VRC IV pinout

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rainwarrior
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Re: VRC IV pinout

Post by rainwarrior »

getafixx wrote:Was there any test roms for use with any of the VRC mappers?
Yes there's this one:
https://forums.nesdev.com/viewtopic.php ... 16#p203716
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getafixx
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Re: VRC IV pinout

Post by getafixx »

Thanks! I'll give these a go.
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krzysiobal
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Re: VRC IV pinout

Post by krzysiobal »

Accidentally, during fixing broken Gimmick VRC4 hack, named Suikan Pipe I did some testing to the AX5208C chip, which is pirate VRC4 with 1-1 pinout.

Image

What i've found out is that:
* pin 16, which was meant to be CHR_A18 in original VRC4 is also present in this chip,
* pin 18, which was unknown, is some kind of output. For each of those different addresses, that VRC4 can recognize: $X00Y, where X={0, ..., $f}, Y={0, 1, 2, 3}
this pin is driven low only during write cycle to $9003
* PRG swap is only present at $9002, not also at $9003
lidnariq
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Re: VRC IV pinout

Post by lidnariq »

Do we know whether those behaviors just happen to be present in the original VRC4 also?
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krzysiobal
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Re: VRC IV pinout

Post by krzysiobal »

I tested the original VRC4 at it behaves the same way as pirate AX5208C - both in having the special reg at $9003 and having the PRG swap reg only at $9002.

Image Image

Also, the mirroring reg sits only at $9000.
Image

Wonder what is at $9001.

(I tested the pirate VRC2 = 23C3662 and it seems to also have the mirroring reg only at $9000)
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Ben Boldt
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Re: VRC IV pinout

Post by Ben Boldt »

I get very excited when I hear "unknown register" :mrgreen:
lidnariq
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Re: VRC IV pinout

Post by lidnariq »

krzysiobal wrote:(I tested the pirate VRC2 = 23C3662 and it seems to also have the mirroring reg only at $9000)
If true of the licensed VRC2 also, that's weird... it would contradict Konami's documentation that says that it's present across the entire region.
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krzysiobal
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Re: VRC IV pinout

Post by krzysiobal »

I did some more testing to all the pirate VRC2 carts that I have (every chip was removed from the original PCB and tested outside) and here are the results:

Mirroring reg only at $9000:
* 23C3662, found in Kid Dracula [famicom])

Mirroring reg at $9000/$9001/$9002/$9003:
* nameless one, found in pirate Teenage Mutant Ninja Turtles - FC20
* AX-40G, found in pirate Teenage Mutant Ninja Turtles - FC10
* 23C269, found in Don Doko Don
* AX5705, found in Dragon Ball Z2 / Z3
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tiretrak
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Re: VRC IV pinout

Post by tiretrak »

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krzysiobal
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Re: VRC IV pinout

Post by krzysiobal »

This is your PCB.
If only one game can be selected, writing to latch (74161) does not work.
Either because
1) the /RESET pin is held in,
2) write signal is not generated properly.

My suspect is that the value of capacitors you have soldered (C1, C4) are incorrect.
C1 should be 1n-10n
C4 should be tens of pF (56pf or 68pf)
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tiretrak
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Re: VRC IV pinout

Post by tiretrak »

krzysiobal wrote: Tue Jan 05, 2021 3:40 pm This is your PCB.
If only one game can be selected, writing to latch (74161) does not work.
Either because
1) the /RESET pin is held in,
2) write signal is not generated properly.

My suspect is that the value of capacitors you have soldered (C1, C4) are incorrect.
C1 should be 1n-10n
C4 should be tens of pF (56pf or 68pf)
thank you.
its work
mir2sila
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Re: VRC IV pinout

Post by mir2sila »

Friends, can anyone help with the reproduction on the VRC-4?
lidnariq
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Re: VRC IV pinout

Post by lidnariq »

Please stop reposting your requests on the forums here. This forum isn't active enough that a person won't have seen your other posts but will instead see this one.
mir2sila
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Re: VRC IV pinout

Post by mir2sila »

lidnariq wrote: Tue May 18, 2021 7:37 pm Please stop reposting your requests on the forums here. This forum isn't active enough that a person won't have seen your other posts but will instead see this one.
OK
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