> 2) Is the screen drawn all at once or one scanline at a time? I would think it
> needs to be drawn one scanline at a time for it to be accurate. I say this
> because the C64 uses raster interrupts that can modify the screen in real time.
I think the most accurate (while still reasonably efficient) way is to detect all write accesses to video registers and memory and render everything up to the current pixel when one happens. You can even change the trapping range every scanline to make things slightly faster. Modern PCs can handle it anyway.