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JEMM386 is an Expanded Memory Manager. JEMM386 requires a 80386+ CPU.

JEMM386 has to be loaded in CONFIG.SYS / FDCONFIG.SYS. Load JEMM386 as DEVICE=JEMM386.EXE in CONFIG.SYS (although it is an ".exe"-file!)


 DEVICE=[drive][path][jemm386.exe] [options]
        drive  The drive letter, e.g. C:
        path   The directory, e.g. \example\

or run it from the command line:

 [drive][path][jemm386.exe] [options]


+A20/NOA20     A20-disable emulation on/off (default on).
 ALTBOOT       Use alternate reboot strategy.
 B=####        Specify lowest segment address for EMS banking
 D=###         Set DMA buffer size in kB (default=64, max is 128).
 EMX           Increased EMX DOS extender compatibility.
 FASTBOOT      Fast reboot. Requires Jemm386 to be loaded in CONFIG.SYS.
 FRAME=E000    Set EMS page frame (FRAME=NONE disables frame). Any value
               between 8000 and E000 is accepted, but not all will work.
 I=D000-D7FF   Force a region to be used for UMBs. Without this option
               range C000-EFFF is scanned for unused pages. May also be
               used to add (parts of) regions A000-BFFF or F000-F7FF
               as UMBs. Don't use this option if you don't know what
               you are doing!
 I=TEST        Scan ROMs for unused pages, include found regions as UMBs.
 [MAX=]#####   Limit for VCPI (and EMS if < 32M) memory in kB
               (default 120 MB).
 MIN=#####     Reserve up to ##### kB for EMS/VCPI memory on init
 NOCHECK       Disallow access to address space without RAM (MMIO)
 NOEMS         Disable EMS handling. Use NOEMS to get more            
               free UMBs if you need no EMS.
 NODYN         No dynamic XMS memory allocation (use MIN= to set fix
 NOHI          Don't move resident part into first UMB.
 NOINVLPG      Don't use INVLPG opcode.
+PGE/NOPGE     Page Global Enable feature usage on/off (default off).
 RAM/NORAM     Try to supply UMBs on/off (default on).
 S=D000-D7FF   Assume Shadow-RAM activated by UMBPCI, include it as UMB.
 SB            SoundBlaster driver compatibility mode.
 SPLIT         Regain partially used EPROM 4k pages for UMBs.
+VCPI/NOVCPI   VCPI Support on/off (default on).
 VDS/NOVDS     Virtual DMA Services on/off (default on).
+VME/NOVME     V86-Mode Extensions on/off (default on).
 VERBOSE       Display additional details during start (abbr: /V).
 X=D000-D7FF   Exclude region from being touched or used by Jemm386.
               X=D000-D7FF can be needed e.g. for some network.
 X=TEST        Scan memory region C000-EFFF for UMB exclusion.
 /?            Shows the help.
'+': option can be set dynamically by running Jemm386 from the command

When invoked from the command line Jemm386 additionally will understand:

   LOAD        install
   UNLOAD      uninstall