Microsoft KB Archive/26082

= QB87 Hang or Bad Numbers When &quot;Divide By Zero&quot; on PC-DOS 3.20 =

Article ID: 26082

Article Last Modified on 11/21/2006



This article was previously published under Q26082



SUMMARY
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 &quot;divide by zero.&quot; 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 &quot;Microsoft QuickBasic Version 3.00 Update&quot; 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 &quot;For Systems with a Math Coprocessor.&quot; 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.



MORE INFORMATION
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.

Additional query words: QuickBas

Keywords: KB26082

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