24 May
2016
24 May
'16
3:10 p.m.
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