Texas Instruments 3000 - Manual (Page 158)

TravelMate 3000 Memory Areas
MS-DOS directly accesses up to 640 KB of RAM for the execution of programs and
commands and for storing temporary data. MS-DOS cannot directly access memory
beyond this 640-KB limit. The amount of standard default RAM (640 KB) in the
TravelMate 3000 is displayed on the Setup Program menu as Standard (Memory), and it
can be changed in 64-KB increments if your application program requires it.
MS-DOS accesses different areas of the computer's memory in different ways. The
following memory map shows the available memory and how MS-DOS uses it.
Configuring Memory F-3