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From: fenger@galaxy.cps.msu.edu (Steven V Fenger)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: Loop Omnisync non-interlaced monitors (anyone have one?)
Message-ID: <1991Apr20.032214.13755@msuinfo.cl.msu.edu>
Date: 20 Apr 91 03:22:14 GMT
References: <1991Apr17.164509.19165@d.cs.okstate.edu> <1991Apr19.185311.6972@leland.Stanford.EDU> <28109@uflorida.cis.ufl.EDU>
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Organization: Michigan State University, Computer Science Department
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In article <28109@uflorida.cis.ufl.EDU> jdb@reef.cis.ufl.edu (Brian K. W. Hook) writes:
>TIME OUT!
>
>This discussion has been throwing around the phrase "scan rate" a wee bit
>too much.  I think we need to start clarifying "horizontal" and "vertical"
>since I, for one, am becoming confused.
>
>Sure, that new Sigma card does 72hZ.  But isn't that VSR (vertical scan
>rate)?  And doesn't that determine flickeriness?  A monitor that does 15-48
>is pretty good from what I here.  But that is HSR!  *NOT* VSR!  How can a
>monitor that does 48kHz work with a 72kHz card?  It WON'T.  Why?  Because
>they are too different ratings!
>
>Brian
>
>PS I'm STILL confused! :-)

Very good points.  "Scan rate" is being used as a catch all phrase.  But
there is a thread of truth here.  The verticle sync rate is not totally
independant of the horizontal sync.  A higher VSR requires a higher HSR.
For instance, you cannot have a 72Hz VSR and a 48kHz HSR to display
1024x768 (but it can work for 800x600).

Here are some specs from my VGA Wonder+:

HSR	VSR	Res
56.4kHz	69.7Hz	1024x768 ni
48.3	59.6	1024x768 ni
48.0	72.0	800x600 ni
37.6	60.0	800x600 ni
36.7	69.8	640x480 ni
35.5	87.0	1024x768 i
35.0	56.0	800x600 i
33.8	96.0	800x600 i
31.5	60.0	640x480 ni

Notice that the higher the VSR, the higher the HSR is needed for the
same screen resolution.

Steven Fenger
fenger@frith.egr.msu.edu  \
fenger@cps.msu.edu         >  But all roads lead to fenger@galaxy.cps.msu.edu
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