AGEMAME HQ

Or time hole, if you prefer.

These MPU4 test ROMs have highlighted a major weakness in how the 6840ptm driver operates.

Rather than keeping a strict counter and subtracting values on every cycle, the driver converts the counter into an output frequency, and uses that for timing. Fine, unless you need to use the external clock pins. There’s currently code in place that makes the driver work by pausing the timer, and then just letting it run while the pin is activated. Up until now, that’s been fine, but is not the way it should behave.

Over the next few cycles, I’m going to look into ways of making this behaviour more accurate, while preserving as much of the existing interface as I can. You may notice problems developing in AGEMAME, as I’ll be running the new code in u builds until ready to sign off on it and submit it to MAME. MAME will retain the original version until completion.