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From: soohoo@cory.Berkeley.EDU (Ken "kens" Soohoo)
Newsgroups: comp.sys.atari.st
Subject: Re: Atari ST Screen Dump Info Sought
Summary: Thoughts on how to steal alt-help...
Message-ID: <10678@pasteur.Berkeley.EDU>
Date: 4 Mar 89 19:21:26 GMT
References: <3958@druhi.ATT.COM> <10597@pasteur.Berkeley.EDU> <3292@hermes.ai.mit.edu>
Sender: news@pasteur.Berkeley.EDU
Reply-To: soohoo@cory.Berkeley.EDU.UUCP (Ken "kens" Soohoo)
Organization: University of California, Berkeley
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In article <3292@hermes.ai.mit.edu> jpexg@hermes.ai.mit.edu (John Purbrick) writes:
>> ... for the Atari Laser Printer (SLM804) there's a screen dumper that
>> steals the Alt-Help and outputs the correct data over the DMA to print
>> to the laser printer...
>> --Kenneth Soohoo	(soohoo@cory.Berkeley.Edu)
>
>How does a program do this? Presumably terminate-and-stay-resident, but how
>does it intercept keypresses?
>

John, I'm not sure how this SDUMP program does this itself, but I would
create a terminate & stay res as suggested, and then sit on the keyboard
interrupt vector -- find the appropriate keys in the packet coming in
and just not pass them to the system.  Once you've got contrl there,
you should be able to do anything with the screen... Don't know about the
specifics (use Kbdvbase() to grab the system keyboard vector, that's about
all I know), sorry.
--Kenneth Soohoo	(soohoo@cory.Berkeley.Edu)
  Atari 400/800/600xl/800xl/1200/130xe/65xe/xe game/7800, 1040ST/MEGA hacker
  "It could be worse, you could get hit by a truck..."
  My opinions are my OWN, _not_ necessarily Atari's.