Re: [Freedos-devel] New freeware DOS memory manager: EMS Magic

[tom e. <te...@dr...>]

>> A couple of corrections...
more corrections ;)

>> ...

>>> There is even an EMM286.EXE driver for machines with a 286 CPU floating around
>>> the Internet that basically does the same thing EMM386 from MS does (including
>>> providing virtualized EMS).
>>
>> Never seen that one. But the 286 memory managers I saw, such as
>> BlueMax, used the _chipset_ to map RAM into UMBs, not the CPU. The 286
>> doesn't have a hardware MMU and can't do this. This meant that 286
>> memory managers were specific to the motherboard chipset. BlueMax
>> worked on IBM 286 PS/2s and nothing else. There was also a Chips &
>> Technologies one I read about.

> I don't know exactly how EMM286 works -- it may be in fact be quite different than EMM386. 
By it's description https://ibm-pc.org/drivers/memory/EMM286.ZIP it's essentially the same 
as the starter of this thread https://www.emsmagic.com/. «EMS Magic is an expanded memory (EMS) emulator for DOS programs.

simulated EMS, but no UMB.

>  I do know that it provides essentially the same functionality as EMM386.  Also, if you use the EMS provided by EMM286, it seems to reboot the CPU to exit the Page Frame (i.e., it is VERY slow and isn't as useful as it is with EMM386).

AFAIR rebooting a 80286 required some order of millisecond(s). While far slower then a 80386 (didn't require this reboot),
but but much faster then a disk access which is was often used to access data > 640KB. So it's usefullness depended 
on the way the program would use EMS.


>> x86-64 removes support for V86 mode, and I believe, for 286 protect mode too.
Nope. a current X64 still has real mode and V86 mode. However both are not available with a 64Bit host OS.

AFAIK 286 protect mode too is available from x86-64, too.

However there are so few 286 protected mode programs in the wild, that they are rather irrelevant. They all died with OS/2.

Insofar 8088 mode programs (Lotus 1-2-3 r2, Wordperfect, SuperCalc, As Easy As, Quattro Pro) are probably much more relevant.
And that's where the thread started;)



Tom