Re: UMB and 386/486 --> status of FreeDOS emm386 etc.

Hi, to react to "please have ONE memory manager only":
This is not really a good idea, here is why:

DR DOS emm386: XMS, EMS, UMB, DPMI, VCPI, not GPL
Freemm386: Will take ages to be done, EMS, UMB, VCPI.
FreeDOS emm386: Only GPL solution so far, EMS, UMB, no VCPI.
MS emm386: EMS, UMB, VCPI. Made by MS, uhm...

DR DOS himem: not GPL
MS DOS himem: by MS
FreeDOS himem: max. 64 MB, written mostly in C, by Tom.
FreeDOS fdxms: max. 64 MB, written mostly in ASM, by Martin.
FreeDOS fdxms286: max., uhm, 16? MB, by Martin, for 286.
FreeDOS fdxxms: max 256? MB, by Martin.

FreeDOS emm386 only runs with FreeDOS himem. It -should- work with
FDxms286 and FDxms as well, but some unknown incompatibilities remain.
It is usually hard for Tom and Martin to work together on one project,
but over the time, their 2 XMS manager families inherit each others
features.

It would be an idea to fix the incompatibilities... By the way, you
must not use FreeDOS emm386 together with a > 64 MB able XMS manager,
because the current version of FreeDOS emm386 does not activate the
memory beyond that boundary, and your XMS manager will get quite
confused about the gone part.

I think it should be possible to fix the unknown incompatibilities in
either FDxms286 or FDxms, so that it can work together with FreeDOS
emm386. I know, Tom would say: Why use FDxms, my Himem does the same!
But for the records: If it does the same, I would prefer to be able
to use all two/three...

I know that FDxms can be compatible to MS emm386, but I do not know
which of the others are compatible to MS emm386.

I know that DR emm386 prefers to run without any other XMS managers,
but it seems to be compatible to FDxxms/FDxms. I am not 100% sure, and
I did not check which of the others are compatible.

I know that neither Tom nor Martin would be willing to abandon their
versions of XMS managers and let them become part of the "jeweils"
other version. Hm, how do you translate this? I meant, neither Tom
nor Martin would want their C / ASM code to be rewritten in ASM / C.
But in the end, the projects are quite similar.

Toms version is optimized for FreeDOS emm386 compatibility.
FDxxms is specialized to offer BIG amounts of XMS.
FDxms is very similar to Toms version.
FDxms286 only uses the BIOS for copying, which should give high compatibility
and run even on 286s. I think it only uses 24bit 286 style segment descriptors
(which it provides to the BIOS), so it is limited to only 16 MB of RAM.

I hope I could clarify a few points :-).

PS: FDxms is supposed to auto-fallback to using the BIOS (in 386 style), which
should make it FreeDOS emm386 compatible. However, there are still some
unknown issues left. At least MS/DR emm386 can cope with them, but they are
too bad for FreeDOS emm386, so those two are incompatible, as said above.

Eric