VRC IV pinout

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rainwarrior
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Re: VRC IV pinout

Post by rainwarrior » Mon Jul 23, 2018 1:13 pm

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 » Mon Jul 23, 2018 2:49 pm

Thanks! I'll give these a go.

krzysiobal
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Re: VRC IV pinout

Post by krzysiobal » Mon Feb 04, 2019 5:34 pm

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 » Mon Feb 04, 2019 6:16 pm

Do we know whether those behaviors just happen to be present in the original VRC4 also?

krzysiobal
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Re: VRC IV pinout

Post by krzysiobal » Fri Jul 12, 2019 6:01 am

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 » Fri Jul 12, 2019 10:03 am

I get very excited when I hear "unknown register" :mrgreen:

lidnariq
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Re: VRC IV pinout

Post by lidnariq » Fri Jul 12, 2019 10:31 am

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.
H, V フラグレジス夕にテ一夕を書き込むには, 9000H~9FFFHを使用します.
    D0 (H, V) 切リ換え) 0:H, 1:V

krzysiobal
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Re: VRC IV pinout

Post by krzysiobal » Sat Jul 13, 2019 3:24 am

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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