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[TUTORIAL] Overclock for Gradius III original game board

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Just in time for my next PCBs order
 
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Instead of just switching two fixed frequency crystals, I was thinking of using a SI5351 clock generator with something like a Pi Pico and a OLED screen, which would let you adjust the frequency freely using a rotary encoder or something like that. Of course that's a lot more involved than just switching between two fixed frequencies.
 
alamone said:
Instead of just switching two fixed frequency crystals, I was thinking of using a SI5351 clock generator with something like a Pi Pico and a OLED screen, which would let you adjust the frequency freely using a rotary encoder or something like that. Of course that's a lot more involved than just switching between two fixed frequencies.
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It's also a good solution, but you aren't going to be changing freq while playing. You are going to use one freq while playing the game
 
Yes, once you have a frequency you like, you can just use that, but finding one that balances the amount of slowdown you like, is why the adjustable frequency is useful, instead of having to find many different oscillators. Adjusting on the fly might also be useful if you want to adjust slowdown for a particular stage. Alternatively, you could just try it in MAME first and use the overclock sliders to find an overclock frequency that you like.
 
alamone said:
Yes, once you have a frequency you like, you can just use that, but finding one that balances the amount of slowdown you like, is why the adjustable frequency is useful, instead of having to find many different oscillators. Adjusting on the fly might also be useful if you want to adjust slowdown for a particular stage. Alternatively, you could just try it in MAME first and use the overclock sliders to find an overclock frequency that you like.
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Upping more the MHz makes necessary to change both motorolas 68000 or they will suffer too much overclock. It's a good idea what you propose, really, but too much work on a 600€ game board
 
alamone said:
Yes, actually I bought some 16MHz 68ks for this purpose... just have to get around to it lol...
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Then you'll tell us, but sincerely, I think is a bit excesive to use 2x Motorola 68000-16 and by that reason use oscillators above 12Mhz. Probably many rams aren't prepared to work that way, also for the graphic section/customs that have to coordinate with its own oscillator with the new CPU speed.

Please take care of your game with those tests.
 
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