From: skip@tacky.cs.olemiss.edu (Skip Sauls)
Subject: Re: REALLY confused about monitors - for A1200
Organization: University of Mississippi, Dept. of Computer Science
Date: Thu, 19 Nov 1992 01:14:37 GMT

In article <1992Nov19.094743.58855@qut.edu.au> barham@qut.edu.au writes:
>hilton@leechs.lzo.dec.com (Greg Hilton) writes:
>> I hope someone can explain something about monitors to me.
>>
>> I'm considering buying a 1200, now I've heard it will work on SVGA
>> monitors, however as I understand it the 1200 has a number of
>> different modes:
>>
>>     So according to my reviews the 1200 has the following modes:

And I have tried to fill in a few gaps.

       1280 x 512
>>     1280 x 400
       1280 x 256
>>     1280 x 200
       1024 x 1024
       1024 x 800
>>      800 x 600
        800 x 300
        640 x 1024
        640 x 960
        640 x 800
        640 x 512
>>      640 x 480
>>      640 x 400
        640 x 256
>>      640 x 200
        400 x 600
        400 x 300
        320 x 1024 
        320 x 960 
        320 x 800 
        320 x 512
        320 x 480
>>      320 x 400
        320 x 256
>>      320 x 200
        160 x 1024 
        160 x 960
        160 x 800 
        160 x 512 
        160 x 480
        160 x 400 
        160 x 256 
        160 x 200 
      
>>
>>     All modes offer 256,000 colours from a palette of 16.7m.
>>
>>     Would a SVGA monitor be able to DISPLAY all of these,
>>     with/without flicker?
>
>An SVGA monitor that covers the appropriate frequency range would
>work with all of these modes.  Super-hires, 800x600 (and maybe
>640x960 at a guess) would be interlaced, everything else not if you
>have mode promotion on.

Most SVGA monitors won't display the 24kHz and 15kHz modes at all.  As
for interlaced, if the mode is interlaced, say 640x960, it will flicker
no matter what monitor is used.  However, some modes such as the Euro 72
Productivity interlaced 640x800 mode do not flicker too badly.

>>     Would a multisync be able to DISPLAY all of these
>>     with/without flicker?
>
>Ho does a multisync monitor differ from a SVGA monitor?  Aren't SVGA
>monitors really multisync monitors?  I thought they would have to be.
>Answer as above.

There is no real SVGA standard as of yet, and in fact any board offering
more than stock VGA can be called SVGA.  Most of the SVGA monitors are
"multisync" only in the sense that they can handle a few extra modes.
Commonly, they can handle 640x480, 800x600, 1024x768, and often a few
others, but many of the AGA modes will not work.  Even the 800x600 mode
is incompatible with most SVGA monitors, despite the fact that the 
resolution is the same.

>> Would the 'standard' C= 1084 monitor work ok?
>
>Yep, but you wouldn't be able to get non-interlaced higher-res
>displays.
>
>> If anyone could explain what overscan and interlace means,
>> and what they would mean to a user, I would also be grateful.
>
>Interlace: To get higher resolution from a given bandwidth (forgive
>any inappropriate use of proprietry terms %^), the electron beam does
>the odd lines on its first sweep, then the even lines on the next
>sweep.  This results in flicker because the refresh rate of any given
>pixel id halved.
>
>Overscan: TV's display their picture beyond the visible edge of the
>screen.  This area is called overscan.  The Amiga lets you use the
>overscan area, which may be visible on your monitor, to get more
>pixels on the screen.  You can adjust the amount of overscan used so
>that your screens go right to the very edge of the vidible portion of
>the monitor.

This is true for some monitors, but not for many multisyncs and SVGA
monitors.  While great for video applications, I personally do not 
feel it is needed for most work.  The added real estate is great, but if 
it were off-screen it would be doing me no good.

>Tim.

Skip Sauls, Amiga Advocate
skip@tacky.cs.olemiss.edu

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