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Date: Fri, 21 Feb 1997 01:04:17 +1100
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199702201404.BAA02379@godzilla.zeta.org.au>
To: bde@zeta.org.au, eivind@dimaga.com
Subject: Re: Screen flickering
Cc: brian@awfulhak.demon.co.uk, hackers@freebsd.org
Sender: owner-hackers@freebsd.org
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>>Otherwise, the best that can be done is probably something like:
>
>Nope.  If there is a *timer* interrupt available, you can use it to create
>a vertical blanking interrupt by tweaking start point and delay.  'Nuff said?

Well, there isn't a timer interrupt available, and keeping a timer
interrupt in sync would require large code and/or large runtime overheads.

For extra credit, use the standard timer to provide interrupts at HZ Hz,
(normally 100), the screen refresh rate, and whatever is requested by
acquire_timer_0() (which should be a multiple of 100 Hz <= 16000 Hz).
The HZ Hz interrupt must not have significantly more drift or jitter
than it does now.  Well, there isn't a timer interrupt available :-).

Bruce