Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!ames!elroy!hacgate!tcville!sed170!lee
From: lee@sed170.HAC.COM (John Lee )
Newsgroups: comp.sys.amiga.tech
Subject: Which timers are free?
Keywords: timers
Message-ID: <272@sed170.HAC.COM>
Date: 23 Dec 88 18:56:40 GMT
Reply-To: lee@sed170.UUCP (John Lee (ird))
Organization: Hughes Aircraft Co., El Segundo, CA
Lines: 32


I have an application that must send a pulse to mouse port 2 and must be
synched to the VBLANK interrupt, but must occur a fixed time after the
interrupt.  I have several options, including using the copper to actually do
the output via the user copper list, but I wonder what would happen if the
screen is dragged down or subtended (put behind other screens.)  This code
must be multitasking/OS/Intuition/Workbench friendly.

The idea I have would be to:
	1) Establish a VBLANK interrupt handler.  This would start the timer
		on each VBLANK.
	2) Establish a timer interrupt handler.  This would send the pulse
		to mouse port 2.

Creating and establishing the two handlers are easy.  So, what's my problem?
I need to know which timer is free to allocate for my use and if there is a
better way to go about it.  I just read the article by Robert "Kodiak" Burns
in reply to a different question which said that the two timers in CIAB are
free, but I wish to confirm this (I also seem to recall that that only one
timer generates a hardware interrupt.)

I'd appreciate any help, questions, critiques, and donations.  Thank you!

					John Lee

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