HIMEM.SYS is the DOS memory manager that enables extended memory above 1,024KB on your system, including the High Memory Area from 1,024KB to 1,088KB. The HIMEM.SYS driver is loaded in the CONFIG.SYS file with the following syntax:
	DEVICE=[d:\path]HIMEM.SYS [switches]
	DEVICE=C:\DOS\HIMEM.SYS /int15=1024
HIMEM.SYS Switches
SwitchPurpose
/a20control:on|offDetermines status of the HMA A20 line.
/cpuclock:on|offDetermines whether HIMEM.SYS will modify system clock speed. The default is off.
/eisaAllocates maximum amount of extended memory. Required for EISA systems with 16MB of memory or more.
/hmamin=nnnSpecifies minimum memory space a program must request in order for DOS to load it into the HMA. The number nnn will be in kilobytes. Only one program can load into HMA. The default size is 0KB.
/int15=nnnReserves nnn kilobytes for handling of int 15, which is used by certain older programs. The default size is 0KB.
/machine:nameDefines the specific computer type using a predefined code (required by some systems that HIMEM.SYS cannot detect).
/numhandles=nnMaximum memory block handles for extended memory. The default is 32.
/shadowram:on|offSets the status of shardow RAM.
/verboseCalls for status messages by HIMEM.SYS when it starts up.