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From: hyc@math.lsa.umich.edu (Howard Chu)
Newsgroups: comp.sys.atari.st
Subject: Re: What will "overscan" give me?
Keywords: overscan,atari-st
Message-ID: <1990Oct19.203325.14938@math.lsa.umich.edu>
Date: 19 Oct 90 20:33:25 GMT
References: <jlong.656337729@cassiopeia>
Sender: usenet@math.lsa.umich.edu
Organization: University of Michigan Math Dept., Ann Arbor
Lines: 51

In article <jlong.656337729@cassiopeia> jlong@radc.af.mil (Jeff Long) writes:
>I have a 1040STF,TOS14,Mono-monitor:  Does overscan only work for color
>systems?  I read the docs and they mentioned a monochrome mode, but not
>very detailed.  Will I see a larger screen on my monitor??  Will the
>black, wasted areas be utilized?  Will it work with NeoDesk 2.05 (or
>NeoDesk 3.0 providing Gribniff EVER sends it to me!!), what about Flash1.6
>or Uniterm??  Will my Showdvi previewer use a larger screen?
>Will this guy ever quit asking question?  Are you still reading this??

Overscan works for both color and monochrome. On an Atari SM124 monochrome
monitor you will get 688x480 pixels, without any adjustments to the monitor.
(The author has since announced that he has tweaked it to display 720. Dunno
how.)So yes, the black wasted areas get utilized.

Neodesk 2.05 works fine with Overscan. Uniterm does not. I have a patched
version of Uniterm 2.0d that does. (It was too much effort for me to consider
doing it again for 2.0e...) I don't use Flash, so I don't know about that.
I haven't installed the font files on my system, so have never tried any of
the DVI previews. Dunno.

MGR works... 

The standard version of overscan puts the video system into 50 hz (PAL) mode.
If you're particularly sensitive to video flicker, you'll notice the change.
I think it's the only way to make it worthwhile though - you have 340 (?)
scan lines at 50 hz, and you can tweak the video display to 280 scan lines.
At 60hz, there are only 262 scan lines, and you can only get 224 video lines
total. (This is for color, btw. Monochrome is as I described above.)

I noticed that the hardware limit for monochrome seems to be around 500 lines,
so getting 480 is probably about the most you'll see. I haven't seen anyone
get near 800 horizontal though.
>
>Sorry, got carried away for a moment...  But seriously, if anyone could give
>us a brief, "real-world" view of what overscan (and overscan_60) will do
>and post to the net (I think this is of interest net wide) I would really
>appreciate it!!
>
>
>--
>-------------------------------------------------------------------------------
>|    Capt Jeff Long                                 longj@lonex.radc.af.mil   |
>|    Rome Air Development Center                    (315) 330-7751            |
>|    Communications Networking Branch               (DSN) 587-7751            |


--
  -- Howard Chu @ University of Michigan
  one million data bits stored on a chip, one million bits per chip
	if one of those data bits happens to flip,
		one million data bits stored on the chip...