Howard Price wrote: > Do you know how many T-states you get a frame, then?
There are always 384 t-states per line for the 312 screen lines = 119808 t-states. > Pref. with memory contention in Mode 4???? > Just writing a timing program in IM2.... Unfortunately it's not that simple to work out! :-/ The delays from contention depends on the instructions you're using, and where the ASIC is drawing at the time your code is running. You'll certainly see the extra delays when writing to ports 248 and above, or when the ASIC is drawing the main screen area. I'm confident that the current SimCoupé is already accurate enough for you to be able to develop your Mode 4 IM2 routines on it and have it run the same on a real SAM. In the last few days I've worked out the mode 1 contention delays, and Dave Laundon is nearly done with a unified implementation for all timings, which now gives correct ROM timings too. It already passes all the CPU Speed tests, and there's just a tiny bit more to do. So, the next public SimCoupé should have flawless timing for _anything_ you throw at it in any mode. :-) Si
