IBM PC hacking

[Tony Duell]

> 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