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 ... )