DOS memory manager

A memory manager is software that allows DOS to manage more than one megabyte of memory or to manage its first megabyte more effectively. Since the early days of DOS, third party memory managers, such as QEMM and 386MAX, have used every trick in the book to move TSRs and drivers out of the lower 640K and into the 384K upper memory area (UMA).

Starting with DOS 5, DOS includes its own memory managers. HIMEM.SYS manages extended memory, and EMM386.EXE manages expanded memory. See DOS HIMEM.SYS, DOS EMM386.EXE, DOS Memmaker, memory allocation, PC memory map, EMS, XMS, VCPI and DPMI. Also see PC operating environments.

               DOS Memory Areas
   Conventional memory        0-640K
   Upper memory area (UMA)  640-1024K
   High memory area (HMA)  1024-1088K
   Extended memory         1024 and up
   Expanded memory         Bank switched memory

Popular non-Microsoft memory managers for DOS are QEMM, 386MAX and NETROOM.