[Coco] CoCo 3 RGB to CGA conversion

[Bill Barnes]

I believe your problems also lie in the fact that you CM-10 (that was the original CoCo RGB monitor, right?) is an RGBa, the IBM is RGBi. Meaning that the IBM CGA (IIRC) is only capable of about 16 colors (IIRC). while the CM-10 was capable of 32-bit color (16 million?) It may work, but as you notice the colors are off.

You can, of course as you noted, skip connecting pin 7, and route it to external [amplified] speakers, albeit the RCA sound jack would probably be better for that.

-Later!   -WB-    -- BABIC Computer Consulting.


--- On Sat, 3/14/09, N8WQ <exwn8jef at gmail.com> wrote:

> From: N8WQ <exwn8jef at gmail.com>
> Subject: [Coco] CoCo 3 RGB to CGA conversion
> To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
> Date: Saturday, March 14, 2009, 6:17 PM
> Fellow CoCo users,
> Last night my faithful CM-10 monitor let out some smoke (if
> you know what I mean, LOL). The only other monitor I had
> laying around was my IBM 5153 CGA Color Monitor. I plugged
> it into my homebrew CoCo tower and I have video but the
> colors are off. I compared the pin assignments on the IBM
> monitor to the CoCo 3 RGB outputs and all pins are the same
> except pins 6 and 7.
> 
> On my CoCo tower I wired up a DB9 connector to plug my
> CM-10 into.
> 
> IBM 5153             CoCo 3 RGB connector
> ---------------       ---------------
> pin 6 = Intensity     pin 6 = Polarity
> pin 7 = Reserved   pin 7 = Sound
> 
> So I need to remove wire to pin 7. What should I do about
> pin 6?
> 
> H-freq is 15.75 khz, and V-freq is 60 hz on the 5153
> monitor.
> 
> Alan Jones
> 
> -- N8WQ - Canal Winchester, Ohio
> http://exwn8jef.googlepages.com/home
> 
> 
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