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 highmemory area (HMA) lies above 640KB and can be accessed on

MS-DOS computers that have an A20 handler.