knudsen@ihnss.UUCP (09/20/83)
The Canadian's comment on "never twice the same color" got me thinking that you MIGHT be able to get a consistent odd-even scanline color burst by changing the Coco's 6847 VDG chip to a 6847Y. That is the "interlace" version. The existing non-interlace chip putss out 60 identical frames per second, so you get at most 525/2 scan lines on your TV (only 192 are really used, but the borders and overscan get the rest). The interlace version, like a real TV signal, alternates odd and even scan liness with each frame, so you get 30 even frames and 30 odd ones per second. The visual effect would look smoother (scan lines less visible), but maybe fuzzier. The REAL QUESTION is whether the Interlace chip would give a consistently phased color burst sso that artifact colors would always initialize the same way. The 6847Y will just plug into a Coco, no mods. However, I've never sseen this chip offered for sale -- you might have to go to an industrial supplier. --Someday OS-9 will come.... mike k