SUMMARY

EMM386.EXE and some versions of EMM386.SYS will detect which version of HIMEM.SYS is loaded. If an early version of HIMEM.SYS is detected (for example, version 2.04), EMM386 will issue the following message:

EMM386 may load successfully despite the incorrect version of HIMEM.SYS. If EMM386 loads, it will allocate all XMS memory available from HIMEM.SYS, which may cause problems for other programs that use XMS memory.

Microsoft recommends that any combination of driver versions that yield the above message not be used. The latest versions of each driver should be used, and these versions should not be mixed. A table of driver versions for MS-DOS versions 4.0 and later and Windows versions 3.0 and later is included below.

Driver         MS-DOS 4.01   Windows 3.0   Windows 3.0a   MS-DOS 5.0
------         -----------   -----------   ------------   ----------

HIMEM.SYS        2.04          2.60          2.60           2.77
SMARTDRV.SYS     2.10          3.03          3.03           3.13
RAMDRIVE.SYS     2.12          3.04          3.06           3.06
EMM386           4.00        4.10.0419     4.10.0419      *4.20.06x

* EMM386 version 4.20.06x, shipped with MS-DOS 5.0, has an .EXE
  extension to allow some command line processing. Previous versions
  of EMM386 had an .SYS extension, which act solely as device drivers.