EMS/XMS memory driver needed

From: Captain Napalm <spc_at_armigeron.com>
Date: Tue Aug 11 09:18:37 1998

It was thus said that the Great Lawrence Walker once stated:
>
> Has he actually powered up this beast yet ? I had an XT from
> Phillips that had 768k onboard that I passed on to a friend and I
> don't remember it having any sort of memory manager. IIRC the first
> time I used it with DOS 3.2 floppies, I was amazed as the mem counter
> went up to 640 and just kept going. I imagined it was some trick they
> did in bios.
> If his doesn't use the full ram, I'll double check with my friend in case I
> missed something. I've also got several 286 mem managers someplace here
> but I doubt if they will work with an XT.

  The infamous 640K limit isn't a fault of Microsoft (well, partly, but not
entirely) but of IBM. The memory map of an IBM PC (or PClone) has RAM
stopping at $9FFFF, or 640K. Memory starting at $A0000 is reserved and if I
recall, it's mapped out as:

        $00000 RAM
        $A0000 Reserved or EGA/VGA graphics memory
        $B0000 MDA or CGA graphics memory
        $C0000 Reserved or Expansion ROM
        $D0000 Reserved or Expansion ROM
        $E0000 Reserved, Expansion ROM or Extended BIOS
        $F0000 BIOS

  More or less. But you have to remember, that's for a 100% compatible IBM
PC clone. Remove that restriction and you can have more memory. MS-DOS can
work fine with more memory, but its problem is that the memory has to be
contiguous (Thanks Microsoft. And while you're at it, could you make it
non-reentrant? Perfect ... ).

  -spc (Remembers more of this than he wants to ... )
Received on Tue Aug 11 1998 - 09:18:37 BST