Replica IBM 5150 PC motherboard

Fred Cisin cisin at
Thu Mar 8 17:42:52 CST 2018

On Thu, 8 Mar 2018, Paul Berger via cctalk wrote:
> Hmmmm I don't remember my original PC having all the chips in sockets nor do 
> I recall it having 64Kb DRAMs.  I clearly recall that it had one bank of 
> 16Kb DRAMs soldered down and sockets for three more banks of 16Kb chips.  
> The only other sockets on the board where for the ROM, CPU, and math 
> coprocessor.  hardly a fathful reproduction.

If I remember correctly, the original PC/5150 BIOS supported a maximum of 
544K; later BIOS could handle 640K.

What were the details for modifying a 64-256 5150 to 640K on the 
motherboard?  (It was not the same as converting 5160).
It did NOT involve unsoldering the 64K Bank0.

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