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Microsoft KB Archive/104189

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Knowledge Base

MSD Reports an 80287 Math Coprocessor as an 80387

Article ID: 104189

Article Last Modified on 11/23/1999


  • 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

This article was previously published under Q104189


The Microsoft Diagnostics (MSD) utility versions 2.0a (which ships with Windows 3.1) and 2.01 (which ships with MS-DOS 6.0) may report an 80287 math coprocessor as an 80387 coprocessor.

Other diagnostic software may display similar results or say that the coprocessor is not functioning properly.


This problem is caused by the design of the hardware.


The following 80287 math coprocessors have been confirmed by their manufacturers as being detected incorrectly by various diagnostic software programs or utilities:

  • Intel 287XL
  • Cyrix 82S87

To obtain correct information regarding your 80287 coprocessor, use diagnostic software provided with the hardware, or call the manufacturer for assistance.

Intel Customer Support (800) 538-3373 or (503) 629-7354
Cyrix Customer Support (800) 462-9749 or (214) 994-8387

Intel has a "FaxBack" number that you can use to obtain diagnostic information. To obtain the Intel FaxBack article #3064, "Intel Math CoProcessors and Diagnostic Programs," call Intel FaxBack at (800) 525-3019 or (503) 629-7576.

Additional query words: 6.22 6.00 6.20 287 387 PROCESSOR CO 3.1 MATHCO

Keywords: KB104189