How EMM386 and Windows 3.1 Relate (82711)


The information in this article applies to:

  • Microsoft Windows 3.1
  • Microsoft Windows 3.11
This article was previously published under Q82711

SUMMARY

This article describes how Microsoft Windows handles memory on a system running EMM386.EXE.

MORE INFORMATION

Include/Exclude Precedence

An X= parameter added to the EMM386.EXE device line is directly adopted by Windows. Any EMMInclude= or EMMExclude= entry is overridden by any X= parameter on the EMM386.EXE device line in the CONFIG.SYS file. For example, the following line in your CONFIG.SYS takes precedence over any conflicting entry: 
     device=c:\windows\emm386.exe X=C000-CFFF noems
When Windows executes, it takes this information before it checks the SYSTEM.INI file. Even if the SYSTEM.INI file contains a contradictory line, for example: 
     EMMInclude=C000-CFFF
Windows keeps the EMM386.EXE parameter.

The same precedence that an EMM386.EXE exclusion takes is true for the I= (inclusion) parameter.

DMA Buffer Size Parameter

The D= (DMA buffer size) parameter is not adopted by Windows. If it is necessary to allocate a larger DMA buffer for EMM386.EXE, it is probably necessary to add the following to the CONFIG.SYS file. For example, add:

device=c:\windows\emm386.exe D=96 noems

This would affect anything running under MS-DOS. However, when Windows is started, the DMA buffer size returns to its default. For the above example, you should also add the following line to the [386Enh] section of the SYSTEM.INI file:

DMABufferSize=96

REFERENCES

For more information on EMM386.EXE, see the "Microsoft Windows User's Guide" version 3.1 manual. For information on using the SYSTEM.INI file, see the SYSINI.WRI file in the Windows subdirectory.
Modification Type:MajorLast Reviewed:10/13/2003
Keywords:KB82711
©2003 Microsoft Corporation. All rights reserved.