13 Sep
2005
13 Sep
'05
4:45 p.m.
I remember a little shop here in Santa Ana which had
the first clone of
the IBM PC. It was a single board which had 640k memory, allowed
using 64k memories, instead of the 16K memory that the PC and XT
earlier models used.
DId any IBM PC/ST motherboards use 16K DRAMs. Yes, I know the standard
memory mapping PROM could be set up to use 4 rows of 4816s (64K o nthe
mainboard), but did IBM ever do that? There's no mention of it in my TechRef.
The PC used either EProms, (16K I think) and the Roms
that were
shipped with the BIOS were registered. The standard Data I/O would
Do you mean there were internal data latches in the IBM ROMs?
not read them since they were not programmable, and
needed their
output enabled to read the data.
But once someone had them in the 2716's, it was easy to get them
running in your superboard.
Surely it was trivial to use DEBUG or similar to dump the appropriate
area of memory to disk...
First systems had a 63 watt P/S, and IBM cards if you could find
them for video. Also there was no floppy controller on the first
board.
AFAIK, no IBM PC, PC/XT, PC/XT-286, PC/AT, or PC-jr had a floppy (or hard
disk) contorller on the mainboard. None had parallel ports either, and
the PC-jr was the only one to have video and a serial port on the mainboard.
-tony