An update on the strange board: I checked the clock circuit, and the empty XT oscillator is just an alternative source for the color clock. Yes, not for dot clock, it's for color clock. The circuit is not worth drawing down, it is mostly a mix between the older one from schematic #326106 and the newer one from #251138. The output of XT is always connected to that side of FB16 that is also connected to pin 10 of U31. But there is a jumper (half moons) on the bottom side of the board that can be used to disconnect the output of U31. That's all there can be done. I don't know if any boards were ever manufactured that way, because the possibility to adjust the color clock was not possible in this configuration. Probably U31 and the components around it were not installed at all in that case. Some other component locations are empty, they're C35, C37, C55, C58, C73, C80, C87, R23. R22 is just a jumper wire. Except C37 these are exactly the differences between the two documented boards, the new board doesn't have these components locations at all. C37 actually is installed in all large board C64 revisions I just checked, so maybe it was just left out by mistake. The bottom side also has the PAL-G/I jumper I already missed: it says "OPEN I.PAL SHORT G.PAL" and it's closed. There's also a board identification that says "FAB NO. 251022 REV.A". Unfortunately I don't have these numbers from the other boards. Nicolas - This message was sent through the cbm-hackers mailing list. To unsubscribe: echo unsubscribe | mail firstname.lastname@example.org.
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