Base memory
<hardware, jargon> 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.
