Expanded Memory Specification

(E-M-S)

The first specification to allow more active memory than the one megabyte allowed by the Intel 8086 CPU. The expansion used memory that was paged into the 1MB as needed. (Now largely obsolete since CPUs can address far larger memory spaces directly.)

Expanded memory works by paging memory from an expanded memory pool into memory areas the CPU can directly address. An expanded memory manager (EMM) keeps track of which memory page(s) are needed at any time. Using this technique the life of the 8086 and 8088 processors was extended.

You might also see this memory specification referred to as LIM for the co-developers: Lotus, Intel, and Microsoft.

More Information

• PC Memory Architecture