[comp.sys.apple2] Interrupts on the IIgs

AABENSON@MTUS5.BITNET (12/16/90)

On the Apple IIc and IIc+, I ***THINK*** (that means correct me if I'm wrong,
but do it in a nice way) that the only interrupts available are ones generated
by the serial ports.  I mean the only ones that you can get without adding
extra hardware -- okay, there IS the mouse, but who cares?!  Anyway, on the
IIgs, you have several sources of interrupts (without adding any extra hard-
ware.  The serial ports, the mouse, VBL interrupts (1/60 second), scanline
interrupts when in superhires mode (after any/every scanline you want), the
Ensoniq chip (after a waveform has completed its cycle -- kind of useful for
timing, because you can have it play a "flat" wave (all $80), and then select
a frequency to play it at.  No sound will be generated, but you can set it
to interrupt whenever you want just by adjusting the frequency of the sound
being played.), and I'm sure there's a few useless ones that I'm forgetting.
The most useful would be the scanline interrupts and the sound interrupts (in
my opinion).  Oh, there's also 1/4 second interrupts and 1 second interrupts.
1/4 second interrupts are reserved for Appletalk (Good point! Nobody DOES use
that, do they?) and the heartbeat task manager uses the VBL interrupts, but
you can just as easily setup a hearbeat task.

Well, that's all I can think of off the top of my head.  Anybody else think
of any?

- Andrew.

Internet:  aabenson@balance.cs.mtu.edu
Bitnet:    AABENSON@MTUS5.BITNET