Capcom CPS1 C-board fix

[lix]

Well mine had solder bridges across some of pins as I had to clean them up before installing, so they were at least tinned and not checked, they definitely weren't pristine.

 

[John Bennett]

Exactly what I was thinking! As long as there's an FPGA with enough
power and gates, I would've thought there's a multipin socket or
whatever that can be soldered in place of the chip and the "repro"
slotted into it. I suspect it'll happen at some point (hopefully!)

The hardware side would be tricky, not least the 5v -> 3.3v aspect as it's virtually impossible to find anything 5v tolerant that would be big enough. But certainly possible somehow, even if it was a small sub pcb with 160 wires to solder I wouldn't care if it meant a working A board

But that's actually the easy bit...

First you've got the actual decapping and delayering of a donor chip. The B21 was done by arcadehacker (actually someone else did the decap, can't remember who) I think they focused just on the small section that contains the programming logic and sram that stores the key.

Now, if they did capture the whole chip (hi res photos etc.) and they're available somewhere, then that's a massive step taken towards doing a B chip replacement. If the A chip has been done at all, I have no idea.

Next up, we've got the real business, the actual reversing of the logic at the silicon level. It takes somebody very knowledgeable in such things to be able to recognize individual gates and interconnections, and then even with a veteran of such things, it's a very time consuming and error prone job, eventually turning the whole thing into a giant schematic or logic definition.

I remember reading Furrteks blog, how it took something like 200+ hours to do just one of the NeoGeo customs!

Hopefully someone capable will step up. I'd certainly donate towards the effort, I'm sure many others would too.

I used to aspire to recreating the chip by trying to 'infer' the contents by looking at similar hardware and older Capcom stuff (2D is all variations on common design techniques), but, as said, I don't think there's anything out there big enough and 5V, so you end up with voltage translation everywhere.

And then there's the fact that the chip on the main board seems to fail more and, as you say, that's going to require you to get a bit, erm, creative with how to mount a replacement.

And then by that point you start to think you've made such a 'frankenboard', then why not just stick everything on a new PCB with a 68k and a Z80 and make it a multiboard.

And then I think, sod it, it's all madness, just use a PI

 

[Ace`]

Well mine had solder bridges across some of pins as I had to clean them up before installing, so they were at least tinned and not checked, they definitely weren't pristine.

Interesting, you got them from utsource? maybe they did resort to pulls as they started to run out then. Mine all had the same date codes and were very clean with no sign of solder.

 

[rockbottom]

I used to aspire to recreating the chip by trying to 'infer' the contents by looking at similar hardware and older Capcom stuff (2D is all variations on common design techniques)....

Interesting, I often wonder if looking at how the bootlegs work would help as well, after all on the face of it they seem to implement both the A and B with usually something like a TCP10 or ACT1 (early 90's field programmable gate arrays), handful of PAL/GALs and sprinkling of discrete.

Sure they're far from perfect but they're doing the bulk of it.

Perhaps one could even use some NOS 5v parts, I often watch auctions for such, some interesting stuff comes up time-to-time, job lots in 100s etc. enough for a good run, not like one would look to make a million.

 

[rockbottom]

Well mine had solder bridges across some of pins as I had to clean them up before installing, so they were at least tinned and not checked, they definitely weren't pristine.

Interesting, you got them from utsource? maybe they did resort to pulls as they started to run out then. Mine all had the same date codes and were very clean with no sign of solder.

I realised long ago, any components from China, no point trying to work out what they really are or came from. Fake, re-branded, pulls, factory 2nds that went in the bin (then came out again!)

can be literally anything, all you can do is see if they work or not

 

[John Bennett]

I used to aspire to recreating the chip by trying to 'infer' the contents by looking at similar hardware and older Capcom stuff (2D is all variations on common design techniques)....

Interesting, I often wonder if looking at how the bootlegs work would help as well, after all on the face of it they seem to implement both the A and B with usually something like a TCP10 or ACT1 (early 90's field programmable gate arrays), handful of PAL/GALs and sprinkling of discrete.

Sure they're far from perfect but they're doing the bulk of it.

Perhaps one could even use some NOS 5v parts, I often watch auctions for such, some interesting stuff comes up time-to-time, job lots in 100s etc. enough for a good run, not like one would look to make a million.

Some of the bootlegs are entirely PALs/GALs, although I expect they're protected (I've got a couple, just not tried reading them). They're not quite 1:1 with the original game though - you can see MAME having to do different interpretations to make the GFX display correctly.

My thought was that if you take something like Ghosts & Goblins, where the schematics are available, you can (eventually) see how it does the various layers (SRAM, counters, comparators etc - probably obvious to some old-school games programmers, but took me a lot of staring at schematics

). I'd say this is a more advanced version of that with line scrolling and other stuff. How it's split over the two chips, I don't know - I defer to those who've looked at this more, like the O.P. Feels better to understand, break-down and recreate than to attempt to clone 1:1.

The Forgotten Worlds schematics effectively show the pinout for the C-board too.

It also bears some resemblance to the x68000 system.

But then there's all the pins for DRAM controllers and other bits and pieces thrown in.

I figured it was just too much work and other things took my interest. But then I'm relatively unskilled in such areas, so don't let me detract - may not be that hard for some to do .

John Bennett2019-09-16 20:30:29

 

[yoganuggy]

Looks like someone is aiming for full cps2 schematic documentation including the customs

https://gitlab.com/loic.petit/cps2-reverse

 

[Monstermug]

NOS c boards for sale. Get em while they are still hot. Apparently a bunch of A boards have been found too but I can't find where the link to that one is.

https://www.daywin.net/products/unmodified-cps1-b-21-c-boards

Monstermug2020-07-20 19:19:07

 

[Brettster]

I got a couple delivered this week, they look mint, just need to figure out how to reprogram them now

Also heard the A board were 1.5's with the sound hardware repopulated I guess that's where these NOS C boards have come from

 

[Equites]

I got a couple delivered this week, they look mint, just need to figure out how to reprogram them now

Also heard the A board were 1.5's with the sound hardware repopulated I guess that's where these NOS C boards have come from

What games can be used on these C boards?

 

[yoganuggy]

It's mainly for the new darksoft cps1 multi due to be released soon. This c board is compatible. There is a thread about it on the arcade-projects.com forum.

 

[Brettster]

I got a couple delivered this week, they look mint, just need to figure out how to reprogram them now

Also heard the A board were 1.5's with the sound hardware repopulated I guess that's where these NOS C boards have come from

What games can be used on these C boards?

They have the B21 chip on them, which can be used for any game if you provide it with the keys

http://github.com/TwistedTom/ArcadeHacker_CPS1

or when the cps1 infinikey comes out use that for an even easier way

 

[Monstermug]

I got a couple delivered this week, they look mint, just need to figure out how to reprogram them now

Also heard the A board were 1.5's with the sound hardware repopulated I guess that's where these NOS C boards have come from

Any links to where I can find A boards from?

Yes you can use Aarons rom patcher to make any game work with these c boards.

 

[MDK]

I got a couple delivered this week, they look mint, just need to figure out how to reprogram them now

Also heard the A board were 1.5's with the sound hardware repopulated I guess that's where these NOS C boards have come from

Any links to where I can find A boards from?

Yes you can use Aarons rom patcher to make any game work with these c boards.

The A boards were available via sheep nova but a few people have messaged him and been told there out of stock. Just the c-boards left now via Lydz.

 

[lix]

Yup, I got five and they arrived the other day. Programmed a couple so far with the De-suicider by Eduardo and they work great.

 

[Monstermug]

So you got to program these regardless weather you use the patch roms?

 

[lix]

You don't have to, I find it easier to program the B-21 to be whatever it needs to be and it keeps it all as original hardware and eproms.

The C board will need the battery removing and modding to permanently default to B-01 if you use patched roms.

Personal preference and depends on if you use them to fix individual CPS1 boards or are planning to use with a multigame conversion.

 

[Monstermug]

You don't have to, I find it easier to program the B-21 to be whatever it needs to be and it keeps it all as original hardware and eproms.

The C board will need the battery removing and modding to permanently default to B-01 if you use patched roms.

Personal preference and depends on if you use them to fix individual CPS1 boards or are planning to use with a multigame conversion.

Ahh I bought two of those c boards and plugged in with patched and unpatched roms and got blank suicided screen. Should I just remove battery and try again with patched roms?

 

[lix]

Ahh I bought two of those c boards and plugged in with patched and unpatched roms and got blank suicided screen. Should I just remove battery and try again with patched roms?

I think you have to do more than just remove the battery, cutting some tracks to pins 45 & 46 on the B-21 custom chip? I'm just going on the information here: http://www.arcadecollecting.com/dead/dead.html

But I think GadgetFreaks patcher (if that's what you are using?) autodetects what CPS B-21 keys are installed and works anyway? I don't know alas. The C boards may have random keys and need to be blanked, which I guess you do by discharging the battery and optionally doing the mod.

 

[Monstermug]

Thanks for that! Yes i am using gadgetfreak rom patcher and not 100% up to date on exactly how the cps1 ppu works fully yet although I have tried to read up as much as possible on it. Patched rom did work on a random SF2 B-21 so I assumed it works for all B-21 including one already encrypted with a game rom program. Got a ardruino programmer ordered a few days ago so will program it when it arrives.

Funny enough the battery on these still reads 2.7v. I thought they would have been totally dead by now

Monstermug2020-08-01 13:19:13