First Edition (June 1988) First Edition (June 1988)
Radio KZ1O provides this manual "as is," without warranty of
any kind, either expressed or implied, including, but not
limited to, the particular purpose. KZ1O may make
improvements and/or changes in the product(s) and/or the
program(s) described in this manual at any time.
This product could include technical inaccuracies or
typographical errors. Changes are periodically made to the
information herein; these changes will be incorporated in
new editions of the publication.
All specifications subject to change without notice.
(c) Radio KZ1O 1988
Second Printing July,1988
Manual rev: A
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Notes:
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Preface
This manual describes the operation of the software program
IAU.EXE IAU.EXE. It describes the technical details of operation
and includes some general information about fixed disks.
IAU IAU is a program which changes the physical arrangement of
data on the computer's hard disk in order for the CPU to be
able to access (read and write) the data in the least amount
of time. This causes the computer system to operate in the
fastest possible manner.
This manual describes some basics of hard disk operation.
Then it explains what the "interleave factor" is, and why it
might be changed. A description of the software algorithm
follows.
A section is included containing frequently-asked questions
and their answers about the program.
Appendix A contains application notes. Appendix B shows
some of the display screens that you will see when running
the program.
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Contents ____
Page _______ Subject
1 Computer Data Storage
2 Interleave
4 Read, Re-format, Write
5 Question and Answer
6 Pictorial display
11 Appendix A- Application notes
B-1 Appendix B- Figures
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Computer Data Storage Computer Data Storage
Modern personal computers use rotating magnetic media for
data storage. These include floppy disks (3.5, 5.25, 8 inch
diameter) and fixed (5.25, 8 inch) disks. The data is
stored and retrieved on the disk by means of flux changes in
the magnetic coating of the surface of the media.
Floppy disks are typically made of Mylartm with a coating of
ferro-magnetic (iron) particles on both sides. The disk
retains the flexible quality of the Mylartm. This round
disk is then sealed in a square plastic jacket, which keeps
all but a small area of the media exposed.
The data is written and read analogously to the way a
musical record is made, and later played. The information
is contained in circular patterns of the disk. However, an
LP has the information recorded in a spiral; the floppy disk
has its data in concentric rings (like a dart board). The
LP spins at 33 R.P.M.; the floppy disk spins at 300 R.P.M.
(or in some systems, 360 R.P.M.) The floppy disk, depending
on several factors, can save from 160 thousand bytes (called
160K) to over a million (a "megabyte").
An interesting experiment is to take one of these floppies
out of its protective jacket and look at the media. Be sure
that the disk that you do this to has no important
information on it! Once you open the protective jacket, it
and the disk shouldn't ever be put back into the drive!
Hard disks are very similar to the floppy disk counterpart.
They are round, they have a coating of magnetic particles,
and they have data on both sides of the media. However,
they spin much faster in the drive (3600 R.P.M.), hold more
information (20, 30, 40, or more megabytes), and do not
bend. They are also not designed to be removed from the
computer as with floppies.
The early (1980) personal computer hard disks had capacities
of 5 megabytes. They were single-platter devices, with
their 160 data tracks far apart by today's standards.
However, progress in design and manufacturing has made
thousand-track, multi-platter hard disk systems commonplace
(and cheaper in today's dollars than the older ones!).
Thus, you can now have at your disposal, on your desk, a
computer system with many "K" of RAM, many "meg" of hard
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disk storage, rivaling the big systems of last decade in
performance, cost, and storage.
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Interleave Interleave
It helps to understand the following description if you can
visualize what the data sectors "look" like on the disk.
Imagine a pizza, cut into seventeen slices. Then, imagine
you had some round cookie cutters in larger and larger
diameters. When you have cut the pizza, first into slices
(sectors) and then into cookie circles (cylinders, or
tracks), you would end up with a bunch of pizza pieces that
look like large fingernail clippings.
If you can bear to continue this analogy just a little
longer, each of those clippings would compare to a sector of
512 bytes on the hard disk. You can easily determine the
capacity of the hard disk using a calculator and the formula
CAPACITY = 512 x TOTAL SECTORS
If, instead, you had five pizzas stacked up before you did
the cutting, you would have ended up with more sectors.
This is what happens with multi-platter hard disk units. If
you had toppings on both sides of the dough on each pizza,
you would have approximated the layout of modern PC hard
disks. Each side with toppings relates to a data side,
which is read by a separate head.
The formula above for disk capacity is, finally,
CAPACITY = 512 x SECTORS PER TRACK x TRACKS PER
PLATTER x TOTAL HEADS
The answer is in bytes.
As the disk spins, the sectors go by the read-write head.
You can calculate the speed that the bits go by if you want
to. With 17 sectors, 512 bytes per sector, and at 3600
R.P.M., that's 31,334,400 data bytes per minute, or
4,177,920 data bits per second. Since each sector has some
"overhead", that is, extra data in the sector which allows
the controller circuitry to access the data, the bits-per-
second is a little higher than that. Typically you will see
this parameter as 5 megabits per second.
4,177,920 bits per second means 522,240 bytes per second.
If you attempted to read one track from the disk, you must
be able to take it at that rate: the disk will not stop
spinning while your CPU digests the data. (The IBM XT is
not able to transfer the data via its DMA controller this
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fast; in fact, it can only manage about 100K bytes per
second. The reasons for this are beyond the scope of this
description.) If the CPU isn't ready for the second sector
when the disk drive is ready to send it, the disk spins, and
17 milliseconds later the sector shows up under the
read/write head again. By now, the CPU is ready for it, and
it accepts it. However, this will slow your data transfer
rate down by a factor of 18, dropping it to 29,013 bytes per
second! Poor, indeed!
What would happen if you only recorded four sectors on every
track, with evenly-spaced gaps between them? There would be
enough time between sectors for the CPU to transfer the data
before the next one showed up. Now your transfer rate would
be four sectors per spin, instead of one. The disadvantage
is that your capacity just shrunk by a factor of more than
four.
A compromise is available. The data can be placed on the
disk in a way that allows enough time between sectors for
the computer to read them as fast as they come by, and
having the track full of sectors. If you write the four
sectors, as described above, but then put sector number five
immediately after sector number one, then sector number six
immediately after number two, and so on. It would take four
or five spins to get all seventeen sectors. This isn't 500K
bytes per second, but it's four times faster than reading
one sector per spin.
The process just described is called interleaving interleaving. This is
the way that your data is placed on your hard disk.
The The interleave factor is defined as the number interleave factor is defined as the number of of
times the disk must spin in order to read times the disk must spin in order to read all of all of
the sectors on disk in order, from the sectors on disk in order, from sector number sector number
one to sector number n (the highest number). one to sector number n (the highest number).
An interleave of one (or called "one-to-one") is the fastest
possible: one whole track is read in one revolution. The
sectors are stored on the disk as 1-2-3-4-5-6-7-8-9-10-11-
12-13-14-15-16-17. An interleave of two (2:1) has the
sectors stored on the disk as 1-10-2-11-3-12-4-13-5-14-6-15-
7-16-8-17-9. The typical IBM AT comes to you with an
interleave of three, and the typical XT comes to you with an
interleave of five or six.
Who decides what interleave is right for your system? The
person who installs the hard disk. If you bought the system
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ready to go, it was your dealer who did it. If you built
the system from subsystems (mail order, for example), it was
probably you who did it (perhaps unknowingly). A generally
safe value is determined for a certain type of system
(processor type, speed in MHz, networking requirements,
etc.), and this "magic number" is then used for all similar
systems.
There is a big performance penalty if the interleave is too
small -- in fact, if you are off by one in that direction
it's like having an interleave of, say, 19 instead of 2, or
20 instead of 3. Since the controller misses the second
sector of each multi-sector read (called "blowing a rev"),
an extra revolution is required for each sector to be read.
So it's important to not have the interleave too small. But
what about having the value too high? Not a terrible thing,
but you still aren't getting the most performance out of
your system. The CPU is saying "gimme" when the controller
is saying "hang on, it's coming."
The best situation to have is to experimentally determine
the best interleave for your specific computer, with all of
your peripherals connected, and then change the interleave
to that value.
That's what your new program does. And it does it without
messing up the data that you already have stored there.
Read, Re-format, Write Read, Re-format, Write
The sectors are placed by an operation called "low-level
format." This is distinguished from a "regular format"
because it is not done by the FORMAT program on your DOS
disk. That program really just arranges the DOS data on the
already-formatted hard disk.
As most computer users know, formatting wipes out your data.
You don't want to format a disk which has non-replaceable
data on it. That's why the FORMAT program asks you, "Are
you sure?" It's a drastic thing.
In order to change (or initially set) the hard disk
interleave, each track must be formatted (low-level format)
specifically for that value. As you may guess, this type of
format also wipes out any data which is there. So if you
want to re-format your hard disk, you save all your data
onto floppies or tape backup; then re-format; then restore
from your backup media. Uggh. That's so painful that most
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people aren't interested in doing it. Besides, if anything
goes wrong during the restore, and/or your backup media is
altered or damaged, you will lose some or all of your
data... forever. Double-uggh.
The IAU IAU program saves you all of the headaches, and gives
you all of the optimum performance you can get.
After determining the optimum interleave for your disk
drive, the program proceeds to change it. It reads an
entire track into memory, then formats the track to the new
value, then writes the data back to the same track (but at
the new interleave). This continues for the entire disk.
When it's done, your disk will be better than new.
But before you run the program, run one of the popular
performance analyzer programs (such as Peter's SI program,
or one of the Core tests). Then run IAU. Then run the
performance test again. You will be pleasantly surprised
with the increase in performance.
The greatest part of all this is that you really are getting
something for nothing! All of that performance potential
was always there; you simply are getting your money's worth
now.
If you run the program, and you agree with me -- that your
disk performance is really better -- please read the section
about ShareWare, at the end of the manual.
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Pictorial Display Pictorial Display
With the release of version 1.7, you can observe a pictorial
of your hard disk system on the display. The only
requirement is that you have an E.G.A. or V.G.A. adapter
installed, with either monochrome or color capability.
The pictorial will show you what the inside of the hard disk
looks like (platters and heads), and will show you what the
data would look like if you could see it on the disk. The
interleave measured by the program is what is used for this
picture. So you must select the "M"easure option before you
are shown any graphics. When you have measured the current
value, then select "I"nformation (see figure 9 in appendix
B). The graphic display will look like figure 10 in the
appendix.
The program which does this is MAKEPIC.EXE. This was also
written in Turbo 'C', using the graphics routines available
in version 1.5.
If you want to run MAKEPIC directly from the command line,
the calling parameters are:
MAKEPIC drive interleave rpm
The third parameter is optional; if you leave it off,
MAKEPIC will measure the R.P.M. at run time.
We are interested in your comments about this program.
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Question and Answer Question and Answer
This section addresses some of the frequently-asked
questions about interleave and the IAU program.
Q Q Will IAU work with my computer system?
A: A: Yes, if you have an IBM or compatible system with one
or two hard disks, at least 256K of RAM, an IBM-supported
video system (MDA, CGA, EGA, CGA) or de-facto standard
(Hercules, Plantronics) video system.
Q: Q: What about two hard disks? Which one will the program
work with?
A: A: The program detects that you have more than one, and
asks you which one it should use. Once you answer the
question, that is the only drive which the program will
access until you exit the program. You may specify the
drive from the command line, also (see below).
Q: Q: What if I have more than one partition on my hard disk?
Can the program deal with that? How about if it's not a DOS
partition?
A: A: The program operates at the physical device level.
That means that if you have your physical drive split up
into two or more logical drives, it makes no difference.
Logical partitions do not change the physical structure of
the hard disk. If you want to change just one partition of
your hard disk, you can select a cylinder range for the
program to adjust.
Q: Q: Does the program work with R.L.L. drives?
A: A: No, if they don't have 17 sectors per track. We have
found that RLL drive manufacturers use a different method of
setting the interleave during a format track call, and have
chosen not to support R.L.L. drives, except on a case-by-
case manufacturer-supplied driver basis.
Q: Q: I'm concerned about Trojan Horse, or virus, programs.
How do I know if someone has tampered with IAU.EXE?
A: A: Good question. A file compression program called PKARC
(and its companion PKXARC) can be instructed to give
information about the archive file, like this:
C>PKXARC /V ILEAVE16
You should see this type of information:
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Filename Length Method Size Ratio Date
Time CRC
-------- ------ ------ ------ ----- ----
---- ---
IAU.EXE 66118 Squashed 52270 21% 06-16-88
16:32:46 6A4E
MAILER.EXE 12330 Crunched 9059 27% 06-08-88
14:51:20 5677
PARK.COM 9690 Crunched 8257 15% 06-14-88
10:15:40 5FD9
----- ------ ------ -----
0003 88138 69586 22%
The PKXARC program prints its sign-on information just
before that is displayed. The file size of ILEAVE16.ARC is
69,747 bytes, and should have a date of 17-Jun-88, and a
time of 4:51 p.m. Later versions of the program will have
different values. Since the author has no control over the
integrity of downloaded programs, it is a good idea to get a
floppy direct from the source.
The CRC value will change if any part of the program is
altered by unauthorized persons. If these values aren't the
same as when you got the program, something is wrong.
If you have gotten a self-extracting archive file, or if
some programs have been added to the archive, there might be
more than three files shown - that is OK. Just be sure that
the CRC values are the same as when you got the program from
me.
Q: Q: Even if this is the real version of the program, how do
I know whether or not it will trash my hard disk?
A: A: Another good question. This type of program is
potentially destructive to your data. Some manufacturers of
hard disk controllers do not follow the IBM method of
performing read, write, and/or format commands. It is
possible that some of your data could be lost. You should
try the program on the "test" cylinder, and be satisfied
with the results, before you do it to the whole disk.
Q: Q: What is the "test cylinder?"
A: A: This is the track which is closest to the middle of the
disk (and it has a higher number than any tracks which have
your data on them). It is used by diagnostic programs to
perform tests, and is a guaranteed safe place to perform
testing. It is guaranteed to have no media defects on it,
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and is guaranteed to be OK if a program erases whatever data
happens to be on it.
Q: Q: What should I do before running the program?
A: A: _______________________________________________________ _______________________________________________________ YOU SHOULD ALWAYS HAVE A CURRENT BACKUP OF ALL THE DATA YOU SHOULD ALWAYS HAVE A CURRENT BACKUP OF ALL THE DATA ____________________________________________________________ ____________________________________________________________
YOU WANT TO KEEP. THIS IS TRUE WHETHER OR NOT YOU CHOOSE TO YOU WANT TO KEEP. THIS IS TRUE WHETHER OR NOT YOU CHOOSE TO __________________________________________ __________________________________________
RUN THE IAU PROGRAM. BACKUPS SHOULD BE A RUN THE IAU PROGRAM. BACKUPS SHOULD BE A REGULAR PART OF _______________ _______________ REGULAR PART OF ________________________ ________________________
YOUR COMPUTER OPERATION! YOUR COMPUTER OPERATION!
Q: Q: How do I work the program?
A: A: The program looks like spreadsheet programs look. See
figure 1 in Appendix B. You press the cursor keys (located
to the right of the Enter key on most PCs) to select the
option that you want. Each selection will be shown
highlighted as you pass by. Underneath the option is a
brief description of what will happen if you press enter.
Most options have "sub-options", that is, you will be shown
a new list of options when you choose. This method of
option entry is easy for most people to get used to.
Q: Q: What is the proper sequence to use for the first time
user?
A: A: Measure the test track (see Figure 2). Then determine
the optimum value for the test track (Figure 4). Change the
interleave value on the test track to the optimum value
determined (Figures 5 & 6). Then re-measure the test track,
to see if the change actually took place.
Q: Q: What about "on-line help?"
A: A: The main menu (the first screen with options) has a
"Help" selection which is a summary of this manual. You may
refer to it whenever you forgot some of the basics about
interleave. Registered users can get more help by pressing
the F1 key when a menu is up. At that time they will be
able to view the file IAU.HLP which is provided with
ILEAVE17.EXE for registered users. You can also run the
program with a command line parameter of "?" and get a quick
description of the program, that is, you type
IAU ? (and press Enter).
Q: Q: What if the program has trouble reading data from the
disk?
A: A: If it can't read a track, it skips it, and leaves it at
the old interleave value. In this way, it never makes the
disk worse than it was. If you select a track for
"Optimize" which is unreadable, the program will tell you to
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select another one. Any read, format, or write errors which
occur during the interleave operation will be displayed on
the screen. Some errors are expected and you should not
panic.
Q: Q: Can I get this error log to print out? How about to a
disk file?
A: A: Yes. When you invoke the program, use the command line
argument logfile=xxx, where xxx is the name of a file
(LOGFILE.PRN, etc.), or a device (such as PRN, COM1, etc.)
Q: Q: When I run the program with my (older) XT, it starts
off great, but then takes longer and longer for each track.
At this rate, it will take all night!
A: A: That's OK, though, since you only run this program
once, but there is a way around this. Stop the current
operation, and exit the program. Then, run it again with
the "RECAL" command line option.
Q: Q: How do I stop the program once it gets started changing
the interleave?
A: A: If you press the Escape key during the re-interleave
operation, you will be returned to the menu. Do not press
CTRL-C or CTRL-BREAK while this program is running. You
have been warned.
Q: Q: Ouch. What if I have some other kind of error which
causes an immediate drop to DOS? Like the infamous "Abort,
Retry, Ignore" message? And I have to choose "Abort" for
some reason?
A: A: That's not so bad, except for this: BE BE SURE THAT IN SURE THAT IN
THAT CASE, YOU REBOOT THE SYSTEM BEFORE YOU THAT CASE, YOU REBOOT THE SYSTEM BEFORE YOU READ OR WRITE READ OR WRITE
THE HARD DISK. THIS IS VERY IMPORTANT IN THE HARD DISK. THIS IS VERY IMPORTANT IN CASES WHERE YOU CASES WHERE YOU
ABNORMALLY EXIT THE PROGRAM. ABNORMALLY EXIT THE PROGRAM.
Q: Q: What is a "command line argument?" What do they do?
How do I use them? Why should I?
A: A: Command line arguments are options that you can give to
a program. For example, when you type DIR A: you are
telling the system that you want a directory, but for drive
"A". And when you tell the FORMAT program to put the
operating system on the disk, you give the /S command line
argument. IAU has six command line
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arguments. They are: ________
Argument ________ Function
/ALTER allows you to change the drive table
/CACHE allows operation of the program when
using a cache program
LOGFILE= specifies that errors will be sent to
this device or file
/RECAL allows better operation with controllers
which
recalibrate before each format-track
operation
/VAL= allows you to select a default
interleave value from the command
line
/COMPAT Skips the IBM compatibility byte check
at the beginning of
the program
/DRIVE= Allows you to specify either drive 0 or
1 from the command
line.
/? or ? Display a brief description of the
program and the revision level.
Most of the time, you won't use any of these. ALTER is
dangerous for those who don't know what they're doing.
CACHE might be required in some systems, and the program
will tell you if yours is one of them. LOGFILE was
discussed earlier. Note that LOGFILE does not use a switch
character (slash) as all the others do.
Q: Q: When I am finished running the program, it tells me
that I should register the copy! I already did! How do I
get rid of that message?
A: A: If it really bothers you that much, you can give this
command to DOS after you boot your system: SET IAU=Q. Then
when you run the program, the message will be suppressed.
Q Q: What about the other files in the archive? What are
they for?
A: A: PARK is a program which will place the read/write heads
at a safe place for transportation. If you don't run this
(or a similar program) before physically moving the
computer, a bump could cause the disk to be permanently
damaged. This program puts the heads in what the
manufacturer calls the "landing zone," where no data is
stored. MAILER is a program which allows you to contact the
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author, either for the registration fee, or for comments
about the program. It prints out an envelope on your
printer which can be used for mailing. Other public domain
programs may be tossed in from time to time which might be
useful for IAU users.
Q: Q: How many copies of the program are there?
A: A: It's hard to know how many copies of a shareware
program are being used. There have been about 900 people
(as of July, 1988) who have expressed interest in one form
or another.
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Q: Q: What is "Share Ware?"
A: A: You know, don't you? It's where you get a program and
try it out to see if you like it. Then you like it, and
keep using it. Then you say, "That's a nice program! I'll
bet a commercial version of this would cost hundreds of
dollars! So I don't feel too bad sending the author the
paltry sum that he/she suggests. That way I know I'll get
on the update list and be able to ask questions over the
phone!"
Since you are reading this manual, it means that you have
requested the manual with a donation. Thank you. This makes
it all worthwhile for me.
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Appendix A Appendix A
Application Notes Application Notes
Application notes describe changes or other items of
interest to users of the program. Minor program bugs are
also described, with their possible solutions. The
application notes begin on the next page.
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APPLICATION NOTE 1 - FLOATING POINT SUPPORT
PROBLEM:
During the actual "Change interleave" operation, the
percent complete indicator jumps all over the place,
instead of showing a steady increase as it progresses.
CAUSE:
The Auto-87 detect logic of the run-time package in
Turbo C doesn't always work - or - your SETUP
parameters indicate that you have a numeric co-
processor when in fact you don't (or it's not
responding).
SOLUTION:
Before you run the program, enter this at the DOS
prompt:
SET 87=N
This will tell the run-time math package that there is
no numeric co-processor.
AFFECTING:
This problem affects the display only, and has no
effect on the hard disk. No noticeable effect on
program speed is noticed. The problem is eliminated
in version 1.7
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APPLICATION NOTE 2 - DISK ERRORS DURING HARD DISK READ/WRITE
PROBLEM:
During the re-formatting operation, error codes appear
in the ERROR CODE window on the screen. Some users
are concerned about these errors, and their meaning.
CAUSE:
Some errors are caused by previously-unknown bad
sectors; however, the majority are caused by tracks
that are marked bad and will not ever be used by the
operating system.
SOLUTION:
Use the list below to determine if the error was
previously encountered (error code 0A). If so, there
is no chance for danger; if not, you should run one of
the utilities which can update your FAT (Norton's
DISKTEST, DOS' DETECT, etc.).
Error Meaning
-------- ----------------------------------------
CC Write fault
BB Undefined error
AA Drive not ready
40 Seek failed
20 Bad controller
11 ECC corrected data error
10 Bad ECC on disk read
0A Bad sector flag detected
05 Reset failed
04 Sector not found
02 Address mark not found
01 Bad command from program
There are a few more error codes possible; however,
these cover the majority of types that you will see.
In these cases, the IAU program will not change
anything on that track.
AFFECTING:
XT, AT. Users can verify that there was no change to
the interleave using the (M)easure option for the
track in error.
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APPLICATION NOTE 3 - INTERNAL ERROR CODES
PROBLEM:
Some users have reported error codes generated during
the running of
the program.
CAUSE:
Run-time errors which can not be handled or determined.
SOLUTION:
Varied - depending on the cause of the problem(s).
Version 1.7
of IAU has the following error codes:
1 No hard drives detected in system
99 Controller RAM diagnostic fails
98 Drive diagnostic fails
97 Controller diagnostic fails
45 Not enough system RAM to execute (check tsr's,
ramdisks, etc.)
33 Same as 45
Those are all "fatal" errors, meaning that the program
cannot recover
from the condition. The message is in the format of:
Fatal error: xx
where xx is a number from the list above.
Another type of problem can occur which will be
displayed as
Error # xx
And the number will be a two-digit (hex) value. This
means that
the BIOS compatibility byte is not IBM-compatible. You
may bypass
this check by entering the program with the /COMPAT
command line
argument.
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Appendix B Appendix B
Figures Figures
The figures on the following pages are referred to in the
preceding text. They consist of "screen dumps" from the
