[Coco] CoCo RGB video timing and levels

[jdaggett at gate.net]

Mike

NTSC is 15,734 Hz line frequency or 63.557microseconds. The 
CM8 and the Coco in 80 character text mode has a line frequency 
of 15,701 Hz or 63.690 microseconds. 

james

On 23 Aug 2004 at 19:46, KnudsenMJ at aol.com wrote:

From:           	KnudsenMJ at aol.com
Date sent:      	Mon, 23 Aug 2004 19:46:56 EDT
Subject:        	Re: [Coco] CoCo RGB video timing and 
levels
To:             	coco at maltedmedia.com
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> In a message dated 8/23/04 11:37:51 AM Eastern Daylight Time,
> james at skwirl.ca writes:
> 
> > Based on this, and the standard size
> >  of an NTSC frame, it seems that the pixel clock would be 10MHz, am
> >  I right in that calculation? or around 11 MHz for a 720 width NTSC
> >  frame.
> 
> I'd say you are pretty close.  One NTSC scan line is about 64 us long,
> so for 640 pixels that's 10 MHz.
> 
> To measure it more accurately, you would use a good oscilloscope.  If
> you don't have one, I'd suggest you get one before getting too deep
> into this project.  Hit a local Ham Fest or haunt eBay.  There are
> Oriental knockoffs of name-brand scopes that are pretty good bang for
> the buck.  --Mike K.
> 
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