China DOS Union

What exactly is the difference between DEVICE and DEVICEHIGH in Config.sys?
Sometimes DEVICE= is used, sometimes DEVICEHIGH is used. I don't know when to use DEVICE= and when to use DEVICEHIGH. Also, which one should be used before HIMEM.SYS? And if SMARTDRV.EXE is added in autoexec.bat, does HIMEM.SYS have to be added in Config.sys? Thanks in advance for the reply!

[ Last edited by mxfsun on 2006-3-29 at 17:14 ]

device only loads the device driver into conventional memory, while devicehigh loads it into upper memory. Of course, there is a prerequisite: you must already have upper memory space made available. If you haven't made it available, or if the available space has run out, it doesn't matter if you use the devicehigh statement—it just won't go up there and will still be loaded into conventional memory.
Because smartdrv must use XMS as the disk buffer, XMS space must already be made available before using it. DOS's built-in extended memory manager is himem.sys; you can also replace it with another third-party memory manager such as qemm386.sys. In short, as long as it can provide XMS, that's fine.

Then how should I enable XMS? Thanks for the reply!

? Haven't I already answered it: “DOS's built-in extended memory manager is himem.sys; you can also replace it with another third-party memory manager such as qemm386.sys”

device=[d:\path\]himem.sys
or
device=[d:\path\]qemm386.sys

The part in square brackets is optional; you should write it yourself according to your actual path. Of course, these two memory managers have many parameters as well, but generally the defaults will work normally.

It means enabling UMB