IBM 5150 maximum memory?

Tony Duell ard at
Sun Apr 27 12:44:35 CDT 2008

> I use the introduction of the Peanut as proof that IBM was still 
> suffering from the shock of having customers flock to buy the PC.  As 
> they discovered, even the unwashed public had its limits as to what 
> could be passed off as an IBM product.  Or maybe it was just the 
> result of a drunken bet.  You forgot the complete lack of DMA and, 
> shall we say, "anemic" interrupt handling facility?

I beleive it was possible to add a DMA chip on the expansion bus of the 
PCjr. The necessary bus control signals, and even the DRQ and DACK lines 
for the floppy controller, are there.

Not that many people did, of course...


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