22 Feb
2006
22 Feb
'06
5:24 p.m.
On Thu, 23 Feb 2006, Tony Duell wrote:
By lore, Gordon Letwin was responsible for coding a hack which used the
keyboard controller MPU to reset the CPU and throw it back into real mode.
I guess it worked, but was incredibly slow.
Yup.
Because once in protected mode on the 286, you can't get out unless
you reset the CPU.
-spc (I think you could get out by tripple faulting ... )
Could you, in general. I think you can on the PC/AT, but I seem to recall
a circuit that detects the odd state of the bus status lines if you get a
triple fault, and then resets the CPU, or toggles a pin on the keyboard
controller, or...