strangest systems I've sent email from

Swift Griggs swiftgriggs at
Tue May 24 17:10:27 CDT 2016

On Tue, 24 May 2016, Guy Sotomayor Jr wrote:
> The initial implementation of the A20 gate was implemented by the 
> keyboard controller(!) because it was discovered late in the PC AT 
> development cycle and we couldn?t add more logic to the board (but we 
> could add some wires).

That's very bizzare. It still makes me feel dirty just thinking about it, 
but it's interesting nonetheless. I wonder about some of the "clever hack" 
software that squeezed a tad bit more memory by dancing around/in 
previously reserved memory. Isn't that sort of how Quarterdeck got started 
? I also remember XMS and EMS and all that fun, though the Amiga geek 
inside me is screaming that I shouldn't reveal that.


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