Yep, two suggestions:paulb wrote:If I understand you correctly here, what you're suggesting may be related to something someone else suggested, although that (generating colour mixes) may have been considered separately from attempting to put different colour information on alternate "625" lines (merely animating different screens quickly enough, regardless of where they end up precisely on the 625-line display) particularly as I think it was one of the US machines that was the subject of the technique (and so may have been using a different kind of display altogether).
- take advantage of the effective lowpass filter on chrominance if using UHF or modified-machine colour composite to invent extra colours.
- as you're able to detect whether the machine is outputting the odd or even field, produce a genuine interlaced display.
I meant before it was eliminated, the ROM-with-a-picture-in-it being the most recent thing I can run on the version of my code that interlaces. Though, caveat: I've attempted to do better than every so often repeating a frame twice to map from 50Hz to your display's output rate and, right now, am using a terrible camera model. Which amplifies judder. But the line at the top vanishing and appearing and ditto for the one at the bottom are hopefully appropriate?paulb wrote:No, I don't think so. One of davidb's objectives was to eliminate the kind of judder that the GIF exhibits.
(EDIT: I can see the extra green bar at the bottom on your "... on TV" picture, which I'm assuming to be real hardware rather than an emulator?)
Update on Joe Blade: I just had an error in my fast loading code and hadn't bothered trying it with real tape emulation for a while. With real tape emulation it works perfectly. It relies on the converse case to Northern Star and Southern Belle: that tape input will also signal the transmit data empty interrupt, but only in a very trivial way: it relies upon the transmit data empty bit being set in the interrupt status register after it has completed loading, to get past an initial check. An anti-piracy measure, at a guess, to prevent loading from disk. Subsequently it's probably just using the 50Hz and display end interrupts normally, though it appears to use a polling loop rather than actually enabling interrupts.