A frame should actually be htotal (converted to pixel clocks, so times 8 or 9 dot clocks) times vtotal (in lines). The lines past horizontal/vertical display end are counted just like normally displayed lines, just not rendering anything at that point. So 800 horizontal clocks times the 500ish …

I seem to recall that "Vertical Retrace" (both the status bit and the optional interrupt) is triggered by the scanline counter reaching Vertical Displayed End. The intention must have been to inform the program "okay now you can write to video memory without worrying about screen tearing". …

superfury wrote on 2022-09-12, 20:40: You can run UniPCemu and dump the VGA state when it's running the retrace test. I'm afraid I haven't had much luck getting UniPCemu to run at all... but say I get it running where would this VGA state dump feature be found?

Hello all, I've been writing yet another hobby IBM PC emulator, and several posts here have been incredibly useful resources on CGA timings, etc. I was a bit hesitant to ask but this seems like the place to get the answer, so, here's my first post. I've encountered a bit of a puzzling roadblock …