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OVERFLOW.DOC
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1992-03-13
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OVERFLOW
version 1.0
__________________
by Lonny A. Eachus
OVERFLOW.EXE and OVERFLOW.DOC are Copyright (c) 1992 by Lonny A. Eachus. All
rights reserved. OVERFLOW.EXE created with Microsoft BASIC PDS 7.1. Portions
may be Copyright (c) Microsoft Coporation.
This program has been tested and been found to work reliably in all cases for
which it has been tried as of this writing. However, due to the variety and
complexity of different computer configurations, the author cannot
guarantee the accuracy of its results in all cases. Therefore,
the author offers no warranty of any kind in regard to its
operation or use. The author will not be liable for any
damages caused by the operation or use of OVERFLOW.
This program and documentation may be copied and distributed freely, provided
that (1) they may not be copied, sold, or used for profit and (2) they are
distributed together in original form. NO additions, deletions, or
modifications to either the program or documentation are allowed.
No organizations or persons may use this software for profit
in any way without written permission from the author,
except as otherwise provided by law. Original
distribution is in the form of a compressed
file created with PKZIP version 1.10.
PKZIP is copyright (c) PKWARE Inc.
* Purpose of OVERFLOW
___________________
OVERFLOW was designed to detect a defect in some PC-compatible computers that
use floating point math coprocessors. The defect causes them to freeze, or lock
up, when a numeric overflow occurs. This can cause serious problems if not
corrected. It has been noticed on some Micronics 486 motherboards.
* Who should use OVERFLOW
_______________________
If you have a 286 or later model computer with a math coprocessor (including
486 machines), you should check to see if it has this defect. OVERFLOW takes
only a second to run, and will tell you if you have a defective part.
* Why you should check your computer
__________________________________
This is not a "minor bug" that can be safely ignored. Software is often
designed to trap an overflow condition and then generate an error message,
allowing you to change your program or data if an error occurs. If the error is
not trapped, a program will normally abort and kick you back to the operating
system (DOS in most cases). There is nothing especially harmful about this.
If your computer locks up instead, you may not know where in the program the
error occurred. Some programs completely cease to function. If you are a
programmer, you may find that you can not debug your programs. Even worse,
locking up a computer while a program is running can cause file allocation
errors on disks. These errors are cumulative and can cause lost or corrupt
files, up to and including the loss of everything on your hard disk.
* System Requirements
___________________
I.B.M. compatible computer with a 286 or later CPU, running any DOS version
later than 2.1. Although OVERFLOW tests for coprocessor errors, it does NOT
need a math coprocessor to run. This was done so that results can be compared
with another computer if a defect is found.
* Running the program
___________________
Just copy the file OVERFLOW.EXE to a convenient disk. Change to whatever disk
and directory the program is on, and type OVERFLOW at the DOS prompt, then hit
<ENTER>. It does not much matter whether the program is on a hard disk. It will
run just as well from a floppy. Since OVERFLOW tests only the math coprocessor
and CPU, it runs very quickly. Results should be almost immediate.
WARNING!!! OVERFLOW can cause your computer to lock up. If the computer is
networked, take appropriate measures to shut down the network before running
OVERFLOW. Never run OVERFLOW from within another program. Doing so may corrupt
other files if this defect exists on your computer.
* Interpreting Results
____________________
What OVERFLOW does is just that - it generates numeric overflows and traps the
errors in software. If your coprocessor is working properly (or if you DON'T
have a coprocessor - more on that later), the program will run through a series
of tests and print a TEST COMPLETE message near the bottom of the screen. If
you see TEST COMPLETE, your computer is working properly. On the other hand, if
this overflow defect appears, your computer will LOCK UP during some stage of
the test. There is no way to get around this. Between the bars that follow is
an actual screen dump made after OVERFLOW has run to completion.
▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒
PC NUMERIC OVERFLOW TEST
written by
Lonny A. Eachus 03/13/92
-------------------------------------------------------------------------------
This program tests for numeric-overflow defects in computers with floating-point
math coprocessors. This test is only valid for 286 or later computers that have
coprocessors installed. You should see the words TEST COMPLETE in reverse video
near the bottom of your screen. If you do NOT see this line, the program did not
finish running and you may have a defective part. Read OVERFLOW.DOC for details.
------------------------------------------------------------------------------
INTEGER OVERFLOW TEST ------------- O.K.
LONG INTEGER OVERFLOW TEST -------- O.K.
SINGLE PRECISION OVERFLOW TEST ---- O.K.
DOUBLE PRECISION OVERFLOW TEST ---- O.K.
CURRENCY TYPE OVERFLOW TEST ------- O.K.
TEST COMPLETE - THIS COMPUTER IS O.K.
HIT ANY KEY TO EXIT
▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒
The line that reads TEST COMPLETE should appear flashing, in reverse video,
almost immediately. That effect cannot be reproduced in this text file.
If you have a numeric-overflow defect in your computer, OVERFLOW will lock up
your computer at some point during the test. You will NOT see the TEST COMPLETE
line near the bottom of the screen. Between the following bars is an example of
a screen after OVERFLOW has found a defect.
▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒
PC NUMERIC OVERFLOW TEST
written by
Lonny A. Eachus 03/13/92
-------------------------------------------------------------------------------
This program tests for numeric-overflow defects in computers with floating-point
math coprocessors. This test is only valid for 286 or later computers that have
coprocessors installed. You should see the words TEST COMPLETE in reverse video
near the bottom of your screen. If you do NOT see this line, the program did not
finish running and you may have a defective part. Read OVERFLOW.DOC for details.
------------------------------------------------------------------------------
INTEGER OVERFLOW TEST ------------- O.K.
LONG INTEGER OVERFLOW TEST ------
▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒
You can see that not all the tests have been completed and the bottom part of
the screen is blank. The computer is locked up. If your screen looks something
like this - if you don't see TEST COMPLETE - almost IMMEDIATELY - after
running the program, you have a problem.
* IF OVERFLOW LOCKS UP . . .
__________________________
Your computer is probably defective. The first step is to try to reboot it using
the <CTRL>-<ALT>-<DEL> keys. Consult your DOS manual if you don't know what this
means. If that does not cause a reboot, your computer is DEFINITELY defective.
Use the RESET button (or turn the computer off and then on again).
For a final check, if there is any question whether OVERFLOW has run properly,
you can run it on another computer (preferably a different brand) and compare
the screens. OVERFLOW will run to completion on any normal 286 or later PC that
does NOT have a coprocessor, and most of those that do. If a coprocessor is not
present, OVERFLOW emulates coprocessor functions in software so that you can see
how the screen should appear when everything works properly.
Call Technical Support
______________________
If you suspect a defective computer, call the Technical Support number for the
manufacturer of your particular machine. Explain the situation. Reputable
companies should replace defective parts that are still under warranty.
The exact hardware cause of this problem is a hard one to track down, so it may
be necessary to replace the entire motherboard. If this is what it takes to
solve the problem, so be it. It should still be covered under the warranty. If
Tech Support argues with you about whether there is a real problem, INSIST.
This is a SERIOUS DEFECT that can cause the complete loss of important data and
expensive software.
If necessary, read the pertinent sections of this .DOC file to Technical or
Customer Support personnel. File allocation errors are no joke. Hardware errors
that can cause them are not acceptable in a PC-compatible computer.
* A note about defective computers
________________________________
A trade magazine recently printed that this problem has been detected in some
486 computers from Gateway 2000. I found some of the ones at my office to be
defective, BUT NOT ALL OF THEM! DO NOT call Technical Support just because
you have a Gateway 486. TEST IT FIRST! We have found Gateways in general to be
solid, reliable, quality (not to mention inexpensive) computers. If you DO have
a defective computer, Gateway will fix it if is under warranty.
The motherboards Gateway uses for their 486 computers are usually manufactured
by Micronics, who also sell motherboards to other computer vendors. There may
be many brands of computer out there that have this defect.