On Sat, 18 Dec 1999 00:00:03 +0000, Or Botton wrote:
> Hm.. and how about SysRq? ("System Request"?) Whats that one for?
>
I'm not for sure if what I'm going to say it's true in its
entirety, but I'm going to tell what I know (or what I think I know).
The SysReq key has no function so you can press it until your
finger hurts: nothing will happen. But as always you can do program
which does something when you press this key. One way to do this is
replacing the interrupt 9 (the one that is generated whenever the
keyboard sends a code) and reading the port 60h to get the scancode of
the key pressed. You have to be careful using this method because you
have to remember to tell the controler of the keyboard that the
program has finished reading the key through the port 61h (put the
seventh bit on and then off) and remeber also to deny IRQs when you
change the interrupt vector and reenable them then and remeber to tell
the interrupts controler when the interrupt has finished... It's
pretty complicated.
I have looked to a reference manual and I have seen that the
BIOS interrupt 16h, funcion 12h can be used and you will obtain in the
bit seven of AH the status of SysReq.
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