The MS-DOS (or PC-DOS) operating system only allows 640K of RAM memory to be used by the operating system and application programs. To get around this barrier, Lotus, Intel and Microsoft agreed upon a standard method of expanding memory beyond the DOS limit. This standard, known as expanded," LIM, or EMS memory, allows applications to allocate memory beyond the DOS limit by breaking this memory use. Expanded memory on an 8088 computer is added in the form of a separate memory card. 80286 and 80386 computers have the added capability of allowing their "extended" memory emulate expanded memory by using special device drivers or memory managers. (7/96)
PC memory conforming to the LIM EMS 4.0 spec. Gives access to more than 640K of memory on Intel processors before the 80386. Used in a number of Windows-based products. EMM386.EXE is an expanded memory emulator for 80386 and newer machines. Obsolete.
Memory that can be used by some DOS software to access more than the normal 640K (technically, more than 1Mb). 80386, 80386SX, and 80486 computers can create expanded memory readily by using an EMS (expanded memory specification) driver provided with DOS, through Microsoft Windows, or through a memory manager such as Quarterdeck QEMM or Qualitas 386 To The Max. To use expanded memory, a program must be EMS-aware or run under an environment such as Microsoft Windows. 8088- and 80286-based computers often need special hardware to run expanded memory. See also memory