RevEng Posted March 14, 2021 Share Posted March 14, 2021 Apparently both the TIA and Maria WSYNC registers both work to wait for sync in 7800 mode. The interesting thing is, both chips have their own horizontal sync and counters, which are running in parallel. I put together a quick little demo that shows a few color bars drawn with the background color and each kind of WSYNC. Basically the idea is hit WSYNC, change the color, wait for 40 cycles, and then change the color back to black. At the start of the TIA WSYNC rectangle, I need to hit RSYNC, so TIA begins the bars aligned with Maria, and drifts more after each line. Apologies for the crap photo, but it's better than none, which was the choice. Interestingly the TIA line is longer, despite running at Maria speeds for most of the line. On the occasional run of the program, the TIA bar alignment flickers badly. I think the free running TIA sync gets messed up if you hit RSYNC on a particular cycle. Maybe. I don't think there's anything of practical of use here (hence "pointless curiosity") but I thought it was kind of fun to have a peek at TIA's video generation going on behind the scenes. tiamariasync.bas.a78 tiamariasync.bas.bin 6 Quote Link to comment Share on other sites More sharing options...
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