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

Hi, Alain wrote:

> I have nothing against FreeDOS EMM386. I have against Micro$ofts's.
> What is the completion state of FreeDOS EMM386? Is it stable? What
> services are running? Does it provide UMB?

FreeDOS emm386 is stable IF you use it with the himem that comes with
it. After fixing all known incompatibilities, there are still some
unknown incompatibilities with FDXMS left :-(.
You cannot use it with > 64 MB RAM, as the page tables will point to
the void for the RAM beyond that pointer, even for things loaded
-before- emm386. That is, using FDXXMS with FreeDOS emm386 is futile
as a way to get > 64 MB of sum(EMS, XMS).

FreeDOS emm386 supports UMBs and EMS. Its big downside is that it does
not support VCPI. For that reason, you cannot run any protected mode
programs (like programs that use DPMI, for example djgpp compiled
programs) after loading FreeDOS emm386.

I personally prefer using UMBPCI for getting UMBs (alternative choices
are HIRAM, URAM, RDOSUMB), but this means that I have no EMS (I normally
do not need EMS). You can find a list of supported hardware for UMBPCI
and the like in the technotes (#177 I think). If your hardware is
supported, you have UMBs in a very efficient way. If not, you must use
any variant of emm386 to get UMBs. An example of non-supported hardware
are AMD KT133 motherboards for Athlon, as far as I remember. Alas, cool
processor and not too expxensive!

For having UMB -AND- EMS, I use DR DOS emm386. This also has a built-in
DPMI host for protected mode software, but it also offers the normal
VCPI support. If you have it with DPMI=ON in your config.sys, some low
level drivers may break. But in normal EMS/UMB only mode, it is very
neat. You must use VERSION=4.01 in config.sys or my personal patched
version or have a kernel that offers > 64k RAM to device drivers to use
it (I HOPE that 2027 will), because it uses lots of RAM for a short
moment during installation (but then frees most of it, moving itself
beyond the 1 MB boundary).

PS: Some versions of MS emm386 work as well, some others do not. The
configuration is a bit tricky. But you did not want to use it anyway :-).

Eric