DOS Dos

DOS Dos

A CONFIG.SYS setting as of DOS 5 that (1) allows part of DOS to be loaded into the HMA area (1024-1088K), and (2) allows drivers and TSRs to be loaded into the UMA (640-1024K) region.

To load part of DOS into the HMA, HIMEM.SYS (or some other XMS driver) must precede the dos= command in CONFIG.SYS, for example:

    device=himem.sys     XMS driver
    dos=high             load DOS high

To allow drivers and TSRs to be loaded into unused memory blocks (UMBs) in the UMA, both HIMEM.SYS (or some other XMS driver) and EMM386.EXE (or some other upper memory provider) must precede the dos= command, for example:

  device=himem.sys           XMS driver
  device=emm386.exe noems    UMA provider
  dos=umb                    allow UMA to be used

Both functions can be activated on the same line
with

               dos=high,umb

See DOS Loadhigh, DOS HIMEM.SYS and DOS EMM386.EXE.