RE: [stella] problems with monitor syncing

Subject: RE: [stella] problems with monitor syncing
From: "Fred Quimby" <c9r@xxxxxxxxxxx>
Date: Mon, 2 May 2005 17:59:06 -0400
99% of VGA monitors cannot sync to a horizontal frequency lower than about 
twice that of a television (i.e. most VGA's can't do less than about 30 
kHz.)  Some really old VGA monitors will, but I wouldn't expect that people 
are going to own these monitors.

A workable solution would be to store the data from each scanline in a 
buffer.  Once full, output the buffer at twice the speed, and do it twice.  
In fact this is exactly what many simple TV to VGA converters do.

>From: Adam Wozniak <adam@xxxxxxxxxxxxxxxx>
>Reply-To: stella@xxxxxxxxxxxxxxxxxx
>To: stella@xxxxxxxxxxxxxxxxxx,  <fpga2600@xxxxxxxxxxxxxxxx>
>Subject: [stella] problems with monitor syncing
>Date: Mon, 2 May 2005 17:38:21 -0400
>Hash: SHA1
>These are images of my FPGA TIA driving my VGA monitor.  (Space Invaders,
>if you can't tell.)
>It looks as though the monitor cannot sync to the horizontal frequency
>I'm giving it.  The image is totally stable vertically (i.e. no rolling
>or anything), but it looks as though each line is wrapped around the
>screen twice (one and a half times?).  Look closely at the score; note
>the large gaps between pixels, both horizontally and vertically.
>Unfortunately I don't have a scope handy to measure frequencies.
>Is it possible my hsync is correct, but that my monitor sucks?  Or have
>I done something else wrong?
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