sega saturn 20pin modchip info

[qabbalist]

http://www.crazynation.org/SEGA/Saturn/cd_tech.htm

i stumbled across this info while looking for 20pin modchip install mod

[APE]

Its well known at this point.

[APE]

Because I want to bump this to get it some attention:

Due to what is probably my lack of higher engineering experience I'm having trouble figuring this all out:
http://www.segastyle.com/model1Alt.html

Clearly this isn't a difficult guide to follow. I'm able to piece together what edge/connector pin goes to what pin on what component without too much trouble. Datasheets are easily found for the ICs on the modchip being modified in that guide however they differ slightly to the modchip in front of me - though they are functionally equivalent.

However what I'm not quite able to piece together is what all of those components are doing in terms of modchippery. Ex. clock, data strobe, etc as OP's URL attempts to diagram with the caveat that the 21 pin information is unconfirmed and clearly incomplete. This wouldn't be a problem on its own as pure curiosity is great but I'm not going nuts over this purely for curiosity's sake.




The SSIC7A, an older revision of the modchip used in the aforementioned guide. There are more components than the 8B and the 7A relies entirely upon through hole components where as the 8B uses mostly surface mount components.

The greater number of components increases the complexity of the modchip and as a result I'm not able to take the information I've pieced together and apply it directly to the 7A.

My question: am I overthinking things or is it as simple as tracing the same connector/gold finger connections to their destination and wiring it up in the same fashion completely ignoring that the components are different?

[Druid II]

I think the first 21-to-20-pin guide came from a guy who simply compared the pinouts and rewired things accordingly, but don't quote me on that. The decade-old thread is still up at segaxtreme though.

[APE]

Probably as it was exactly what I was initially trying to do. Ideally I should strip the board of components, photograph both sides and draw up a schematic. With that modifying the PCB for 20 pin usage and having them actually made would be a snap albeit a steep price just to get started.

And then there is the matter of dumping the PIC which is likely locked down to prevent it from being dumped. Acid decapping sounds fine and dandy - if I had the equipment.

[Bad_Ad84]

You just need to trace what pins are swapped. Most of the pins are directly connected, so it doesnt matter what is actually on that pin. The only important pins are the non directly connected. you just need to figure out about 5-6 pin swaps.

I still intend to do this with the rob webb chips when I get time, shouldnt be very difficult.

[fasman]

I dont know if this will any use to any one, but Ive got a old, Saturn mod, it only uses two ic's to work(One a PIC other I cant make out), and has connectors for both 21 pin and 20 pin.

At very least you can desolder everything and and visially or with a continuity meter find out what pins goes where(20 to 21 pin), but considering how basic it is maybe some one can dump the PIC, and reverse engineer it into something we can actually build ourselves using a FPGA and custom PCB....

I can send it to who ever thinks they can use it.

PS Didnt get this one from the site but found it in a old broken Saturn...

Edit: will upload pics tonight

[Bad_Ad84]

I'd be happy to look at it. Willing to return it if there's no progress.

But the PIC is likely locked/protected.

Also, you wouldn't need a FPGA...

[fasman]

I'd be happy to look at it. Willing to return it if there's no progress.

But the PIC is likely locked/protected.

Also, you wouldn't need a FPGA...

Nice, I will upload pictures tonight, it would be nice if it isnt locked or protected :), and I will post it for you sometime next week if you still want it.

Your right it would probably wont need a FPGA, but I think with bottom end FPGA's getting cheaper, it might be better just to have a single chip solution, but to be honest I dont know a thing about how these work or what the second IC actually does :shrug:

PS it would be great if we could make our own Saturn mods :P

[Bad_Ad84]

I agree, it would be a good solution.

Even if the chip is locked, assuming only 1 chip is programmed (or needs dumping) we could probably fund raise enough to get the chip decapped and read. Making DIY saturn mods available.

Anyway, all speculation until I see the mod you have,

[fasman]

Here you go:






Chips name is 7004
IC1: pic16C54A
IC2: ICP 22cv10ap
ctq10711
708FU -25

Other text: SS CD RN??

[Bad_Ad84]

Extremely easy to trace which pins will need moving and where to.

If you wouldnt mine sending me it, I will test on a rob webb chip and post the details for everyone.

[APE]

Simple and with fewer parts than the SSIC line, I like it.

[fasman]

Good to hear, just PM me a address and I will send it on Monday ,will probably take a week or two to get to you :)

[l_oliveira]

I have an bucket full of malfunctioning SS modchips. I have a lot of early chips, including some of the type Fasman posted. :shrug:

[Bad_Ad84]

Want rid of them? :)

[l_oliveira]

Want rid of them? :)

As they're malfunctioning items I don't think it's appropriate to sell.

Anyway we can keep talking on PM about them. :nod:

At the moment I lack proper tools to take an decent picture of it... :shrug:

Before people start sending PMs regarding it, I shall mention again, they're faulty and been sitting on a ice cream pot for more than 10 years now:



At best I think they would be useful for reverse engineering. :shrug:

[Druid II]

I wouldn't mind getting some of those to tinker around with either (if you'd get rid of them for shipping price only).

[qabbalist]

Extremely easy to trace which pins will need moving and where to.

If you wouldnt mine sending me it, I will test on a rob webb chip and post the details for everyone.

any progress at all with rob's chip/info on these older chips?

[fasman]

Shipped the chip last week to Bad AD but it will probably take another 1-3 weeks to get to him from South Africa...