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 Post subject: CPS2 B boards, original roms, no battery.... no problem!
PostPosted: Wed Oct 10, 2018 12:19 am 


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So a few weeks ago I saw a post on Twitter where a Japanese user had what appeared to be some type of PIC microcontroller connected to a CPS2 B board, giving the impression it was loading the decryption key at every boot so there is no battery needed. Unfortunately it seems impossible to re-find random things on Twitter, and it was all in Japanese anyway.

However, it got me thinking about trying to implement that same concept using an Arduino Nano since they're fairly small, clones are extremely cheap, and basically just need a mini USB cable to program them. I forked the ArcadeHacker CPS2 Arduino key writer (https://github.com/ArcadeHacker/ArcadeHacker_CPS2) and modified it to work on (assumingly) any Arduino without an LCD shield. You would just put the key on it for the game you install it in, then you could just boot the game battery-less forever with no altered/phoenixed roms, in theory.

https://github.com/cr4zymanz0r/No-Battery-CPS2
I used the serial monitor in the Arduino IDE to verify it's outputting the key correctly, but I haven't had time to solder it into a B board to test on actual hardware yet.

One drawback I noticed is that writing the key exactly how the ArcadeHacker program does, it takes roughly 9 seconds for it to write the key. This means basically each time you power on the game it'd take an additional 9 seconds to boot. I assume this can probably be shortened since there are multiple delays in the code, but I don't know if the CPS2 hardware gets fickle if the key is written too quickly. I know the Darksoft CPS2 multikits just rewrite the key at power-on for the last game you loaded, and I was thinking it was nearly instant, but I'd need to go back and check.


Last edited by cr4zymanz0r on Thu Oct 11, 2018 3:56 am, edited 2 times in total.

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 Post subject: Re: CPS2 B boards, original roms, no battery.... no problem?
PostPosted: Thu Oct 11, 2018 1:25 am 


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Ok, I got a chance to hook this up today and test it out and it works. I also was able to drastically reduce the key write time so that booting is barely any longer than on battery. I'm uncertain if the much faster key writing might cause issues or not on some B board revisions, but it worked fine on the 93646B-6 revision that I tried.

Here's just a couple of quick basic pics I took of the install: https://imgur.com/a/ZO8hIGM . The Arduino Nano is just mounted with a double sided 3M adhesive pad
No more worrying about battery corrosion, changing batteries, or reflashing keys manually :)


Last edited by cr4zymanz0r on Thu Oct 11, 2018 3:56 am, edited 1 time in total.

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 Post subject: Re: CPS2 B boards, original roms, no battery.... no problem!
PostPosted: Thu Oct 11, 2018 3:30 am 


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Brilliant, man, just brilliant! Game changer, for sure. :)

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 Post subject: Re: CPS2 B boards, original roms, no battery.... no problem!
PostPosted: Thu Oct 11, 2018 4:29 am 


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The price of the nano makes it a very reasonable solution, in some cases even cheaper than a battery change (in my country for instance), which I find unbelievable.

Thank you, it is great to have a variety of options.
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 Post subject: Re: CPS2 B boards, original roms, no battery.... no problem!
PostPosted: Thu Oct 11, 2018 5:38 pm 


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So, one negative thought on this. Is it possible that doing repeated writes to the encryption controller will cause it to become unwritable at some point? I mean effectively, they were designed to be re-written to maybe once, twice at the most. I don't think capcom predicted that the games would have a lifespan much beyond probably 1 battery failure.

it's probably a low likelihood, but just a thought.

I suppose the new revision Darksoft kit users who are using the encryption key writing feature would be the case study on this. I've got a nano on order, definitely want to give this a try. :)


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 Post subject: Re: CPS2 B boards, original roms, no battery.... no problem!
PostPosted: Thu Oct 11, 2018 7:35 pm 


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NoAffinity wrote:
So, one negative thought on this. Is it possible that doing repeated writes to the encryption controller will cause it to become unwritable at some point? I mean effectively, they were designed to be re-written to maybe once, twice at the most. I don't think capcom predicted that the games would have a lifespan much beyond probably 1 battery failure.

it's probably a low likelihood, but just a thought.

I suppose the new revision Darksoft kit users who are using the encryption key writing feature would be the case study on this. I've got a nano on order, definitely want to give this a try. :)


My guess is since it has to be battery backed normally that it's some type of RAM/SRAM, which wouldn't really have a limited amount of writes to my knowledge. That's just educated guessing on my part though. I bet Artemio would know more.


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 Post subject: Re: CPS2 B boards, original roms, no battery.... no problem!
PostPosted: Thu Oct 11, 2018 7:55 pm 


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Would also be interesting to see if this is a potential solution for the folks that have had so much difficulty with rev -4 boards (myself included). Going to use my ST board as a guinea pig, which I had trouble desuiciding at one point.


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 Post subject: Re: CPS2 B boards, original roms, no battery.... no problem!
PostPosted: Thu Oct 11, 2018 8:15 pm 


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NoAffinity wrote:
Would also be interesting to see if this is a potential solution for the folks that have had so much difficulty with rev -4 boards (myself included). Going to use my ST board as a guinea pig, which I had trouble desuiciding at one point.


If you've had trouble with the regular ArcadeHacker CPS2 Arduino key writer, you'll probably be in the same boat with this. Mine is basically doing the exact same key writing process (just no menu selection part), with the only real difference being I lowered the delays in the code so it wouldn't add 9 seconds to boot time. I've got 2 other B boards on battery that I intend to mod as well soon, but I don't know what revisions they are until I open them up.


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 Post subject: Re: CPS2 B boards, original roms, no battery.... no problem!
PostPosted: Thu Oct 11, 2018 11:01 pm 


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cr4zymanz0r wrote:
So a few weeks ago I saw a post on Twitter where a Japanese user had what appeared to be some type of PIC microcontroller connected to a CPS2 B board, giving the impression it was loading the decryption key at every boot so there is no battery needed. Unfortunately it seems impossible to re-find random things on Twitter, and it was all in Japanese anyway.

This came up recently on my timeline: https://twitter.com/konosuke/status/1050062876617129984

The same user posted several tweets showing their work on the project.


Btw, would this modification also work on a dead/suicided B board?

Sorry I am not really up to speed on the latest CPS2 developments...
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 Post subject: Re: CPS2 B boards, original roms, no battery.... no problem!
PostPosted: Thu Oct 11, 2018 11:40 pm 


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llaoyllakcuf wrote:
Btw, would this modification also work on a dead/suicided B board?

Yes, it will work on a suicided board. It's just reloading the decryption key at every boot that the battery normally retains in memory. You just need to make sure it's one you know the only issue it has is the suicide battery dying, not some mystery condition non-working one on ebay ;)


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 Post subject: Re: CPS2 B boards, original roms, no battery.... no problem!
PostPosted: Fri Oct 12, 2018 12:13 am 



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NoAffinity wrote:
So, one negative thought on this. Is it possible that doing repeated writes to the encryption controller will cause it to become unwritable at some point? I mean effectively, they were designed to be re-written to maybe once, twice at the most. I don't think capcom predicted that the games would have a lifespan much beyond probably 1 battery failure.

it's probably a low likelihood, but just a thought.

I suppose the new revision Darksoft kit users who are using the encryption key writing feature would be the case study on this. I've got a nano on order, definitely want to give this a try. :)


According to Leo, the key is stored in RAM and "SRAM and DRAM have absolutely no limits on how many times it can be written or read."

( from https://www.arcade-projects.com/forums/ ... #post76341 )

So should be a non-issue.


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 Post subject: Re: CPS2 B boards, original roms, no battery.... no problem!
PostPosted: Fri Oct 12, 2018 12:34 am 


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@cr4zymanz0r

Nice, thanks for the clarification.

I've got a handful of legit B boards that were in storage for years and it's cool to hear about an alternative to the Phoenix roms. :)
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 Post subject: Re: CPS2 B boards, original roms, no battery.... no problem!
PostPosted: Fri Oct 12, 2018 2:06 am 


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Thanks for digging up the confirmation, fluxcore. I was willing to try it either way but that's good space of mind.

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 Post subject: Re: CPS2 B boards, original roms, no battery.... no problem!
PostPosted: Sat Oct 13, 2018 3:34 am 


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I updated the album with some basic pics of a couple more installs: https://imgur.com/a/ZO8hIGM
* Another 93646B-6 revision
* 93646B-3 revision (has a resistor connecting DATA (A32 on CN2) to ground)

I don't have anymore original rom B boards left now. Maybe I'll get some more in the future.


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 Post subject: Re: CPS2 B boards, original roms, no battery.... no problem!
PostPosted: Sat Oct 13, 2018 9:01 am 


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This is a very imaginative solution for those who don't want to use a battery yet who still want to play the original, unmodified code. Very nice work. :D

Because of the lack of the CN9 header on B board revisions 93646B-3 and 93646B-4 I guess it won't be possible to easily connect up the Nano (wires will need to be soldered to suitable points instead), although the the header is of course present on B board revisions revisions 93646B-5, 93646B-6, 93646B-7, 97691A-3, 97691A-4 so that's nice and easy. :)

http://arcadehacker.blogspot.com/2016/0 ... guide.html
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 Post subject: Re: CPS2 B boards, original roms, no battery.... no problem!
PostPosted: Sat Oct 13, 2018 4:28 pm 


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For boards without CN9, you can simply solder to the solder side of these pins, and i'm guessing there's another pin on that connector to grab 5V power from as well.

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 Post subject: Re: CPS2 B boards, original roms, no battery.... no problem!
PostPosted: Sat Oct 13, 2018 7:34 pm 


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In my zoomed in picture you can see where I grabbed 5V from (it's the orange wire) https://i.imgur.com/GBXhCCm.jpg

There's many places you can grab ground a 5V from. You can just hook the B board to the A board and (with everything off) use a multimeter to probe one of the 5V pins on the JAMMA edge then start probing around on the B board to find easy 5V solder points.


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 Post subject: Re: CPS2 B boards, original roms, no battery.... no problem!
PostPosted: Sun Oct 14, 2018 7:07 am 


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I see that there's now another new method that does the same thing, the Infinikey:

https://www.arcade-projects.com/forums/ ... /&pageNo=1

And the PIC chip already mentioned of course.

It's great to have all of these alternatives, they account for all preferences. :D
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