On Mon, 4 Feb 2002 email@example.com wrote: > > than I expected; any idea what the node pulled high by R266 > > (2K2) is for? > > I don't know what IC251 is but connecting two outputs means it is a > OC-uotput IMHO. The resistor makes sure of a defined level when none of > those outputs are active. My brain must have been on strike when I first thought about that circuit. The node is always low unless RGBI is 1100. In that case, the outputs of the invertors on the R and G paths will be high, and the diodes on the B and I paths will be connected to invertor outputs which are also high. This is then inverted by IC252/6C and pulls the main G node low through a 1K resistor (R271). I think it's basically a little modification that makes dark yellow look more like brown. To be true to Commodore's intentions for the C128 VDC, I think you have to incorporate this into VDC SCART leads. It's a matter of personal taste, of course. I would be interested to hear if there are any Commodore 80 column RGBI monitors which don't have this circuit. Richard Message was sent through the cbm-hackers mailing list
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