Tony Duell wrote:
>
> >
> > Tony Duell wrote:
> > >The first requirement is that you're mad.
> >
> > Now that you're foaming blue at the mouth, you could give the speech
> > about how to use the keyboard interface chip to bring the 286 into
> > real mode and back again... :-)
>
> Sure, it's not _that_ hard...
>
> The problem is that the i80286 can go from real mode to protected mode,
> but not back again. At least not without a hardware reset.
>
> Now, the keyboard controller output port bit 0 will, if pulsed low, reset
> the microprocessor. There's a keyboard controller command for that -
> 0xF1. You send that to output port 0x64. You also need to set the system
> flag (send 0x60, 0x04 to port 0x64 (or maybe 0x60,0x05)), set the CMOS
> shutdown bye (location 0x0F in the RTC) to 0x0A (to mean a user defined
> reset), and set IO_ROM_INIT (far pointer at 0x0040:0067 (offset) and
> 0x0040:0069 (segment) to point to your code. Or at least that's what I
> think you do - it's late and I'm readign the BIOS code as I type...
Yes, Tony, obviously "The first requirement is that you're mad." (We're
not talking _angry_ here, kids! "Mad" in English isn't the same thing
as in American.)
--
Ward Griffiths
They say that politics makes strange bedfellows.
Of course, the main reason they cuddle up is to screw somebody else.
Michael Flynn, _Rogue Star_
Received on Tue May 12 1998 - 20:08:51 BST