Nintendo SNES PlayStation finally uncovered! [READ THE FIRST POST BEFORE POSTING!]

Anyone know of a product that contains an NEC D75P308GF? It is a chip on the CD ROM unit.

https://twitter.com/byuu_san/status/757743689779253249

 

That "P" in the part number means "PROM" - it's an OTP part for prototyping and low-volume production, so it's very unlikely that a device used in a different application would have the same code.

If you can find someone that still has the design kit for that generation of CD players then the reference source for the syscon MCU would likely provide some interesting hints (annoyingly, I used to have this - but it was 20+ years ago and I have no idea where it is now...).

 

Yeah, the hope is that they can find another unit that possibly might have the same or similar code to dump the chip. They need it for emulation. Not to mention that they don't want to take the chip off a one-of-a-kind piece of hardware. But if it is likely that this has custom code on it, we might be out of luck anyways.

 

Well according to this source:
http://www.fixya.com/support/t191451-nad_5340_cd_player_1988_no_display
It's also featured in the NAD 5340 CD player.

 

Heck's update

 

I hope they emulate the chip, and get that cd drive working.

 

Well the datasheet says you can put it in read/verify mode with 12.5v on Vpp so I suppose its theoretically possible. But is also says its supports UV-erase, and I don't see a window on that part so unless it is on the back I may be looking at the wrong one, but the pin counts are matching for the physical package. Also the outputs are lining up almost exactly with CN701. I don't think I would want to be probing around on the actual unit with that voltage level unless I knew exactly what I was doing however.

It is tough to say without knowing what Sony's process was at that period but it would pretty much a shot in the dark to take an OTP dump from a similar part and use that to try and emulate what was on the controller. Maybe they had boilerplate controller code that they used in all their parts, but it is unlikely.

What is the need to get the ROM off the chip for anyway? Is it broken, or do they just need it for emulation?

 

So, when he says that they want to try and use some of the custom games people have created for the CD-ROM, how would this work? Could there be some sort of disc verification that the drive does? I understand these games were made using the ROM dump of the cart for the system, but what are the chances that this would work?

If this has been explained before, I'm sorry.

 

As i thought in an earlier post of mine. Because all the tests for the CD unit were ok, i knew it had to be a dud laser why it would not recognize a CD. It would be great to see this thing boot up a game from cd.

 

Yes, there could be disc verification. That's exactly what I was thinking too. But at least music cd's would work. There's also the chance he had a disc in his attic too.

 

Where was it said by one of them that they had a CD along with it? I have seen it mentioned many times by others, but never read them say this. Maybe it was in a video I didn't see? Just curious, as I also searched the first page of this thread to see if there was a link to one of them saying that. Not that I am doubtful, just seems like such an obvious piece to examine.

 

AFAIK he said he thought he may have a disc. Nothing very conclusive.

 

I msgd the main guy (Daniel, is it?) on Reddit the other day and asked about the disc. He clarified that they found out all the discs they got from that auction that this console was found with were actually just music CDs, although he thinks there still could be a game disc among them that they haven't found yet.

So it seems the reason the "disc" that was first being mentioned suddenly vanished is because they figured out it wasn't a game.

 

He's on here too btw.

 

Bramsworth, update your 2016 prototype thread.

 

It's a pretty early proto, I would guess there is no copy protection yet. It would just making pressing test disks harder.

 

Plus given the era and with CD burners not being as common place as they are today I'd say they wouldn't have really bothered in the first place

 

There probably would have been some on the retail unit, like the Saturn's wobble. Nothing too complex. Nintendo would have learnt from pirates with the NES/SNES/GB.

 

For low level emulation of the drive. I would say they assume certain things in the emulation that exists now. The same thing I believe exists with Playstation emulators where they just assumed how things worked but much later on the CD controller can now actually be emulated with a ROM dump of its firmware.

 

It's hard to say - the other machines that were produced around the same period didn't use media protection - probably because at that point both CD recorders and the media were so expensive that it just wasn't seen as a major threat. It clearly doesn't implement the same protection system that the retail PlayStation has, since that requires a bunch of analog processing circuits to demodulate the tracking error signal, and there is no sign of them on the photos of the boards.

The other thing is that with the PlayStation we had access to the developer documentation - which had a list of the CD controller commands and their arguments. With the SNES PlayStation, we don't have that - the only reference is the code in the boot ROM in that cartridge, which provides enough information to know what you have to emulate to get the boot function working, but not about any other features that might be present but unused by the boot ROM.