EMM386
 | This article needs additional citations for verification. (December 2009) |
Intel 80386 | |
|---|---|
| Type | Expanded memory manager, Command |
EMM386 is the
Overview
EMM386.EXE can map memory into unused blocks in the upper memory area (UMA), allowing device drivers and terminate-and-stay-resident programs to be "loaded high", preserving conventional memory.
The technique probably first appeared with the development of
EMM386 uses the processor's
It temporarily shuts down during a Windows session in 386 Enhanced mode, with Windows' protected mode kernel taking over its role.
Windows uses the GEMMIS API to take over memory management from EMM386.EXE. Global EMM Import Specification (GEMMIS) is supported via a document available to a select number of memory-manager vendors ("Windows/386 Paging Import Specification").[3][4][5][6]
Only a few memory managers implemented the GEMMIS API, some of the ones that include it are: EMM386.EXE, Quarterdeck
None of the FreeDOS memory managers (HIMEMX.EXE, JEMM386.EXE, JEMMEX.EXE) implement the GEMMIS API and Windows fails to start when running in conjunction with JEMMxxx since Windows fails to take over the memory management role.
Cannot run Windows while the currently installed protected-mode software is running.
Quit the protected-mode software, and then try again. You may need to restart your computer.
With JEMMxx, it is possible to run Windows 3.x and Windows for Workgroups 3.1x in limited capabilities by forcing Windows to use Standard Mode; i.e. using 80286 Protected Mode, not 80386 Enhanced Mode. Three conditions are required:
- limit total XMS to 64MB
- EMS must be enabled, can't use NOEMS option. For example JEMMEX X2MAX=65422
- Windows operate in Standard Mode only, WIN /S or WIN /2
Note that Windows in standard mode is limited in functionality, it lacks virtual memory, it skips the [386Enh] section in SYSTEM.INI and any device drivers in [386Enh] are not loaded.
History
| Bundled with | Date | Filename | Version |
|---|---|---|---|
| MS-DOS 4.01 | November 1988 | EMM386.SYS | 4.00 |
| Windows 3.0 | May 1990 | EMM386.SYS | 4.10.0419 |
| MS-DOS 5.0 | June 1991 | EMM386.EXE | 4.20.06x |
| IBM PC DOS 5.0 | June 1991 | EMM386.EXE | 4.20.06x |
| IBM PC DOS 5.02 | September 1992 | EMM386.EXE | 4.33 |
| MS-DOS 5.00a | November 1992 | EMM386.EXE | 4.33 |
Windows 3.1 |
April 1992 | EMM386.EXE | 4.44 |
Windows for Workgroups 3.1 |
October 1992 | EMM386.EXE | 4.44 |
| MS-DOS 6.0 | March 1993 | EMM386.EXE | 4.45 |
| IBM PC DOS 6.1 | June 1993 | EMM386.EXE | 4.45 |
| MS-DOS 6.2 | September 1993 | EMM386.EXE | 4.48 |
| Windows 3.11 | November 1993 | EMM386.EXE | 4.48 |
Windows for Workgroups 3.11 |
November 1993 | EMM386.EXE | 4.48 |
| MS-DOS 6.21 | March 1994 | EMM386.EXE | 4.48 |
| IBM PC DOS 6.3 | April 1994 | EMM386.EXE | 4.48 |
| MS-DOS 6.22 | June 1994 | EMM386.EXE | 4.49 |
| IBM PC DOS 7.0 | April 1995 | EMM386.EXE | 4.50 |
| IBM PC DOS 2000 | May 1998 | EMM386.EXE | 4.50 |
| Windows 95 | August 1995 | EMM386.EXE | 4.95 |
| Windows 98 | June 1998 | EMM386.EXE | 4.95 |
See also
- Upper memory area (UMA)
- Extended memory (XMS)
- Expanded memory (EMS)
- List of DOS commands
References
- ^ "Datalight ROM-DOS User's Guide" (PDF). www.datalight.com.
- ^ Platt, Robert; Spiegl, W. (2008) [2003]. "Command: EMM386". Archived from the original on 2017-08-23. Retrieved 2015-10-21.
- ^ a b Okazaki, Taku; Schulman, Andrew (1994-09-01). "The Windows Global EMM Import Interface". Dr. Dobb's Journal. Undocumented Corner (9). Archived from the original on 2017-08-23. Retrieved 2015-10-21. [1] Archived 2014-05-29 at archive.today [2] [3]
- Brown, Ralf D.; Schulman, Andrew (July 1994). "QPI: The QEMM-386 Programming Interface". Dr. Dobb's Journal. Undocumented Corner. San Mateo, California: 123–131. Archivedfrom the original on 2017-08-23. Retrieved 2017-08-23.
- ^ Lespinasse, Michel. "How to kick out a memory manager". Amiens, France: Walken / Impact Studios. Archived from the original on 2017-01-04. Retrieved 2015-10-21.
- ^ Paul, Matthias R. (2002-08-13). "Suche freien Speicherbereich unterhalb von 1 MB, der nicht von OS überschrieben wird" (in German). Newsgroup: de.comp.lang.assembler.x86. Archived from the original on 2017-09-04. Retrieved 2017-09-03.
- ^ "Q98768 - Troubleshooting MS-DOS 6.x and EMM386.EXE".
- ^ "EMM386 Troubleshooting and Technical Information (78557)".
- ^ "EMM386 and Early Versions of HIMEM.SYS (74977)".
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