Texas Instruments TravelMate 4000M, User Reference Manual, Page: 257 / 295

Extended Memory
Extended memory is internal system
RAM
above 1024 KB.
MS-DOS
or your applications (that support extended
memory) can access Extended memory if your system is
configured with an extended memory driver (
XMS
).
Extended memory drivers manage the extended memory
ensuring that two programs do not use the same part of
memory. The enhanced mode of MS Windows uses
extended memory to multitask applications.
MS-DOS
includes the
HIMEM.SYS
extended memory driver.
HIMEM.SYS
is defined in your
CONFIG.SYS
file where it is
automatically loaded each time you boot the system.
HIMEM.SYS
also enables
MS-DOS
programs to use an extra
64-KB region located just above the 1-MB mark for storage
of code and data. This area is known as high memory area
(
HMA)
.
n
Note:
MS-DOS
can also be loaded in
HMA
to free up
conventional memory. Refer to your MS-DOS User’s Manual
for instructions.
n
Note: Some application programs that run in 386
enhanced mode (such as Windows) require special extended
memory managers. Use the extended memory manager
provided with your application, if available. Otherwise, use
HIMEM.SYS
, the
MS-DOS
version furnished with your
computer.
You can define part of extended memory as one or more
RAM
disks using the
RAMDRIVE.SYS
device driver. Details are
provided in the next section.
Memory Areas
Configuring Memory F-3