On 2023-01-13 12:49 a.m., Jim Brain wrote: > Adding in the 10th bit would have made every X "magic value" boolean > logic instance have to have another input, which was probably > considered risky, as I think the 65 cycle VIC was last to arrive (so > the design was already in use, and no one wanted to QA a complete new > design.) Yes, that makes good sense, and yes, I believe the 65-cycle VIC was adapted from the 64-cycle design. > It does appear to be a hack, though. I assume the 65 cycle design was > because of complaints on sync with certain televisions? I haven't found a good explanation of why they went from 64-cycle to 65-cycle. Wikipedia has this totally un-sourced claim: "The 64 color clocks on the initial VIC-II was done with the intention of allowing NTSC artifact color in high resolution bitmap mode as the Atari 8-bit computers did, but that idea was quickly dropped." On 2023-01-13 4:24 p.m., peter_at_rittwage.com wrote: > I know there have been some die photos of the 6569, but I'm not sure > anyone has decapped a 6567 and taken good photos. I've been looking the last couple days, and it seems all the die photos are of the 6569. RobinReceived on 2023-01-14 04:00:02
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