XMS memory

[mikebw@bilow.bilow.uu.ids.net (Mike Bilow)]

Klarsen wrote in a message to Mike Bilow:

 K>     This is not new but wish to bring it to light again. I
 K> was making  a large version of jnos 1.10i and saw in
 K> config.h that XMS memory can not  be used.

Correct.

 K>     Since I run Windows it is counter-productive to use EMS.
 K> The EMS  driver cannot be loaded high so it takes 50k of ram
 K> away from EVERY dos  window! But a .pif file can set up a
 K> dos window to have any amount up to  a meg of XMS memory
 K> available to the application in that window.

NOS uses neither XMS nor EMS.  What it can use is the EMS page frame.  This is
very different from ordinary EMS-using programs, and is usually incompatible
with them.  EMS does provide for saving and restoring state around task
switches, even from inside TSRs, but NOS does not implement any of that.

As for Windows, you should be able to make the EMS page frame appear to be in
UMB space, not consuming conventional memory space.  How much XMS or EMS memory
is available to NOS is irrelevant, since no such memory is ever actually
allocated.

 K>     I am incapable of making the changes necessary to allow
 K> use of  XMS memorry so am asking that one of you good
 K> programers take this on as  a task. I know many nos users
 K> will thank you for getting this fixed.

It is a major piece of work to use paged memory of any kind.  EMS is paged
through a frame window fixed in size and position, while XMS is copied back and
forth into a settable window.

-- Mike