MS-DOS Customers Who Want Windows 3.1 EMM386.EXE (81476)

The information in this article applies to:
    Microsoft MS-DOS operating system 5.0
    Microsoft MS-DOS operating system 5.0a
    Microsoft MS-DOS operating system 6.0
    Microsoft MS-DOS operating system 6.2
    Microsoft MS-DOS operating system 6.21
    Microsoft Windows 3.0
    Microsoft Windows 3.0a
    Microsoft Windows 3.1
    Microsoft Windows 3.11

This article was previously published under Q81476


Microsoft Windows versions 3.1 and 3.11 will run in standard mode when EMM386.EXE is providing upper memory blocks (UMBs). Microsoft Windows version 3.0 will not run in standard mode if EMM386.EXE is providing UMBs.

Changes were made in Windows 3.1 to allow Windows to run in standard mode with EMM386. There were no changes made EMM386 to support this.


Standard mode Windows 3.1 is VCPI-compliant; standard mode Windows 3.0 is not. VCPI is an industry protocol to allow 386-based memory managers like EMM386 to cooperate with 286-protected mode DOS extenders. For example, Lotus 1-2-3 3.x and standard mode Windows have built-in DOS extenders. As the first 386-based memory managers were LIMulators, VCPI is actually an extension to the Lotus-Intel-Microsoft Expanded Memory Specification (LIM EMS).

Microsoft is aware that some third-party companies have released special versions of 80386 memory managers that allow a specific release of Windows to run in standard mode. Microsoft, however, chose not to change the memory manager; rather, we changed Windows to work with any 80386 memory manager that is VCPI compliant.

Examples of VCPI compliant 386 memory managers include EMM386, QEMM, 386MAX, BLUEMAX, and CEMM. Check your product's documentation for details. Note that if the product provides both XMS and EMS memory, the driver must support XMS 3.0, not 2.0.

The products included here, QEMM, 386MAX, BLUEMAX, and CEMM, are manufactured by vendors independent of Microsoft; we make no warranty, implied or otherwise, regarding these products' performance or reliability.

Modification Type: Major Last Reviewed: 11/26/2003
Keywords: KB81476