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CPS A-Board Differences

So in other words, 12Mhz games on a 10Mhz board, not great.

10Mhz games on a 12Mhz board, no issues. “Arcade Perfect” exactly gow the game was meant to be experienced (90% of the time).

Sorry guys im trying to learn more about the CPS1 hardware is all.
 
Basically you can say a 10MHz game runs perfectly fine on a 12MHz A-board.
Just when it gets heavier for the CPU to run (multiple enemies on screen in Final Fight, big combo’s in SF2WW etc.) the 12MHz board will have less noticeable slowdows.
That is my experience when swapping back n forth.
 
PascalP said:
Basically you can say a 10MHz game runs perfectly fine on a 12MHz A-board.
Just when it gets heavier for the CPU to run (multiple enemies on screen in Final Fight, big combo’s in SF2WW etc.) the 12MHz board will have less noticeable slowdows.
That is my experience when swapping back n forth.
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Thank you for clearing that up! Thanks again everybody!
 
Follow up question, which may have been answered but if so I missed it. Any conclusive make/model of 12mhz crystal that's been known to work for "upgrades"? In addition, any issues with using a Z80A or Z80B?
 
Not the cleanest desoldering job, but all pads are intact (working on these old PCBs stresses me out). Kind of interesting, there are pads for multiple possible crystal configurations and the screening lists three different part numbers. I'll be trying to put in a socket so that I can swap out the crystal if needed (this is a CPS1 "short" I'm upgrading from 10mhz to 12mhz).
IMG_0865.jpg
 
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So put in a socket, and tried a 12mhz crystal with mixed results. On my Chinese 32-in-1 board, I am getting corrupted graphics which I had previously put down to running at 10mhz. With my SF2 WW B+C it runs, but the graphics are a little jittery. So I'm thinking that I have compatibility issues with the 12mhz crystal I grabbed (question mark). The multi board I have works fine in it's original A board as far as graphics go, but the board has sound issues (will be replacing the Z80 and seeing what that does, but the board has a lot of poor quality repairs on it and what looks like recycled parts. What I'm thinking I'll try next is pulling the crystal from the bad board, and putting it in the good one and seeing what that does.

Update: tried swapping the 12mhz crystal from the board with working graphics (when used with the Chinese 32-in-1) to the clean board, and it still has corrupted graphics... I then tried the new 12mhz crystal in the bad board (without audio) and the graphics are fine. So something is causing issues with the multi board, and it's not the crystal.

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you can run a 10MHz crystal on a 12MHz 6800, but you shouldn't run a 12MHz crystal on a 10MHz 6800
 
twistedsymphony said:
you can run a 10MHz crystal on a 12MHz 6800, but you shouldn't run a 12MHz crystal on a 10MHz 6800
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Yup, realizing I was misunderstanding the crystal upgrade conversations. Ah wells. Guess I have to figure out how to fix the old board. Thinking it’s the z80 crystal so the process hasn’t been a total loss (assuming I’m correct).
 
twistedsymphony said:
you can run a 10MHz crystal on a 12MHz 6800, but you shouldn't run a 12MHz crystal on a 10MHz 6800
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Not true. The 10mhz 68k' overclock just fine. Quite a few in the community report upgrading their 10mhz boards with no issue.

Also @PascalP can you provide some video evidence of benefits seen on something like sf2:ww big combos on a 12mhz board? We saw that sf2hf runs faster on a 12mhz board. But, ce and ww exhibit no speed differences when paired with either A board. I am interested to see actual documented differeneces/improvements when games are running in a 12mhz board.
 
YesAffinity said:
Not true. The 10mhz 68k' overclock just fine. Quite a few in the community report upgrading their 10mhz boards with no issue.
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Perhaps, but it does not seem to solve for the compatibility issues where my B+C multi-board is showing corrupt graphics. It does not do this on an original 12mhz board, albeit one that has the funky Chinese sound system rewiring that has since failed. I'm sourcing a stock 12mhz board that I'll try out to see if it's some other weird modification they did that I don't know about or an incompatibility with an overclocked board.
 
twistedsymphony said:
I never said you can't, just that it's not recommended.

If anyone has issues resulting from overclocking though I'll be sure to send them your way for support. :D
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I don't recall offering any guarantees or warranties. Just summarizing the experience and opinions stated by others, including at least one MAME dev (who stated the 68k's overclock fine), and as well as my own experience. Any modding comes with the caveat of "proceed at your own risk" and "YMMV", I don't think it needs to be added to every single post/statement made on these forums.
 
YesAffinity said:
Not true. The 10mhz 68k' overclock just fine.
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YesAffinity said:
I don't recall offering any guarantees or warranties.
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I was recommending against it, per the chip manufacturer's own rating. If you decide you want to invalidate that and say it's "not true" then you should be prepared to stand behind that statement.

I have no problems with you summarizing the experience of others. I DO have a problem if you want start recommending people do things against the advice of others and then not willing to stand behind that recommendation.
 
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@YesAffinity I don’t have video evidence of it, nor a possibility (or time) to record it.
I just ‘know’ it feels different to me. Also I thought it was quite noticeable with Final Fight when I swapped some A boards around.
But to help my own OCD every CPS1 game I have is paired with the correct A board (and thus speed) as when it was released.
 
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