For example, if the following message is displayed when HIMEM.SYS
Installed A20 handler number 7,2.
the first number, 7, refers to the machine number. You can change this
number by including the /MACHINE switch on the DEVICE command for
HIMEM.SYS in your CONFIG.SYS file.
The second number, 2, refers to a delay number that is relevant for
certain IBM AT compatible machines. You cannot specify the delay
number; it is determined automatically by HIMEM.SYS.
In the example above, the Toshiba A20 handler (machine number = 7) is
installed using delay number 2.
There are only three valid delay numbers: 0, 1, 2. Also, there are
only specific valid combinations of machine and delay numbers. A delay
number of 0 is never displayed; the absence of a delay number implies
a delay number of 0. (Therefore, "1" is equivalent to "1,0".) The
following list details the valid combinations of machine and delay
numbers under MS-DOS 5.0. All machine numbers not listed here are not
associated with delay numbers.
Machine Code Machine Number, Delay Number
The following combinations identify identical A20 handlers:
11 = 1
12,1 = 1,1
13,2 = 1,2
If you specify /MACHINE:1 as a HIMEM.SYS parameter, HIMEM will
automatically attempt to determine which of the three delays is
appropriate. However, if you specify /MACHINE number 11, 12, or 13,
HIMEM.SYS will not attempt to determine the correct delay value.
Instead, it will use the delay value as shown in the previous table.
For example, if you specify /MACHINE:11, HIMEM.SYS will use machine
number 1 ("at") with delay number 0.
These alternative values for "at" are useful only if you cannot load
HIMEM.SYS on an IBM AT compatible computer.