BBS: Inland Empire Archive
Date: 04-17-92 (20:48) Number: 90
From: STEVE HALKO Refer#: NONE
To: DICK DENNISON Recvd: NO
Subj: Re: reboot with qb Conf: (2) Quik_Bas
DD> JV> OUT &H64, &HFE
DD> JV> ^^^^^^^^^^^^^^
DD> JV> | It performs a cold boot via the keyboard reset line.
DD>MB> What would this be if you wanted a
DD>You cannot use this method for a warm boot - for that you'll need the
DD>far jmp with call absolute. Also, this method should not work on a
DD>8088 or 8086 for a very interesting reason having to do with protected
DD>mode reentrance. (Steve Halko - can you elaborate on this ??)
Er . . . you must have mistaken me for an expert! I think it won't
work on 8088/8086 machines because I don't believe they even have a
port 64h. Port 64h was added in IBM AT's as a means of accessing the
newly added 8042 Keyboard Controller. XT's used an 8048 Keyboard
Controller which was not directly accessible to the programmer -
however, some keyboard parameters and functions were available thru
ports 60h/61h (which were connected to the 8255 Programmable
Peripheral Interface, PPI).
On a 286, the usual use of the OUT &H64, &HFE is to go from protected
mode to real mode. In 386/486's, there's a much more elegant (and
faster) way, but the OUT will still work, I believe.
* SLMR 2.1a * It's my parity and I'll baud if I want to!
--- DB B1065/002487
* Origin: Gulf Coast BBS -QuickSHARE #2- (904)563-2547 HST/V.32bis (1:365/12)