE VIDEO RAM AREA.
;--MAKE ES:DI ->DISPLAY_ADDRESS
MOV BX,DISPLAY_ADDRESS
MOV ES,BX
MOV DI,0
;--SET SI, SO DS:SI -> MSG
MOV SI,OFFSET MSG
MOV AL,ATTRIBUTE
;--SET DIRECTION FLAG TO AUTO INCREMENT SI,DI IN STRING
; OPERATIONS
CLD
;--TURN THE CRT BEAM OFF DURING VERTICAL RETRACE PERIOD TO AVOID
; "SNOW" ON COLOR MONITOR.
CALL VIDEO_OFF
;--MOVE `MSG' INTO VIDEO RAM.
DIS1: MOVSB ;MOVES DS:SI -> ES:DI ( MSG TO SCREEN)
; INCREMENTS SI AND DI BY ONE
STOSB ;MOVES AL ( ATTRIBUTE BYTE ) TO ES:DI
; AND INCREMENTS DI ONLY
CMP BYTE PTR[SI],'$' ;'$' IS STRING TERMINATOR.IF [SI] -> $,
JNE DIS1 ; THEN MSG HAS BEEN DISPLAYED.
;--TURN THE BEAM ON
CALL VIDEO_ON
POP SI
POP ES
POP DI
POP CX
POP BX
POP AX
RET
DISPLAY ENDP
;------------------------------------------------------------------------------
;------------------------------------------------------------------------------
;ROUTINE FORE_GROUND
;
; BRIEF:
; INCREMENTS "FOREGROUND" BY ONE. IF FOREGROUND IS NOT IN THE
; RANGE 0 <= FOREGROUND <= 15 THEN FOREGROUND IS SET = 0.
;
; INPUT:
; FOREGROUND
;
; OUTPUT:
; ATTRIBUTE CORRESPONDING TO NEW VALUE OF FOREGROUND
;------------------------------------------------------------------------------
FORE_GROUND PROC NEAR
INC FOREGROUND
CMP FOREGROUND,15 ;15 IS MAX ALLOWED FOREGROUND COLOR
JBE FOR1
;--FOREGROUND > 15, SO RESET IT TO 0.
MOV FOREGROUND,0
FOR1: CALL SET_COLOR ;DETERMINE "ATTRIBUTE" VALUE FOR OLD
; BACKGROUND, NEW FOREGROUND VALUES.
RET
FORE_GROUND ENDP
;------------------------------------------------------------------------------
;------------------------------------------------------------------------------
;ROUTINE GET_KEY
;
; BRIEF:
; RETURNS SCAN CODE OF KEY PRESSED. KEY NOT ECHOES ON SCREEN.
;
; INPUT:
; NONE. WAITS FOR A KEY TO BE PRESSED,
;
; OUTPUT:
; EXT_CODE SET TO "YES" IF AN EXTENDED CODE KEY PRESSED;
; ELSE "NO".
;
; KEYIN CONTAINS THE SCAN CODE OF THE KEY PRESSED.
;------------------------------------------------------------------------------
GET_KEY PROC NEAR
PUSH AX
MOV EXT_CODE,NO ;ASSUME NON EXTENDED CODE KEY PRESSED
MOV AH,0 ;INTERRUPT FOR KEYBOARD INPUT
INT 16H
CMP AL,0 ;AL = 0 MEANS AN EXTENDED CODE
JE GET1
;-- A NON-EXTENDED KEY WAS STRUCK
MOV KEYIN,AL ;MOVE SCAN CODE # INTO KEYIN
POP AX
RET
;-- AN EXTENDED KEY WAS STRUCK
GET1: MOV EXT_CODE,YES ;SET EXTENDED CODE INDICATOR
MOV KEYIN,AH ;MOVE SCAN CODE INTO `KEYIN'
POP AX
RET
GET_KEY ENDP
;------------------------------------------------------------------------------
;------------------------------------------------------------------------------
;ROUTINE GOOD_BYE
;
; BRIEF:
; DISPLAYS MESSAGE `This program needs the color adapter.
; Sorry!'
;
; INPUT:
; FARWELL ( DEFINED IN OUR DATA SEGMENT )
;
; OUTPUT:
; FARWELL MESSAGE IS DISPLAYED.
;------------------------------------------------------------------------------
GOOD_BYE PROC NEAR
PUSH AX
PUSH DX
;--BEEP USER AND DISPLAY FARWELL MESSAGE
MOV AH,9 ;REQUEST "PRINT STRING" SERVICE
MOV DX,OFFSET FARWELL ;DX POINTS TO FARWELL
INT 21H ;INVOKE "PRINT STRING" SERVICE
POP DX
POP AX
RET
GOOD_BYE ENDP
;------------------------------------------------------------------------------
;------------------------------------------------------------------------------
;ROUTINE INIT
;
; BRIEF:
; CHECKS FOR COLOR ADAPTER. IF FOUND THEN SETS DISPLAY_ADDRESS
; = B800H, COLOR = 1, FOREGROUND = WHITE, AND BACKGROUND =
; BLACK. ATTRIBUTE IS ALSO SET.
;
; INPUT:
; NONE
;
; OUTPUT:
; ATTRIBUTE, BACKGROUND, COLOR, CRT_MODE_SET, DISPLAY_ADDRESS,
; FOREGROUND
;------------------------------------------------------------------------------
INIT PROC NEAR
PUSH AX
PUSH DI
PUSH ES
PUSH SI
;--INT11 IS THE EQUIPMENT DETERMINATION INTERRUPT. EQUIPMENT
; INFORMATION IS RETURNED IN THE AX REGISTER. BITS 4 AND 5 = 1 FOR A
; MONOCHROME CARD.
;--ASSUME B&W EQUIPMENT
MOV DISPLAY_ADDRESS,0B000H
MOV COLOR_CARD,NO
INT 11H
AND AX,0000000000110000B ;BITS 4 AND 5 ARE ON
CMP AX,00110000B
JE INI1 ;EQUALITY MEANS B&W CARD.
;--POINT DISLAY_ADDRESS TO COLOR VIDEO RAM
MOV COLOR_CARD,YES ;COLOR ADAPTER PRESENT
MOV DISPLAY_ADDRESS,0B800H
;--TECH. REF.MANUAL SUGGESTS TURNING VIDEO OFF WHEN CHANGING
; MODE ( THIS REDUCES BOUNCING OF PANEL ON SCREEN ).
CALL VIDEO_OFF
;--SET MODE TO 80x25 ALPHA COLOR MODE.
MOV AH,0 ;REQUEST SET MODE SERVICE
MOV AL,3 ;80x25 ALPHA COLOR MODE SPECIFIED
INT 10H ;INVOKE SET MODE SERVICE
;--MODE SET ACCOMPLISHED. TURN BEAM ON.
CALL VIDEO_ON
;--SET FOREGROUND AND BACKGROUND COLORS TO WHITE ( 15) AND
; BLACK (0) RESPECTIVELY.
MOV FOREGROUND,15
MOV BACKGROUND,0
CALL SET_COLOR ;RETURNS THE VALUE ATTRIBUTE
;--GET VALUE OF CRT_MODE_SET VALUE
;--MAKE ES:DI -> CRT_MODE_SET IN OUR DATA SEGMENT
MOV AX,SEG CRT_MODE_SET
MOV ES,AX ;ES = SEGMENT OF CRT_MODE_SET
MOV DI,OFFSET CRT_MODE_SET ;ES:DI ->CRT_MODE_SET
;--MAKE DS:SI -> CRT_MODE_SET AS DETERMINED BY SET MODE ENTRY
; POINT OF VIDEO_IO ). CRT_MODE_SET RESIDES AS ABSOLUTE
; ADDRESS 465H = 40:65.
PUSH DS
MOV AX,40H
MOV DS,AX ;DS = 40H
MOV SI,65H ;DS:SI = 40:65 = CRT_MODE_SET IN LOW RAM
MOVSB ;MOVE DS:SI -> CRT_MODE_SET IN OUR DATA SEG.
POP DS
INI1: POP SI
POP ES
POP DI
POP AX
RET
INIT ENDP
;------------------------------------------------------------------------------
;------------------------------------------------------------------------------
;ROUTINE KEYS
;
; BRIEF:
; CALLS ROUTINES TO ADJUST THE FOREGROUND, OR BACKGROUND COLOR
;
; INPUT:
; KEYIN - THE SCAN CODE OF THE KEY STRUCK
;
; OUTPUT:
; FOREGROUND OR BACKGROUND COLOR IS ADJUSTED. SETS EXIT = "YES"
; IF F10 PRESSED.
;------------------------------------------------------------------------------
KEYS PROC NEAR
CMP KEYIN,F1 ;F1 KEY( FOREGROUND )
JNE KEY1
CALL FORE_GROUND
RET
KEY1: CMP KEYIN,F2 ;F2 KEY (BACKGROUND )
JNE KEY2
CALL BACK_GROUND
RET
KEY2: CMP KEYIN,F10 ;F10 HIT?
JNE KEY3
MOV EXIT,YES ;YES! INDICATE RETURN TO DOS WANTED
KEY3: RET
KEYS ENDP
;------------------------------------------------------------------------------
;------------------------------------------------------------------------------
;ROUTINE SET_COLOR
;
; BRIEF:
; DETERMINES VALUE OF ATTRIBUTE BASED ON FOREGROUND AND
; BACKGROUND. SET_COLOR SETS BORDER COLOR = BACKGROUND COLOR.
;
;▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄
;
; SEE TECH REFERNCE MANUAL FOR DETAILED EXPLANATION.
;
; 2 BYTE CHARACTER DESCRIPTOR FOR COLOR DISPLAY IN ALPHANUMERIC
; MODE.
;
; -----------------------------------------------------------------
; |< -------- CHARACTER --------->| X | R | G | B | I | R | G | B |
; -----------------------------------------------------------------
; <--------- ATTRIBUTE ---------->
;▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄
;
; ATTRIBUTE
;
; BACKGROUND......... ................... FOREGROUND
; V V V
; ---------------------------------
; | X | R | G | B | I | R | G | B |
; ---------------------------------
;▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄
;
;
; COLOR SELECT REGISTER ( WRITE ONLY - HAS ADDRESS 3D9H ) USED
; TO ADJUST BORDER COLOR
;
; BACKGROUND INTENSITY..... .................. SCREEN BORDER
; V V V
; ---------------------------------
; | X | X | X |BI | I | R | G | B |
; ---------------------------------
;
;------------------------------------------------------------------------------
SET_COLOR PROC NEAR
PUSH AX
PUSH CX
PUSH DX
;--DETERMINE VALUE OF ATTRIBUTE FROM FOREGROUND AND BACKGROUND.
;--SHIFT BACKGROUND INTO UPPER NIBBLE OF AL REGISTER
MOV AL,BACKGROUND
MOV CL,4 ;SHIFT BACKGROUND 4 BITS TO LEFT
SHL AL,CL
;--PUT FOREGROUND IN LOWER NIBBLE, AND SAVE IN ATTRIBUTE
ADD AL,FOREGROUND
MOV ATTRIBUTE,AL
;--SET THE BORDER COLOR TO THAT OF THE BACKGROUND.
MOV DX,3D9H ;3D9 = COLOR SELECT REGISTER
MOV AL,BACKGROUND ;BORDER COLOR = BACKGROUND
OUT DX,AL
POP DX
POP CX
POP AX
RET
SET_COLOR ENDP
;------------------------------------------------------------------------------
;------------------------------------------------------------------------------
;ROUTINE VIDEO_OFF
;
; BRIEF:
; TURNS THE VIDEO BEAM OFF DURING VERTICAL RETRACE PERIOD. IF
; THIS IS NOT DONE WHILE WRITING TO VIDEO RAM THEN "SNOW"
; RESULTS.
;
;▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄
;
; STATUS REGISTER ( 4 BIT READ ONLY - 3DAH )
;
; ---------------------------------
; | X | X | X | X | 1 | X | X | X |
; ---------------------------------
; A ONE IN THE POSITON SHOWN => VIDEO RAM ACCESS CAN BE MADE
; WITHOUT INTERFERING WITH THE DISPLAY.
;
;▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄
;
; MODE SELECT REGISTER ( 6 BIT WRITE ONLY. ADDRESS: 3D8H )
;
; .. DISABLES VIDEO WHEN 0
; V
; ---------------------------------
; | 0 | 0 | 1 | 0 | 0 | 1 | 0 | 1 | = 25H
; ---------------------------------
; 25H => 80x25 COLOR ALPHA MODE, BEAM OFF
;
;------------------------------------------------------------------------------
VIDEO_OFF PROC NEAR
PUSH AX
PUSH DX
;--WAIT FOR VERTICAL RETRACE
MOV DX,3DAH
VID1: IN AL,DX
TEST AL,8
JZ VID1
;--VERTICAL RETRACE HAS BEGUN, SO TURN VIDEO OFF
MOV AL,00100101B
MOV DX,3D8H
OUT DX,AL
POP DX
POP AX
RET
VIDEO_OFF ENDP
;------------------------------------------------------------------------------
;------------------------------------------------------------------------------
;ROUTINE VIDEO_ON
;
; BRIEF:
; TURNS THE VIDEO BEAM ON TO REDISPLAY THE SCREEN.
;
; SEE ROUTINE VIDEO_OFF FOR REGISTER VALUES
;
; INPUT:
; CRT_MODE_SET
;------------------------------------------------------------------------------
VIDEO_ON PROC NEAR
PUSH AX
PUSH DX
MOV AL,CRT_MODE_SET
MOV DX,3D8H
OUT DX,AL
POP DX
POP AX
RET
VIDEO_ON ENDP
;------------------------------------------------------------------------------
MAIN ENDP ;END of Procedure MAIN
CODE ENDS ;END of CODE segment
END MAIN ;END of routine MAIN
INTRO.TXT
Copyright 1984 by ABComputing February 15, 1984
╔═════════════════════════════════════════════════════════════════════════════╗
║ Introduction ║
║ ║
║ by ║
║ ║
║ Bill Salkin - Editor of PC Firing Line ║
╚═════════════════════════════════════════════════════════════════════════════╝
┌─────────────────────────────────────────────────────────────────┐
│ │
│ I have so many ideas that may perhaps be of use in time if │
│ others more penetrating than I go deeply into them and join │
│ the beauty of their minds to the labor of mine. │
│ │
│ Gottfried Leibnitz │
│ │
└─────────────────────────────────────────────────────────────────┘
┌──────────────────────────────────┐
│ Greetings │
└──────────────────────────────────┘
WELCOME to the premier issue of PC Firing Line (PCFL),
the technically oriented magazine for IBM PC users.
Our goals are:
┌─────────────────────────────────────────────────────────────────┐
│ 1. To study the software development process. │
│ │
│ 2. To define and promote good programming practices. Many │
│ articles in PCFL will be accompanied by source code files. │
│ Study source code for its style and aesthetic value, in │
│ addition to mere functionality. │
│ │
│ 3. To serve as a beacon to beginning programmers, and a │
│ valuable communications ground for all. │
│ │
│ 4. To supply inexpensive advertising so new products can │
│ gain recognition. │
└─────────────────────────────────────────────────────────────────┘
PCFL represents a major departure from the traditional
approach taken by magazines. I hope you enjoy this magazine,
and I will appreciate your comments.
┌──────────────────────────────────┐
│ FREEWARE(tm) Defined │
└──────────────────────────────────┘
The term FREEWARE(tm) as used in this magazine means a
marketing approach where the user receives a product with no
initial payment required. The user is required to supply the
medium and postage to transport the product.
Individuals and companies are allowed to make copies
for their non-profit use and to provide copies for other
interested parties.
If the product is not satisfactory in the user's
opinion, no payment is made to the company issuing the
product.
Each user judging the product to be of value is urged
to pay a fee set by the issuing company.
PCFL has embraced this philosophy but also accepts
prepaid subscriptions. Further details are provided in this
introduction.
┌──────────────────────────────────┐
│ Writers & Advertisers │
└──────────────────────────────────┘
I must thank our writers for giving their time to this
effort. Our brave advertisers also deserve mention for
advertising in a magazine PRIOR to seeing the first issue!
┌──────────────────────────────────┐
│ Special Thanks │
└──────────────────────────────────┘
I do not own or have immediate access to a color
monitor. But PCFL does support color ( under the "Set RGB
Colors" panel ). This is due to the generosity of
Businessland. They allowed me to use their RGB monitor for
an unlimited period of time.
┌──────────────────────────────────┐
│ How to Use this Magazine │
└──────────────────────────────────┘
The menu driven shell you are using is for those
wishing to browse through articles. Standard DOS commands
should be used to print an article. ( At the bottom of each
article is the name of the file containing the article. The
one exception is the case of source code files where the
file name is listed at the top of the file.)
The largest file that can be viewed is currently 64K.
┌──────────────────────────────────┐
│ Future Direction │
└──────────────────────────────────┘
PCFL is destined to become a project development
magazine.
Readers are invited to send suggestions for programs we
can design together. A central project will be selected,
designed, and broken into modules. Each module will be
written in a language featured in PCFL (and maybe some that
aren't ). This comparative approach should be valuable to
contrast the different languages.
NOTE: I would like to see books written using this
comparative language approach, possibly with fewer
languages.
┌──────────────────────────────────┐
│ Product Reviews │
└──────────────────────────────────┘
As a service to readers, we review software, hardware,
and books. Review copies of software and books will NOT be
returned.
┌──────────────────────────────────┐
│ Documentation │
└──────────────────────────────────┘
All of us have read documentation that cries for
improvement. Send me your watery-eyed list of product names
in this category. A "winner" will be chosen for rewriting in
PCFL. Don't miss this exciting opportunity to explore those
products that have baffled you for so long!
┌──────────────────────────────────┐
│ Distribution │
└──────────────────────────────────┘
PCFL is bimonthly BUT the second issue will appear in
mid-May ( three months hence ). This three-month period will
be used to distribute PCFL, and to study possible
enhancements.
Permission to place PCFL on bulletin boards, and the
like, is granted provided the integrity of the magazine is
preserved and non-profit use is maintained. Contact
ABComputing if clarification is required.
Readers are encouraged to make copies for their friends
also.
Companies are allowed to make copies for user groups
and individuals.
Companies that would consider including copies of PCFL,
or portions thereof, with their product are invited to
contact us.
Publications are NOT allowed to use our material
without our written permission.
┌──────────────────────────────────┐
│ Revenue │
└──────────────────────────────────┘
This fee schedule is subject to change.
┌───────────────────────┐
│ Single Copies │
└───────────────────────┘
We are currently issuing PCFL on the FREEWARE(tm)
principle: if you send us two formatted double-sided/double-
density diskettes and a postage-paid return mailer, we will
send you the latest version of PCFL at no charge.
As PCFL does cost money to create, those receiving the
above-mentioned free copies may help us defray our costs by
paying $6.00 for each issue of PCFL.
Another option is to send us $12 only and we will
supply the diskette(s), mailer, and postage for PCFL. No
further payment is requested with this option.
Make all checks payable to ABComputing.
┌───────────────────────┐
│ Subscriptions │
└───────────────────────┘
For those wanting the "ultimate" in convenience we
offer a six issue subscription for $72, mailed to your home
or business. ( The subscription starts with our second
issue.)
Make all checks payable to ABComputing.
┌───────────────────────┐
│ Sponsors │
└───────────────────────┘
Sponsors pay a fee of $150 (or provide the equivalent
in service ). This fee includes one advertisement, six
issues of PCFL, and a position on our sponsors page.
Multiple sponsorships in a given year entitle the
sponsor to only one six-issue subscription.
Make all checks payable to ABComputing.
┌──────────────────────────────────┐
│ Advertising Medium │
└──────────────────────────────────┘
Marketing software is an expensive proposition.
Advertisements in many magazines cost $2,000 (and up ) per
full page for a one-time insertion.
I suspect that good quality software is languishing for
lack of advertising capital. PCFL is meant to provide an
alternative for the disenfranchised masses that can not
afford such rates. Our current rates are $30 per screen for
a one-time insertion.
The more readers we have, the better exposure your
product will have. Tell your friends about our magazine, and
make copies for them.
┌──────────────────────────────────┐
│ For Color Monitors Only │
└──────────────────────────────────┘
The program COLORFUL.EXE on this diskette allows users
of an RGB monitor to change the foreground, background, or
border colors of the screen.
When the user exits this program the colors are NOT
reset. This allows one to find pleasant color combinations
and use them under DOS.
The program is invoked by typing COLORFUL after the DOS
prompt:
A>COLORFUL
and pressing the ENTER key.
┌──────────────────────────────────┐
│ Printers │
└──────────────────────────────────┘
Most printers do not reproduce the full IBM character
set. In particular, many of the nice graphics displayable on
the IBM monitor ( and used in PCFL ) may print as "garbage"
or at least not as expected.
The routine PRETTY1.EXE on this diskette, will cause
the printer to print "extended" graphic characters as a
series of asterisks.
To invoke this module, type PRETTY1 after the DOS
prompt:
A>PRETTY1
and press the ENTER key.
Then, printing the box
┌──────┐
│ Hi! │
└──────┘
will actually result in the printing of
********
* Hi! *
********
┌──────────────────────────────────┐
│ Where to Write │
└──────────────────────────────────┘
Address all correspondence to:
ABComputing
P.O. Box 5503
North Hollywood, CA 91616-5503
ATTENTION: Bill Salkin
( The company name is pronounced "ABC Computing" but the
spelling uses one "C".)
Send a S.A.S.E if you wish a reply.
┌──────────────────────────────────┐
│ Conclusion │
└──────────────────────────────────┘
PCFL will act as a major force in the discussion of the
software development process and technical knowledge
pertaining to the IBM PC. May the force be with you?
┌──────────────────────────────────┐
│ File Name: ██ intro.txt ██ │
└──────────────────────────────────┘
LISP1.TXT
Copyright 1984 by Gary M. Rader
╔═════════════════════════════════════════════════════════════════════════════╗
║ Why Not Lisp? ║
║ ║
║ by ║
║ ║
║ Gary M. Rader ║
╚═════════════════════════════════════════════════════════════════════════════╝
┌──────────────────────────────────┐
│ Introduction │
└──────────────────────────────────┘
Browsing through almost any personal computer journal
will yield at least one (if not many) programs computer
hobbyists can use on their personal computer. These programs
are invariably written in BASIC. Occasionally one finds
programs written in Pascal, Assembly or, in what seems to be
the current favorite of software developers, C. Other
languages are mentioned in articles, often without programs
- Fortran, Cobol, Forth, APL, Modula-2, Ada, and even Logo.
The language that never seems to appear is Lisp. Why? The
impression is that Lisp is either subhuman (subcomputer?),
superhuman, or beyond comprehension. This article examines
some of the strengths and weaknesses of Lisp, and compares
it to other microcomputer languages.
┌──────────────────────────────────┐
│ History │
└──────────────────────────────────┘
Lisp was one of the first high level languages
developed for digital computers. Fortran and Cobol were
developed in the same time frame. Unlike those languages,
Lisp has never been standardized, and several dialects
exist. MacLisp from the Massachusetts Institute of
Technology (MIT) and InterLisp from Stanford University are
two main dialects. However, one dialect can generally
imitate another so lack of standardization usually causes no
serious problem.
Lisp was initially developed by John McCarthy while at
MIT. Traditionally, it has been used mainly for symbol
manipulation, primarily in the area of artificial
intelligence. Symbol manipulation is the complement of
arithmetic. It deals with structures as opposed to numbers.
Probably the most familiar symbol manipulation application
is a word processing program in which words (symbols) are
manipulated. Other examples include compilers, interpreters,
data base systems, computer games, and business graphics. In
the area of natural language processing, pluralizing a noun
such as "key" to "keys" is an example of symbol
manipulation.
Historically, Lisp systems were slow with minimal
arithmetic capabilities. These deficiencies have been
largely overcome, but the image persists and Lisp is rarely
found outside university environments. Another reason for
its nonacceptance was the lack of good tutorial material.
The arrival of Winston and Horn's excellent book LISP
(Addison Wesley, 1981, paper) has rectified this situation.
(EDITOR'S NOTE: Apparently, laziness is the only valid
remaining reason not to learn Lisp.) This is the book of
choice for learning Lisp.
┌──────────────────────────────────┐
│ What Distinguishes Lisp? │
└──────────────────────────────────┘
What Distinguishes Lisp from other Languages?
1. First, Lisp is interactive, like BASIC and APL. This
greatly speeds program development and debugging. Like APL
(and partly like BASIC) variables are not declared.
Developed programs can be compiled for increased speed.
2. One of Lisp's most powerful features is its ability to
generate code and execute it. For example, to satisfy a
user's query, a data base program might first generate an
appropriate program and then execute (or "evaluate" as we
say in Lisp) it. APL has a similar capability. This is
possible because Lisp programs and Lisp data have identical
structures.
3. Lisp compilers are unique in that they can handle a
mixture of both compiled and interpreted code. That is,
under Lisp a system of interpreted AND compiled programs can
be run! Some of these programs can be compiled, and the
others will be interpreted. This allows a program to have
the speed of a compiled program together with the above
mentioned flexibility of "evaluating" generated code.
4. Various types of macros facilitate translations and
redefinition of the Lisp language. New languages can be
built from Lisp relatively easily using macros. The original
Logo was initially created this way.
5. Another powerful feature is that of function types in
which the number of arguments can be variable or fixed.
These arguments can be either evaluated or unevaluated. Most
languages require the number of arguments to be fixed. APL
allows a variable number (as long as it is either 0, 1 or
2). The Lisp function PLUS is a built-in function which
takes a variable number of arguments. It can be used to add
an indefinite number of numbers, not just a pair of numbers.
The evaluated/unevaluated feature is similar to call-by-
value and call-by-name used in other languages.
6. "Bignums" permit unlimited precision integer arithmetic
thereby eliminating the problem of round-off errors. In
certain engineering and applied mathematics situations the
problem of round-off can be very serious.
7. Strings, functions, and variable names can be of
unlimited length. This allows the creation of completely
descriptive names without the need for abbreviations.
8. The main Lisp data structure is the linked list, which
allows the development of general structures, even circular
graphs. The links (pointers) are transparent to the user.
Other languages such as C allow this capability through the
explicit manipulation of pointers. Linked lists allow
certain operations to be performed much more efficiently
than when arrays are used.
Consider an array of numbers, say X(1), X(2), X(3),
etc. To insert a new third element in this array we shift
each element to the next element in the array and set X(3)
to the new number. In Lisp, this is accomplished by linking
X(2) to the new element, and then linking the new element to
X(3). For long sequences the linked list approach is
significantly faster than using arrays.
9. Lisp is a functional language - it uses function calls,
and this makes it structured, almost naturally. All Lisp
programs are systems of functions with a top level function
calling subfunctions and so on. New functions can be defined
in isolation and used as if they were primitive Lisp
operations.
10. Lisp has perhaps the most powerful set of debugging
features of any language. Break points can be set and the
environment examined when a break occurs. The input
arguments and results of executing specified functions can
be displayed selectively during program execution. You can
create unique and powerful debugging facilities by
appropriately redefining the "evaluate function" mechanism
of Lisp.
┌──────────────────────────────────┐
│ Drawbacks │
└──────────────────────────────────┘
1. One drawback of present day Lisp is the reclamation of
memory. Referred to as "garbage collecting," it occurs
automatically when no free memory is available for creating
new lists or strings (BASIC has a similar drawback).
Processing stops (for a few seconds) until all unused memory
has been reclaimed. This can happen at any time during the
execution of a program. In many cases it will be unnoticed,
but it can happen while a line is being displayed on the
screen! This creates quite a shock and can lead new users to
believe the system has crashed. This also presents problems
for real time programming.
The problem can be reduced when necessary by explicitly
calling the garbage collector at points in the program where
the user will not notice, and by pursuing "garbage
collectionless programming" (by minimizing the creation of
new lists). Research on incremental garbage collectors which
reclaim a little bit of memory with each new usage of memory
will, hopefully, solve this problem. Compiling programs
reduces the length of garbage collections as compiled code
does not need to be processed.
Despite the negative impression created above,
automatic memory management is also one of Lisp's great
strengths. It allows the programmer to concentrate on
solving the problem at hand without being distracted by
conceptually irrelevant details concerning memory (e.g.,
variable declaration, requesting memory from the operating
system, and returning memory when no longer needed). This
undoubtedly is an important reason for Lisp's preeminence in
the world of artificial intelligence.
2. Using lists instead of arrays requires more memory, as
space for links must generally be provided.
3. As data and programs can be widely dispersed in memory,
using Lisp in a virtual memory environment can cause speed
degradation. While following links to a desired data item,
the page containing the actual item might be swapped out in
the course of tracking it down! Of course, this can happen
in other languages such as C in which pointers can point to
other pointers, which point to other pointers.
4. Many people complain that Lisp has too many
parentheses. This is a prejudice, not a drawback. Usually,
if functions and data are suitably formatted ("pretty
printed"), this objection disappears. For those preferring
fewer parentheses, the Lisp driver can be redefined to
provide it. (This was done for the Logo syntax.)
┌──────────────────────────────────┐
│ Lisp on the IBM PC │
└──────────────────────────────────┘
Several Lisps are currently available for the IBM PC.
The Soft Warehouse sells muLISP-83 (also sold by Microsoft),
Integral Quality markets IQLISP, and Norell Data Systems
offers LISP/88.
I have used muLISP-83 for almost half a year and have
been pleasantly impressed by its performance. I have not
used IQLISP but from Integral Quality's brochure it seems
that it is a fully functional Lisp. LISP/88 has just become
available for distribution, and I have no experience with
this product.
muLISP enforces completely structured programming by
not having a GOTO command.(However, exits from loops can be
efficiently performed using the THROW/CATCH combination.) In
addition to the expected functionality, muLISP provides
access to the PC's BIOS through its REGISTER, INTERRUPT, and
PORTIO commands. This is a useful feature for it allows
programmers to easily incorporate graphics, sound, game
paddle communication, and more in their programs. Random I/O
is available. muLISP does not provide arrays or floating
point numbers. (However the Soft Warehouse is currently
implementing floating slash - i.e., floating point in which
the precision is user-defined. This prevents the round-off
problem from resurfacing.)
A program development system and a debugging system are
included with muLISP along with utility files containing
libraries of MacLisp and InterLisp functions. An on-line
tutorial for learning Lisp is also included. (The Soft
Warehouse had developed a tutorial correlated with Winston
and Horn's LISP book but Addison Wesley, the publisher,
demanded a royalty!)
A nice feature for program developers is that
application programs written in muLISP do not require
customers to own the full muLISP system. A small royalty is
paid for use of the muLISP runtime system. Programs are
distributed as .COM files.
IQLISP uses all of the PC's memory while muLISP uses a
maximum of 256K bytes. Arrays and floating point numbers are
provided as is 8087 support. IQLISP does not have random
I/O.
Both Lisps allow user-defined machine language routines
to be called from within programs. Both include a "string"
data type. muLISP is allegedly 4 to 7 times faster than
IQLISP. One reason is that muLISP functions are compiled
into "distilled" code (similar to Pascal's p-code) before
interpretation. Another is that IQLISP accommodates a larger
address space.
Both companies state they will be offering a Lisp
compiler. When I contacted Integral Quality last Spring,
they indicated that a Lisp compiler would be available by
now. To my knowledge, it is not yet available. The compiler
from the Soft Warehouse will be ready in late 1984.
LISP/88 may or may not be in the same league as these
two. However, it definitely has one notable feature - a
price of $49.95!
┌──────────────────────────────────┐
│ Conclusion │
└──────────────────────────────────┘
Unjustified prejudices continue to restrain
microcomputer users from learning and using Lisp. Several
quality microcomputer implementations are available along
with an excellent book for learning Lisp. Lisp provides
powerful capabilities, many of which are unavailable in
other languages.
Three Lisps are currently available for the IBM PC -
muLISP, IQLISP, and LISP/88. A review of muLISP, and IQLISP
appears in PC Magazine (December, 1983).
┌───────────────────────────────────────┐
│ Products mentioned in this article │
├───────────────────────────────────────┤
│ │
│ IQLISP ($175) │
│ Integral Quality │
│ P. O. Box 31970 │
│ Seattle, Washington 98103 │
│ (206) 527-2918 │
│ │
├───────────────────────────────────────┤
│ │
│ LISP/88 ($49.95) │
│ Norell Data Systems │
│ 3400 Wilshire Blvd. │
│ P. O. Box 70127 │
│ Los Angeles, California 90010 │
│ (213) 257-2026 │
│ │
├───────────────────────────────────────┤
│ │
│ muLISP-83 ($250) │
│ The Soft Warehouse │
│ P. O. Box 11174 │
│ Honolulu, Hawaii 96828-0174 │
│ (808) 734-5801 │
│ │
└───────────────────────────────────────┘
┌──────────────────────────────────┐
│ File Name: ██ lisp1.txt ██ │
└──────────────────────────────────┘
LIST1.ASM
;COPYRIGHT 1984 BY ABComputing
;
; ┌───────────────────────────────────────────────────────────────────┐
; │ │
; │ THIS FILE CONTAINS THREE ROUTINES THAT WILL BE DISCUSSED IN │
; │ THE NEXT "Introduction to Assembly Language" COLUMN. │
; │ │
; │ A LINE OF THE FORM │
; │ │
; │ END XXXXXX ;END of routine XXXXXX │
; │ │
; │ INDICATES THE END OF A ROUTINE │
; │ │
; │ SPLIT THIS FILE INTO THREE FILES:1) DISPLAY.ASM, 2) CLEAR.ASM │
; │ AND 3) DELETE.ASM. │
; │ │
; │ USE THE BATCH FILE 0.BAT MENTIONED IN THIS MONTH'S ASSEMBLY │
; │ ARTICLE TO RUN EACH OF THESE FILES. │
; │ │
; │ EACH FILE SHOULD ASSEMBLE AND LINK WITHOUT WARNINGS OR ERRORS. │
; │ │
; └───────────────────────────────────────────────────────────────────┘
;
;
; ┌──────────────────────────────────┐
; │ File Name: ██ list1.asm ██ │
; └──────────────────────────────────┘
;COPYRIGHT 1984 BY ABComputing
;
; ┌───────────────────────────────────────────────────────────────────┐
; │ │
; │ THIS ROUTINE DISPLAYS THE STRING "I have the world on a │
; │ string", AND RETURNS TO DOS. │
; │ │
; │ PLACE THIS ROUTINE IN FILE : DISPLAY.ASM │
; │ │
; └───────────────────────────────────────────────────────────────────┘
;
;------------------------------------------------------------------------
DATA SEGMENT PARA
STRINGY DB 'I have the world on a string','$'
DATA ENDS
;------------------------------------------------------------------------
;------------------------------------------------------------------------
STACK SEGMENT PARA STACK 'STACK'
DB 40H DUP('STCK')
STACK ENDS
;------------------------------------------------------------------------
;------------------------------------------------------------------------
CODE SEGMENT PARA
ASSUME CS:CODE, DS:DATA, SS:STACK
;--STANDARD LINKAGE TO DOS
DISPLAY PROC FAR ;DO
PUSH DS ;
SUB AX,AX ;
PUSH AX ; NOT
MOV AX,DATA ;
MOV DS,AX ; ALTER!
;--PRINT THE STRING "STRINGY"
MOV AH,9 ;REQUEST DISPLAY STRING OPTION
MOV DX,OFFSET STRINGY ;DX HAS THE ADDRESS OF STRINGY
INT 21H ;INVOKE DISPLAY STRING OPTION
;-- RETURN TO DOS
RET ;RETurn to DOS
DISPLAY ENDP ;END of Procedure
CODE ENDS ;END of code Segment
;------------------------------------------------------------------------
END DISPLAY ;END of routine DISPLAY
;COPYRIGHT 1984 BY ABComputing
;
; ┌───────────────────────────────────────────────────────────────────┐
; │ │
; │ THIS ROUTINE CLEARS THE SCREEN BY MAKING A BIOS CALL. │
; │ │
; │ PLACE THIS ROUTINE IN FILE : CLEAR.ASM │
; │ │
; └───────────────────────────────────────────────────────────────────┘
;
;------------------------------------------------------------------------
DATA SEGMENT PARA
DATA ENDS
;------------------------------------------------------------------------
;------------------------------------------------------------------------
STACK SEGMENT PARA STACK 'STACK'
DB 40H DUP('STCK')
STACK ENDS
;------------------------------------------------------------------------
;------------------------------------------------------------------------
CODE SEGMENT PARA
ASSUME CS:CODE, DS:DATA, SS:STACK
;--STANDARD LINKAGE TO DOS
CLEAR PROC FAR ;DO
PUSH DS ;
SUB AX,AX ;
PUSH AX ; NOT
MOV AX,DATA ;
MOV DS,AX ; ALTER!
;--NOTE 24 DECIMAL = 18H, AND 79 DECIMAL = 4FH
MOV AH,6 ;REQUEST SCROLL SCREEN SERVICE
MOV AL,0 ;SCROLL ENTIRE WINDOW
MOV BH,7 ;WHITE FOREGROUND, BLACK BACKGROUND
MOV CX,0000H ;UPPER LEFT CORNER (0,0 )
MOV DX,184FH ;LOWER RIGHT ( 24,79 )
INT 10H ;INVOKE SCROLL SCREEN SERVICE
;-- RETURN TO DOS
RET ;RETurn to DOS
CLEAR ENDP ;END of Procedure
CODE ENDS ;END of code Segment
;------------------------------------------------------------------------
END CLEAR ;END of routine CLEAR
;COPYRIGHT 1984 BY ABComputing
;
; ┌───────────────────────────────────────────────────────────────────┐
; │ │
; │ THIS ROUTINE DELETES THE FILE "B:TRASH.TXT" BY MAKING A DOS │
; │ CALL. │
; │ │
; │ THE FILE IS ASSUMED TO EXIST. │
; │ │
; │ PLACE THIS ROUTINE IN FILE : DELETE.ASM │
; │ │
; └───────────────────────────────────────────────────────────────────┘
;
;------------------------------------------------------------------------
DATA SEGMENT PARA
FCB DB 2,'TRASH ','TXT',25 DUP(0) ;ESTABLISH FCB FOR "B:TRASH.TXT"
DATA ENDS
;------------------------------------------------------------------------
;------------------------------------------------------------------------
STACK SEGMENT PARA STACK 'STACK'
DB 40H DUP('STCK')
STACK ENDS
;------------------------------------------------------------------------
;------------------------------------------------------------------------
CODE SEGMENT PARA
ASSUME CS:CODE, DS:DATA, SS:STACK
;--STANDARD LINKAGE TO DOS
DELETE PROC FAR ;DO
PUSH DS ;
SUB AX,AX ;
PUSH AX ; NOT
MOV AX,DATA ;
MOV DS,AX ; ALTER!
;--PREPARE TO DELETE FILE
MOV AH,13H ;REQUEST DELETE FILE SERVICE
MOV DX,OFFSET FCB ;DX -> FCB OF FILE TO BE DELETED
INT 21H ;INVOKE DELETE FILE SERVICE
;-- RETURN TO DOS
RET ;RETurn to DOS
DELETE ENDP ;END of Procedure
CODE ENDS ;END of code Segment
;------------------------------------------------------------------------
END DELETE ;END of routine DELETE
MEMORY.TXT
Copyright 1984 by ABComputing
╔═════════════════════════════════════════════════════════════════════════════╗
║ Memory - More for Less ║
║ ║
║ by ║
║ ║
║ Ken Holcombe ║
╚═════════════════════════════════════════════════════════════════════════════╝
EDITOR'S NOTE: When I first read this article I was so
impressed with its humor and homespun flavor that I opted
not to edit it.
┌──────────────────────────────────┐
│ Old Motherboards │
└──────────────────────────────────┘
For those of you who purchased your IBM-PC long ago and
can only expand to 64K of RAM on the motherboard, did you
really think you would be satisfied with that? Are you? With
PC/MS DOS getting increasingly sophisticated and larger, and
with the abundance of RAM DISK, print spooling and
partitioning programs, 64K on a PC can really make you feel
left out. There are hundreds of thousands of IBM PCs with
the "old" motherboard that uses 16K bit chips for RAM
memory. The newer PCs use the 64K chips.
Though the PC uses a 16 bit microprocessor, fortunately
for us thrifty folks it has an 8 bit bus; therefore each
bank of memory has a chip for each bit (8) and a chip for
parity for a total of 9 chips per bank. (A sixteen bit bus
requires 16 chips plus one for parity for each bank,
therefore almost twice as expensive! Come on, you purists;
the 8088 isn't that much slower than the 8086 - the 8087
takes out most of the real sluggishness, number crunching).
With 9 chips per bank and 4 banks on the motherboard,
the old PC's come to the grand total of 64K without using a
memory expansion card. A fully populated "new" motherboard
has 256K. I built a memory expansion card by buying a TK
Engineering bareboard that added 256K more for a total of
320K. (With a bareboard, you buy the parts and install them
yourself.) As most of you have discovered, memory is like
money; the more you have, the more ways you find to use
more. Besides, I just love it when people with TRS-80s and
Apples ask me how much RAM I have. I started considering the
options for going beyond 320K, keeping in mind that I
eventually want to wind up with at least 640K, the DOS BIOS
"ceiling."
┌──────────────────────────────────┐
│ Heartburn │
└──────────────────────────────────┘
However I did it, it had to be cheap; that's just a
basic part of my personality (and my budget, which some say
has a lot to do with determining your personality). The AST
megaplus card was almost within reach, but I don't like the
idea of piggybacking RAM banks; I would still wind up with
only 576K and I worried about the heat build-up with 4 banks
of RAM sitting directly on top of another 4 banks of heat
producing RAM. Use another slot to get the last 64K, you
say? Forget the last 64K, you say and be content with 576K?
Well, there is a board on the market now that allows you to
install 576K on it for a total of 640K without piggybacking
and using only one slot, but it doesn't have all the other
functions that the Megaplus does.
Any way you cut it, I'm being penalized for buying an
early PC. It really burns me up that my reward for being one
of the first to recognize the advantages of an IBM was being
stuck with those rinky-dink 4116 16K chips on the
motherboard. Oh yea, they're cheap - I can get 'em for $1
apiece but they use almost the same amount of power as the
64K chips with 1/4 the density. I want to save that power
supply for bigger and better things. (Worst of all, the 4116
is the same RAM chip that the TRS-80 and other 8-biters use.
I do have some pride, you know. Incidentally, there are
those who say that the 8088 is really an 8-bit
microprocessor. I don't care what they call it, it can
directly address a megabyte. Try that on your 6502 or Z-80;
you'll be selecting banks more than you'll be computing.)
The more I thought about it, the more I knew that I would
have to get rid of those 4116s and get some 4164s - somehow,
someway cheap.
The 64K chips themselves aren't expensive- about $5
apiece from the right places - but one can't just take out
the 4116 and install the 4164: the 4116 requires +12,-12,
and +5 volts. The 4164 needs only +5 and some of the pin
connections are different from the 4116.
┌──────────────────────────────────┐
│ Bareboards at Bare-bottom Prices │
└──────────────────────────────────┘
There are several companies making bareboards for the
motherboard that use the 64K chips. The cheapest is from
Netronics at $89.95 with $140 more for a complete kit. Super
Computer has either a PC or an XT bareboard for $95. Both of
these companies have many other bareboards, kits, and
assembled units for the PC covering all functions and
combinations, e.g., 4 drive disk controllers with parallel
printer port, clock/calendar,and hard disk SASI interface,
etc.
Display Telecommunications Corporation has a
bareboard/motherboard that can accept the 64K chip or the
256K chip for $99.95. Others are more expensive, like the
Colorado Computer Peripherals bare motherboard (sounds kind
of kinky to me) for $175. The most expensive is the bare
motherboard from Micromint, Inc., at $300, although it does
have more functions built on the board. You pay a mint (some
pun intended) since these are designed by Mr. Hardware
himself, Steve Ciarcia of Byte fame. Micromint offers the
motherboard completely assembled, as does Edge Micro
Systems.
I decided against all of these because the assembled
ones cost more than I wanted to spend and the bareboards
would take too long to finish. I didn't want my computer out
of commission for more than a couple of hours.
Another viable option was a kit from Add-MEM that sells
for $69.95. Ah, the price was right and I was able to talk
my wife into giving it to me for Xmas. Well, it's in and it
works. The three banks on the motherboard that are socketed
are emptied of the 16K chips; the chips in bank 0 are
soldered in by IBM and are left in though electrically
disconnected. Assembling the Add-MEM kit consists of
soldering 29 tiny pins, one resistor, 35 bypass capacitors
(they leave one off because of space constraints ) and 36
sockets to a small printed circuit board. With sixteen pins
on each socket, that's a lot of soldering and it might be
worth it to pay $30 more for an assembled board if soldering
isn't therapeutic for you.
┌──────────────────────────────────┐
│ 512K is Nice as Rice │
└──────────────────────────────────┘
I prefer the kit because I like to solder in the chips
directly and not use the sockets. I know that makes them
harder to replace, but I think that most RAM chip
malfunctions are actually bad socket connections. Sure it
works when you put in a new chip; in essence you fixed the
bad connection. In any event, you wind up with a small PC
board that plugs into the banks 1,2, and 3 sockets with
these 29 little pins sticking out on the bottom of the
Add-MEM PC board. (PC stood for printed circuit long before
it meant personal computer; you know, back in those old days
when we thought it was really amazing that PC boards had
foil on both sides.) You cut through the foil in a few
places on the motherboard, solder a few wires from the
Add-MEM board to the motherboard, and voila- 256K without
using any slots. I put back my TK board, set the dip
switches, and decided that 512K is nice as rice.
┌──────────────────────────────────┐
│ Doing the Dirty Work │
└──────────────────────────────────┘
It takes a certain personality type to purchase this
kit. I have some friends who think that the motherboard was
built in the Holy of Holies, and the thought of taking a
knife and cutting though some foil on the motherboard is
like a thousand fingernails on a chalkboard to them. To them
I recommend Sorbus Service: they will install a 256K
motherboard for $208 in Phoenix. That is labor included;
they don't sell parts. The price may not be that low at the
Sorbus service center nearest you. The Sorbus center in San
Antonio first quoted me a price of $354 and then decided
that they didn't want to do it at all. Oh well, I am very
happy with my Add MEM modification.
I have my sights set on 640K now. Netronics has a
bareboard with 256K memory and serial port for $39.95 Let's
see; that would take me to 640K and even beyond. Maybe I'll
wait to see how cheap the 256K chips get - the cheapest I
can locate now are $42 bucks apiece; they need to be about
half that before I'm interested. But just imagine that
Mega-board from Display Telecommunications with only 4 banks
on the motherboard and one megabyte staring you in the face.
Isn't it fun to dream? Incidentally, Add-MEM has as much as
promised a modification to use the 256K chips that should be
inexpensive. The 256K chip has one additional address pin
connection that the 64K chip doesn't; other than that, they
are identical.
┌──────────────────────────────────┐
│ Objectivity │
└──────────────────────────────────┘
Do I have anything bad to say about Add-MEM to prove
that I'm really being objective? Well, Add-MEM says you can
eliminate the lengthly power-on diagnostics if you set the
DIP switches on the motherboard to 0K of RAM. That didn't
work for me at all. Also, they say that if you use the
sockets on the little PC board, you can use only two
low-slung boards. (Compare the disk controller board and the
color graphics board - the color graphics is low-slung as
well as being longer. Low-slung boards provide a little more
room to install parts.) They say if you leave the sockets
off and solder the RAM chips in directly, all five slots can
use low-slung cards. I say baloney; if you use the sockets
or not, you can only squeeze in two low slungs. And if you
do use the sockets, even the regular boards are going to be
a tight fit, like resting right on the socketed chips. I
just installed a Quadcolor I board and now I'm wondering if
there is going to be room for the Quadcolor II board to
piggyback on it. Oh well, I can always get one of those
bareboard motherboards. I need something to do on these cold
winter nights. Or maybe I can remove the soldered-in 16K
chips left on the motherboard and the sockets under the
Add-MEM board and solder in the Add-MEM board directly to
lower it a little. The Add-MEM board is going to take some
whittling for clearance to do that. But that would solve the
only other problem I had with the Add-MEM modification.
┌──────────────────────────────────┐
│ Trouble at OK Corral │
└──────────────────────────────────┘
While pressing down on the Add-MEM board to seat the 29
pins in the sockets on the motherboard, I unknowingly
cracked a socket. IBM uses double side-wipe DIP sockets for
the RAM and a cracked socket means that the pins don't get
wiped too well. Well, a few days later my computer became
very sensitive; I mean like going bananas if you tapped it
with your finger. I finally located the problem to the
cracked socket and ran a jumper to fix it (my answer for
most of life's problems). I was so happy when my PC started
purring again and could take smacks on the side undaunted; I
was sweating jalapenos there for awhile.
┌──────────────────────────────────┐
│ All or Nothing │
└──────────────────────────────────┘
This brings up a good point: don't take any more of a
gamble then you are willing to suffer the consequences for.
Nearly all of these boards are multi-layer; if something
becomes disconnected in one of the middle layers of a board
because you didn't think a 25-watt soldering iron would be
too hot, it can depress one for quite a while. On the other
hand, do you know that nearly all repairs on PCs are done on
the FRU (field replaceable unit) level ? That means if a
chip is bad on the motherboard, they replace the
motherboard, or at least IBM and Sorbus do. If the disk
controller board malfunctions, it is replaced.
It's a concept the TV manufacturers have been using for
years. There's less for the technician to diagnose, but the
customer pays more because he/she is buying a module. Of
course, labor should be less. That's one of the reasons I do
my own repairs. If I can't fix my color/graphics board, I
just buy a Quadcolor; what have I got to lose? And I can
keep my old board and sell it to somebody who thinks they
know more than I do about fixing it. There's always somebody
like that around in life. If IBM fixes your computer, they
take your old board in exchange and send it to IBM heaven
where angels who know everything fix it and then they sell
it to someone else some day and charge him labor too.
┌──────────────────────────────────┐
│ Static Electricity │
└──────────────────────────────────┘
Care must be exercised when installing RAM chips with
regard to static electricity. My favorite technique used to
be sitting naked in the bathtub with the parts on a TV tray
in my lap. Used to be, I say, until the vent pipe to the
roof was struck by lightning. What hair I have is
permanently "fro-ed." Now I just make sure I'm on a floor
like wood or linoleum and discharge myself to a metallic
ground before I start. It might be good to remove nylon
socks and work on a cookie sheet.
Someone once said that bravery is knowing all the
possible consequences and being willing to accept them.
Well, how much memory have you got now? What are you going
to do about it? You need some kind of a comeback when those
Commodore people say, "Oh yeah, you got that brand with the
weird keyboard, don't cha?"
Add-MEM is now marketing their products through user
groups. In case your user group isn't hip to this, I'll list
Add-MEM's address along with the other references.
┌──────────────────────────────────┐
│ Conclusion │
└──────────────────────────────────┘
To wrap up a few loose ends, I know that not everyone
agrees with my theory about eliminating sockets. I know a
guy who is installing sockets for all the chips on his
motherboard, those that IBM soldered in. Yes, I know that
the best way to unsolder a chip is to cut all the pins
first. No, I don't know for a fact that all the bare
motherboards I mentioned are 100% IBM PC compatible, but I
do know that the biggest incompatibility with "compatibles"
is the ROM and you can always use your old IBM ROM chip.
Yes, I know there are at least three versions of the
IBM ROM including the XT's and that the old one diagnoses
the first 256K of RAM no matter how much you have. Yes, I
know that altering the motherboard as is done with the
Add-MEM modification voids the warranty, but if it's been
less than 90 days since you purchased your PC, I really hope
you don't have the old motherboard anyway. And if you're the
kind of guy or gal who has a service contract, you're
probably kicking yourself for wasting your time reading this
whole thing anyway. And finally, note the thought that IBM
might change out your old motherboard for a new one just
because you're like me and want nothing but 64K or larger
chips. You sure ask a lot of questions!
┌─────────────────────────────────────────────────────────────────────────────┐
│ Addresses and phone numbers of companies mentioned in this article │
├─────────────────────────────────────┬───────────────────────────────────────┤
│ Add-MEM │ Colorado Computer Peripherals │
│ 22151 Redwood Road │ R.R. 6, Box 7-D │
│ Castro Valley, CA 94546 │ Golden, CO 80403 │
│ (415) 886-5443 │ (303) 278-7172 │
├─────────────────────────────────────┼───────────────────────────────────────┤
│ Display Telecommunications Corp. │ Edge Micro Systems, Inc. │
│ 4100 Spring Valley Road │ 2350 Walsh Avenue │
│ Suite 400 │ Santa Clara, CA 95051 │
│ Dallas, TX 75234 │ (408) 980-9866 │
│ (214) 991-1644 │ │
├─────────────────────────────────────┼───────────────────────────────────────┤
│ Micromint Inc. │ Netronics R&D, Ltd. │
│ 561 Willow Avenue │ 333 Litchfield Road │
│ Cedarhurst, NY 11516 │ New Milford, CT 06776 │
│ Order: 1-800-645-3479 │ 1-800-243-7428 │
│ Info: (516) 374-6793 │ In CT use (203) 354-9375 │
├─────────────────────────────────────┼───────────────────────────────────────┤
│ Sorbus Service Center │ Super Computer, Inc. │
│ Phoenix, AZ │ 1710 E. Newport Circle, Suite P │
│ (602) 997-1064 │ Santa Ana, CA 92705 │
│ Manager: Leonard Goodman │ (714) 540-1880 │
├─────────────────────────────────────┼───────────────────────────────────────┤
│ TK Engineering │ │
│ P.O. Box 1936 │ │
│ Corona, CA 91720 │ │
│ (714) 736-0572 │ │
└─────────────────────────────────────┴───────────────────────────────────────┘
┌──────────────────────────────────┐
│ File Name: ██ memory.txt ██ │
└──────────────────────────────────┘
METABAS.TXT
Copyright 1984 by ABComputing
┌────────────────────┐
│ MetaBASIC REVIEW │
┌────────────────────────────────────────────────────────────────────┐
│ │
│ Reviewed by Bill Salkin │
│ │
│ Product Name MetaBASIC │
│ Description Structured BASIC preprocessor │
│ │
│ Overall Rating Very good │
│ │
│ Company Name Software 128 │
│ Address 363 Walden Street, Concord, MA 01742 │
│ (617) 369-6400 │
│ │
│ Version 1.0 │
│ Price $75 │
│ Copy protected No │
│ RAM needed 64K │
│ DOS level 1.0, 1.1, 2.0 │
└────────────────────────────────────────────────────────────────────┘
┌────────────────────┐
│ MetaBASIC REVIEW │
┌────────────────────────────────────────────────────────────────────┐
│ │
│ Manual Well written. Needs more sample programs │
│ illustrating MetaBASIC features. │
│ │
│ Unusual 1. Combination of features taken from other │
│ Features languages ( PASCAL, FORTRAN, BASIC ). │
│ 2. Allows for separate subroutines with │
│ calling sequences and argument lists. │
│ │
│ Omissions Does not present full set of standard structures. │
│ "DO CASE" is missing ( though the equivalent │
│ IF..ELSEIF..ELSEIF..ELSE is present). "Repeat │
│ until" structure is also missing. │
└────────────────────────────────────────────────────────────────────┘
┌────────────────────┐
│ MetaBASIC REVIEW │
┌────────────────────────────────────────────────────────────────────┐
│ │
│ │
│ Comments Reasonably fast when done on RAM disk. │
│ MetaBASIC uses many intermediate files │
│ so RAM disk is the best approach. │
│ │
│ Code generated is compatible with the │
│ BASIC compiler. │
│ │
│ │
│ │
│ │
│ │
└────────────────────────────────────────────────────────────────────┘
┌──────────────────────────────────┐
│ Introduction │
└──────────────────────────────────┘
MetaBASIC ( abbreviated MB ) is a BASIC preprocessor
that converts structured MetaBASIC code into standard BASIC.
A MetaBASIC program consists of standard BASIC keywords, and
special MetaBASIC constructs. A tilde "~", or equivalently
the word META, differentiates standard BASIC commands from
METABASIC commands.
┌──────────────────────────────────┐
│ Data Initialization Structures │
└──────────────────────────────────┘
MB has borrowed heavily from other languages. The data
initialization method is borrowed from FORTRAN, and uses the
~DATA ( read MetaDATA ) statement. For example, to set the
variable PI equal to 3.14159 the MB statement is
~DATA PI/ 3.14159/
and to set X,Y,Z to 0 use:
~DATA X,Y,Z / 3*0 /
┌──────────────────────────────────┐
│ Record Structures │
└──────────────────────────────────┘
The record structures are borrowed from Pascal. The
following example defines a METArecord SHOES and initializes
the members in this record.
~RECORD SHOES (BROWN,WHITE,GREEN)
SHOES.BROWN = 1
SHOES.WHITE = 3
SHOES.GREEN = 2
The MB manual assumes that you are somewhat familiar
with these types of constructs, as the examples given in the
user manual are not sufficiently good for novices. The
manual is otherwise, very well written and readable.
┌──────────────────────────────────┐
│ Separate Compilation │
└──────────────────────────────────┘
Separate subroutines with calling sequences are sup-
ported. For example, the statement
~CALL MESSAGE( "HELLO")
(in file MAIN.BAS ) calls the subprogram MESSAGE ( in file
MESSAGE.BAS) to display the string "HELLO".
To convert the MetaBASIC source file "MAIN.BAS" to
standard BASIC type
A>mb MAIN;
and press the ENTER key. The following is displayed:
MetaBASIC, Version 1.0
(c) Copyright 1983, SOFTWARE 128
Processing Main Program File: MAIN.BAS
Processing Subprogram File: MESSAGE.BAS
A>
Notice that subprograms are searched for automatically
by the MB preprocessor.
The preprocessor generates a "hash" or composite file
containing standard BASIC which runs under the BASIC
interpreter.
┌──────────────────────────────────┐
│ Cross-reference │
└──────────────────────────────────┘
If the BASIC interpreter reports an error in a
composite file the user need not examine the composite code
to determine the source of the error.
Instead, exit BASIC, invoke the cross-reference program
and key the line number of the error reported by the
interpreter. The cross-reference program returns the name of
the MetaBASIC file, and the line number in this file of the
corresponding statement.
┌──────────────────────────────────┐
│ Error-handling │
└──────────────────────────────────┘
The error messages displayed by either processor are
clear and coherent. ( This is fortunate as the manual lacks
an ERROR MESSAGES section.) Occasionally an error may
generate a flurry of spurious messages.
┌──────────────────────────────────┐
│ Examples │
└──────────────────────────────────┘
This review closes by examining samples of code
generated by the MB preprocessor. I do not claim these are
the best or worst examples one could use.
The following examples also show that MetaBASIC source
code does not require line numbers.
▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄
Example 1:
Input
┌──────────────────────────────────┐
│ ~DATA PI/ 3.14159/ │
│ ~DATA X,Y,Z / 3*0 / │
│ │
│ OPTION BASE 1 │
│ DIM SALES(6) │
│ ~DATA SALES() / 1,2,3,4,5,6/ │
└──────────────────────────────────┘
│
███ MB preprocessor
│
v Output
┌─────────────────────────────────────────────────────────┐
│ 1 DIM A..#(00000),A..%(00000),A..!(00005),A..$(00000) │
│ 2 AAA!=3.14159 │
│ 4 BAA!=0 │
│ 5 CAA!=0 │
│ 6 DAA!=0 │
│ 11 N%=0:FOR I%=0 TO 5: │
│ 12 N%=N%+1 │
│ 13 IF N%>=1 AND N%<2 THEN A..!(I%)=1 │
│ 14 IF N%>=2 AND N%<3 THEN A..!(I%)=2 │
│ 15 IF N%>=3 AND N%<4 THEN A..!(I%)=3 │
│ 16 IF N%>=4 AND N%<5 THEN A..!(I%)=4 │
│ 17 IF N%>=5 AND N%<6 THEN A..!(I%)=5 │
│ 18 IF N%>=6 AND N%<7 THEN A..!(I%)=6 │
│ 19 NEXT: │
│ 21 END │
└─────────────────────────────────────────────────────────┘
Very peculiar code, particularly lines having the form
(IF N% >=1 and N% < 2 ).
▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄
Example 2:
In this example, a main driver routine ( in file
MAIN.BAS ) calls subprogram MESSAGE ( in file MESSAGE.BAS)
to display "HELLO".
MAIN.BAS MESSAGE.BAS
┌───────────────────────────────┐ ┌───────────────────────────────┐
│ ~CALL MESSAGE( "HELLO") │ │ ~SUBPROGRAM MESSAGE( MSG$ ) │
│ END │ │ PRINT MSG$ │
│ │ │ ~RETURN │
└───────────────────────────────┘ └───────────────────────────────┘
└────────.───────┘
│
███ MB preprocessor
│
v
┌─────────────────────────────────────────────────────────┐
│ 1 DIM A..#(00000),A..%(00000),A..!(00000),A..$(00000) │
│ 2 AAA$="HELLO":GOSUB 00007: │
│ 4 END │
│ 7 PRINT AAA$ │
│ 8 RETURN │
│ 9 STOP │
└─────────────────────────────────────────────────────────┘
▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄
Example 3:
This example illustrates the ~IF.. ~ELSEIF.. ~ELSE..
construct.
┌──────────────────────────────────┐
│ ~IF ( X = 1 ) THEN │
│ X = 2 │
│ ~ELSEIF ( Y = 1 ) THEN │
│ Y = 2 │
│ ~ELSE │
│ X = 0 │
│ Y = 0 │
│ ~ENDIF │
│ │
│ END │
└──────────────────────────────────┘
└────────.───────┘
│
███ MB preprocessor
│
v
┌─────────────────────────────────────────────────────────┐
│ 1 DIM A..#(00000),A..%(00000),A..!(00000),A..$(00000) │
│ 3 IF NOT((AAA!=1))GOTO 00007 │
│ 5 AAA!=2 │
│ 6 GOTO 00016 │
│ 7 IF NOT((BAA!=1))GOTO 00012 │
│ 9 BAA!=2 │
│ 10 GOTO 00016 │
│ 12 AAA!=0 │
│ 13 BAA!=0 │
│ 16 END │
└─────────────────────────────────────────────────────────┘
If a condition is not met, the entire section of code
pertaining to that condition is skipped. ( Contrast this
with the C language where a "break" statement must be used
to avoid falling through a switch.)
▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄
Example 4:
Running the composite file (shown below) prints the
values "0" and "1", not "1" and "2". Study the composite
file to see why.
MAIN.BAS BIG.BAS
┌───────────────────────────────┐ ┌───────────────────────────────┐
│ DIM LIN(3) │ │ ~SUBPROGRAM BIG ( MEM ) │
│ │ │ DIM MEM(3) │
│ ~CALL BIG( LIN(1) ) │ │ │
│ PRINT LIN(1) │ │ MEM(1) = 1 │
│ PRINT LIN(2) │ │ MEM(2) = 2 │
│ │ │ │
│ END │ │ ~RETURN │
└───────────────────────────────┘ └───────────────────────────────┘
└────────.───────┘
│
███ MB preprocessor
│
v
┌─────────────────────────────────────────────────────────┐
│ 1 DIM A..#(00000),A..%(00000),A..!(00003),A..$(00000) │
│ 5 BAA%=(1):GOSUB 00013: │
│ 6 PRINT A..!(1) │
│ 7 PRINT A..!(2) │
│ 9 END │
│ 13 A..!(BAA%+1)=1 │
│ 14 A..!(BAA%+2)=2 │
│ 15 RETURN │
│ 16 STOP │
└─────────────────────────────────────────────────────────┘
▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄
Example 5:
This example illustrates Random I/O in MetaBASIC.
The file "FILE" is opened and the METArecord SHOES is
written to this file. ( The METArecord SHOES contains three
members: BROWN, WHITE, and GREEN - for monochrome fans.) The
same record is then read and the members BROWN and GREEN
displayed.
┌────────────────────────────────────┐
│ ~RECORD SHOES (BROWN,GREEN) │
│ │
│ SHOES.BROWN = 1 │
│ SHOES.GREEN = 2 │
│ │
│ RECNUM = 6 │
│ │
│ OPEN "FILE" AS #1,SHOES │
│ │
│ WRITE #1, RECNUM, SHOES │
│ READ #1, RECNUM, SHOES │
│ │
│ PRINT SHOES.BROWN │
│ PRINT SHOES.GREEN │
│ │
│ CLOSE │
│ END │
└────────────────────────────────────┘
│
███ MB preprocessor
│
v
┌─────────────────────────────────────────────────────────┐
│ 1 DIM A..#(00000),A..%(00000),A..!(00000),A..$(00000) │
│ 5 AAA!=1 │
│ 6 BAA!=2 │
│ 7 CAA!=6 │
│ 8 OPEN "FILE" AS 1 LEN=8 │
│ 9 FIELD 1,4 AS V1.1$,4 AS V1.2$ │
│ 10 LSET V1.1$=MKS$(AAA!) │
│ 11 LSET V1.2$=MKS$(BAA!) │
│ 12 PUT 1,CAA! │
│ 13 GET 1,CAA! │
│ 14 AAA!=CVS(V1.1$) │
│ 15 BAA!=CVS(V1.2$) │
│ 17 PRINT AAA! │
│ 18 PRINT BAA! │
│ 19 CLOSE │
│ 20 END │
│ 24 END │
└─────────────────────────────────────────────────────────┘
Look at all those CVS's and MKS$. Nice to forget them,
isn't it?
Also note the two ENDS statements in lines 20 and 24.
No BASIC programmer would do that (I hope!). If we want
luxury, we must be willing to accept certain penalties.
▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄
┌──────────────────────────────────┐
│ Conclusion │
└──────────────────────────────────┘
In summary, MetaBASIC is an interesting and useful
asset for those engaged in writing BASIC code.
┌──────────────────────────────────┐
│ File Name: ██ metabas.txt ██ │
└──────────────────────────────────┘
ODDS.TXT
Copyright 1984 by ABComputing
╔═════════════════════════════════════════════════════════════════════════════╗
║ The Odds and Evens Manual ║
║ ║
║ ( a garage sale of definitions ) ║
║ ║
║ ( gathered from the garage of Bill Salkin ) ║
╚═════════════════════════════════════════════════════════════════════════════╝
This is actually a glossary that will grow and continue to
haunt us in the coming months. Be popular, be liked by your
friends, win the admiration of your boss! Send your words of
wisdom ( and definitions, too! ) for inclusion in this
glossary.
┌──────────────────────────────────┐
│ Buffer │
└──────────────────────────────────┘
A temporary storage area used to compensate for a speed
imbalance between a sending and receiving device.
Think of a buffer as a doctor's waiting room. Patients
must wait until the doctor can attend to them.
┌──────────────────────────────────┐
│ Chip │
└──────────────────────────────────┘
A recent government re-design of the spider. Spiders
not complying with this design modification may receive 1
year in the "can," a 5-fly fine.
Actually, a thin silicon wafer on the order of
one-quarter inch by one-quarter inch. It contains the
equivalent of thousands of transistors, and is the bulwark
of the technological age.
┌──────────────────────────────────┐
│ 8088 Chip │
└──────────────────────────────────┘
The "brain" of the PC is the 8088 chip. I have seen
software for the PC selling for $80.88. (Who said computer
folk don't have a sense of humor? )
┌──────────────────────────────────┐
│ 8087 Chip │
└──────────────────────────────────┘
The "personal slide rule."
Actually a companion processor to the 8088 that
specializes in evaluating mathematical functions with great
accuracy and speed.
This chip does NOT come with the PC as a standard
feature but may be added.
┌──────────────────────────────────┐
│ DOS │
└──────────────────────────────────┘
Not the Spanish number 2! DOS can be thought of as the
"Director Of Services" for the PC. DOS interprets and
communicates your request for service ( such as printing a
file ) to the hardware. It acts on your behalf and shields
you from the inner workings of the PC.
The full meaning of DOS is DISK OPERATING SYSTEM - a
term as imposing as it is long. But if you think of DOS as
it was just described, then you have grasped its
significance to the end user.
"DOS" is both a generic and a specific term. DOS is
generic for DISK OPERATING SYSTEM, and when the PC is
discussed it's usually PC DOS.
Another DOS for the IBM-PC is called CPM-86. CPM ( a
predecessor of CPM-86 ) was one of the earliest operating
systems available for personal computers and is well known
in computer circles.
These two operating systems ( IBM DOS and CPM-86 ) are
not compatible, and programs written under one will not work
on the other without modification. For this reason, when
you purchase software, be certain the product is compatible
with your DOS.
A new DOS 2.0 for the IBM XT ( a glorified IBM PC ) is
available, but it is more "feature" packed and complicated
to learn than earlier releases.
DOS 2.0 also has, in my opinion, a potential file
integrity problem. A prime offender is the "twin filename"
problem as indicated in the directory excerpt:
BOOKS 5101 1-01-80 12:11a
METABAS TXT 16148 1-01-80 5:01a
1 BAT 24 1-01-80 12:14a
METABAS TXT 0 1-01-80 5:01a
Yes! METABAS.TXT is listed twice in the directory.
Which one would you erase? Many times this goes unnoticed as
"chkdsk" does not report any error. Use DOS 2.0 only if you
need its advanced features or can afford to possibly lose
some files.
┌──────────────────────────────────┐
│ Edlin │
└──────────────────────────────────┘
EDLIN is the word for "misery" in twenty languages and
English is no exception. This demon is an archaic line
editor that users should not consider learning.
Suggestion: delete EDLIN from your DOS disk, and
purchase a quality word processor, or text editor. Also
delete Edlin from all instructional courses teaching DOS.
IBM should have supplied, in place of Edlin, a quality
full screen editor called MR. ED. Advertising slogan:
"Learning MR. ED is just horseplay!"
┌──────────────────────────────────┐
│ Hard Disk │
└──────────────────────────────────┘
A storage device capable of storing immense amounts of
information ( the equivalent of several thousand pages in a
book ). The methods used to store and access files under DOS
1.0, 1.1, were not adequate to handle the potential volume
of files on a hard disk. DOS 2.0 uses a hierarchical method
by which files can be placed into partitions.
┌──────────────────────────────────┐
│ Hardware │
└──────────────────────────────────┘
The tangible aspect of a computer system. Examples are
the disk drives, printer, monitor, and system unit.
Hardware and Software work as a team to make the
computer run as claimed in the advertisements.
┌──────────────────────────────────┐
│ K │
└──────────────────────────────────┘
A "K" is 1024 bytes. Just a little more than 1000
bytes. Recall that a byte is a unit of storage equivalent to
one character. A completely filled screen ( 25 rows by 80
columns ) of text is 2000 bytes or approximately 2K.
If your PC is a "64K" machine then you have 64 times
1024 = 65536 bytes of storage in RAM.
┌──────────────────────────────────┐
│ Loop │
└──────────────────────────────────┘
A dog chasing its tail.
Actually a program structure that causes a sequence of
instructions to be repeated.
┌──────────────────────────────────┐
│ Modem │
└──────────────────────────────────┘
Your computer's telephone. It allows your computer to
"talk" over the telephone lines to other computers.
Example: Your computer, with the help of a modem, can
send messages to a modem-equipped computer in another state.
The transmission can be captured immediately by the
receiving terminal. Nothing lost in the mail, no late
deliveries, no excuses.
┌──────────────────────────────────┐
│ Monitor │
└──────────────────────────────────┘
A television-like device used to view information.
There are three main varieties: 1) Monochrome, 2) Composite,
and 3) RGB.
The monochrome monitor - called the spoiler - has
extremely high resolution and crisply formed characters. It
is an excellent choice for word processing. Graphics ability
is limited to drawing horizontal and vertical lines and
special block characters. ( Hardware may be purchased to
extend this graphic ability.) Color is limited to shades of
green, and black.
A composite monitor can be either monochrome or color.
This monitor is a cost compromise between a monochrome and
an RGB. The color fidelity is often not as accurate as that
of an RGB, nor is the text quality as "crisp" as that
of a monochrome monitor.
The RGB monitor supports full color and allows the
drawing of geometric figures, such as an ellipse. It is the
type of color monitor you would purchase after receiving a
large inheritance
┌──────────────────────────────────┐
│ PCjr │
└──────────────────────────────────┘
A pint sized PC with few innovative features. It has a
memory size restricted to 128K and does not officially
support the monochrome adapter. Many of the limitations are
artificial and imposed to prevent price competition with the
PC and PC XT.
RUMOR: Its true purpose is to serve as part of a LAN -
local area network - whereby many users can share common
resources (modems, hard disk, etc.) It is not financially
feasible for many small businesses to purchase a separate PC
or PC XT for each employee. An inexpensive computer, with
limited power, but capable of tapping the resource pool is a
cost effective approach. Enter the PCjr.
┌──────────────────────────────────┐
│ Protocol │
└──────────────────────────────────┘
Rules, standards, agreements, or conventions.
LAYMAN'S EXPLANATION: You say either and I say EYEther,
You say neither and I say NYther; either, EYEther, neither,
NYther, let's call the whole thing off!
┌──────────────────────────────────┐
│ RAM │
└──────────────────────────────────┘
The "memory" or "scratchpad" of your computer.
Information stored in RAM is lost if power is removed even
temporarily. As RAM has no moving parts, unlike a physical
disk drive, it is fast and silent.
┌──────────────────────────────────┐
│ RAM Disk │
└──────────────────────────────────┘
A portion of RAM memory is treated as if it were a
physical disk. Programs are loaded into this RAM disk and
all DOS commands that apply to a physical disk apply to the
RAM disk.
Why RAM disk? 1) There is no wear on a physical disk,
2) RAM has no moving parts, so programs and data can be
accessed far faster than on any other storage media, and 3)
the general noise level of the computer will diminish. The
sweet sound of silence is worth the price.
┌──────────────────────────────────┐
│ Software │
└──────────────────────────────────┘
The intangible aspect of a computer system - magnetic
spots on the surface of a disk.
An analogy: music is to a record as software is to a
disk.
Hardware and Software work as a team to make the
computer run as claimed in the advertisements.
┌──────────────────────────────────┐
│ User-friendly │
└──────────────────────────────────┘
A magic potion that solves all problems - except
reading the user's manual. A rough translation is "nice to
use." Frequently confused with the term "beginner-friendly."
Beginner-friendly software is often over protective and
becomes tedious and dictatorial to advanced users.
Purchase software that provides a protective shell for
the beginner and a direct method to use the program for
advanced users.
┌──────────────────────────────────┐
│ Word Processor │
└──────────────────────────────────┘
A tool oriented to the production of business letters,
where appearance is paramount.
With a word processor corrections to a manuscript are
made on the screen before the document is printed. The
document is printed only when all errors in grammar,
punctuation, and styling, etc. have been removed ( ...at
least this is the idea. A few errors always defy detectiom.)
This saves paper too.
┌──────────────────────────────────┐
│ File Name: ██ odds.txt ██ │
└──────────────────────────────────┘
PAS1.TXT
Copyright 1984 by ABComputing
╔═════════════════════════════════════════════════════════════════════════════╗
║ A Question of Size ║
║ ║
║ by ║
║ ║
║ Richard Levaro ║
╚═════════════════════════════════════════════════════════════════════════════╝
┌──────────────────────────────────┐
│ Introduction │
└──────────────────────────────────┘
Three of the most popular C Compilers (Lattice,
Computer Innovations and Digital Research) have implemented
so-called large memory models. Much has been made of the
different memory models, but a qualitative evaluation of
their use has not been published in the more well known (if
not encyclopedic) trade press. MS-Pascal (and IBM Pascal)
implement a "large" memory model, which we believe is the
most appropriate.
┌──────────────────────────────────┐
│ Memory Models │
└──────────────────────────────────┘
Because of the segmented nature of the Intel 8086
family architecture, compiler designers must choose a
particular memory model or allocation scheme when designing
the code generation phase. The details of how data is
stored, where code is placed, and calling conventions vary
from compiler to compiler, but there are four basic
possibilities:
1. Small Model - A single segment is reserved for code,
and one is reserved for data. Consequently, programs
can be no larger than 128K, 64K for data and 64K for
code. In the early days of the IBM PC and MS-DOS, it
was a common misconception (propagated by many of the
leading "experts" writing in the trade press) that
the IBM Pascal Compiler used this model.
2. Large Code Model - Multiple segments can be used for
code (however, each compiland, e.g., module, unit, or
function, can be at most 64K), but all data is
restricted to one segment. This model is used by the
MS-Pascal and IBM Pascal compilers. The size of the
program code is restricted only by the linker (and of
course, available real memory), because many
separately compiled pieces can be linked together.
3. Large Data Model - A single segment is reserved for
code, but multiple segments are used for data.
Implementations vary, but often one segment is used
for constants and static variables (pointed to by the
DS register), another segment for the stack (pointed
to by SS), and the remainder of memory used for the
heap (dynamically allocated variables).
4. Large Model - Multiple segments are used for both
code and data; this model is a combination of the
Large Code and Large Data models.
┌──────────────────────────────────┐
│ Advantages and Overhead │
└──────────────────────────────────┘
What are the relative advantages and overhead of the
various models? Fundamentally, the impact is in two areas:
how procedures and functions are called, and how data
addresses (pointer values) are calculated.
There are two ways to call a procedure: near or far
calls. A near call assumes the routine being called is in
the same code segment as the call instruction. Only the
instruction pointer value (in the IP register) need be saved
in anticipation of the return. A far call must save both the
code segment (CS register) and the instruction pointer to
prepare for the return. The overhead for a far call (and
subsequent return) is not much more than for a near call.
Therefore, the large code models allow one to write large
programs without overwhelming overhead.
Large data models involve a different overhead.
Basically, if data resides in separate segments, both a
segment and offset must be calculated. Address arithmetic,
which is one of the most frequent computations, now requires
two 16-bit words instead of just one. An inelegant
implementation of a large data model can disastrously affect
program performance. The advantage of a large data model is
principally the ability to store very large data structures
(for example, arrays). It is rarely that a 64K stack space
is required.
┌──────────────────────────────────┐
│ MS-Pascal and IBM Pascal │
└──────────────────────────────────┘
Microsoft MS-Pascal and IBM Pascal use the large code
model, but the compiler supports a data type (the ADS type)
which makes it possible to use all available memory. The
tradeoff is that execution speed is not overwhelmed by the
large data model overhead, but if extra data space is
needed, the address type can be used to implement it. In our
view, this is the most sensible solution: In most cases 64K
of data is acceptable. Larger data requirements should be
regarded as an exceptional case.
Using the ADS type is very similar to the standard
pointer, except instead of using the NEW procedure to
allocate space on the standard heap it must be done
directly. MS-Pascal Version 3.11, and later versions,
support a library function to allocate space beyond the
standard heap. Space can be allocated using DOS 2.0 function
calls as well.
The program SPACE ( in file list1.pas on this diskette)
shows how to use the MS-Pascal ALLMQQ function to allocate
space, and the ADS type to access the data structure.
The contents of file list1.pas are reproduced below:
{**********************************************************************}
{ }
{ SPACE Example illustrating the use of the ADS type for addressing }
{ data beyond the 64K data space. Storage for the record type }
{ is allocated using the external MS-Pascal function ALLMQQ, }
{ and the returned segment address is assigned to the ADS }
{ variable. }
{______________________________________________________________________}
program space(input,output);
type
comdata = record
msg_no : integer;
msg_cnt : integer;
msg : lstring(128)
end;
var
comdata_ptr : ads of comdata;
function allmqq(no_bytes : word) : adsmem; external;
begin {space}
comdata_ptr := allmqq(132); ! Segment, offset address of record
comdata_ptr^.msg_no := 1;
comdata_ptr^.msg_cnt := 0;
comdata_ptr^.msg := 'Hello World';
if (comdata_ptr^.msg_no > 0) then
writeln(output,comdata_ptr^.msg);
end. {space}
┌──────────────────────────────────┐
│ File Name: ██ pas1.txt ██ │
└──────────────────────────────────┘
PCUGINTR.TXT
Copyright 1984 by ABComputing
╔═════════════════════════════════════════════════════════════════════════════╗
║ Introduction ║
║ ║
║ by ║
║ ║
║ Bill Salkin - Editor of PC Underground ║
╚═════════════════════════════════════════════════════════════════════════════╝
┌──────────────────────────────────┐
│ Greetings │
└──────────────────────────────────┘
PC Underground ( PCUG ) was developed to complement PC
Firing Line. It will NOT address the programming and
technical matters that are better suited for PC Firing
Line.
PCUG will reflect the interests and needs of our
readership. The thrust will be in the direction indicated by
your response.
┌──────────────────────────────────┐
│ Special Thanks │
└──────────────────────────────────┘
I do not own or have immediate access to a color
monitor. But PCFL does support color ( under the "Set RGB
Colors" panel ). This is due to the generosity of
Businessland. They allowed me to use their RGB monitor for
an unlimited period of time.
┌──────────────────────────────────┐
│ How to Use this Magazine │
└──────────────────────────────────┘
The menu driven shell you are using is for those
wishing to browse through articles. Standard DOS commands
should be used to print an article. ( At the bottom of each
article is the name of the file containing the article.)
The largest file that can be viewed is currently 64K.
┌──────────────────────────────────┐
│ Distribution │
└──────────────────────────────────┘
When sufficient interest is displayed PCUG will be
issued as a magazine separate from PC Firing Line. Until
then, I regard PCUG as an "added value" product to PC Firing
Line.
┌──────────────────────────────────┐
│ Articles │
└──────────────────────────────────┘
The initial offering in PCUG is the "Odds and Evens
Manual," and "The 1-2-3 Advantage." The former offering is
actually a glossary, while the latter discusses a
sophisticated use of the spreadsheet 1-2-3.
I have also received several suggestions for the
following introductory columns:
1) 1-2-3,
2) BASIC (!),
3) WORDSTAR.
4) ProKey files for different languages and
different applications.
Considering only the BASIC column, there are many
texts available that treat BASIC for the IBM PC. I would
select four BASIC texts and use them as reference manuals.
Our introductory BASIC course would commence, and the book
with the best section on the topic being discussed will be
cited for further study.
┌──────────────────────────────────┐
│ For Color Monitors Only │
└──────────────────────────────────┘
The program COLORFUL.EXE on this diskette allows users
of an RGB monitor to change the foreground, background, or
border colors of the screen.
When the user exits this program the colors are NOT
reset to white on black. This allows one to find pleasant
color combinations, and use them under DOS.
The program is invoked by typing COLORFUL after the DOS
prompt:
A>COLORFUL
and pressing the ENTER key.
┌──────────────────────────────────┐
│ Printers │
└──────────────────────────────────┘
Most printers do not reproduce the full IBM character
set. In particular, many of the nice graphics displayable on
the IBM monitor ( and used in PCUG ) may print as "garbage"
or at least not as expected.
The routine PRETTY1.EXE on this diskette, will cause
the printer to print "extended" graphic characters as a
series of asterisks.
To invoke this module, type PRETTY1 after the DOS
prompt:
A>PRETTY1
and press the ENTER key.
A box on the display:
┌──────┐
│ Hi! │
└──────┘
will print as:
********
* Hi! *
********
┌──────────────────────────────────┐
│ Where to Write │
└──────────────────────────────────┘
Address all correspondence to:
ABComputing
P.O. Box 5503
North Hollywood, CA 91616-5503
ATTENTION: Bill Salkin
( The company name is pronounced "ABC Computing" but the
spelling uses one "C".)
Send a S.A.S.E if you wish a reply.
┌──────────────────────────────────┐
│ Conclusion │
└──────────────────────────────────┘
Your opinion and interests will strongly influence the
direction of PCUG.
┌──────────────────────────────────┐
│ File Name: ██ pcugintr.txt ██ │
└──────────────────────────────────┘
PE.TXT
Copyright 1984 by ABComputing
┌────────────────────┐
│ Editor's Review │
┌────────────────────────────────────────────────────────────────────┐
│ │
│ Reviewed by Bill Salkin │
│ │
│ Product Name Personal Editor │
│ Description Full screen text editor │
│ │
│ Overall Rating Excellent │
│ │
│ Company Name IBM │
│ │
│ Version 1.0 │
│ Price $100 │
│ Copy Protected No │
│ RAM Needed Manual states 64K │
│ DOS Level 1.0, 1.1, or 2.0 │
│ Monitor(s) Monochrome or Color │
└────────────────────────────────────────────────────────────────────┘
┌────────────────────┐
│ Editor's Review │
┌────────────────────────────────────────────────────────────────────┐
│ │
│ Manual Printed in green and black. Readable │
│ and thorough. │
│ │
│ Problems Display of file fragments when a large file │
│ ( > 3000 lines ) is scrolled. │
│ │
│ Unusual 1. Max of 20 files in memory for editing, │
│ Features 2. Non-alphabetic keys are user definable, │
│ 3. Disk directory can be called up in a file, │
│ 4. When file size exceeds RAM size, a spill file │
│ ( 128K max ) is created to hold the file. │
└────────────────────────────────────────────────────────────────────┘
┌────────────────────┐
│ Editor's Review │
┌────────────────────────────────────────────────────────────────────┐
│ │
│ │
│ Omissions DOS 2.0 tree structured directories, not │
│ supported at this time. │
│ │
│ Right justification not supported │
│ │
│ Inadequate print function. No method provided │
│ to immediately print any portion of a file. │
│ The part to be printed must be copied to an │
│ empty file, and this file printed. │
│ │
│ │
│ │
└────────────────────────────────────────────────────────────────────┘
┌──────────────────────────────────┐
│ Introduction │
└──────────────────────────────────┘
The Personal Editor ( abbreviated PE ) is a well
thought out and implemented full screen text editor.
Horizontal scrolling is supported, all the available RAM in
your PC can be used, line and character operations are
supported, the function of non-alphabetic keys is user-
definable, and a maximum of 20 files can be in memory for
editing.
PE provides so many features that this review will only
attempt to capture the "flavor" of the approaches used.
When PE is invoked, and the IBM copyright page passed,
the screen appears as in Figure 1.
┌────────────────────────────────────────────┐
│ ═══ Top of file ═══ │
│ - │
│ ═══ Bottom of file ═══ │
│ │
│ │
│ │
│ │
│ │
│ │
│ ▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄ │
│ 1 1 Replace │
└────────────────────────────────────────────┘
Figure # 1
In Figure 1, the reverse video line at the bottom of
the screen is called the command line. The area between the
"Top of file" and "Bottom of file" markers is the text
area.
The cursor is initially placed on the command line, and
pressing the "Esc" key alternates the cursor position
between the text area and the command line.
The dash shown in the text area in Figure 1 will be the
position of the cursor when Esc is pressed. While editing a
file, pressing the Esc key causes the cursor position to be
saved and the cursor to move to the command line. Pressing
Esc again restores the cursor position in the text area.
┌──────────────────────────────────┐
│ Function Key Redefinition │
└──────────────────────────────────┘
PE allows all function keys and function key
combinations to be user-defined. This should be regarded as
a necessary item for any quality text editor.
I have reassigned the function keys and saved these
assignments in the file PE.PRO. When PE is invoked it uses
the contents of this file to configure the function keys and
function key combinations.
My PE.PRO file defines the "Home" key as:
def home = [top edge][left edge]
where
def home = "define the Home key to be
the concatenation of"
[top edge ] = move the cursor to the top
line of the screen
[left edge ] = move the cursor to the
leftmost column
When the Home key is pressed, the cursor moves to the
top line of the screen ( maintaining its original column ),
and then moves to the leftmost edge of the screen. This is
the typical, if not wordy, function of the Home key.
This approach to defining function keys is used
throughout PE.
Can you guess the function of the following keys?
def end = [bottom edge][left edge]
def enter = [begin line] [down]
To define the Ctrl-Left, Shift-F4, and Alt-R keys I
use:
def c-left = [left40]
def s-f4 = [split]
def a-r = [redraw]
┌──────────────────────────────────┐
│ Command Line Usage │
└──────────────────────────────────┘
Simple DOS commands such as "erase all.*" are accepted
by PE but more complicated forms such as "copy a:all.* b:"
are not.
Further examples of commands that can be keyed on the
command line are shown in Table 1.
Table 1
┌─────────────────────────────────────┬───────────────────────────────────────┐
│ Example │ Function │
├─────────────────────────────────────┼───────────────────────────────────────┤
│ change /this/that/ * * │ change all occurrences of "this" to │
│ │ "that" from the cursor line to the │
│ │ end of the file. │
├─────────────────────────────────────┼───────────────────────────────────────┤
│ def c-f1 = │ redefine the Ctrl F1 functions key │
│ │ for the current edit session. │
├─────────────────────────────────────┼───────────────────────────────────────┤
│ dir [d:] │ display the directory of the │
│ │ current or requested drive. │
├─────────────────────────────────────┼───────────────────────────────────────┤
│ name │ assigns, or changes, the name of │
│ │ the file being edited. │
├─────────────────────────────────────┼───────────────────────────────────────┤
│ ? tabs │ display tab settings on the command │
│ │ line ( They can then be modified.) │
├─────────────────────────────────────┼───────────────────────────────────────┤
│ ? margins │ display current margin settings │
│ │ (They can then be modified.) │
├─────────────────────────────────────┼───────────────────────────────────────┤
│ ? key <keyname> │ display current key definition │
│ │ (The key can then be redefined.) │
├─────────────────────────────────────┼───────────────────────────────────────┤
│ ? memory │ displays available memory in bytes. │
│ │ │
├─────────────────────────────────────┼───────────────────────────────────────┤
│ set display │ changes the display of the current │
│ │ file. Examples: │
│ │ │
│ │ s display mono │
│ │ s display color 40 │
│ │ s display color 80 │
│ │ s display b/w 40 │
│ │ s display b/w 80 │
└─────────────────────────────────────┴───────────────────────────────────────┘
┌──────────────────────────────────┐
│ Character Block Marking │
└──────────────────────────────────┘
Most text editors allow a block or group of lines to be
deleted, copied, or moved. PE has refined this type of
operation to the CHARACTER level.
The "artwork"
┌──────────────────┐
│ Print Hello │
│ │
└──────────────────┘
can be produced by character block-marking the string
Print Hello
and overlaying it in the box
┌──────────────────┐
│ │
│ │
└──────────────────┘
as described next.
Move the cursor to the "P" in print, and press the Alt
and B ( block mark ) keys. The character "P" is highlighted
in reverse video. Now move the cursor to the "o" in Hello
and press Alt - B, again. The entire phrase "Print Hello" is
highlighted in reverse video.
Next move the cursor inside the box. Pressing Alt-O
(overlay) will copy the block-marked string as follows. The
character in the upper left-hand corner of the block-marked
area ( the "P" ) is positioned at the cursor location. The
next character ( the "r" ) is positioned one column to the
right of the cursor location. This pattern is continued and
the entire string is copied. This feature was used to create
the artwork in PCFL.
┌──────────────────────────────────┐
│ Line Block Marking │
└──────────────────────────────────┘
To copy or move a block of lines on the screen the
first and last lines of the block are marked. A marked line
is shown visually with a reverse video bar extending the
length of the line. A block of marked lines has the entire
area between the first and last lines in reverse video.
(This causes my display to "blush" and can be annoying when
large areas are involved.)
When an area is marked, it can be block-deleted,
block-copied, block-moved, etc. In my PE.PRO file the F1 key
is set to mark the line the cursor is on:
def F1 = [mark line]
To copy a marked line to another location I use the F2
function key:
def f2 = [copy mark][unmark]
┌──────────────────────────────────┐
│ Error Handling │
└──────────────────────────────────┘
PE is marvelously impervious to system errors. It
intercepts them. If you attempt to print a file and the
printer is off, or read a diskette while the disk drive door
is open, PE displays an error message. This is good
programming and not included in many software packages.
┌──────────────────────────────────┐
│ Criticisms │
└──────────────────────────────────┘
I have two criticisms. They are not errors in PE
though.
For no apparent reason, PE has difficulty in dealing
with extremely large files. ( The problem may be related to
"garbage collection." ) For reasonable size files, (<3000
lines) the screen scrolling is very fast. But editing
extremely large files can cause visual fragmentation of the
file being edited. (Scrolling speed slows to a gasping
crawl, also.) The bottom portion of the old screen remains
while the new top portion is in place. A short time later,
the correct bottom part of the display appears.
The problem is not specific to a single large file.
Twenty files may be in memory simultaneously for editing ( a
powerful feature of PE ). The combined size of all files may
aggravate the situation and induce visual fragmentation in
the file being edited. The benefit becomes a burden.
BUT for reasonable file sizes the scrolling is
extremely fast.
My other complaint relates to the deletion of lines
from a file.
To illustrate, suppose we are editing a file with 200
lines. Block-mark lines 1 through 50, and position line 50
at the top of the screen. When these lines are group-deleted
the original line 51 is NOT displayed at the top of the
screen. The original file's line 100 is. ( 50 lines past the
new first line of the file.) After deleting a large number
of lines, the user is greeted with a screen having no
relationship to the screen prior to the deletion. This
aspect of PE is confusing and should be redesigned.
I am not aware of other difficulties with PE.
┌──────────────────────────────────┐
│ Conclusion │
└──────────────────────────────────┘
A superb editor. Extremely flexible and error free....
.... ..... but before rushing to buy PE, you may want to
read my future reviews on text editors. There are "many fish
in the sea" and it will be my pleasure to examine the "catch
of the day" for you.
┌──────────────────────────────────┐
│ File Name: ██ pe.txt ██ │
└──────────────────────────────────┘
SPONSORS.TXT
Copyright 1984 by ABComputing
╔═════════════════════════════════════════════════════════════════════════════╗
║ ║
║ ║
║ Sponsors ║
║ ║
║ ║
╚═════════════════════════════════════════════════════════════════════════════╝
▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄
▌ 2034 Blake Street, Berkeley, CA 94704
▌ Blaise Computing, Inc. (415) 540-5441
▌ Software developers for programmers and
▌ system programmers for both Pascal and C.
▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄
▌ Businessland, Inc. 14144 Ventura Blvd, Sherman Oaks, CA 91403
▌ (818) 788-1170
▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄
▌ 1033 N. Sycamore Avenue, Hollywood, CA 90038
▌ OPAMP TECHNICAL BOOKS (213) 464-4322
▌ Computer books for all interests
▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄
▌ P.O. Box 51454-5454, San Jose, CA 95151
▌ SCIOPT Enterprises (408) 281-0869
▌ Engineering and scientific applications for
▌ the IBM PC and custom 8087 programming.
▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄
▌ 1155 Meridian Avenue, Suite 218
▌ TELECON SYSTEMS San Jose, CA 95125
▌ (408) 275-1659
██████████████████████████████████████████████████████████████████████████████
┌──────────────────────────────────┐
│ File Name: ██ sponsors.txt ██ │
└──────────────────────────────────┘
THINKING.TXT
Copyright 1984 by ABComputing
╔═════════════════════════════════════════════════════════════════════════════╗
║ Creative Thinking ║
║ ║
║ by ║
║ ║
║ Edward Sweeney and Bill Salkin ║
╚═════════════════════════════════════════════════════════════════════════════╝
┌──────────────────────────────────┐
│ The Concept │
└──────────────────────────────────┘
Considering the frequency of prolonged discussions on
the best key arrangement for a keyboard (Dvorak, new ANSI
standard,etc. ), we are convinced that the PERSONAL
keyboard(tm) has great value.
The PERSONAL keyboard ( abbreviated Pk ) allows the
user to define the meaning of each position on the
keyboard.
Merely lifting a keycap with one's fingers and placing
it in a keycap receptor establishes the function of that key
location. No equipment or special software is needed. Only
the human hand is required to modify the Pk.
In the Pk approach, each key generates a unique signal
that is captured by a microprocessor. The origin of the
signal is not important, only the signal. The "A" key
generates a certain signal, and another "A" key on the same
keyboard generates the same signal.
┌──────────────────────────────────┐
│ Possible Implementation │
└──────────────────────────────────┘
┌─────┐ ┌─────┐ ┌─────┐ ┌─────┐ ┌─────┐
... │ Q │ │ W │ │....o│ │ R │ │ T │ ...
│ │ │ │ │.... │ │ │ │ │
└─────┘ └─────┘ └─────┘ └─────┘ └─────┘
The keycap has been removed from the "E" key by lifting
it from the keycap receptor. A large registration pin and
eight smaller pinouts are observed. This exact pattern is
replicated in all key receptors on the PERSONAL keyboard.
The pins that fit into the registration hole and
pinouts are an integral part of the keyCAP. When a pin in
the keycap mates with the corresponding pinout, this pinout
becomes active ( "1" or "on" ). If no pin mates with a
pinout, the pinout is not active ( "0" or off ).
This series of "off", "on" signals generates a
composite signal that identifies the character on the key.
As all key receptors are identical, any key receptor
can be the origin of this signal. Thus, the function of a
location on Pk is determined by the pins in the keycap. An
extremely flexible approach.
The registration pin is used to distinguish keys such
as 6 and 9. Eight pinouts give a maximum of 255 unique
signals. ( A keycap with zero pins is not allowed on Pk.)
Extensions are obvious.
┌──────────────────────────────────┐
│ Applications & Features │
└──────────────────────────────────┘
1. This keyboard is always current and ready to meet the
standards of yesteryear or the future. The Dvorak keyboard
is merely a particular arrangement of keys on the Pk.
2. It can stimulate user experimentation and result in
greater user satisfaction.
e.g., a peck typist could arrange keys
alphabetically
e.g., an individual might desire a bottom
row of numerals in addition to a top row
e.g., all vowels could be placed in the
middle of the row
e.g., Braille keycaps can help the blind.
When voice reproduction becomes commonly
available, voice + braille keycaps can
literally open a world hitherto unseen.
3. Special keys should prove useful. Consider keys for
foreign languages, mathematical symbols, abbreviations
(e.g., R.S.V.P, COD), and even a HELP key. "Universal" keys
should be defined and agreed upon on by computer
manufacturers. ( This idea will probably never reach
fruition) For example, an INDEX key could list the directory
on the current drive on any model or make of computer. There
should not be a need to learn a new command language for
each model of computer.
4. Reduction of errors in job-specific typing situations
by having only needed keys present.
5. Perhaps frequently used keys should occur more than
once on a keyboard ( three ENTER keys? ).
6. Unused keys can be replaced with "inert" ( non-
operational) keycaps that produce no functional output
(signal = 255, say ). An application could be to replace the
"NUM LOCK" toggle key with an inert key to provide a
permanent cursor pad.
7. Studies exist that indicate which keys are used most
frequently. Ignore ( retry, abort? ) the studies! A simple
program can reveal the keys an individual uses most
frequently.
┌──────────────────────────────────┐
│ Conclusion │
└──────────────────────────────────┘
The PERSONAL keyboard is not a gimmick. It will have
significant value for many individuals and can yield
productivity benefits for businesses.
MORAL: Don't mold the person to the keyboard; mold the
keyboard to the person.
┌──────────────────────────────────┐
│ File Name: ██ thinking.txt ██ │
└──────────────────────────────────┘
WRITEUS.TXT
Copyright 1984 by ABComputing
╔═════════════════════════════════════════════════════════════════════════════╗
║ ║
║ ║
║ Please write us! ║
║ ║
║ ║
╚═════════════════════════════════════════════════════════════════════════════╝
This column gathers tidbits, comments, questions, and
reminders that would otherwise be scattered in PCFL.
You may wish to print this file and answer simple
questions on the hardcopy. More extensive answers should be
reserved for a separate sheet of paper.
( This is a postage paid file - I have enclosed a 20
cent stamp for your use! )
┌──────────┐
│ 20 cents │
│**********│
│U.S Snail │
│**********│
└──────────┘
┌──────────────────────────────────┐
│ Tidbits │
└──────────────────────────────────┘
1. PCFL is developing a list of products marketed under
the FREEWARE(tm) approach. This list will contain the names,
addresses, and product descriptions of all such companies
notifying us.
2. Syncon, a manufacturer of magnetic media, is publishing
INFOSCAN, a monthly guide to magazine articles about
microcomputers. To request your free subscription call
(800) 843-9862.
3. January 16, 1984, Computerworld: "ADA nearly ready for
IBM micro." Alsys, Inc., of Waltham, MA, should have two
validated ADA compilers ready by the end of this year ( one
for 8086 systems; the other for Motorola 68000 systems ).
4. The January 1984 issue of THE AMERICAN MATHEMATICAL
MONTHLY has the article "What is Lisp" by Mitchell Wand. The
article demonstrates how sample Lisp programs may be PROVED
correct using mathematical induction.
5. I want PCFL to be available on the SOURCE.
Unfortunately, the SOURCE does not support the extended
character graphics used in PCFL.EXE.
Programs exist to translate EXE modules to HEX format,
and vice versa, but this is a clumsy approach. Your
suggestions are requested.
┌──────────────────────────────────┐
│ Reminders │
└──────────────────────────────────┘
1. PCFL needs articles, book reviews, software reviews,
and more. If you could author such a work, then contact:
ABComputing
P.O. Box 5503
North Hollywood, CA 91616-5503
ATTENTION: Bill Salkin
Our phone number is (818) 509-9002.
Contributions to any column are invited. Especially
needed are writers in BASIC, C, FORTH, PASCAL, and the 8087.
Articles on RATFOR and the UCSD-p operating system are also
sought.
2. PCFL does answer questions. "FIRE" your questions to
ABComputing!
3. Let's start a list of high quality computer products
that cost under $100. Send in your contenders. This list can
serve as a source for product reviews.
4. As mentioned in the Introduction, some products have
documentation that needs "triple by-pass" surgery to make it
readable. Send in your list today.
5. Also, send your contenders for the BEST documented
programs.
6. If your company would consider distributing issues of
PCFL, contact us.
┌──────────────────────────────────┐
│ Questions │
└──────────────────────────────────┘
┌────────────────┐
│ Tidbytes │
└────────────────┘
1. Explain what "structured programming" means to you.
2. How do you determine the name of a subroutine? I have
seen "retrieve_file," "get_file," "get_file_and_key," and
"find_file." The "name it - based on its function" is a
standard approach, but it isn't always successful, as these
illustrations show. Anyone for sub_1, sub_2, sub_3, etc?
(That is, use a numeric sequence.)
3. It is generally regarded as a bad practice to use
"goto" statements in a program. Do you agree with this
sentiment? Why?
4. When in 80X25 text mode on a color monitor, writing to
the video buffer can cause "snow." The first issue of PCFL
waits for the start of the "vertical retrace," turns the
video beam off, writes to video ram, and then turns the beam
on. This eliminates the "snow" but unfortunately impairs
scroll speed.
Future issues of PCFL may wait for the start of the
"horizontal retrace," write one character, and continue in
this manner until an entire panel is moved into video ram.
Test cases indicate that this approach can furnish faster
scrolling than by waiting for the vertical retrace.
Can you suggest other methods for reducing "snow" that
will not impair the scrolling?
5. BASIC is a commonly used computer language despite the
criticism it has received from many parties. Why is BASIC so
popular?
6. PCFL will develop into a project development magazine.
What projects would you like us to design?
7. What programs would you like to see in our GRABBAG
section?
┌────────────────┐
│ Hardware │
└────────────────┘
8. How much RAM does your PC have?
______ K
9. Do you use single- or double-sided drives?
Single ______ Double ______
┌──────────┐
│ Columns │
└──────────┘
10. Which column in PCFL did you find the most interesting?
The least interesting?
11. What new columns would you like us to consider?
┌──────────────────────────────────┐
│ File Name: ██ writeus.txt ██ │
└──────────────────────────────────┘
Directory of PC-SIG Library Disk #0159
Volume in drive A has no label
Directory of A:\
0 BAT 24 1-01-80 12:16a
1-2-3 TXT 10999 1-01-80 3:21a
8087 REV 8494 1-01-80 1:38a
ADA1 TXT 9124 1-01-80 12:05a
ADA1CMP REV 11383 1-01-80 2:06a
ASM1 TXT 17467 1-01-80 1:07a
BIGDEAL ASM 1441 1-01-80 3:21a
C1 TXT 5087 1-01-80 2:28a
COLORFUL EXE 2176 1-01-80 3:19a
CPYRIGHT TXT 1311 1-01-80 12:13a
GO BAT 38 10-19-87 3:56p
DEBUG PAT 94 1-01-80 1:46a
DOS1 TXT 10141 1-01-80 12:04a
DOS2 TXT 2526 1-01-80 2:07a
DOS3 TXT 26984 1-01-80 12:21a
FORT1 TXT 6687 1-01-80 12:52a
GRABBAG ASM 21189 1-01-80 1:30a
GRABBAG EXE 1664 1-01-80 3:03a
INTRO TXT 11118 1-01-80 12:22a
LISP1 TXT 15377 1-01-80 12:54a
LIST1 ADA 4596 1-01-80 12:53a
LIST1 ASM 6301 1-01-80 2:39a
LIST1 C 6037 1-01-80 2:54a
LIST1 PAS 1250 1-01-80 3:09a
MEMORY TXT 18734 1-01-80 12:20a
METABAS TXT 13638 1-01-80 2:24a
ODDS TXT 11768 1-01-80 12:37a
PAS1 TXT 6994 1-01-80 1:39a
PATCH2 BAT 633 1-01-80 1:45a
PCFL EXE 7552 1-01-80 2:56a
PCUGINTR TXT 4992 1-01-80 12:05a
PE TXT 13346 1-01-80 1:03a
PRETTY1 COM 223 1-01-80 3:07a
SPONSORS TXT 1695 1-01-80 2:55a
THINKING TXT 5426 1-01-80 1:04a
TXT ADS 23109 1-01-80 12:11a
WRITERS GDE 2840 1-01-80 12:37a
WRITEUS TXT 5783 1-01-80 1:11a
GO TXT 694 12-02-88 8:47a
FILES159 TXT 1356 12-16-88 2:55p
40 file(s) 300291 bytes
0 bytes free