[Coco] Run of RGB2VGA boards

[Barry Nelson]

Sorry to contradict, but a Commodore 128 uses RGBI, an Amiga (any model) uses analog RGB with a 0.7 volt video signal with characteristics nearly identical to the CoCo 3's RGB signal except the Amiga's video connector has a composite sync output with a standard level composite sync where as the CoCo 3 has only separate positive  pulse H and V sync available on the RGB connector with a very low output voltage. I should know, I have an Amiga 2000, an Amiga 3000, and until very recently an Amiga 4000. The 4000 stopped working a few months agp :(. The 3000 actually has a builtin VGA scan doubler that enables it to output a signal with a 30khz scan rate compatible with most VGA monitors on it's 15 pin VGA connector. The other Amiga models only output 15khz analog RGB video similar to the CoCo 3. I also own a Commodore 128 so I am familiar with it's video out as well.

On Aug 13, 2015, at 10:47 PM, coco-request at maltedmedia.com wrote:

> Date: Thu, 13 Aug 2015 19:47:41 -0700
> From: Steve Batson <steve_batson at yahoo.com>
> To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
> Subject: Re: [Coco] Run of RGB2VGA boards
> Message-ID: <C20A9ECB-57E1-4FFA-BE20-EB93D7ABD234 at yahoo.com>
> Content-Type: text/plain;	charset=windows-1252
> 
> This is from Luis' site.
> 
> RGBI
> 
> Optionally you can modify the board to support RGBI to be used with Tandy 1000, Commodore 128 or Spectrum 128+.  You just add 2x 1K0 resistor for the Bright channel. Make you cable to output the Bright through the RGB input pin 4. WARNING: The R,G and B lines don't have voltage dividers, instead they have a 75R pull down. Connecting it directly could damage the Altera permanently. Use a 150R resistor on the three lines in your cable for the R, G and B lines. The Bright line is already safe by this change. The RGBI can be switched by the switch RGBI