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From: md3b+@andrew.cmu.edu (Matthew Donald Drown)
Newsgroups: comp.sys.cbm
Subject: Re: ML help!!!
Message-ID: <UbLgcf600UgKA2UFdS@andrew.cmu.edu>
Date: 6 Dec 90 22:46:03 GMT
References: <1990Nov30.161424.2348@uoft02.utoledo.edu>,
	<1990Dec3.183605.19548@news.nd.edu>
Organization: Carnegie Mellon, Pittsburgh, PA
Lines: 28
In-Reply-To: <1990Dec3.183605.19548@news.nd.edu>

I haven't done this in a couple years, I have an Amiga now, but for some help.

To set up an IRQ you must set the address you want to be jumped to, in
lo-byte, hi-byte format.  Then your code must end with a JMP $ea31. 
That should be it.  A simle prog that keeps the screen black no matter
what you do would be:

Begin:
  sei
  lda #<irqthingy
  ldx #>irqthingy
  sta $0314
  stx $0315
  cli
  rts

IrqThingy:
  lda #$00
  sta $d020
  jmp $ea31

That should do, more advanced stuff is stopping the interupt at certain
screen spots.  Not much harder, but get this part working first.
-Matt

(BTW, was anyone on QLink 2 years ago?  And if so do you remember a guy
called Nemesis?  That's me, I wrote a demo maker for people.)