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From: izumi@mindseye.berkeley.edu (Izumi Ohzawa)
Newsgroups: comp.sys.next,comp.graphics,comp.misc
Subject: Re: RFI: monitor's resolution < video signal
Message-ID: <1991Apr10.065134.1245@agate.berkeley.edu>
Date: 10 Apr 91 06:51:34 GMT
References: <1991Mar28.072150.5375@cunixf.cc.columbia.edu> <1991Apr10.022848.14504@odin.corp.sgi.com>
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In article <1991Apr10.022848.14504@odin.corp.sgi.com>
   naegle@icon.asd.sgi.com (David Naegle) writes:
>In article <1991Mar28.072150.5375@cunixf.cc.columbia.edu>,
>toshi@cunixf.cc.columbia.edu (Toshi Kawanishi) writes:
>
>>Does anyone know what happens to the image on the screen when
>>the resolution of the monitor is smaller than the resolution
>>required by the video signal?
>
>>I found out from Next that the slab requires a monitor with:
>>	- 68Hz refresh
>>	- 1120 x 832 resolution
>>	- 3 BNC inputs (I guess Sync is on the Green)

You are missing a critical spec which is that the monitor
can sync to 63-64kHz Horizontal scan rates.
Although not many ads for monitors have that info, that's
the most critical info needed for choosing monitors.
Usually, you have to get more technical spec, or users/oweners
manual to get that number.

>
>>My multisync has enough bandwidth to handle the timing, but falls
>>short on the resolution.  My sparse understanding of this subject
>>leads me to believe that I will just lose some pixels.  However, my

I am not sure if your monitor does.  Go get the manual for
the monitor, and check the range for H-scan rate to which
the monitor is able to lock onto.

Many muti-syncs, such as NEC 3D, 4D's can't do it. Neither
does Seiko's CM-1440.  I.E., most monitors sold for
super-VGA for PC's can't be used.
(For example, CM-1440 can lock to 31-40kHz H-scan rate.)

So, look for ads, call manufactures and ask if the
monitor you are interested in can handle 64kHz H scan rate.
Pixel resolutions such as 1024x768, 1120x832 don't mean much.
Ask for someone who knows what "horizontal scan frequency"
means.

Phospher triad pitch, as David says, is important once you
can obtain sync, but many multi-sync monitors won't just
sync to the video signal.  And if you don't get sync, you
get no picture.

>>If this is true, can it damage my monitor?  Or do I worry too much?

And I believe that driving monitors with wrong scan rates
for an extended period of time WILL damage monitors.
It can even be a fire hazard.  Remember orginal IBM PC
monochrome monitor which had exactly this problem.  You
are taking a chance if you believe that newer monitors
are protected from the overload resulting from out-of-range
scan rates.

Izumi Ohzawa             [ $@Bg_78^=;(J ]
USMail: University of California, 360 Minor Hall, Berkeley, CA 94720
Telephone: (415) 642-6440             Fax:  (415) 642-3323
Internet: izumi@violet.berkeley.edu   NeXTmail: izumi@pinoko.berkeley.edu