Capcom CPS1 custom chip query

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IronGiant

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Regarding the surface mounted custom chip marked as "CPS-A-01" on Capcom's CPS1 main boards - what does this chip do exactly?

Is it multi-function or mainly for drawing the sprites?

It's just that I have a few CPS1 main boards, all have sprite problems (or no sprites at all) with known working ROM boards and I can't find anything wrong with the video RAMs, so I'm left thinking it must be that custom.

Thanks
 
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IronGiant

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Nope, not suicided (there's no battery required on the ones I'm working on) - the B and C boards are fine and work perfectly with a known good CPS1 A board.
 
scgon

scgon

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ah sorry, didn't get that they worked fine in a different set up... ok, so yeah, that is weird, will leave this to those more experienced than I.
 
Xian Xi

Xian Xi

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Even though the boards work with other boards it may be just something as simple as a connection issue. The connectors wear out all the time making these problems. Swap the connectors on the board that has problems.
 
Razoola

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If its issues with sprite priority then its liky somone has tried converting the boards to different CPS1 games. Not easy to get around as it requires one to patch the game code so the custom addresses for the game match those of the PCB. Not easy at all, but if you want to try CPS1.C in the graphics dir of the MAME source is a good place to start as it has tables of what games use what hardware IC's.

Raz
 
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IronGiant

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These boards definitely haven't been converted - both are the game Mega Twins - one doesn't have any sprites at all, the other has very corrupted sprites. All ROMs are okay, the B + C board combo works fine on a known good CPS1 main board.

Doesn't appear to be a video RAM fault, looks like a lack of signals from the aforementioned custom CPU.
 
Xian Xi

Xian Xi

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Like I said it's most likely a connection issue. It's common with CPS1 games. If you search the tech forum you will see how common.
 
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IronGiant

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It's not a connection issue, I've buzzed them all through and they're fine.
 
mainman

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IronGiant said:
Regarding the surface mounted custom chip marked as "CPS-A-01" on Capcom's CPS1 main boards - what does this chip do exactly?

Is it multi-function or mainly for drawing the sprites?

It's just that I have a few CPS1 main boards, all have sprite problems (or no sprites at all) with known working ROM boards and I can't find anything wrong with the video RAMs, so I'm left thinking it must be that custom.

Thanks
Click to expand...

It controls the graphic. There are different variation of this chip with CPS-B-21 and supposedly B-01 being the most universal replacement for suicide boards and games made at the end of the cps1 hardware life, please list the cps 1 game you are experimenting with. You must use the right c board for the right game man, not necessarily any c board you have around.
 
Last edited:
MKL

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It's a GPU that's present on both CPS1 and CPS2 motherboards.
 
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IronGiant

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mainman said:
It controls the graphic. There are different variation of this chip with CPS-B-21 and supposedly B-01 being the most universal replacement for suicide boards and games made at the end of the cps1 hardware life, please list the cps 1 game you are experimenting with. You must use the right c board for the right game man, not necessarily any c board you have around.
Click to expand...

Thanks, but I'm referring to the custom on the main board, ie the lower board (CPU board or 'A' board). :)
 
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