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From: jrv@siemens.UUCP
Newsgroups: net.micro.pc
Subject: Re: Alt-PrtSc?
Message-ID: <23900035@siemens.UUCP>
Date: Tue, 4-Nov-86 12:12:00 EST
Article-I.D.: siemens.23900035
Posted: Tue Nov  4 12:12:00 1986
Date-Received: Wed, 5-Nov-86 22:16:22 EST
References: <741@sphinx.UUCP>
Lines: 24
Nf-ID: #R:sphinx:-74100:siemens:23900035:000:1069
Nf-From: siemens!jrv    Nov  4 12:12:00 1986




Looking at the IBM Tech reference the Alt-PrtSc combination is suppressed
in the keyboard interrupt handler (int 9h). For you to get access to it
you would need to provide a substitute for this interrupt handler 
which would provide all the functions of the ROM BIOS routine and generate
something for the key sequence you are interested in. 

So as not to have to duplicate all of the IBM functionality it may be
possible to just look for the PrtSc scan code and process it when the
Alt key is depressed. For all other codes use the IBM routine to process
the data. This then requires you to create your own keyboard buffer which
gets characters from your special processing of certain key sequences and
also from the IBM keyboard buffer for all those keys processed by the
IBM BIOS routine. Then since you have your own keyboard buffer you will have
to provide your own int 16h routine so that most applications can get
access to keyboard data.


Jim Vallino
Siemens Research and Technology Lab.
Princeton, NJ
{allegra,ihnp4,seismo,philabs}!princeton!siemens!jrv