RGB-VGA Converter -- buy or build?

[Tony Duell]

> 
> As previously discussed in this list, and documented on 
> http://www.oldskool.org/pc/cgacal , CGA monitors have circuitry to 
> change color index #6 to a different color.  CGA also has a fourth 
> "intensity" pin.  Does anyone know if some sort of specially-wired cable 
> might be able to convert 4-pin RGBI to something these kinds of 
> converters can take as input and everything will still look decently?

It's goign to take more than a cable. THere must be components involved.

> 
> I ask because I have a need to do video capture of native CGA output. 
> Don't ask :-)

If this is a real CGA card, there is most likely an NTSC-compatible 
composoite colour output available too. It may be on an RCA phono socket 
on the bracket (IBM had that), a header inside, or sometimes on pin 7 
(otherwise unused) of the DE9 socket.

You might look at the IBM CGA card scheamtics. They include the circuit 
to encode the RGBI signals to NTSC composite video.

-tony