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Those look very cool! Though FWIW I wonder if there are differences between the breadboard memory space and IO and busses and the Apple II. I recall the graphic
by jonahbenton 6y ago
Those look very cool! Though FWIW I wonder if there are differences between the breadboard memory space and IO and busses and the Apple II. I recall the graphics screen was fed from RAM at 2000-3fff, with an offscreen buffer in 4000-5fff. And there was a vertical blanking interrupt handler to hook into, so you could organize writes to screen memory when it was not being read by the video machinery, and avoid flicker. Getting that working as a kid- actually seeing butter smooth non-flicker animation in the simple games I was writing- big, big moment.
- joezydeco 6y agoThe Apple ][ hardware did not have a direct way to track vertical blanking. There were hacks that used artifacts in the dynamic memory refresh to sniff out when the VBI was happening. http://www.deater.net/weave/vmwprod/megademo/vapor_lock.html http://www.deater.net/weave/vmwprod/megademo/vapor_lock.html
- jonahbenton 6y agoAh, thank you, that's interesting. I don't recall puzzling through that exact machinery. But I had a IIe, not a II, and looking at resources for that- yeah, I had a rev B motherboard, and remember well working in the double hi res context, both black and white and color: http://www.battlestations.zone/2017/04/apple-ii-double-hi-res-from-ground-up.html http://www.battlestations.zone/2017/04/apple-ii-double-hi-re... So cool.