Microsoft KB Archive/72412

= Math Coprocessor Detection Hangs System in QBasic =

Article ID: 72412

Article Last Modified on 5/10/2003

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APPLIES TO


 * Microsoft MS-DOS 5.0 Standard Edition
 * Microsoft MS-DOS 5.0a
 * Microsoft MS-DOS 6.0 Standard Edition
 * Microsoft MS-DOS 6.2 Standard Edition
 * Microsoft MS-DOS 6.21 Standard Edition
 * Microsoft MS-DOS 6.22 Standard Edition

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This article was previously published under Q72412



SYMPTOMS
When starting MS-DOS QBasic (included with MS-DOS versionS 5.x and 6.x) your system may stop responding (hang).



CAUSE
This problem occurs because of the way the QBasic environment checks for the presence of a math coprocessor chip in your computer.



STATUS
Microsoft has confirmed this to be a problem with MS-DOS versions 5.0, 5.00a, 6.0, 6.2, 6.21, and 6.22. We are researching this problem and will post new information in the Microsoft Knowledge Base as it becomes available.



RESOLUTION
If this problem occurs, reboot your machine and add the following line to your AUTOEXEC.BAT file:

SET NO87=NOMATH

After you add this line to the AUTOEXEC.BAT file, reboot your machine so that this switch can take effect. You should now be able to enter the QBasic interpreter with no difficulty.

NOTE: Setting NO87 does not affect other applications' use of a math coprocessor (with the exception of MS-DOS 6.00 DoubleSpace) because the application has to look for this environment variable.

The environment variable NO87 is a switch to tell the QBasic interpreter that there is no 80x87 chip in your machine. You can set this variable to any value to make NO87 true. Setting NO87 to null (SET NO87=) makes NO87 false, which is the default state.

Although the QBasic interpreter checks for a coprocessor, it doesn't actually use the coprocessor even if it successfully detects one. You do not lose any functionality or speed by setting the NO87 variable to true, even if you have a math coprocessor chip.

The same problem occurs in QuickBasic version 4.5, but the QuickBasic environment can use the coprocessor if it is successfully detected.

Additional query words: dblspace 5.00 5.00a 6.00 6.20 80387 80287 8087

Keywords: KB72412

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