640 KB barrier
Updated: 04/26/2017 by Computer Hope
Alternatively called conventional memory, the 640 KB barrier is the PC compatible limit imposed by DOS mode that allows DOS programs to address a total of only 1 MB of memory. Because the system required 384 KB to be reserved, this left the lower 640 KB for DOS and other programs.
Did you know?
Bill Gates is often misquoted as saying "640 K ought to be enough for anybody."