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From: lunnon@qut.edu.au
Newsgroups: comp.sys.atari.st
Subject: Re: Overscan in monochrome
Message-ID: <1991Feb19.094849.24138@qut.edu.au>
Date: 19 Feb 91 14:48:49 GMT
References: <1991Feb3.213147.24259@sbcs.sunysb.edu> <1991Feb13.223042.1968@math.lsa.umich.edu>
Organization: Queensland University of Technology
Lines: 34

In article <1991Feb13.223042.1968@math.lsa.umich.edu>, hyc@math.lsa.umich.edu (Howard Chu) writes:
> You got 672x480, I got 688x480 on my SM124. I got 736x480 using a multisync
> display (Magicsync+, .28mm dot pitch, supposed to be capable of 1024x768 rez).
> I also got 416x280 and 832x280 in color modes on the multisync.
> 
> So what's it take to get more vertical rez in color - interlace?

Actually, I designed a little (< $5) hardware hack a couple of years ago
which added an interlace mode to the ST. It was interesting to see a flicker
mode on an ST, anyway this $5 hack gave 320*400 640*400 640*800 interlaced
modes to your ST. Actually mono mode (640*800) was actually watchable 'cause
of the 72 Hz V scan rate. Add to that overscan and I guess 736*960 is possible
:-)


This actually was just a gizmo that plugged in into the monitor port between
the ST and your monitor and consisted of two ICs a 74ls74 and a 74ls122 I think
, The object is to delay the vertical sync pulse by half a line relative to
the horizontal sync pulse on every odd, given there was some way to detect
which field was which (GPO) one could flip screens each field to generate
high rez displays.

It turned out that I just could not stand the flicker, so the board is an
unusual curiosity in the bottom of a junk box somewhere.

	BOB
	R.Lunnon@qut.edu.au



> --
>   -- Howard Chu @ University of Michigan
> 
> Flame all you want - we'll take more.