Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!usc!apple!agate!e260-4c!c60c-4ab
From: c60c-4ab@e260-4c.berkeley.edu (Scott Drellishak)
Newsgroups: comp.binaries.ibm.pc.d
Subject: Re: Sys Req - key.
Keywords: SysReq
Message-ID: <1989Dec6.071852.25430@agate.berkeley.edu>
Date: 6 Dec 89 07:18:52 GMT
References: <187@nmtvax.nmt.edu> <1989Dec5.190738.17084@ux1.cso.uiuc.edu> <20358@pasteur.Berkeley.EDU>
Sender: usenet@agate.berkeley.edu (USENET Administrator;;;;ZU44)
Reply-To: c60c-4ab@e260-4c (Scott Drellishak)
Organization: University of California, Berkeley
Lines: 36

In article <20358@pasteur.Berkeley.EDU> cs9a-ax@dorothy.Berkeley.EDU.UUCP (Mike Morrison) writes:
>In article <1989Dec5.190738.17084@ux1.cso.uiuc.edu> wang@cs.uiuc.edu (Eric Wang) writes:
>-In article <187@nmtvax.nmt.edu> jeff@nmtvax.nmt.edu (- Jeff -) writes:
>--This is probably a useless question, but there is a mysterious key on my 
>--XT-keyboard called the 'Sys Req' key. I've seen this key on many other 
>--IBM and compatible keyboards and I am just curious if anyone knows what it 
>--is for and how to access it? I can't seem to find anything in my DOS 3.3 
>--manual about it. Anyone know what this key is for? Just curious...
>-
>-This is only what little I know of SysReq.  It does not claim to be a
>-comprehensive, technical treatise.
>-
>-The SysReq key is indeed a special key.  Of all keys on the keyboard, it is
>-the only one which is NOT processed through the INT 09 Keyboard interrupt.
>-Instead, it has a special interrupt all to itself (INT 15, I believe).  It
>
>This is at least partially false.  On my machine, an XT clone, the sys-req
>key DOES use int 09.  (int 15h is for cassette io).  It generates ascii 00, 
>scan code 37h.  When num-lock is on it generates ascii 77h, scan code 54h.
>The rest of the posting sounds ok to me, though -- I don't have any idea what
>the key is supposed to be used for.
>
>Mike Morrison
>cs9a-ax@dorothy.berkeley.edu
>morrison@ocf.berkeley.edu

On my XT clone, the Sys Req key doesn't generate any ascii or scan codes,
and, according to Peter Norton's Programmer's Guide to the IBM PC (not
actually called that, but close enough), it generates INT 15H with AH equal
to 85H.  It says nothing about the use of this key, however.


( Scott Drellishak
(
(   "You pays your money and you takes your frame of reference."
(                                           - Joe Haldeman, _The Forever War_