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From: ccplumb@rose.uwaterloo.ca (Colin Plumb)
Newsgroups: comp.sys.amiga.programmer
Subject: Re: Is OS supposed to zero the TOD clock registers intermittently?
Keywords: Intuition TOD clock bugs race condition
Message-ID: <1991Mar22.011550.23658@watdragon.waterloo.edu>
Date: 22 Mar 91 01:15:50 GMT
References: <1991Mar21.175806.23729@daffy.cs.wisc.edu>
Sender: daemon@watdragon.waterloo.edu (Owner of Many System Processes)
Organization: University of Waterloo
Lines: 27

pochron@cat17.cs.wisc.edu (David Pochron) wrote:
>In my (apparent) never-ending quest to figure out why my clock keeps going
>haywire when I drag windows around, I decided to look at the 8520 registers
>$BFD800, $BFD900, and $BFDA00 (CIAA-eventLSB, eventMid, and eventMSB for
>those who remember mnemonics)  and see what happens to them when this "blessed"
>event occurs.

Well, my 1.3 Hardware manual says that CIA A is BFEx01 and CIA B is
BFDx00, so you're looking at the CIA B TOD register, which is used
by the graphics.library to synchronise events to the video beam,
i.e. QBSBlit().

I can see why heavy graphics activity could use this counter heavily.

>This TOD clock thing is really messing up "make" and other time-dependent
>utilities!

If you're getting erratic time from the timer.device, then, yes, there's
a bug somewhere, but if you're doing something wierd with the CIA directly,
then the A/B confusion might be causing some problems...

>                             | Canada: One of the world's greatest mysteries..

If you're going to use a literary metaphor, than I guess the U.S. is
a slasher flick...
-- 
	-Colin