IBM PC hacking

Fred Cisin cisin at
Tue Sep 13 19:46:51 CDT 2005

On Wed, 14 Sep 2005, Tony Duell wrote:
> 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 original 5150, during 1981 and part of 1982 had one row of 16K DRAMs
soldered in, and sockets for another three rows.

Later, they switched to one row of 64K DRAMs soldered in, with sockets for
another three rows.  Some (all?) of those motherboards could be trivially
modified to take 2 rows of 64K plus two rows of 256K.

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