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MiSTer-devel / Arcade-Robotron_MiSTer

Arcade Robotron for MiSTer
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SC1 is missing slow mode making the game much too fast (other williams cores have the same issue but it's really visible on robotron) #16

Open vlait opened 3 years ago

vlait commented 3 years ago

The slow mode blit avoids racing ram access with the video circuity and only performs access when video is not doing so. Schematics suggest E is being used to drive the state machine when in slow mode.

Current code doesn't do that because it isn't necessary.(edit: ...in the simulated system - real hardware would not like this)

vlait commented 3 years ago

quick hack at https://github.com/vlait/Arcade-Robotron_MiSTer changed sc1 and williams_cpu, please take a look and if ok add or i can request a pull if thats more convenient

vlait commented 3 years ago

... should add i did not playtest this, just wrote a short test program to do a few thousand blits with normal and slow and compared the time taken with same rom ran in mame

JimmyStones commented 3 years ago

Hi @vlait - thanks for the submission, we're testing it out now (this core supports multiple games so need to make sure there aren't any adverse affects)

JimmyStones commented 3 years ago

@vlait I've merged your change into the latest release - side by side comparisons show it to more much more in sync with the original, good work :)