Registrations are now open. Join us today!
There is still a lot of work to do on the wiki yet! More information about editing can be found here.
Already have an account?

Microsoft KB Archive/39256

From BetaArchive Wiki
Knowledge Base

QuickBasic May Not Function with 25-MHz 80387 Coprocessor

Article ID: 39256

Article Last Modified on 11/21/2006

This article was previously published under Q39256


Customers have reported that QuickBasic version 4.5 does not function correctly with a 25-MHz 80387 math coprocessor chip. The reported problems include the following:

  • Incorrect floating-point numeric results
  • Coprocessor not detected

This problem does not occur on 80387 chips slower or faster than 25 MHz.

Microsoft has not tested QuickBasic version 4.5 with 25-MHz 80387 chips.


To test potential problems, you can compare numeric results with and without the coprocessor by turning on or off QuickBasic's access to the coprocessor. The following MS-DOS command turns off QuickBasic's access to the coprocessor in the current boot session (where any message with one or more characters must follow the equal sign [=]):

set NO87=Coprocessor is currently disabled.

The following command makes the coprocessor accessible again (where no characters follow the [=]):

   set NO87=

One customer reports that QuickBasic 4.5 didn't recognize a 25 MHz 80387 on an Atronics 386B motherboard. Microsoft has not confirmed this information.

Additional query words: QuickBas 4.50

Keywords: KB39256