[Coco] [Color Computer] Opinion time

jdaggett at gate.net jdaggett at gate.net
Sat Apr 1 18:25:27 EST 2006


On 1 Apr 2006 at 12:52, George's Coco Address wrote:

> I wonder why that is.
> What experience did you have with this?
> I thought RGB is pretty much standardized.
> George

RGB for the PC is standardize. The problem is the Coco is not PC RGB compatible. 
Most LCD monitors on the market today are EGA/VGA/SVGA/XVGA resolution 
compatible.  IF the monitor by some weird chance supports Composite video input 
then maybe it will work with the Coco3. The Coco3 is hodge podge signal to some 
extent. CGA standard originally supported two colors, not 16. CGA max resoltion is 
640x200. EGA max resoution is 640x350. 

Secondly the Coco3 outputs positive sync that is TTL levels. The RGB signal is 1.2 
Volts P-P. Mondern VGA monitors require 0.7V P-P for the analog signal. EGA 
monitors require Horizontal pulse positive and vertical pulse negative. VGA 
monitors require both sync pulses negative. 

Modern LCD monitors will not directly accept the COCO signal. Very few monitors 
made today support 15.7KHz horizontal sync which is what the Coco is.

james





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