JRCooper.PA@XEROX.ARPA (01/15/86)
Bill, I can't answer your question about the 800 XL but I can tell you that you don't need all of the video signals that ATARI provides at the connector to make a monitor work. All of the Atari computers deliver Composite video on one of the five pins...I was not aware that they might be machine dependent regarding the actual pin number. If someone would want to use a monochrome monitor then a luminace only signal is available. ***The Pin numbers found on the 5-pin DIN connector have been decided by the DIN (German Standards committee) so don't blame ATARI for that one. An interesting ramification of the signals provided by the 130XE is that a cheap RGB decoder could be built to derive the component colors from the combination of composite luminance and composite chrominance. I haven't fully investigated this yet but you would need a sync stripping circuit, a couple of band pass filters to separate the colors and maybe a few delay lines. RCA makes a few interesting IC's (CA3130--33) that take luminance and chroma signals an turn them into R-Y, B-Y, and G-Y where Y is the luminance portion. Those chips are designed for decoding broadcast signals inside your TV set. Beyond that you will need to then transcode the R-Y,etc. (You don't need the G-Y) signal into RGB for RGB monitors. As I actually get into doing this processing I will post a more coherent description to the net. This is the only way to get RGB out of an atari since the NTSC composite video is computed a a composite signal. Jim Cooper