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From: dale@amiga.UUCP (Dale Luck)
Newsgroups: comp.sys.amiga
Subject: Possible new hack
Message-ID: <1699@amiga.amiga.UUCP>
Date: Tue, 14-Jul-87 17:10:46 EDT
Article-I.D.: amiga.1699
Posted: Tue Jul 14 17:10:46 1987
Date-Received: Thu, 16-Jul-87 07:39:12 EDT
Reply-To: dale@amiga.UUCP (Dale Luck)
Distribution: na
Organization: Commodore-Amiga Inc., 16795 Lark Ave. Suite 106, Los Gatos CA 95030
Lines: 18

For you guys that need 120 hz refresh but can get by with half the number
of lines are your display, you could try this.
I haven't tried this out , but it shoudl work.
Write the beam counter in the middle of the display to bump it down
to the end. I don't remember if the copper can write the beam counter,
the chip designers might have gone crazy again with their arbitrary
limitations. But anyway, write it so it is about 255 or so, it will then
continue counting up to 262 or so and trigger vblank and the display
will start again. Most monitors should not have any trouble with this.
Well, I'm no hardware guy so that is just a guess to.
This response prompted by some guy in toronto wanting to quad lace
the display. I remember the tektronics stereo displays were running at
twice refresh rate so this idea just popped up. Meaning they were
interlacing at 120 instead of 60hz per field.

Oh well,
happy hacking
Dale