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. -Swift