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Q26082: QB87 Hang or Bad Numbers When "Divide By Zero" on PC-DOS 3.20

Article: Q26082
Product(s): See article
Version(s): 3.00
Operating System(s): MS-DOS
Keyword(s): ENDUSER | TAR63164 | mspl13_basic
Last Modified: 10-APR-1989

When floating-point exception error occurs on a machine with a
coprocessor (8087 or 80287), some programs display improper numeric
values or hang in QB87.EXE (the coprocessor version of QuickBASIC
Version 3.00), instead of stopping and displaying a "divide by zero."
There is a problem in IBM PC-DOS Version 3.20 which can cause this
problem in QuickBASIC 3.00 (but not in later versions of QuickBASIC
running on IBM PC-DOS 3.20).

The following is an excerpt from Page Update-7 of the "Microsoft
QuickBASIC Version 3.00 Update" manual:

   IBM PC-DOS Version 3.20 contains a bug that may cause errors when
   QB87 programs are run. You can see which version DOS your computer
   is running by using the DOS VER command.

   If your computer is using IBM PC-DOS Version 3.20, you must install
   the patch from Disk 2 of the set labeled "For Systems with a Math
   Coprocessor." The necessary files are in the subdirectory PATCH.

   To install the patch, follow the directions in the file README.DOC
   in the PATCH subdirectory.

Please note that this patch is not necessary when using QuickBASIC
3.00 programs under MS-DOS 3.20 -- the patch is only for PC-DOS 3.20.

This patch is specific to QuickBASIC 3.00 and PC-DOS 3.20, and does
not apply to later versions of QuickBASIC (which are designed to work
around the problem) or other versions of PC-DOS or MS-DOS.

For QuickBASIC 4.00, 4.00b, or 4.50, a separate article describes a
different patch necessary (in these versions only) to work around a
different MS-DOS 3.20 (not PC-DOS) problem handling coprocessor
floating point exceptions. Query in this KnowledgeBase on the
following: COPROCESSOR AND 4.00B AND EXCEPTIONS AND PATCH.

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