Article ID: 70758 - Last Review: September 24, 2011 - Revision: 3.0

Floating-Point Calculations in Windows Using WIN87EM.DLL

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This article was previously published under Q70758
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SUMMARY

WIN87EM.DLL is a dynamic link library (DLL) that supplies floating-point calculation routines for Windows applications that support math coprocessors. Windows by itself does not use WIN87EM.DLL, but some Windows applications that carry out floating-point calculations require WIN87EM.DLL to be present in the Windows\SYSTEM subdirectory.

For example, Microsoft Excel version 3.0 requires WIN87EM.DLL to be present whether or not your computer has a math coprocessor chip. If WIN87EM.DLL is not present, Excel generates the error message:
Cannot find Win87em.dll" and will not load
If WIN87EM.DLL is damaged, Excel 3.0 attempts to run a second instance of Windows, leaving you in real mode with the error message:
Cannot run this application in real mode
Other Windows applications may require WIN87EM.DLL and may display similar behavior.
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MORE INFORMATION

Microsoft Windows installs WIN87EM.DLL in the Windows\SYSTEM subdirectory. Windows itself does not generate an error upon loading if it is missing. The error does not occur until an application is loaded and requests the dynamic link library (DLL). If the file is missing or damaged, just expand it from your Windows disks into your Windows\SYSTEM subdirectory.

WIN87EM.DLL is on the following Windows 3.0 disks: 
   5.25-inch  1.2 MB   Disk 2
   5.25-inch  360K     Disk 5
   3.5-inch   720K     Disk 3
WIN87EM.DLL is on the following Windows 3.1 disks: 
   5.25-inch  1.2 MB   Disk 4
   3.5-inch   1.44 MB  Disk 4
For information on expanding files, please refer to the README.TXT file in the WINDOWS directory.
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REFERENCES

"Microsoft Windows Guide to Programming," Microsoft Press, section 14.5.7.
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APPLIES TO
  • Microsoft Windows 3.0 Standard Edition
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Keywords: 
KB70758
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