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From: dhmyrdal@solan.unit.no (Dag H}kon Myrdal)
Newsgroups: comp.sys.acorn
Subject: Re: Mode 21 and an NEC 3D Multisync monitor
Message-ID: <1991Jan10.180650.13438@idt.unit.no>
Date: 10 Jan 91 18:06:50 GMT
References: <1991Jan8.214959.7587@watdragon.waterloo.edu>
Sender: news@idt.unit.no (Usenet news admin)
Reply-To: dhmyrdal@solan.unit.no (Dag H}kon Myrdal)
Organization: Norwegian Institue of Technology
Lines: 38

In article <1991Jan8.214959.7587@watdragon.waterloo.edu>, gcwilliams@watdragon.waterloo.edu (Graeme Williams) writes:
|> 
[...] When the Arc is in Mode 21
|> the NEC 3D refuses to display the screen properly, namely it is
|> displaced by about a half screen width to one side. (The undisplayed
|> area actually gets wrapped around and appears on the other side of
|> the display). *NO* amount of fiddling with the various monitor
|> controls to centre the screen will alleviate the problem - they're
|> just not designed to move the screen much more than an 1/8 to a 1/4
|> of a screen sideways. Consequently I can't use Mode 21.
|> 
|> Question: Am I missing something? Is the NEC 3D monitor incompatible
|>           with Mode 21? Or is my 3D monitor somehow faulty/not set
|>           up right inside? Or last (and hopefully least!) is my A310
|>           not performing properly?

When you have a faster hor. scan (ie a "higher" screen mode), the
monitor will shift the start of the left-hand screen border unless the
monitor has circuitry  to adjust for this.
You probably could get the monitor to work in mode 21, but then all
modes with a lower horisontal scan freq. would look like shifted left!!!

To sum it up.... Your problem is not due to a fault, but simply the
Archimedes' many different screen modes. You will need a very fleksible
multi-sync monitor to fully satisfy your Archimedes' capabilities...


--
Dag Haakon Myrdal, student of electronics
--
email:   dhmyrdal@solan.unit.no         (-SUN  internet, Trondheim)
snail:   DH Myrdal, Moholt Alle 2-01, N-7035 Trondheim, Norway
phone:   +47 7 588244
--
About MS-DOS: 
	    "... an OS originally designed for a microprocessor that modern
            kitchen appliances would sneer at...."
		   - Dave Trowbridge, _Computer Technology Review_, Aug 90