SUMMARY
MS-DOS version 5.0 includes HIMEM.SYS version 2.77. MS-DOS version 6.0
includes HIMEM.SYS version 3.07. MS-DOS versions 6.2, 6.21, and 6.22
include HIMEM.SYS version 3.10. These versions include an A20 handler for
the following computers that can be used with the /M: or /MACHINE switch:
CODE Number A20 Handler
---- ------ -----------
at 1 IBM PC/AT
ps2 2 IBM PS/2
pt1cascade 3 Phoenix Cascade BIOS
hpvectra 4 HP Vectra (A and A+)
att6300plus 5 AT&T 6300 Plus
acer1100 6 Acer 1100
toshiba 7 Toshiba 1600 and 1200XE
wyse 8 Wyse 12.5 MHz 286
tulip 9 Tulip SX
zenith 10 Zenith ZBIOS
at1 11 IBM PC/AT
at2 12 IBM PC/AT (alternative delay)
css 12 CSS Labs
at3 13 IBM PC/AT (alternative delay)
philips 13 Philips
fasthp 14 HP Vectra
ibm7552 15 IBM 7552 Industrial Computer
bullmicral 16 Bull Micral 60
dell 17 Dell XBIOS
There are two values that are considered defaults. /M:1 is the
standard default for IBM AT-class machines, and t/M:2 is the standard
default for IBM PS/2 machines. For most 100-percent-compatible
machines, the /M:1, /M:11, /M:12, and /M:13 A-20 handler switches
should work. Although the other switches are hardware specific, one
may be required for proper operation on certain machines.
NOTE: In the above list, the device driver should detect the correct
handler to use. The following computers may need the corresponding
switch added to the CONFIG.SYS file:
System Switch
------ ------
Bull Micral 60 /machine:16
COMPUADD 386 systems /machine:1 or /machine:8
Datamedia 386/486 /machine:2
Hitachi HL500C /machine:8
Intel 301z or 302 /machine:8
JDR 386/33 /machine:1
Toshiba 5100 /machine:7
UNISYS PowerPort /machine:2