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PC-SIG Diskette Library (Disk #1209)
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Information about “HDTEST”
HDTEST performs a read/write test on your hard disk without disturbing
the data currently on it!
HDTEST writes 20 different test patterns to every cluster on the disk,
checks that they can be read back correctly, and then carefully restores
your original data! Extremely sensitive, it can even detect errors
which are minor enough to be corrected by the disk controller's own
error-correcting code (ECC). These errors are normally invisible to the
user but may be the first signs of future disk problems.
The program is also useful for automatic disk repair when you get
intermittent or persistent read errors. Because HDTEST tries harder
than DOS alone, it can often recover almost unreadable data from
both hard and floppy disks and rewrite it -- a real life saver when your
backup fails you.
Simple to use, the program was written to minimize the likelihood of
user error causing data loss on a good disk. HDCHEK, a companion
program, gives you a quick compatibility report to tell you if HDTEST
will run on your system.
BOOTLOAD.DOC
Documentation for BOOTLOAD Copyright 1988, P. R. Fletcher
___________________________ _______________________________
INTRODUCTION
____________
BOOTLOAD is part of the HDTEST package, and is only to be distributed
as part of that package. The program and documentation may only be
used or copied under the conditions laid down for HDTEST in the
REGINFO.DOC or UPDINFO.DOC file on the disk on which the Registered
version of the software is distributed and in HDTEST.DOC for the
Shareware version. The BOOTLOAD program is Copyright by Peter R.
Fletcher, 1988. All rights reserved. It was written in assembly
language and assembled with the Microsoft MASM assembler (V5.1).
BOOTLOAD is used to (re)create the HDTEST distribution diskette's
special boot sector (see the HDTEST documentation). Its most important
use is in preparing a pre-boot diskette which can be used on a system
that does not possess the appropriate type of floppy drive for the
distribution diskette, but it can also be used to add the special boot
sector to a working diskette which is to contain (perhaps) just the
HD .EXE files. BOOTLOAD will function on all normal DOS-compatible
removable media (3.5", 5.25", and 8" floppies), under DOS versions 2.x
through 4.0x.
USING THE PROGRAM
_________________
1) If using a "virgin" diskette, first use the DOS FORMAT command to
format it. BOOTLOAD may also be safely used on a diskette which
contains data.
2) With BOOTLOAD.COM either in your default directory or in your PATH,
give the command "BOOTLOAD [dev:]", where dev is the single-letter
device name of the drive on which you wish to access the diskette.
3) Follow the instructions that are displayed on the screen!
BOOTLOAD will not let you modify the boot sector of a fixed disk, and
will respond appropriately to most other likely error conditions. If
you do not specify a device, it will default to drive A:.
LIMITATIONS AND RESTRICTIONS
____________________________
BOOTLOAD should not (strictly speaking) require any services which
are unique to DOS 2.x or above, but it has not been tested under DOS
1.x. It uses only documented DOS services and requires very little
memory - it should, therefore, run on virtually any hardware. Since it
uses INT 25 and INT 26, it will not run in the DOS compatibility box
___
under OS/2.
ADDITIONAL INFORMATION
______________________
Like all well-behaved programs (!), BOOTLOAD signals successful
completion by returning to DOS with the ERRORLEVEL variable set to
zero. Different small positive values are returned for various errors.
BOOTLOAD.COM is 32000 bytes long, but it consists mainly of empty
space. This is because the code on a diskette's boot sector has to run
Documentation for BOOTLOAD Copyright 1988, P. R. Fletcher
___________________________ _______________________________
at 0:7C00 (Hex) and the easiest way to manage this is to assemble it
at an ORG of 7C00 in the default segment. Since the loader code is
assembled at an ORG of 100, there is a huge amount of unused space in
the memory image that is saved as the .COM file. I regard this as
acceptable in a program that will be used rarely and can be saved in
an archive or in other compressed form when not needed.
Comments, suggestions, etc. may be addressed to the author at:
1515 West Montgomery Avenue
Rosemont
PA 19010
U.S.A.
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FILE1209.TXT
Disk No: 1209
Disk Title: Hdtest
PC-SIG Version: S1.3
Program Title: Hdtest
Author Version: 4.95
Author Registration: $35.00
Special Requirements: None.
HDTEST performs a read/write test on your hard disk without disturbing
the data currently on it!
HDTEST writes 20 different test patterns to every cluster on the disk,
checks that they can be read back correctly, and then carefully restores
your original data! Extremely sensitive, it can even detect errors
which are minor enough to be corrected by the disk controller's own
error-correcting code (ECC) these errors are normally invisible to
the user but may be the first signs of future disk problems.
The program is also useful for automatic disk repair when you get
intermittent or persistent read errors. Because HDTEST tries harder
than DOS alone, it can often recover almost unreadable data from
both hard and floppy disks and rewrite it -- a real life saver when your
backup fails you.
Simple to use, the program was written to minimize the likelihood of
user error causing data loss on a good disk. HDCHEK, a companion
program, gives you a quick compatibility report to tell you if HDTEST
will run on your system.
PC-SIG
1030D East Duane Avenue
Sunnyvale Ca. 94086
(408) 730-9291
(c) Copyright 1989 PC-SIG, Inc.
FIXFAT.DOC
Documentation for FIXFAT Copyright 1989, P. R. Fletcher
_________________________ _______________________________
INTRODUCTION
____________
FIXFAT is part of the HDTEST package, and is distributed with the
Shareware and Registered versions of that software. The program and
documentation may only be used or copied under the conditions laid
down in the DOC files distributed with the package. The program allows
DOS's two on-disk copies of the FAT to be made to correspond, when
they have got "out of sync". This is required for HDCHEK and HDTEST to
run. FIXFAT is only intended to be used when something has happened to
corrupt or alter one copy of the FAT (usually because the second copy
___
was only partially updated when a disk write was immediately followed
by a reboot or use of the "big red switch"). The program cannot repair
the FAT if both copies have become corrupted, nor is it intended to be
a replacement for CHKDSK or the more complex disk repair utilities
that are supplied with (e.g.) the Norton and Mace Utilities (TM).
Users who have, and are comfortable with, the latter utilities will
probably find FIXFAT superfluous. It is intended to provide a simple,
limited, but fairly safe way for less experienced users to correct
minor FAT problems prior to running HDTEST.
FIXFAT is Copyright by Peter R. Fletcher, 1989. All rights are
reserved. It was largely written in C, compiled with the Microsoft C
compiler (V5.1). A few low-level functions were written in assembly
language and assembled with the Microsoft MASM assembler (V5.1). The
program was linked with code from the Microsoft C function libraries
by means of the Microsoft LINK linker (V3.65). It consequently
contains material that is Copyright by Microsoft Corp, 1985-1988. This
material is used under the terms of a license from Microsoft Corp.
USING THE PROGRAM
_________________
You should generally run CHKDSK before running FIXFAT, unless you have
______
some good reason to believe that the primary copy (and only the
_____________
primary copy of the FAT on your disk (FAT 1) has been corrupted. If
____________
CHKDSK reports any problems other than "orphan clusters", you should,
if possible, also back up any irreplaceable files on the disk before
either using CHKDSK with its /F option or running FIXFAT. If both your
FATs have been damaged (e.g. by a defective program writing junk to
the FAT area), neither CHKDSK nor FIXFAT will be able to help you, and
your only hope is to use a disk repair utility such as those provided
with the Mace or Norton Utilities (TM).
The command line syntax for FIXFAT is:
FIXFAT dev[:]
"dev" is the single letter DOS device identifier for the device whose
FAT is to be fixed - the colon is optional. FIXFAT will first read and
compare the two copies of the FAT on the target disk. If they are
identical, this fact will be reported and the program will terminate.
If there are any discrepancies between the two copies of the FAT, the
program will examine them individually for evidence of corruption. If
FAT 1 appears valid, you will be prompted for permission to overwrite
FAT 2 with a copy of FAT 1. If FAT 1 appears invalid but FAT 2 appears
__
Documentation for FIXFAT Copyright 1989, P. R. Fletcher
_________________________ _______________________________
valid, you will similarly be prompted for permission to overwrite FAT
1 with a copy of FAT 2. If neither FAT appears valid, this will be
reported and the program will terminate. In determining whether a copy
of the FAT is valid, FIXFAT makes similar checks to those performed by
CHKDSK, except that "orphan clusters" (chains of clusters with no
corresponding directory entries) are not flagged as problems. The
occasional appearance of orphan clusters was rather common under
versions of DOS prior to 3.0, usually following a program abort, and
these are still not (usually) evidence of major trouble.
LIMITATIONS AND RESTRICTIONS
____________________________
FIXFAT uses the DOS disk interrupts (INT 25 and 26) to access the disk
- the program will not run on hardware/software combinations that do
not support the use of these interrupts (this is almost never a
problem). The program will, however, not run in the DOS compatibility
___
box under OS/2. FIXFAT requires an amount of free memory (over and
above that which it uses for its own code) that is equal to at least
four times the size of the FAT on the target device. For most devices,
512 kB should be more than enough, but a device whose size pushes DOS
4.0's limits may be more than the program can handle.
ADDITIONAL INFORMATION
______________________
Like all well-behaved programs (!), FIXFAT signals successful
completion by returning to DOS with the ERRORLEVEL variable set to
zero. Different small positive values are returned for various errors.
Comments, suggestions, etc. may be addressed to the author at:
1515 West Montgomery Avenue
Rosemont
PA 19010
U.S.A.
Please enclose a s.a.e. if you would like to receive a reply to a
question or a response to a comment.
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GO.TXT
╔═════════════════════════════════════════════════════════════════════════╗
║ <<<< Disk #1209 HDTEST >>>> ║
╠═════════════════════════════════════════════════════════════════════════╣
║ ║
║ To start the program, type: HDTEST (press enter) ║
║ ║
║ To print documentation, type: COPY HDTEST.DOC PRN (press enter) ║
╚═════════════════════════════════════════════════════════════════════════╝
HDTEST.DOC
Documentation for HDTEST V4.95 Copyright 1990, P. R. Fletcher
_______________________________ _______________________________
HDTEST - Hard Disk Test/Repair Utility
______________________________________
Copyright (1984-1990), P. R. Fletcher
_____________________________________
All Rights Reserved
___________________
Distributed by:
P. R. Fletcher (Software)
1515 West Montgomery Avenue
Rosemont
PA 19010
_______
____|__ | (tm)
--| | |-------------------
| ____|__ | Association of
| | |_| Shareware
|__| o | Professionals
-----| | |---------------------
|___|___| MEMBER
Documentation for HDTEST V4.95 Copyright 1990, P. R. Fletcher
_______________________________ _______________________________
TABLE OF CONTENTS
_________________
User-Supported Software 1
Introduction 2
Getting Started - Installation 5
- Testing a Disk 5
Hardware and Software Requirements 7
Limitations and Restrictions 9
Command Line Options - HDCHEK 10
- HDTEST 12
What does HDTEST do? 15
Using the Special Pre-Boot 16
Dealing with Bad Clusters 18
Running HDTEST from a .BAT file 19
Bugs and Other Unpleasant Subjects 20
Changes from Previous Versions 21
Appendix A - Summary of Flag Settings 25
Appendix B - Disk Error Messages 27
Appendix C - Example Program Runs 34
Registration Form 37
Documentation for HDTEST V4.95 Copyright 1990, P. R. Fletcher
_______________________________ _______________________________
USER-SUPPORTED SOFTWARE
_______________________
Much of the software which is available for your computer has, in the
past, been produced and sold on the assumption that you are a crook
and that you will take any available opportunity to cheat software
writers and vendors out of their rightful reward. Such software was
copy-protected within an inch of its (and your computer's) life and
was priced at a level which still guaranteed its producers a profit
even if four or five illegal copies were made for each one sold.
Thankfully, prices of commercial software have (for the most part)
come down somewhat, and copy-protection is becoming much less
prevalent, but buying such software remains something of a lottery -
you often cannot be sure that the software does what you want in the
way you want it done until you have paid for it. User-supported
software (Shareware) is different. You may have got a copy of this
package free from a friend or a bulletin board or (for a nominal fee)
from a users' group or software library. In any case, you have a
perfectly legal working copy of the HDTEST package. You are encouraged
to make as many copies of the package as you like and to distribute
them to all your friends. If, after trying the program out, you find
that it is useful and want to continue to keep and use it, you must
register your copy by sending the registration fee ($35.00, unless you
are already a registered user of DIREDIT, in which case it is $25.00)
together with the completed registration form, to the address on the
form. Only your conscience can make you do this (although you are
____
probably breaking the law if you don't), but bear in mind that the
distributors of "user-supported" software are making the assumption
that you are honest and willing to pay a reasonable price for a useful
program, many commercial software vendors, on the other hand, would
still apparently rather believe you are a crook. You can decide who
you would rather prove right. Registered users are entitled to
support, upgrades, and help with HDTEST-related problems (including
telephone support) for a year from the date of registration.
The author of this program is a member of the Association of Shareware
Professionals (ASP). ASP wants to make sure that the shareware
principle works for you. If you are unable to resolve a shareware-
related problem with an ASP member by contacting the member directly,
ASP may be able to help. The ASP Ombudsman can help you resolve a
dispute or problem with an ASP member, but does not provide technical
support for members' products. Please write to the ASP Ombudsman at
P.O. Box 5786, Bellevue, WA 98006 or send a Compuserve message via
Easyplex to ASP Ombudsman 70007,3536"
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Documentation for HDTEST V4.95 Copyright 1990, P. R. Fletcher
_______________________________ _______________________________
INTRODUCTION
____________
HDTEST was originally written to allow comprehensive Read/Write
testing of hard disks on IBM PCs, XTs, ATs, and "true" compatibles.
The V4.10 release removed many of the hardware restrictions imposed by
earlier (V2.xx and V3.xx) versions of the program and made it useful
for testing most MS-DOS-compatible storage devices currently in use on
IBM-compatible computers, including removable (floppy and hard) disks
and logically partitioned hard disks. The V4.34 release included BIOS-
level support for DOS 3.3 (and above) "extended devices" and more
options for the handling of totally unreadable sectors. The V4.53
release added even more extensive support for IBM-incompatible
hardware and removed the requirement that ANSI.SYS be loaded to
support a proper screen display. The current release adds full support
for the large (> 32Mb) devices allowed by DOS 4.0, the ability to
locate bad spots physically (by track, head, and sector) on the disk,
and some support for the use of .BAT files to run HDTEST on multiple
disks at one "sitting".
Although many programs, including IBM's diagnostics, allow "surface
scanning" and seek testing of hard disks, few that are available to
the average user test whether the whole disk can retain the data that
is or will be written to it. HDTEST's principal "claim to fame" is the
ability thoroughly to test the magnetic media in a device which
contains data while preserving the data (although data loss is
_________________________
unavoidable if an area which is in use has become unreadable). HDTEST
____
tests the disk much more thoroughly than programs such as DFixer,
Mace, and Norton's DT. Mace and DT, like many public domain "disk
test" programs, simply read every cluster on the disk and report on
any errors encountered. DFixer does better, writing 4 test patterns
to every free cluster and checking that they can be read back
correctly, but it makes no attempt to test clusters that are already
in use - the very ones which contain your precious data! Disk
Technician (TM), a product which has come to market fairly recently,
is more closely comparable to HDTEST than any other disk testing
program that I know about. It is, however, much more expensive, is
(functionally, at least) copy-protected, and is not available as
___
Shareware!
In addition to its testing function, HDTEST has been reported to be
useful as an automatic disk repair utility for both hard and floppy
disks which have developed (especially) intermittent or persistent
read errors, preventing or impeding their normal use. Although HDTEST
cannot read the totally unreadable, it tries much harder that DOS does
and will almost always, in the course of its operation, allow you to
recover the entire readable portion(s) of a file with one or more
________
unreadable clusters in it, optionally either remapping all of what it
reads from the disk or replacing bad sectors (the default) or clusters
with NULLs. HDTEST is not an alternative to backing up your floppies
___
and/or hard disk - it may sometimes be able to save your neck when you
_________
forgot or your backup went bad too! On hard disks which have developed
intermittent read errors, running HDTEST can sometimes totally cure
___
the problem, presumably because the "flaky" sectors get rewritten and
the minor misalignments and/or weakening of the magnetic "image" which
were causing the trouble are corrected when the data is rewritten.
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Documentation for HDTEST V4.95 Copyright 1990, P. R. Fletcher
_______________________________ _______________________________
In its default ("slow") mode, HDTEST writes 20 different test patterns
to every cluster on the disk and checks that each pattern can be read
_____
back correctly, while preserving (and eventually restoring) the
contents of the clusters that contain data. HDTEST can even (on many
devices) detect hard disk errors which are minor enough to be
correctable (and corrected) by the disk controller's own "error-
correcting code" (ECC). These errors are normally totally invisible
to programs running under DOS and will not usually be picked up by
other disk test utilities. They may, however, be early signs of
problems that will become significant later, and HDTEST consequently
marks these clusters, too, as bad. As long as HDTEST can read the data
from a flaky cluster correctly once (and it tries quite hard) it will
be able to save the file of which that cluster is a part intact, while
______
marking the cluster so that DOS does not try to use it again. The
program was designed to minimize the likelihood of user error causing
data loss on a good (or slightly bad) disk, and to be as easy as
possible to use - it could not be made very fast, since multiple bit
patterns have to be written to and read from each cluster, and this
takes a significant time even on a fast hard disk. The program does,
however, have a less sensitive "fast" test mode, which writes only two
test patterns to each block and is recommended for use when
testing/repairing floppy disks and/or to correct intermittent problems
or rule out gross problems on a hard disk.
The program can be used to test/repair single and double-sided 8- and
9-sector minifloppies (if you have plenty of patience!), as well as
______
AT-format 1.2Mb minifloppies, 8" standard floppies, and 3.5"
microfloppies (with the same proviso regarding a need for patience).
HDTEST's companion program, HDCHEK, simply examines the logical
structure of the system and target device and gives a short report on
what it finds. It does not write to the disk, and is provided
___
principally to allow a quick and easy, but fairly reliable, check on
the compatibility between HDTEST and a given software/hardware
configuration. As part of its report, HDCHEK notes at what level (DOS
interrupts only, INT 13, or direct entry to the BIOS) it was able to
access the target device, which has a bearing on HDTEST's ability to
detect certain types of errors. In general, if HDCHEK runs
__________
successfully on a system and target device, then HDTEST can be
expected to do so, although the latter program requires much more
available memory.
The HDTEST package is distributed as "User-supported Software". If you
intend to continue using the program, you are required to become a
Registered user. Send a completed copy of the Registration Form (which
is included in this documentation), together with a check or money
order for $35.00 (+ $5.00 for shipping outside the continent of North
America) to me at the address which appears on the form. Please also
add $2.50 (or equivalent) if you want the software on a 1.2 Mb HD
floppy or a 3.5" minifloppy, rather than a 360 Kb DSDD floppy, and
specify which you want on the Reg. form. Checks and money orders in
denominations other than U.S. dollars are acceptable, but please add a
further $10.00 for bank charges before using the current exchange rate
to calculate the fee in the currency in which you are paying. On
receiving your Registration, I will send you a personalized copy of
the latest, enhanced, version of the HDTEST package (currently V4.91),
and register you for a year's support. Registration entitles you to be
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Documentation for HDTEST V4.95 Copyright 1990, P. R. Fletcher
_______________________________ _______________________________
notified of upgrades, bug fixes, newly discovered incompatibilities,
etc., and to ask for (and get) necessary help in adapting the program
to work on your hardware. I cannot guarantee to make HDTEST work with
every possible combination of hardware and software, but I will
promise to try to solve problems as they come up, and I will return
your Registration fee if I cannot support HDTEST on your system.
Support is available TO REGISTERED USERS ONLY by mail, BIXmail,
________________________
Compuserve EMail and telephone. Please also bear in mind that my
willingness and ability to continue to support and enhance these
programs will be directly dependent on users' willingness to pay the
Registration fee and (to some extent) inversely dependent on the
number of questions I get that could be answered by reading the docu-
mentation(!).
The HD programs were written principally in C, compiled by the
Microsoft C compiler (Version 5.10) using its "small" memory model,
and linked with code from the distributed Microsoft C object libraries
using the Microsoft LINK program (Version 4.06). Portions of the
distributed program are consequently Copyright (C) by Microsoft Corp.,
1985 - 1988. All rights reserved. These portions are used under the
terms of a license from Microsoft Corp. Some low-level functions were
written in assembly language and assembled by the Microsoft MASM Macro
Assembler (Version 5.10).
The HD programs were written with care and have been tested on a
number of different systems. I cannot, however, give any guarantee as
to their performance on a specific system, nor can I accept liability
for any actual or consequential loss resulting from their use. The
programs may only be used and/or copied in their original form.
Unauthorized modifications and/or the use of all or part of the
programs in other software, commercial or otherwise, are strictly
prohibited.
The HD programs owe a lot of their value to suggestions and bug
reports (more of the former than the latter, fortunately) from
Registered users. They were originally written in response to a
"challenge" issued by Roedy Green on Bix, and their further
development has also been significantly influenced by his input.
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Documentation for HDTEST V4.95 Copyright 1990, P. R. Fletcher
_______________________________ _______________________________
GETTING STARTED - INSTALLATION
______________________________
1) If you received the HDTEST package on a disk, use the DOS DISKCOPY
program to make a duplicate of the distribution disk, put the original
away in a safe place, and use the duplicate as your working disk.
Otherwise, use COPY to save a copy of the HDTEST distributions files
to a floppy disk, and put it away.
2) HDTEST does not require any special installation procedure. You may
run HDCHEK and HDTEST from your working floppy disk or from a
subdirectory on your hard disk. If you wish to keep and run the
programs on your hard disk, you will probably find it most convenient
to COPY them to a subdirectory which is one of those included in your
DOS PATH (see your DOS Reference Manual). Only the two main .EXE files
(HDTEST.EXE and HDCHEK.EXE) need normally be kept on-line.
BOOTLOAD.COM is only used or needed to create a special boot disk, if
you find you need to use one.
3) If you wish to be able to refer to this documentation on-line, you
should follow the instructions in the README.1ST file on the
distribution disk to produce a .TXT file (without underlining) and
keep that file in your documentation subdirectory.
GETTING STARTED - TESTING A DISK
________________________________
This section gives step by step instructions for running HDCHEK and
HDTEST on the C: drive of a standard IBM PC, XT, AT, or 100%
compatible. Subsequent sections of this documentation go into much
more detail about some of the program's other features and options,
and should help to explain and let you deal with any problems which
you may encounter. Note that you should never attempt to run HDTEST
_____
under a multi-tasking or multi-user operating system, nor activate any
"pop-up" program (e.g. SideKick) while the program is running.
1) Make sure that you have current backups of all the files on drive
C:. This is particularly important when running the program for the
first time on a given system.
2) Run DOS's CHKDSK program on drive C: and correct any errors
reported by it before proceeding further.
3) Make the drive and/or directory which contains HDCHEK.EXE and
HDTEST.EXE your current drive and/or directory.
4) If you are not running HDTEST from your A> drive, insert a
formatted, non-write-protected floppy disk in drive A. HDTEST will
write an ASCII log file called HDTESTC0.LOG to the disk in drive A -
any other files on it will be undisturbed.
5) Give the command: "HDCHEK C:". After a certain amount of disk
activity has taken place, and certainly within a minute or two, your
screen should look like one of the examples given in Appendix C. If
any errors are reported, DO NOT PROCEED until you have read the rest
______________
of the documentation and/or are sure you know what is going on.
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Documentation for HDTEST V4.95 Copyright 1990, P. R. Fletcher
_______________________________ _______________________________
6) If HDCHEK reported no errors, give the command "HDTEST C: A:".
____________________________
After some disk activity, the program will prompt for replies to three
questions - press <Return> in response to each prompt. The program
will report its progress to the screen and will record any problems
encountered in the log file on the floppy disk. Depending on the size
of your DOS partition and the access time of the disk, a complete run
of HDTEST (in its normal, "slow", mode) will take between 2 and 5
hours. Your intervention will only be required if a recovered bad
_____
cluster is found in a "hidden", "system", or write-protected file,
when you will be asked to approve remapping; otherwise, bad clusters
will be automatically remapped. HDTEST can be aborted at any time by
pressing <Esc> and responding to the "Are you sure...." prompt by
pressing <Return>.
7) If HDTEST finishes testing without finding any bad clusters, it
will simply record that fact and the finishing time in the log file
and return to the DOS prompt. Otherwise, when read/write testing has
been completed (or terminated, by entering <Esc>), you will be
prompted for permission to complete the remapping process by updating
the disk FATs and Directories. Pressing <Return> will allow this to
take place, and you will then be returned to the DOS prompt.
8) N.B. If HDTEST reported and remapped any bad clusters and you are
____ ___
using the DOS (3.3 and above) FASTOPEN utility, or any other
directory- or file-cacheing software, you should reboot your system
before proceeding with other work on it.
9) In any event, if HDTEST reported and remapped some bad clusters,
you should read the section on "Dealing with bad clusters" later in
this documentation.
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Documentation for HDTEST V4.95 Copyright 1990, P. R. Fletcher
_______________________________ _______________________________
HARDWARE & SOFTWARE REQUIREMENTS
________________________________
HDTEST and HDCHEK make a number of assumptions about the environment
in which they are operating. They will, generally speaking, abort with
an informative error message if they find one of these assumptions to
be untrue! They require MS/PC-DOS 2.x or above and (for HDTEST) up to
about 320 Kb of free memory (the exact amount required depends on the
size and other characteristics of the device being tested) to run -
the presence of more memory may (slightly) increase HDTEST's speed
when testing devices with large cluster sizes. The device to be tested
must be usable as a normal DOS device - commands such as DIR, COPY,
and CHKDSK should be valid for it and for files and subdirectories on
it. It need not, however, be bootable. Only the DOS partition(s) of a
multi-operating-system disk can be tested, but all the partitions of a
disk that is divided into multiple DOS partitions can be tested (one
___
by one). This version of HDTEST fully supports DOS 3.3 (and above)
extended partitions, and will test them as thoroughly as it does
normal DOS partitions. HDTEST's support for other disk partitioning
software is provided only to the extent that DOS support is provided
by the producers of that software.
If you wish to use HDTEST to test a new hard disk which is to be
____
configured to support multiple operating systems, you should first
configure it as one or more DOS partitions, test it in that
configuration, and then reconfigure it as you intend to use it. If you
__
have low-level disk formatting software which allows you to specify
bad sectors and/or tracks to be "locked out", you can use HDTEST's /G
option on the DOS partition(s) to produce a list of defects, which
can then be used in reformatting the disk. Note that HDTEST can only
____
be used as a test for areas of the disk that are to be devoted to
____
other operating systems - when you repartition the disk, any remapping
and/or marking of bad clusters which HDTEST may have done in the DOS
partition is lost.
Ideally, for normal hard disks, the BIOS handler for interrupt 13
should be capable of handling (at least) normal disk reads and writes
(sub-functions 2 and 3) in a way that is compatible with that
documented for the XT hard disk adapter (and AT BIOS) in IBM's
technical documentation. This should be no problem for most disk
systems on IBM PCs and most compatibles. HDTEST may, however, be
forced to use the (somewhat more limiting) DOS device interface when
used with non-bootable hard disks and/or with hard disks which require
special device drivers to be installed, and will be forced to use the
DOS device interface when dealing with disks partitioned by means
other that the DOS 3.3 (and above) utilities.
Earlier V4.xx releases of HDCHEK and HDTEST would abort if run on
small (<= 10 Mb) hard disks which had been patched to use a cluster
size smaller than the DOS standard (and 16-bit FATs). This deficiency
has been corrected in the current version, but very small (less than
1024 clusters) partitions may still cause problems if 16-bit FATs are
used (there is no good reason why such partitions should use 16-bit
FATs).
If run under DOS 3.0 or above on an IBM INT 13 compatible hard disk,
The HD programs attempt to locate and use the ROM BIOS INT 13 entry
point, rather than the normal INT 13 vector (which DOS 3.x intercepts
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and interferes with). By default, for machines with 8088, 8086, 80188,
80186, or equivalent CPUs the programs assume that, if a ROM is
___________
present at absolute address C8000H, it contains the hard disk BIOS and
_______ ___
has initialization code starting at offset 3. This assumption is true
for all hard disks which "plug in" to the IBM PC and XT. It may not be
true for all clones which come with hard disks installed, although it
is likely to be true for most of them. Also by default, the programs
assume that the hard disk BIOS in systems with 80286 or 80386
processors is in the "system" ROM at absolute address F0000H, but make
no more specific assumptions about its exact location. Problems (up to
__
and including system halts) may occur if none of the special flags is
set and your system is configured in a way that is not consistent with
these assumptions. Such problems are almost guaranteed for PC or XT
systems if the initialization code does not start at offset 3 in the
ROM. If you know that your hard disk ROM is located somewhere other
than at the default segment address and/or does not obey the "rules",
you can use the /H flag to tell the programs where to look for it.
Unless you know that your system is particularly non-IBM-compatible,
however, it is usually worth trying to run the HD programs in their
default mode first. Problem hardware should respond to one of the
approaches described in the "Using the Special Preboot" section of
this documentation. The use of all the command line flags is discussed
in more detail below.
Note that, since HDTEST remaps bad clusters to free space, there is
not much point in running it on a disk which has none (as shown by DIR
or CHKDSK), since the program will abort immediately if it finds a bad
cluster. Unless you have a really flaky disk, however, you should not
need more than a couple of hundred Kb free to remap any reasonably
probable number of bad clusters.
This version of the HD programs does not require an ANSI console
driver (such as ANSI.SYS) to be loaded. The programs will, however,
continue to function correctly if such a driver is present.
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LIMITATIONS AND RESTRICTIONS
____________________________
The current version of HDTEST still has a few (mainly theoretical)
limitations, most of which result from the way data is stored
internally by the program. None of them are "etched in stone",
although some could only be avoided at the cost of slowing down what
is already (and necessarily) far from a fast program. The known
limitations are as follows:
1) Maximum cluster size = 65,528 bytes. I do not believe that a DOS
disk can ever have clusters larger than 64 Kb, but my limit is a few
less than that and may, since sector and cluster sizes tend to run in
powers of 2, effectively limit cluster size to 32 Kb - this should be
enough for most people!.
2) Because of certain limitations of the chips used to support direct
memory access (DMA, the method used to transfer data from disk to
memory and vice versa) in the IBM PC and most clones and compatibles,
HDTEST may be unable to use available memory efficiently when cluster
sizes (and the buffers needed to hold them) are large. This
inefficiency can result in "Insufficient Memory" or "Memory
Allocation" errors, even on systems with more than the minimum 320 Kb
of free memory prescribed above. The only cure for this is to free up
(or buy!) more memory (remove RAMdisks, remove resident software,
etc.).
3) The current version of HDTEST will run, in its default mode, on ATs
and most AT clones, but may not be able to detect corrected ECC errors
when run in that mode on some of the clones - a warning message will
be displayed when the program initializes itself if corrected ECC
errors are not being detected. Appropriate use of the extended form of
the /H flag or the /U flag, as described in the "Using the Special
Preboot" section of this documentation, will allow detection of
corrected ECC errors on almost all hardware. The program will not
___
detect corrected ECC errors when invoked with the /I flag (under DOS
3.0 or above) or with the /D flag.
4) For reasons which are poorly understood (at least by the author!),
HDTEST runs very slowly on Epson Equity II systems, particularly when
____
used to test "plug-in" hard drives of the "Hardcard" or "Flashcard"
variety. For this hardware, the estimated run times given elsewhere in
the documentation need to be multiplied by about 2.5. There is some
__________ ___
reason to think that this problem may be related to an excessively
"optimistic" interleave setting on (at least) some of these systems.
5) HDTEST or HDCHEK will, by default, abort with an informative error
message if the program detects that the (80286 or better) CPU that it
is running on is not in "real" mode, since this normally means that a
(possibly multitasking) OS other than MS/PC-DOS is running and that
HDTEST cannot be guaranteed unchallenged access to the hardware. The
presence of LIM 4.0 expanded memory emulators such as QEMM-386 or
386^Max, which use the 80386's "virtual 8086" mode to allow remapping
of extended memory into unoccupied space in the area between 640 Kb
and 1 Mb, will cause a similar abort, unless the driver is inactive
(turned "OFF"). This safety feature can be bypassed by the use of the
/V command line option (see below).
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6) HDCHEK and HDTEST will operate normally (except than the /U or /H
flags will generally be needed to use the low-level interface) on
(very large) hard disks with more than 1024 cylinders, provided that
the partition being tested does not begin or end above cylinder 1023.
______
If the partition starts below and ends above this point, HDCHEK will
issue a warning and HDTEST will abort unless the /D flag is used. If
the partition starts above cylinder 1023, both HDCHEK and HDTEST will
abort without the /D flag.
COMMAND LINE OPTIONS
____________________
Always run HDCHEK on any new hardware/software configuration before
______
you attempt to run HDTEST (at least the first time). The latter
program has been written as conservatively as possible, but it is not
possible to predict the behavior of every conceivable combination of
hardware and operating system when dealing with a program which
bypasses most of the controls which normally protect the user from
destroying his world. HDCHEK is invoked with the command line:
HDCHEK device [/A] [/Cn | /CQ] [/D | /I | /U] [/Hnnnn[:nnnn] [/M] [/V]
"device" is the device to be tested (e.g. A:, B:, etc. - the colons
are permitted but not required). For versions of HDCHEK from V4.35,
___
the spaces between the device identifier and the flags (and between
different flags) are optional - the command lines "HDCHEK C:/C2/D" and
"HDCHEK C: /C2 /D" are equivalent.
The /A(T) flag is used to tell the HD program that it is being run on
an IBM AT. Setting the /A flag allows the programs to deal correctly
with a known bug in the IBM AT floppy disk controller BIOS when HDTEST
is used on 1.2 Mb "AT format" 5.25" floppy disks. If the /A flag is
set and the CPU is not an 80286 or better, you will be asked to
confirm that you wish to use AT defaults (HD BIOS at F0000H).
N.B. the definition of the /A flag changed (slightly) at V4.71 - it
___________________________________________________________________
need now only be used if you are testing a 1.2 Mb floppy disk on a
__________________________________________________________________
"vanilla" IBM AT. It may still be used to change the default BIOS
_________________________________________________________________
segment to F0000H on a PC or XT class machine, but the use of the /H
____________________________________________________________________
flag for this purpose is preferred.
___________________________________
The /C flag has two variants. It is used, immediately followed by a
single decimal digit ("n") in systems which do not support IBM's INT
11 "equipment determination" BIOS function (e.g. the Tandy 2000). The
parameter ("n") is the number of floppy drives attached to the system,
which would otherwise be determined by the program, using INT 11. The
second variant should be used on Compaq computers - here, the flag is
followed by a "Q", instead of a number. This variant enables large
device support (as for IBM DOS 4.00) under Compaq DOS 3.31.
The /D(OS interrupts) flag forces HDCHEK to use the hardware-
independent DOS interrupt 25 for access to the target device. It is
usually not required, since the program is usually smart enough to
_______ _______
recognize devices which have to be accessed this way (e.g. logical
disk partitions other than those created as DOS 3.3 (and above)
"Extended Devices", non-bootable hard disks, some removable-media hard
disks). If the /D flag is not used, the program will issue a warning
___
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message if it finds it has to use the DOS interrupts.
N.B. the definition of the /D flag changed at V4.00 - the new /I flag
_____________________________________________________________________
has the same effect as the old (pre-V4.00) /D flag. Only one of these
_____________________________________________________________________
flags may be present on the command line.
_________________________________________
The /I(nterrupt 13) flag has no effect under DOS 2.x. Under DOS 3.0
or above, it forces HDCHEK to use the existing INT 13 vector (which it
always does under DOS 2.x), and prevents the program from trying to
determine the ROM BIOS entry point; the flag should be used if you
know that your system's fixed disk BIOS uses INT 13 but does not
follow IBM's "rules" or if the program crashes the system when invoked
without it.
The /H(ex BIOS address) flag is normally used (with a single numeric
argument) to tell the HD programs that the ROM BIOS of the device
being tested is located at nnnn, which is interpreted as a Hexadecimal
segment address, rather than at C800, which is the default for PC and
XT class machines, or F000, which is the default for systems using a
80286 or better CPU. There must be no space between the H and the
number. The extended form of the /H flag (e.g. /HF000:80D5) forces the
HD programs to use the given address as the ROM BIOS INT 13 entry
____________________________
point. Its use is documented in more detail in the "Using the Special
_____
Preboot" section of this documentation.
The /M(ulti-track read problem) flag forces HDCHEK to split up disk
accesses that would otherwise require the BIOS to read data from more
than one track in a single "bite". Its use is documented in more
detail in the "Using the Special Preboot" section of this
documentation.
The /U(se INT 68) flag forces the HD programs to use the existing INT
68 vector (which must have been set up to point to an appropriate
location!) instead of locating and using the INT 13 BIOS entry point.
The use of this flag is documented in more detail in the "Using the
Special Preboot" section of this documentation.
The /V(irtual mode) flag bypasses the code which prevents the HD
programs from working when the (80286 or better) CPU is not in "real
mode". It should only be used when the programs are being run under a
____
single-tasking operating system which is using "virtual mode" only for
____
memory-mapping. Certain LIM 4.0 expanded memory emulators for 386
machines use the processor's virtual mode for this purpose. The two
most well-known examples of this software are QEMM-386 and 386^Max.
The HD programs are "DESQview aware", and will abort if run under
DESQview, even if the /V flag is used. They will not be able to
protect you from the (probably disastrous) consequences of using the
/V flag to run them under other multi-tasking OSes (such as VM-386).
After a short delay, during most of which the specified device will be
active, a description of the device's logical structure will be disp-
layed. After a further delay, and more disk activity, a message will
be printed giving the number of files and subdirectories found on the
disk, and the program will exit back to DOS. Note that the total
number of files and subdirectories reported by HDCHEK will be greater
than the sum of the counts reported by CHKDSK. This is because HDCHEK
counts the "." and ".." entries in subdirectories and CHKDSK doesn't.
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Errors and/or problems encountered, if any, will be reported on in
some detail. A number of example screen displays and log files
produced by running HDCHEK (and HDTEST) on different systems will be
found in Appendix C at the end of this documentation. If HDCHEK tells
you that you have a bad 8088 chip, believe it - some early 8088s had a
bug which allowed them to be interrupted while changing their stack
frame* - this is not benign, and can cause all sorts of rare,
otherwise almost inexplicable, problems. The only cure is to replace
the CPU (which is, fortunately, not a particularly expensive
proposition these days). If HDCHEK reports a discrepancy between the
two FATs, HDTEST will abort. The FIXFAT program (on the distribution
disk) may be able to correct this problem - see FIXFAT.DOC, also on
the distribution disk.
Always run the DOS CHKDSK program immediately before running HDTEST on
a disk. If CHKDSK reports any problems, its /F option (or other means)
should be used to correct them before HDTEST is run.
____________________
HDTEST is invoked with the command line:
HDTEST device1 [device2[:pathname]] [optional parameters]
"optional parameters" may include one or more of the following:
[/A] [/B] [/Cn | /CQ] [/D | /I | /U] [/F] [/G[V]] [/Hnnnn[:nnnn]] [/M]
[/N] [/P] [/R[n]] [/Snnnnn] [/U] [/V] [/X] [/Yn] [/Z[n]]
"device1" is the name of the device to be tested, as for HDCHEK.
"device2" (which, if present, must be different from "device1") is the
____
name of a device on which a log file is to be written, which may be
immediately followed by a file- or path-name for the log file. If
only a device name (with or without a colon) is specified for the log
file, a file called HDTESTdn.LOG will be written to the default
directory on the specified device. "d" in this file specification is
replaced by the single-character specifier of the device being tested,
while "n" is replaced by the lowest decimal digit which results in the
creation of a new file (previous log files will not be overwritten).
___ ___
If all ten possible log file names for this test device have already
been used, the program will prompt for a new name. If a directory path
(ending in a backslash (\)) is specified as device2, HDTESTdn.LOG will
be created in the specified directory. If a full pathname is specified
(not ending in a backslash), a file with that pathname will be opened
___
as the log file. In this case (only), any pre-existing file of the
same name will be overwritten. If "device2" is not specified, errors
are reported to the console terminal. The DOS console redirection
facility should not be used to redirect them elsewhere.
___
_____________________________________________________________________
* See "Chips in Transition", by Bob Smith. PC Tech J. 4:4 (Apr. 1986):
__________
56-69. The code which the HD programs use to identify the CPU and
diagnose this problem is adapted from the CPUID program described in
this article and from code from subsequent, related, articles in that
(now defunct) magazine.
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For versions of HDTEST from V4.35, the spaces between the device
identifier and the flags (and between different flags) are optional -
the command lines "HDTEST C:/A/F" and "HDTEST C: /A /F" are
equivalent.
The /A, /C, /D, /H, /I, /M, /U, and /V flags have the same meaning and
effect that they do for HDCHEK. When used for HDTEST, the /D flag
forces the use of INT 25 to read from and INT 26 to write to the
target disk.
The /B(oot/Partition sector test) flag forces the program to include
the boot/partition sector (track 0, head 0, sector 1) in the DOS area
for the purposes of read/write testing. The default action is only to
perform read and seek tests on this sector, even if read/write testing
of the DOS area is specified. Since the boot/partition sector is
effectively read-only under normal circumstances (it is only written
_______
to during low-level formatting, and by FDISK and other disk
__
partitioning programs), read/write testing is less vital than for the
rest of the disk. In addition, at least one hard disk controller (a
Western Digital board which allows a single disk to be addressed as
two "physical" devices) will not allow test patterns to be written to
this sector. Certain devices (chiefly RAMdisks) appear to DOS to be
hard disks but do not, in fact, possess boot/partition sectors. On
these devices, HDTEST will report check/test results on the
boot/partition sector while actually reading/writing the device's boot
sector - the latter sector will simply end up being checked/tested
twice under these circumstances.
The /F(ast mode) flag causes the program to use only two test patterns
(all 1s and all 0s) for read/write testing. It is intended for use on
floppy disks and for "quick and dirty" testing of other devices.
The /G(ive error details) flag causes the program to determine the
location of errors occurring during testing of the disk's data area at
the sector level (they are normally handled at the cluster level), and
to report on the location of all bad sectors found. The report is
written to the log device or file after all testing is finished. By
_____________________________
default, only an error code is given for each bad sector - if a V (for
"verbose"!) is appended to the flag, the error code is expanded to a
report similar to that given for each bad cluster. This flag is
ineffective (and ignored) if HDTEST is using DOS interrupts, either
because the /D flag was set or because the program was not able to
access the disk at the BIOS level.
The /N(o Query) flag disables the individual prompts for confirmation
which the program normally issues before remapping clusters which are
marked as "Reserved" or which are part of a file which is marked as
"System", "Hidden", or "Readonly". The /N flag does not prevent the
___
program from prompting for confirmation before updating the disk.
The /P(rint) flag causes the log file to be directed to the PRN device
(normally LPT1), and overrides any "device2" specification.
The /R(epeat)n flag causes HDTEST to go through n complete testing
cycles. Omitting n, or setting it to zero, causes HDTEST to run
continuously until terminated by pressing <Esc>). Instead of stopping
after completing the testing of allocated data clusters, the program
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immediately starts again with the DOS area. Any bad clusters found and
flagged in the first pass should be reported as "already marked as
bad" in subsequent passes. The /R flag implicitly sets the /N flag.
The /S(tart)nnnnn flag causes HDTEST to start testing occupied
________
clusters at cluster number nnnnn (expressed as a decimal number).
_______
There must be no space between the "S" and the number. This option
will mainly be useful when a previous run of HDTEST was interrupted
(by pressing <Esc>), since it allows you to start where you left off.
Note that, in order to be sure that data is not remapped to a bad
area, HDTEST always tests all empty clusters before starting to test
______ ___
occupied clusters. For this reason, using the /S flag will not result
in a large time saving if your disk is nearly empty, and it will make
the most difference on a full, or nearly full, disk.
The /Y(es, please remap)n flag causes HDTEST to remap up to n (a
decimal number) bad clusters without prompting for confirmation. It is
effective only if HDTEST is allowed to run to completion, and is
intended to allow the program to be run unattended on multiple disks
from a .BAT file. If more than n bad clusters are found or if the
program is aborted (by pressing <Esc>), the normal prompt for
confirmation is issued before any bad clusters are remapped. See
"Running HDTEST from a .BAT file".
The /X(clude bad clusters) flag causes HDTEST not to test clusters
___
that are already marked as bad by FORMAT or previous runs of HDTEST
(the default is to test all clusters every time the program is run).
___
This saves some time when testing a disk with a substantial number of
known defects. The marked clusters will be reported as bad but will
not be retested. The /X flag overrides the /G flag for previously
marked clusters - no bad sector report will appear for these clusters
if both flags are used.
The /Z(ero bad sectors)n flag controls how HDTEST deals with sectors
that could not be read correctly (due to unrecoverable read errors)
when it remaps bad clusters. Versions of HDTEST up to and including
V4.10 (somewhat cavalierly) disregarded the remaining contents of the
entire cluster if one or more sectors in it were unreadable, and
remapped it to a cluster of NULLs. The default action is now to
replace only the unreadable sector(s) with NULLs, transferring the
_________
remaining sectors intact to the remapped cluster. There are, however,
two other options, which can be chosen by setting n to 0 or 2 (if n is
omitted, 1, or any other number, the default action is taken). Setting
n to 0 uses the old default (remaps the bad cluster to a cluster of
___ _______
NULLs), while setting n to 2 goes to the other extreme and copies all
data read (some of which is almost certainly invalid) to the remapped
cluster. It is always safe and often advisable to use the /Z2 option
provided that you do not try to use any non-ASCII files that have been
______________________________________________________________________
remapped with unrecovered read errors and this (/Z) option. Remapped
___________________________________________________________
ASCII files can be inspected with an editor and fixed up where
necessary - non-ASCII files (e.g. .EXE, .COM, .WKS files) may appear
to be undamaged (the program may run, the worksheet be readable, etc.)
but they can still contain small changes which will cause trouble
later, and they cannot easily be checked. The large "holes" which /Z
options 0 and 1 leave in such files usually allows it to be much more
obvious that they are defective!
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WHAT DOES HDTEST DO?
____________________
After displaying its copyright message, HDTEST reads the FATs and
scans the root directory and all subdirectory trees of the specified
device before initiating a short dialogue. All questions are of the
"Yes/No" type and should be answered by typing "Y" or "N" (case does
not matter) and pressing the <Return> key. Pressing the <Return> key
alone is equivalent to giving the default response (which appears in
square brackets at the end of each prompt). HDTEST then proceeds to
test the specified device. By default, the DOS area (boot sector,
FATs, and root directory) is not subjected to Read/Write testing,
since failures in this area usually make themselves apparent fairly
rapidly. The user can, however, choose to run these tests on the DOS
area too, or to limit testing to read and seek tests only over the
whole partition.
In its reports to the screen, HDTEST uses the convention that read-
only testing is "Checking" while read/write testing is "Testing" - it
always "checks" the boot/partition sector and the rest of the DOS
area, but only "tests" them if requested to do so.
In "checking" or "testing" a block (sector or cluster), HDTEST first
reads it (retrying, if necessary, up to five times) and then does the
longest possible seek away from it before attempting to read it again.
"Checking" is complete at this point. "Testing" continues with the
program sequentially writing 20 (or 2, for "fast mode") different bit
patterns to the block and checking that each one can be read
correctly, before rewriting the original contents of the block (and
reading it again to ensure that it has been restored correctly).
Errors that occur at any point in this process are reported and (if
the block is in the data area - errors in the DOS area are always
treated as fatal) the block is remapped. If an error is detected in a
"Reserved" cluster or in one that is part of a file which is marked as
"System", "Hidden", or "Readonly", the user is normally asked for
confirmation before the cluster is remapped, otherwise it is assumed
that remapping is desired.
HDTEST keeps a copy of the FAT and a map of the device's directory
structure in memory. A bad cluster is remapped by transferring its
contents to a free cluster and (if the bad cluster was in use)
changing all necessary FAT and directory entries in memory so that the
pointer chain which maintains the structure of the affected file or
subdirectory remains valid. The bad cluster's FAT entry is then
altered to identify it as bad to DOS. The device's FATs and
________
directories are not altered until the whole device has been scanned,
and then only after the user has confirmed that it is OK to proceed.
This means that a power failure and/or an inadvertent power-off which
occurs while the program is running will cause the loss of, at most,
one cluster of data and of no FAT or root directory information
(unless you are very unlucky and it happens after you have confirmed
____
that you want a damaged data area to be remapped and while this is
being done). If a power failure and/or power-off occurs while a
cluster which contains the directory information of a subdirectory is
being tested, part or all of that subdirectory will probably become
inaccessible to DOS, although the data in it will remain on the disk
and be potentially recoverable with the aid of (e.g.) the Norton
Utilities (TM).
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You can safely interrupt the testing process part way through (by
pressing the <Esc> key) with no risk of leaving a partially updated
FAT or directory. If you do interrupt the program in this way, you
will be given the option of updating the disk, so that bad clusters
which were detected before <Esc> was pressed can be remapped.
Errors which occur in the program's initialization phase cause it to
abort with an error message and (sometimes) a hexadecimal error code.
The meaning of the error code is context-dependent and it is useful
only to technical support personnel (i.e. the author!). Errors
detected during read-write testing only cause the program to abort if
they occur during testing of the DOS area, or if remapping is
impossible (only likely to happen if the disk is full). In any event,
a description of the error is written to the log file (if any) and/or
to the screen. This specifies the cluster or (for the DOS area) sector
number and the name of the affected file (if any), and defines the
type(s) of error which occurred. Appendix B contains a discussion of
some of the more technical aspects of data storage on disks (floppy
and hard), and includes more information about some of the possible
errors that may be encountered.
HDTEST takes a very long time to run to completion because of the
____
large number of reads and writes it does for each cluster. A typical
time for full testing ("slow" mode) of an XT disk (10 Mb) would be 2
hrs; full disk testing on a 30 Mb Enhanced AT takes at least 4 hrs.
Note also that using the /D or /G flags will substantially slow down
the testing of disks with significant numbers of bad spots. Using the
/X flag as well will allow the physical location of new defects to be
reported without requiring that known bad areas be exhaustively
retested.
USING THE SPECIAL PRE-BOOT
__________________________
All IBM systems (at least non-PS/2 ones - I have little experience,
yet, with the new line of IBM hardware) - and almost all clones
capable of running IBM PC-DOS (rather than "generic" MS-DOS) should
also run the HD programs with no problems, and should allow them to
locate and use the ROM BIOS INT 13 entry point with no help from the
user. Less compatible systems have presented more problems in the
past, but this version of HDTEST is distributed with a supplemental
program (BOOTLOAD) which can be used to modify the boot sector on a
floppy disk and create a special pre-boot floppy to allow
identification and use of the "real" INT 13 entry point on almost any
MS-DOS-compatible system. Once created by BOOTLOAD, the special boot
sector will be correctly duplicated if copy the disk by using the DOS
____
"DISKCOPY" command - it will not be copied by a "COPY *.*" command.
___
Further documentation for the BOOTLOAD program (BOOTLOAD.DOC) should
have been included in this package.
After using BOOTLOAD to create the special pre-boot disk, insert it in
the boot drive (normally drive A), then (re)boot your system as you
normally do (either by switching it on or by pressing the <Ctrl>-
<Alt>-<Del> combination or its equivalent for your hardware). After
performing its self-test, the system's BIOS will load and pass control
to the code on the boot sector of the floppy. On a normally FORMATTed
floppy disk, this code attempts to locate the MS-DOS system files at
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the beginning of the disk's root directory and to load and execute
them. The HDTEST boot disk will not load DOS (even if you SYS the
disk) - it simply reads and reports on the contents of the INT 13
vector (which DOS has not yet had a chance to tamper with, since it
has not been loaded) and conditionally transfers the vector to the INT
68 location. The INT 68 location is normally unused in MS-DOS systems
- it is defined that way by IBM - and is usually loaded either with
zeroes or with a pointer to some "do-nothing" code by the BIOS
bootstrap. The HD programs use it for the "real" INT 13 vector,
normally saving the original contents of the location on entry and
restoring them on exit. This behavior is modified by specifying the /U
switch on the command line. The HDTEST boot sector code will only
transfer the "real" INT 13 BIOS entry point to the INT 68 location if
the latter contains either zeroes or the same vector as INT 69. In the
______ __
latter case (since there is no point in having two "real" interrupt
vectors pointing at the same place), it is assumed that both are
pointing at "do-nothing" code. If the INT 68 vector is neither 0:0 nor
_______ ___
the same as the INT 69 vector, the preboot code will leave it alone
and report that the INT 13 vector was not transferred, otherwise it
will confirm that the transfer has taken place - in any event, you
will be given an opportunity to write down the vector and can then
remove the disk and press a key to allow the boot process to complete.
If you need to boot from a floppy disk, for some reason, a new,
bootable, disk can be inserted before you press the key to continue.
If the preboot reported that the INT 13 vector was successfully
transferred, you should simply specify the /U flag on the HDTEST or
HDCHEK command line, in addition to the "short" form of the /H flag
______________
(if the BIOS ROM is at an unusual location for the class of machine).
The requirement for the /H flag with unusual hardware allows the
program to do some additional "reasonableness checking". Unless some
other software interferes with it, the INT 68 vector will then
continue to be set up correctly for use by the HD programs until the
system is switched off or rebooted.
If the preboot was not able to transfer the vector, or if you know
that a device driver or resident program loaded by your DOS uses INT
68, you should invoke the HD programs with the "long" form of the /H
flag, specifying the full address displayed by the preboot. No error
checking is attempted in this case - if you mistype the address, the
first time the program attempts to access the disk, it will jump to a
(effectively) random location in ROM, with potentially disastrous
results. If it is feasible, use of the pre-boot disk and the /U flag
is preferable (in terms of safety, if for no other reason) to that of
the "long" form of /H.
The following example may help to clarify matters. You have a clone
system with a BIOS ROM location that is non-standard. The HDTEST boot
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disk reports that the INT 13 entry point is at E000:13AC, and that the
vector has been successfully transferred. You may now run HDTEST with
the command line:
HDTEST C: A: /U /HE000
____
You may also, now or later, with or without prior use of the pre-boot,
_______________
run HDTEST with the command line:
HDTEST C: A: /HE000:13AC
_________
Note that the /H flag is not needed with the /U flag if the segment
___
address of the hard disk BIOS is the usual value for the system type
___________________
(as determined by the processor). For a system based on an 8088, 8086,
80188, or 80186 processor, this "usual" value is C800. For all other
systems, the "usual" value is F000.
One further problem may be encountered - certain hard disk BIOSes do
not exactly comply with IBM standards in dealing with disk accesses
that cross track boundaries, and will produce frequent errors when
such accesses are attempted. It was this "multi-track read" problem
which resulted in a number of previously apparently 99.99% IBM-
compatible systems failing to run IBM PC-DOS 3.3 (which was the first
version of DOS actually to attempt such accesses). IBM issued a "fix"
for this problem, in the form of a program which, when run on the
"bad" system, creates a device driver which protects the BIOS from
being asked to do something that it can't. This device driver does its
job by intercepting INT 13, and will, of course, do nothing to help
the HD programs if they are bypassing that interrupt. Use the /M flag
with the HD programs if you have a system on which PC-DOS 3.3 or above
will not run without being "fixed" as described. It forces the
programs to split up the multi-track accesses into manageable chunks -
this can be expected to cause a substantial slowing of the programs'
operation.
DEALING WITH BAD CLUSTERS
_________________________
It is not unusual for a new hard disk to have a small, constant,
_____ ________
number of bad clusters. IBM's quality control standards allow, for
example, 5% of the surface area of a disk to be bad (!). These pre-
existing bad clusters, which correspond to imperfections in the
magnetic coating on the disk, will normally be detected and marked by
the DOS FORMAT program, and HDTEST will report them as "already marked
as bad". This should not be regarded as evidence of any real problem
with the disk, although some suppliers (not including IBM) will
___
replace such disks under warranty if pressed to do so. It is also not
unusual for a disk to develop a few more defects as it ages. When
___
these do develop, they are also subsequently constant in size and
position, and will be reported as "already marked as bad" by HDTEST on
runs subsequent to that during which they are first found. The
occasional appearance (and subsequent persistence) of a new bad
__________
cluster is, therefore, not necessarily evidence of serious trouble
developing. However, if more than one or two new bad clusters are
reported by HDTEST, and especially if two consecutive runs (or passes,
if the /R flag is set) of HDTEST report different bad clusters, there
_________
is a good chance that the hard disk or controller is developing a
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serious problem - the disk should be backed up immediately and the
disk and/or controller sent for repair at the earliest opportunity.
New bad clusters in the data area are automatically mapped out by
HDTEST, and no further action is necessary. Bad sectors in the DOS
area can be handled in two ways:
1) If you are able to do a low-level format on your hard disk (most
_________
makers of "add-on" hard disks supply a method of doing this, either in
the form of a short program, or by giving instructions for running a
program in the ROM BIOS from DEBUG), back up the entire hard disk
______
(including any non-DOS partitions), run the low-level format, use
FDISK to repartition the disk, and then run the DOS FORMAT program. If
HDTEST now reports no errors in the DOS area you can restore all your
files and continue to use the disk. You should, however, use HDTEST to
test (at least) the DOS area fairly frequently for a month or so to be
sure that the problems are not going to recur.
2) If you do not have the means to do a low-level format, or if you
follow the above instructions and HDTEST continues to report errors in
the DOS area, your only other choice is to back up the DOS partition,
reconfigure the disk with FDISK so that the new DOS partition starts
above the bad area, reFORMAT it, and restore all of the old files to
the new DOS partition (which will unavoidably be a little smaller than
the old).
If the hard disk's boot/partition sector (track 0, Head 0, sector 1)
becomes bad, the disk is useless and must be replaced. This sector is
only subjected to read/write testing if the /B flag is specified on
__________
the command line, so any reported errors (in sector -1) during normal
__
testing represent a problem reading the sector and are likely to be
_______
significant. Problems encountered during read/write testing of this
sector do not always indicate a significant problem - certain
___
controller cards may not allow test patterns to be written to it,
resulting in a report of multiple errors on read/write testing.
Consequently, if multiple errors are reported on read/write testing of
the boot/partition sector, but read-only testing proceeds without
problems and the rest of the disk seems to be OK, there is probably no
cause for concern.
RUNNING HDTEST FROM A .BAT FILE
_______________________________
Versions of HDTEST from V4.75 can be run from a .BAT file (e.g. for
unattended testing of multiple disks) without the user losing the
ability to "escape" cleanly from the program. The /Y flag also allows
the user to specify a maximum number of new bad clusters for each disk
to be remapped "automatically", so that the .BAT file will normally
just keep going but will pause and wait for input if something
terrible seems to have happened to a disk. In order to run HDTEST from
a .BAT file, it is necessary to prepare both the .BAT file with your
____
usual HDTEST command lines, generally including the /Y and /N flags,
and a second ASCII file containing the answers to HDTEST's initial
___
questions, one per line. DOS's input redirection ("<") command is used
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to "feed" these answers to HDTEST. If the "answer" file is called
(e.g.) ANSWERS.TXT, each line in the .BAT file will look like:
HDTEST dev1 dev2 /opt1 /opt2 <ANSWERS.TXT
____________
If you do not wish to read/write test the DOS area of the disk, your
answer file can consist of three blank lines. If you do wish to
__
read/write test the DOS area, the first line of the answer file can be
blank, the next two must start with a "y" and the fourth can be blank.
___
In order to allow HDTEST to be interrupted from the keyboard, if
necessary, the program terminates input redirection before starting
testing the disk, so anything in the answer file after the answers to
_____
HDTEST's initial questions will be ignored.
On exit, HDTEST now returns a meaningful ERRORLEVEL, which can be
tested from a .BAT file by means of DOS's "IF ERRORLEVEL" syntax.
Versions of the program prior to V4.81 returned an ERRORLEVEL of 1 on
aborts and 0 otherwise - HDCHEK still does this. The current version
of HDTEST normally returns an ERRORLEVEL equal to the number of new
bad clusters found. On aborts it returns 254, and, if deliberately
terminated by the user (either by answering "N" to the last question
in the introductory dialogue or by pressing and confirming <Esc>
during testing), it returns 255.
Note that this application of HDTEST is really intended for advanced
users, and I am aware that this description is somewhat cursory - more
help in using it can, if necessary, be obtained directly from me.
BUGS AND OTHER UNPLEASANT SUBJECTS
__________________________________
Although, like all programmers, I like to think that my product is
perfect, it is possible that there are a few bugs lurking in the
depths of the program, and likely that some combination of software
and hardware exists which HDTEST cannot figure out and/or cope with.
If you think you have found a bug and/or if you cannot get either of
the programs to work on your system, do the following:
1) Reread this documentation! Make sure that you are doing exactly
what the documentation says to do. Make sure (if you are testing a
drive with removable media) that the media is not write-protected.
2) Boot your system from a "virgin" DOS disk - preferably a copy of
your DOS distribution disk - and try to run the HD programs again. If
they run in this environment but not in your normal DOS environment,
try reconstructing the system under which they failed by adding things
one by one until the problem recurs. If you find a specific piece of
software which causes the trouble, let me know about the
incompatibility.
3) If the above approaches do not help, or if HDCHEK runs but HDTEST
bombs (the reverse should never happen), send me as detailed a
description of the problem as possible and I will do my best to
diagnose and fix it. A bug report should always include a full
______
description of the system being used (hardware and software), as well
___
as a copy of the output from a run of HDCHEK.
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I can be contacted by U.S. mail at the address given earlier in the
documentation, by BIXMail to pfletcher, or by Compuserve EMail to
72255,305.
CHANGES FROM PREVIOUS VERSIONS
______________________________
The first version of the HD programs actually released (not including
beta-test versions) was V2.60. The programs have grown and developed
gradually, for the most part, but the pre-V4.65 releases listed below
have constituted the most significant "watersheds" - features added
and changes made between the listed releases are treated here as if
_______
first included in the next listed release, so some individuals for
____
whom this is an upgrade may have packages with some, but not all, of
the features listed for a given release. Note that the previous V4.45
Shareware version of the program is not listed here - it was identical
to V4.41 except that it included the "fix" for the deficiency which
was corrected at V4.70 in the Registered version. Unless otherwise
noted, both programs were affected by the listed changes.
Version 4.95 (this version)
____________
1) Added code to prevent undetected "wrap-around" when using existing
INT 13 on a disk with more than 1024 cylinders.
Version 4.94
____________
1) Copyright screen displayed for minimum of 2 seconds (may be longer
if program is being run on a large device).
Version 4.93
____________
1) Deficiency allowing "queueing" of keystrokes in typeahead buffer
fixed. <Esc> now produces (almost) immediate response even if other
key(s) have been pressed first.
Version 4.92
____________
1) /V option added to bypass "virtual mode" prohibition.
Version 4.91
____________
1) Problem with FAT comparison error report for > 64 Kb FATs
introduced at V4.90 corrected (HDCHEK).
(Version 4.90
____________
1) Previous restriction on testable FAT size (was 64 Kb) removed.
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Version 4.84
____________
1) Minor change to reporting of initialization errors (HDCHEK).
Version 4.83
____________
1) Remainder of fix for bug noted at V4.80!
Version 4.81
____________
1) Meaningful ERRORLEVEL returned on exit (see "Running HDTEST from a
.BAT file) (HDTEST).
Version 4.80
____________
1) Bug causing the programs to fail if a subdirectory were physically
located beyond the 32 Mb boundary on a large (> 32 Mb) device
partially located and corrected.
Version 4.75
____________
1) Log file specification capabilities enhanced (HDTEST).
2) /Y flag and .BAT file support added (HDTEST).
Version 4.71
____________
1) Fully automatic setting of default ROM BIOS location by CPU type.
Meaning of and requirement for /A flag modified.
Version 4.70
____________
1) Deficiency causing "fallback" to DOS interrupt level under some
circumstances when attempting to test "extended devices" on a second
physical hard drive fixed. The Shareware V4.45 also included this
"fix".
Version 4.66
____________
1) Support for large devices under Compaq DOS 3.31 added (see
description of /C flag).
Version 4.65
____________
1) DOS 4.0 support added (including BIOS-level access to large
partitions), but see notes on V4.8x.
2) Minor changes made to final screen & file output format (HDTEST).
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3) Minor improvements made to memory allocation algorithms.
4) /G option added (HDTEST).
5) /X option added (HDTEST).
Version 4.54
____________
1) Deficiency in CPU recognition code (which caused fast AT clones
sometimes not to appear to be ATs) fixed.
___
2) ANSI.SYS requirement removed.
3) Semi-automatic CPU recognition added.
4) Pre-boot functionality, /M option, /U option, and extended
(segment:offset) form of /H option added.
Version 4.41
____________
1) Deficiency (introduced at V4.00) causing HDCHEK to issue an
incorrect error report on an abort resulting from a FAT comparison
error corrected.
2) Minor deficiency, causing HDTEST to create an empty log file on the
specified device when both a log device and the /P option were
specified, corrected.
3) Work-around for hardware multi-sector read ECC problem (see
Appendix B) added (HDTEST).
4) Support for small (<= 10 Mb) hard disks patched to have small
clusters and 16-bit FATs added.
5) Requirement that command line option flags be separated by one or
more spaces or tabs removed.
6) /R option added (to HDTEST) for multi-pass disk testing.
Version 4.30
____________
1) Support for BIOS-level access to DOS 3.3 extended partitions added.
2) /Z option added (to HDTEST) to control remapping of unreadable
sectors in bad clusters.
Version 4.10
____________
1) Assorted minor changes made to screen displays.
2) /C option added to allow the programs to be used on some non-IBM
compatible MS-DOS systems.
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3) /D option redefined - old /D option became new /I option.
4) /F option added (to HDTEST).
5) "Short" form of /H option added.
Version 3.13
____________
1) Assorted minor bugs and deficiencies in error reporting and
termination routines fixed (HDTEST).
2) Minor bug affecting reporting of multiple corrected ECC errors
fixed (HDTEST).
3) Disk reset added before retry on all errors (HDTEST).
4) Absolute limit on number of files and directories on device
removed.
5) Display of total sector/cluster count during testing added
(HDTEST).
6) /A option added.
7) /B option added (HDTEST).
Version 2.73
____________
1) Bug (in V2.60) which could cause bad termination and possible
subdirectory inconsistencies if a sector which was not in use was
found to be bad, fixed (HDTEST).
2) Bug (in V2.70) which caused HDTEST to enter a terminal input loop
if ANSI.SYS was not loaded and <Esc> was entered to abort it, fixed.
3) Minor bug in V2.60 (which resulted in a failed directory scan if
the program was run on a write-protected device) fixed.
4) Internal changes made to avoid interference with expanded memory
device handlers.
5) Ability to update disk after HDTEST terminated by user (typing
<Esc>) added.
6) /S option to start checking occupied clusters at a given cluster
number added (HDTEST).
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APPENDIX A - SUMMARY OF FLAG SETTINGS
_____________________________________
/A(T) - used to tell the HD program that it is being run on an IBM AT
(HDCHEK and HDTEST). /A is not equivalent to /HF000.
/B(oot/Partition sector test) - used to include the hard disk
boot/partition sector in the DOS area for the purposes of read/write
testing (HDTEST only).
/C(lone BIOS)n - used in systems which do not support the IBM BIOS's
INT 11 "equipment determination" BIOS function (e.g. the Tandy 2000).
The parameter ("n") is the number of floppy drives attached to the
system, which is otherwise determined automatically (HDCHEK and
HDTEST).
/CQ (Compaq) - used to indicate that the program is running on a
Compaq system. If DOS 3.31 (or above) is in use, large (> 32 Mb)
devices are supported (HDCHEK and HDTEST).
/D(OS interrupts) forces the program to use only DOS interrupts
(INT 25 and INT 26) for access to the target device. May not be
combined with the /I, /H, or /U flag (HDCHEK and HDTEST).
/F(ast mode) limits read/write testing to the use of two patterns only
(HDTEST only).
/G(ive error details) allows the physical disk location of bad sectors
to be identified (HDTEST only).
/H(ex BIOS address)nnnn[:nnnn] - used to tell the HD programs that the
ROM BIOS of the device being tested is located at nnnn, which is
interpreted as a Hexadecimal segment address, rather than at the (CPU-
dependent) default. The extended (segment:offset) form of the command
is used to force the programs to use the given address as the INT 13
entry point (HDCHEK and HDTEST).
/I(nterrupt 13) - forces the program to use the existing INT 13
vector. This is the default under DOS 2.x. May not be combined with
the /D, /H, or /U flag (HDCHEK and HDTEST).
/M(ulti-track read problem) - bypasses the multi-track read problem
which also prevents certain otherwise IBM-compatible clones from
running PC-DOS 3.3 (HDCHEK and HDTEST).
/N(o Query) - disables the individual prompts for confirmation which
the program normally issues before remapping "special" clusters - does
not prevent the program from prompting for confirmation before
___
updating the disk (HDTEST only).
/P(rint) - causes the log file to be directed to the PRN device
(HDTEST only).
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/R(epeat)n - causes HDTEST to perform n complete testing cycles (or to
continue until interrupted for n=0) (HDTEST only).
/S(tart from)nnnnn - causes HDTEST to start testing occupied clusters
________
at cluster number nnnnn (expressed as a decimal number) (HDTEST only).
/U(se existing INT 68 vector) - causes the HD programs to use the
existing INT 68 vector as the INT 13 entry point (HDCHEK and HDTEST).
______
/V(irtual mode) - bypasses normal prohibition on running program if
80286 or better CPU is operating in "virtual mode". Allows use with
QEMM-386 and 386^Max.
/X(clude marked bad sectors) - causes HDTEST to report on but not
retest clusters that are already marked as bad (HDTEST only).
/Y(es, please remap)n - allows HDTEST to update the disk by remapping
up to n new bad sectors without prompting for confirmation (HDTEST
_______
only).
/Z(ap bad sectors)n - controls remapping of unreadable sectors in bad
clusters (HDTEST only) - n may have one of the following values:
0 - Remap clusters with any unreadable sectors to all NULLs
1 (default) - Remap only actual unreadable sectors to NULLs
2 - Transfer all data read to the new cluster
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APPENDIX B - DISK ERROR MESSAGES
________________________________
Users of earlier versions of this software repeatedly requested that I
provide a more detailed explanation of the significance of some of the
error messages displayed by HDTEST when it encounters a bad sector or
cluster on the disk. It is not possible to do this without assuming
(or imparting) a more detailed understanding of the "nitty-gritty"
details of data storage on hard and floppy disks than most people want
or need, let alone possess. This Appendix is not, therefore, "required
reading" for the safe or effective use of the HD programs. It is
intended as a tutorial for those who would like to understand some-
thing more of what is really going on on their hard or floppy disk
______
drive when the little red light comes on.
For the purposes of what follows, it is (fortunately) not necessary to
know or understand exactly how changes in magnetic flux on the surface
of a hard (or floppy) disk are translated into binary data, or vice
versa. That could be the subject of another long dissertation. I will
simply take for granted that binary data, conceptually organized into
8-bit bytes, can be read and written by the disk drive hardware under
the command of its controller (which usually resides on a separate
card plugged into one of the computer's expansion slots). I will be
describing how blocks of data are physically arranged on a disk and
how the disk controller goes about ensuring that the data it reads has
not been corrupted since it was written.
I propose to start off by referring to some of the error-detection and
error-correction techniques and procedures that are applied to data
stored on magnetic media. These techniques and procedures are
necessary because, although magnetic media are very reliable and the
technology of recording and playback is well understood, there always
remains the possibility that a defect in the medium or some other
intercurrent problem may cause the sequence of bytes read back from a
disk or tape to be something other than a perfect duplicate of the
sequence that was stored. If a single copy of the raw data were all
that were recorded, there would be no way of immediately detecting
(let alone correcting) such an error. It might be brought to light
when the file that was changed caused problems when it is used by or
executed as a program, but it might not become apparent until it had
propagated itself through and caused problems or errors in multiple
other programs or files. This would clearly be an unacceptable state
of affairs. In order to prevent this from occurring, then, there
should be some means of checking data which is read in from storage
for errors, and/or (preferably) of correcting any errors which may
have occurred before any use is made of the data.
______
Although error checking and/or correction can (and sometimes does)
take place at any level from that of the application program down to
that of the device controller, I am only going to describe the means
that are used by hard and floppy disk controllers. When a block of
data is passed to the controller to be written to the disk, a series
of arithmetical operations is performed in sequence on all the bytes
in the block, to produce a 2-byte (for diskettes) or multi-byte (for
hard drives) code. The diskette controller implements what is known as
a cyclic redundancy check (CRC) algorithm, which is optimized to allow
detection of all single bit errors and many longer error bursts (it is
_________
reasonable to assume that errors will most probably either affect a
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single bit at random or, if they result from media defects, a number
of adjacent bits). The longer (at least 32-bit) error correcting code
(ECC) calculated by a hard disk controller gives enough information to
allow detection and correction of, at least, all single bit errors and
______________
detection of most likely longer error bursts. The CRC or ECC is saved
on disk with the data and is read back in by the controller when the
data is read. The controller then compares the saved CRC or ECC with
one newly calculated from the data. If the two are identical, the data
is assumed to be valid and a successful read is signalled. If there is
a discrepancy, a diskette controller always returns the data with a
"CRC error", since the CRC code does not contain enough information to
allow the incorrect bit or bits to be identified. On a hard disk, if
the ECC comparison suggests a correctable error, it will be corrected,
and the read call will return with a "Corrected ECC Error" code but
with (presumably) valid data in the transfer buffer. If a more
extensive error is detected, on the other hand, the call returns with
a "Uncorrectable ECC Error" code (which is the same as the CRC error
code).
The 32-bit ECC used by IBM and many compatible disk manufacturers
allows correction of single-bit errors only. Manufacturers of other,
____
usually more expensive, controllers use longer and more complex ECCs,
to allow the correction of some multi-bit errors, but the necessity to
minimize the time taken to calculate the ECC (which is part of "access
time") sets tight limits on how complex it can be. ECC error
correction is unfortunately not infallible. It is possible for a
___
complex, uncorrectable error to result in the same ECC disparity as a
__
different, correctable, error, so that invalid "corrected" data can be
______
returned. The longer and more complex the ECC, the less likely this
becomes, but there is no way of completely avoiding this ambiguity,
short of keeping multiple copies of the data on the disk. In addition,
some hard disk controllers* apparently abort with the "corrected ECC
error" code immediately on encountering a sector containing such an
___________
error, even if it is not the last sector in the block specified by a
___
(multi-sector) read request. This non-intuitive (to say the least of
it) behavior can combine with DOS 3.x's habit of ignoring corrected
________
ECC errors to result in apparently inexplicable disk-related problems,
up to and including system crashes (if the file in which the problem
occurred contained executable code). This hardware deficiency may be
related to the problems which have plagued users of DOS 3.3 on some
(previously) apparently IBM-compatible non-IBM hardware, since these
also result from (similar but distinct) deficiencies in the clones'
handling of multi-sector disk reads. Prior to V4.36, HDTEST did retry
___
corrected ECC errors which were reported on the first read of a
cluster, but would eventually (if the corrected error persisted)
accept the data read as valid and copy and remap it to a "good"
cluster. This could cause trouble if the controller had the "immediate
abort on corrected ECC error" problem described above and the ECC
___
error were not in the last sector of the cluster, since the sectors
after the "bad" one would not have been read, and would be lost
(actually replaced by the corresponding sectors from the previous
________
cluster read) after remapping. On a machine with this problem, DOS
_____________________________________________________________________
* This behavior is known to occur with some early Western Digital
controllers (1002A-WX1, 1002S-WX2) but it may occur with others, too.
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would not, of course, have done any better than the earlier versions
of HDTEST at reading the bad cluster, and HDTEST at least warned you
that there was a problem, but the behavior described was certainly not
ideal. From V4.36, HDTEST rereads clusters in which a persistent
corrected ECC error is reported on the initial read sector by sector,
________________
to ensure that all the data in the cluster is transferred when it is
___
remapped. In most cases (as long as the ECC error was really
______
correctable), this will save the cluster (and the file of which it is
a part) intact.
DOS allows the programmer and/or computer user to think of and deal
with disk data in terms of files, lines, and/or records, but data is
always moved between a disk and memory a sector at a time. Any disk
read or write request passed to DOS eventually gets translated into a
command to read or write one or more sectors on the disk, commencing
at a specified head, track, and sector. A floppy disk may have either
one or two usable surfaces, corresponding to the top and bottom of the
________
disk. A hard disk usually has at least two surfaces, and may have
more, since multiple physical "platters" are frequently incorporated
in a single device. Each surface is normally accessed by and
corresponds to a single read/write head, which moves radially across
____
it, although one surface on newer disks is often reserved for "servo"
tracks, which are written with a special pattern that allows the
controller to ensure that the read/write heads are kept exactly
aligned with the data tracks. For a single device, the (data) heads
are, by convention, numbered sequentially from zero up to one less
than the total number present. Each surface is further divided into a
number of circumferential tracks (or cylinders) and each track is
______ _________
divided into a number of sectors. Again by convention, the tracks on
_______
each surface are also numbered sequentially from zero, with track zero
being the outermost track. The sectors on each track are normally
numbered from one to a number corresponding to the total number of
___
sectors on the track, but adjacent sectors do not normally have
___
consecutive sector numbers. A typical arrangement of the seventeen
sectors on a single track of an XT hard disk, for example, would be as
follows: 1,8,15,5,12,2,9,16,6,13,3,10,17,7,14,4,11. This "inter-
______
leaving" of sectors helps to make multi-sector disk reads and writes
_______
more efficient. The controller requires a finite time to process the
data from one sector before it can start reading (or writing) the
next. During this time, of course, the disk continues to rotate and
one or more of the sectors which physically "follow" the one that was
last accessed pass under the read/write head unread. Ideally, the
interleave (number of physical sectors separating consecutively
numbered sectors) should be such that the next sector is just about to
come under the read-write head when the controller is free to deal
with it, but, because this time is not exactly predictable, it is
better to be too conservative (as IBM usually is) and make it one or
two sectors longer than necessary than to be too optimistic. Too small
an interleave value is very undesirable, because it results in the
controller having to wait almost a complete disk rotation time for
each sector it misses to come round again.
At the beginning of each disk sector is an address mark, a short,
____________
recognizable (to the controller) bit sequence containing the track and
sector number. The process of writing the address marks for each
sector on a disk is known as "low-level" or "sector" formatting. The
DOS FORMAT program does this when it is run on floppy disks, but on
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hard disks the DOS program merely makes sure that all required address
marks are present - they are created by the disk manufacturer or
supplier's low-level format program, which may or may not be available
to the end user. After each address mark there follows a short gap (to
allow the controller time to recognize and respond to the address
mark), then the raw data, then the CRC or ECC data. A sector normally
contains 512 bytes of raw data, but DOS (and HDTEST) can recognize and
deal appropriately with devices with non-standard sector sizes.
When a sector read/write command is passed to the disk controller, it
(the controller) causes the disk's read/write head to move (seek) to
____
the specified track, waits a few milliseconds for it to settle down,
and then starts to "pay attention to" the data passing underneath it.
The controller locates and reads the address marks to confirm that the
read/write head is positioned at the correct track and to identify
each sector. If data is being read from the disk, the raw data and
recorded CRC or ECC from the requested sector(s) are transferred into
the disk controller's internal buffers and (assuming that no errors
are detected), thence to main memory. If data is being written, the
controller derives the error-checking data from the raw data and
writes both to the disk. Some of this process is under the direct
control of the controller hardware, but it is supervised by the
device's ROM BIOS, which is responsible for error-reporting. Errors
can occur at almost any stage of the read/write process, but (if the
disk is working at all) usually result from media defects or problems
developing in the mechanical components of the hard disk drive. Media
defects, once present, are generally constant in size and position
(although jarring a disk while it is being written to may sometimes
generate a temporary bad sector).
_________
When HDTEST detects an error during read/write testing of a sector or
cluster which has not previously been marked as bad, a (normally)
four-line error message is printed, either to the screen (by default),
to the printer (/P option), or to the logging file (if an output
device was specified). The first line of the message simply indicates
the sector or cluster number at which the error occurred. The second
line indicates what sort of error was detected and during what phase
of read/write testing it occurred. The third line indicates whether
HDTEST was able to recover and/or remap the data from the bad sector
or cluster, and the fourth indicates either the file which a bad
cluster formed part of or that the cluster was not in use. If it was
not possible to read one or more sectors from a cluster which
contained data (unrecoverable read error), a further two-line message
is printed which notes how many sectors were unreadable and how the
_______
data from the bad cluster has been remapped (which depends on whether
a /Zn option was specified on the command line). If the /M flag is not
specified when HDTEST is run on a system that suffers from the "multi-
track read" problems discussed in the main part of the documentation,
multiple bad clusters may be reported with no errors persisting on
__
sector-by sector reading. These reports should disappear if the /M
flag is used.
If the "verbose" form of the /G option is used, the bad sector report
will contain the equivalent of the second and third lines of the bad
cluster report for each bad sector. Note that, if the /X option is not
___________________
used to prevent testing of previously flagged bad clusters, these may
give rise to spurious warnings of possible data loss in the third line
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of the bad sector report. If no unrecoverable bad clusters were
________
reported, such warnings can safely be ignored. If the default form of
the /G option is used, the bad sector report gives only a Hex error
code for each bad sector. The LSB of this code is the value returned
(in AH) by INT 13. The MSB of the code depends on the phase of testing
during which the error occurred. In general, if the first digit (of a
four digit code) is C or above, an unrecoverable error occurred, but
error codes FFFD through FFFF have special meanings and indicate
recovered errors.
When the program detects an error during read/write testing of a
sector in the DOS area, only the first three lines described above are
printed and the program aborts. The remainder of this Appendix
contains more details of and further information on the possible
contents of lines two and three of HDTEST's disk error message.
The second line of the disk read/write error message will usually take
the form: "[Error Type] occurred during [phase of testing]". Possible
values for [Error Type] are as follows (in alphabetical order):
Address Mark Not Found - this is a fairly common error reported for
bad blocks which are present from "scratch" on a new disk, since a
significant media defect may well not retain sector formatting data
and/or the manufacturer may have made sure that a known bad track on
the disk will not be used by deliberately not writing address marks
there. If new bad clusters are reported with this error message, it is
likely that the hard disk surface has been physically damaged (perhaps
by a shock to the drive) but possible that the controller has a
problem.
Bad Controller - this means what it says, but check that all boards
and cables are properly seated before giving up.
Bad Sector - the BIOS was instructed to read a sector number which
should not (according to its configuration data) exist on the device.
This indicates either an internal program error or that the program is
having a problem determining the physical layout of the disk. Check
the values reported by HDCHEK against those in the disk documentation.
Bad Track - analogous to "Bad Sector".
Buffer Comparison - the data read from a sector differs from that
written to it. This should not happen, since it suggests either that
the device's error-detection functionality has failed or that it has
been overwhelmed. If it does occur, the most likely causes are
controller and memory problems (in that order of likelihood).
Corrected ECC - as discussed at some length above, the data retrieved
from a hard disk was incorrect but the device's error-correction
hardware was (probably) able to correct it.
DMA Boundary Violation - should not occur (HDTEST positions its
buffers to avoid crossing segment boundaries). Suggests either an
internal program error or a controller/BIOS problem.
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Hardware Timeout - a seek or other operation was not completed within
the maximum time allowed by the BIOS. Check connections, reseat
boards, otherwise suspect the mechanics of the disk.
Init Fail - should not occur (on a working disk).
Internal - internal program error. Make sure that your working copy of
HDTEST has not been corrupted. The disk is probably not defective.
Invalid Command - should not occur. Treat as Internal Error.
Multiple Errors - one or more additional errors occurred while HDTEST
was attempting to recover from an initial one. Multiple phase report
lines will be printed but the error types cannot be further specified.
Recovered - HDTEST recovered from the error and did not report on the
error type (should not occur).
Reset Fail - The device could not be reset (after an error). Usually
indicates major problems with the disk or controller, but check
connections, etc.
Sector Not Found - the requested sector's address mark was not found.
Likely to result from a media defect.
Seek Fail - after a seek to a track, the controller found that the
read/write head was not positioned correctly. Usually indicates a
significant problem with the (drive) hardware.
Sense Fail - the controller cannot find the drive! Check connections,
etc.
Uncorrected ECC - data error too major to be corrected. Usually a
media defect. This message will also be produced if a CRC error is
detected on a floppy disk.
Undefined - the BIOS cannot figure out what went wrong, but something
did!
Unknown - likewise!
Write Protection - HDTEST is attempting to write to a write-protected
device.
Possible forms for the rest of the second line are as follows:
... Error (unrecovered) occurred during first read - the cluster could
not be read without error in five tries before a seek to the other
"end" of the disk.
... Error occurred during first read - the error occurred during the
first read but was recovered after one or more retries.
... Error occurred during read after seek - the error occurred when
the cluster was read after a seek away.
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... Error occurred during pattern read/writes - the error occurred
during the pattern read/write phase of testing.
... Error occurred during final write - the error occurred when the
saved copy of the cluster was being restored to the disk.
... Error occurred during read after final write - the error occurred
when the restored cluster was being read back.
... (Buffer comparison) error occurred after final read - the copy of
the cluster read back after restoration to the disk differed from its
original memory image.
There are only three basic forms of the third line:
This error is (or "These errors are") recoverable (no data loss has
occurred). - the bad cluster was read successfully and has been
successfully restored to its original form, but it remains suspect and
will (with your permission) be remapped.
This error is unrecoverable, but remapping is possible. - the bad
cluster was read successfully but has not been restored to its
___
original form. Remapping should be successful, but the data will be
lost if this is not permitted.
This error is unrecoverable, and data may be lost! - the bad cluster
was not read successfully and will be remapped as provided by the
value of the /Z switch parameter if remapping is permitted. In any
event, some data loss has almost certainly occurred.
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_______________________________ _______________________________
APPENDIX C - EXAMPLE PROGRAM RUNS
_________________________________
Screen display from successful run of HDCHEK on partition occupying the
whole of a 20 Mb hard disk:
Device C: appears to be the DOS partition of a hard disk
It contains 41531 sectors
It starts at absolute sector 17 on the disk {THIS IS CORRECT}
_______________
The total partition size is approximately 20 Mb
There are 4 heads and 17 sectors/track
Sector size is 512 bytes
Each of the 2 (16 bit) FATs occupies 41 sectors
The Root Directory occupies 32 sectors
The data area starts at DOS sector 115, and contains 10354 clusters, each
consisting of 4 sectors
The directory scan was successful; a total of 1260 files and subdirectories
was found.
Screen display from successful run of HDCHEK on a freshly FORMATted DSDD
9-sector floppy disk:
Device A: is not a hard disk - using DOS interrupts
Device A: is a floppy disk
The disk contains 720 sectors
There are 2 heads and 9 sectors/track
Sector size is 512 bytes
Each of the 2 (12 bit) FATs occupies 2 sectors
The Root Directory occupies 7 sectors
The data area starts at DOS sector 12, and contains 354 clusters, each
consisting of 2 sectors
The directory scan was successful; a total of 0 files and subdirectories
was found.
Screen display from run of HDCHEK on 20 Mb DOS partition - directory
structure bad or unrecognizable:
Device C: appears to be the DOS partition of a hard disk
It contains 41531 sectors
It starts at absolute sector 17 on the disk
The total partition size is approximately 20 Mb
There are 4 heads and 17 sectors/track
Sector size is 512 bytes
Each of the 2 (16 bit) FATs occupies 41 sectors
The Root Directory occupies 32 sectors
The data area starts at DOS sector 115, and contains 10354 clusters, each
consisting of 4 sectors
The preliminary directory scan failed.
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Screen display from run of HDCHEK on 20 Mb DOS partition - FATs not
identical:
FATS are different
FAT discrepancy at byte 20F - FAT 1 has FF; FAT 2 has F8
Continue comparison (Y/N)? [Y]: n {user input}
_
Device C: appears to be the DOS partition of a hard disk
It contains 41531 sectors
It starts at absolute sector 17 on the disk
The total partition size is approximately 20 Mb
There are 4 heads and 17 sectors/track
Sector size is 512 bytes
Each of the 2 (16 bit) FATs occupies 41 sectors
The Root Directory occupies 32 sectors
The data area starts at DOS sector 115, and contains 10354 clusters, each
consisting of 4 sectors
Screen display from run of HDCHEK - program unable to deduce disk
structure - disk not recognizable as a DOS device:
Unrecognized media descriptor byte! - see error code
Error Code = F1 {F1 is not a media descriptor byte used by DOS}
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Log file from successful run of HDTEST on 20 Mb DOS partition:
HDTEST Log File - Wed Jan 07 11:44:52 1986
Testing Device C:
No new bad clusters identified - HDTEST finished.
Wed Jan 07 16:10:41 1987
Log file from run of HDTEST on 20 Mb DOS partition - one bad cluster
detected and remapped:
HDTEST Log File - Mon Jan 05 21:09:32 1987
Testing Device C:
Read/Write error at cluster number 7623!!
Corrected ECC error occurred during pattern read/writes
This error is recoverable (no data loss has occurred).
Bad cluster is in file \MYFILES\DATA5\FFT1234.DAT
1 new bad clusters identified, marked, and remapped - HDTEST finished.
Tue Jan 06 05:08:04 1987
Page 36
REGISTRATION FORM - HDTEST V4.95
________________________________
Please complete this form and return it with a check or money order for
$35.00 (+ $5.00 for shipping outside North America) or equivalent to:
Peter R. Fletcher
1515 West Montgomery Avenue
Rosemont
PA 19010
U.S.A.
None of the information on this form will be passed on to any other
individual or commercial organization.
--------------------------------------------------------------------------
This information is required to process your Registration:
Last Name:____________________________ Other Names:______________________
Address:______________________________ Town/City:________________________
State:_____________ Post Code:____________ Telephone:_________________
(evenings/weekends)
I understand that this software is supplied without warranty, express or
implied, and agree not to hold its author liable for any direct or
consequential loss arising out of my use of it.
Signature:______________________________
-------------------------------------------------------------------------
You are requested, but not required, also to answer the following
questions:
On What type(s) of computer are you using HDTEST? _________________________
CPU (8088, 8086, etc.)? __________ Amount of RAM (kB)? ____________
Type & Size of Hard Disk(s)? ____________________________________
Make and Type of Hard Disk Controller(s)? ______________________________
Do you own a Modem? Y N
Are you a member of BIX? Y N Compuserve? Y N
How did you obtain/hear about this program?
Did you think that the $35.00 registration fee for this program was:
Very Good Value? About Right? Excessively High?
Are there any other utility programs that you would like to see made
available as "User Supported Software"? What sort of programs?
Directory of PC-SIG Library Disk #1209
Volume in drive A has no label
Directory of A:\
BOOTLOAD COM 32000 8-28-88 1:35p
BOOTLOAD DOC 4613 2-22-90 5:31p
FIXFAT DOC 6908 2-22-90 5:32p
FIXFAT EXE 12627 3-14-89 1:23p
HDCHEK EXE 54370 3-10-90 3:13p
HDTEST DOC 136738 3-10-90 3:09p
HDTEST EXE 60522 3-10-90 3:13p
HDTEST OVV 4010 3-10-90 2:02p
MAKETXT EXE 8227 4-17-88 12:26p
README 1ST 1522 3-10-90 3:19p
GO BAT 38 4-21-88 9:08a
GO TXT 617 3-02-90 10:38p
FILE1209 TXT 2591 4-22-90 7:37p
13 file(s) 324783 bytes
29696 bytes free