Important Notice

The pages on this site contain documentation for very old MS-DOS software, purely for historical purposes. If you're looking for up-to-date documentation, particularly for programming, you should not rely on the information found here, as it will be woefully out of date.

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Using HIMEM.SYS
The HIMEM.SYS device driver conforms to the XMS (Extended Memory
Specification) version 2.0. It allows MS-DOS programs on 80286 and later
systems with extended memory to access an extra 64K segment of memory
for code and data. This memory segment is located just above the 1 Mb
boundary and is called the High Memory Area. To use HIMEM.SYS with your
computer, you must have an 80286 or later processor and DOS version 3.0
or later.
 
To install HIMEM.SYS, include the following command line in your
CONFIG.SYS file:
 
          Device=[d:][path]HIMEM.SYS[/HMAMIN=tsrmin][/NUMHANDLES=handles]
 
If you install other device drivers that use extended memory calls, place
the commands that install them in the CONFIG.SYS file after the
above command line.
 
The HIMEM.SYS device driver syntax contains the following options:
 
Option              Function
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tsrmin              Specifies the minimum amount of memory, in kilobytes,
                    a Terminate and Stay Resident (TSR) program must have
                    to be placed in the High Memory Area (HMA). The minimum
                    value is 0, the maximum value is 63, and the default
                    value is 0. To ensure that QBX has access to the HMA,
                    set tsrmin to 63 (64,512 bytes).
 
handles             Sets the maximum number of Extended Memory Block (EMB)
                    handles, in kilobytes, that HIMEM.SYS supports.
                    The minimum value is 1, the maximum value is 128,
                    and the default value is 32. Each additional handle
                    requires an additional 6 bytes of resident memory.
                    This option has no effect on the use of extended memory
                    by QBX since these handles give access to addresses
                    above the HMA, which QBX cannot use.
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  See Also    ◄Using RAMDRIVE.SYS►
              ◄Using SMARTDRV.SYS►