How can I find the position of the electron gun (i.e. actively changing pixel/scanline) on the ZX Spectrum?
Different Spectrum models have slightly different timings.
If this is not possible, is there a way of waiting for some form of vertical sync event? (i.e. at the top of the bottom of the screen.)
There is a 3 byte frame counter at address 23672.
23672 FRAMES
3 byte (least significant first), frame counter. Incremented every 20ms.
I'm making the assumption that this is incremented by the 50Hz interrupt. So I'll just poll it in a loop until the least significant byte changes.