DOS memory manager
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DOS memory managerSoftware that allowed DOS to manage more than one megabyte of memory or to manage its first megabyte more effectively. Third party memory managers, such as QEMM, 386MAX and NETROOM, 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 included its own memory managers: HIMEM.SYS managed extended memory (real memory), and EMM386.EXE managed bank-switched expanded memory.
In Windows, EMM386.EXE was eliminated, but HIMEM.SYS was carried over for compatibility up to Windows XP. See HIMEM.SYS, EMM386.EXE, memory allocation, PC memory map, EMS, XMS, VCPI, DPMI and PC operating environments.
DOS MEMORY AREAS Conventional 0-640K Upper (UMA) 640-1024K High (HMA) 1024-1088K Extended 1024 and up Expanded Bank switched memory