[A83] Re: [ON] interrupts

To: <assembly-83@lists.ticalc.org>
Subject: [A83] Re: [ON] interrupts
From: "Henk Poley" <HPoley@DDS.nl>
Date: Sat, 23 Feb 2002 08:33:35 +0100
Reply-To: assembly-83@lists.ticalc.org


> Van: SUCKER from the old days <sucker_pvn@hotmail.com>
> 
> I know pressing [ON] creates an interrupt. But is it only
> one or does it creates new interupts until the [ON] is
> released?(I also wonder why the cursor blinks that funny
> way when [ON] is pressed)
> 
>       SUCKER

When you press the [On] key it immediately toggles the interupt-pin of the
Z80. This will (uhm) set the interrupt flipflops inside the processor, so
the Z80 won't listen to anny other interrupt untill you execute an EI. So
only one interrupt should be 'generated'.

Try searching "Z80 pinout" with google.com or debriefing.com, but double
check the things you found, there are some bad documents around.

About the blinking, that's some sort of 'bug' in the TIOS. Since the
system-interrupt ($0038) does things like updating the cursor-blink and the
run-indicator, and pressing the [On] key also toggles this interrupt,
things mix a bit up in timing.

As far as I know...

	Henk Poley <><

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