base memory
The lowest 640 {kilobytes} of memory in an
{IBM PC}-compatible computer running {MS-DOS}. Other PC
{operating systems} can usually compensate and "ignore" the
fact that there is a 640K limit to base memory. This was put
in place because the original {CPU} - the {Intel 8088} - could
only access one {megabyte} of memory, and {IBM} wanted to
reserve the upper 384KB for {device drivers}. The {high
memory area} (HMA) lies above 640KB and can be accessed on
MS-DOS computers that have an {A20 handler}.
(1997-05-30)