SuperDisc What exactly doesn't work with the prototype?

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nocash
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SuperDisc What exactly doesn't work with the prototype?

Post by nocash » Thu Mar 10, 2016 1:48 pm

I've read that CDROM drive of the SuperDisc prototype doesn't work - but what exacty doesn't work with it?
- does the tray motor allow to eject/insert discs?
- does the disc spin up?
- does it react to Audio discs?
- does it react to Mode 1 PC cdrom discs?
- does it react to Mode 2 PSX game discs?
- does the ADPCM test mode allow to play XA-ADPCM sectors (eg. found on many PSX discs)?
- are there any error messages?

I've also read that Sound doesn't work, and that the console didn't include a power supply. That's both sounding a bit like some missing supply voltage: Normal SNES mainboards are running everything at 5VDC, except for the sound amplifier which requires a different voltage (9VDC in case of SNES, but in case of a "Playstation" it could be also something like 7.5VDC as used in PSX/PSone). A missing supply voltage would also explain any problems with the CDROM motors.
- what kind of power supply connector does that thing use (how many pins, which voltages)?
- did somebody check if the voltages are actually reaching the chips/motors?

Sorry if that stuff has been already answered elsewhere, but there are so many posts about the console that it's hard to keep track of the current state of the prototype.

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LuigiBlood
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Re: SuperDisc What exactly doesn't work with the prototype?

Post by LuigiBlood » Thu Mar 10, 2016 2:09 pm

This video answers most of your questions: https://youtu.be/JT15xl4ZzOI?t=150
It's the first boot of the system, and also the Self Check.
Basically "NO CD-ROM SYSTEM" appears on screen, and they tried to press the Eject button, where absolutely nothing happens.

About the Sound, we know that SPC700 totally works, else they wouldn't have been able to play games on it, so probably just the sound output is having problems.

About the AC adapter needed for it, thankfully, the first picture of this album is very high quality and shows enough detail to figure everything out: http://imgur.com/a/Ll9kS

There's also this article at Engadget: http://www.engadget.com/2015/11/06/nint ... -it-works/
An expert tried to look at it and said the drive is definitely receiving power but couldn't figure out where the problem is.

nocash
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Re: SuperDisc What exactly doesn't work with the prototype?

Post by nocash » Thu Mar 10, 2016 8:57 pm

Video just shows "We'll need you to do this in order to continue using Google services" preceeded by some non-legible text (probably requesting to eat animals or to buy something new for continuing to use the internet). Anyways, if the video just shows nothing to happen when pushing Eject then it's probably not too interesting. I hope they tried the cdrom eject button (not the inviting big round cartridge eject button). Selftest shows OK or NG on the different tests?

After seeing the green cdrom/power LED glowing on one of the photos, I couldn't tell how much impressive work the expert invested when saying that the drive is definetely receiving power. Could mean anything from gazing at the LED, measuring +5VDC, or also drawing extensive schematics and checking all supply pins that might require stuff like 3.5V or 7.5V. Power supply problems would still seem to be the best explanation for cdrom and audio problems.

My checklist would be:
- Did somebody connect something like +24V to the console (would probably destroy everything except +5V components).
- Did somebody use a supply with wrong polarity (if there's no diode at supply input (?) then it could cause same destruction).
- Are the supply pins of the cdrom and audio amp chips receiving the correct voltages, if not, check fuses, solder points, and so on.
- Somehow spin the Eject motor, manually, using your fingers if necessary, to see if there's still a CDR/CDROM disc in the drive.
- Even if repairing turns out too difficult, at least dumping the 8Kbyte mechacon PROM should be easy (see the uPD75P308 datasheet for the flowchart; there doesn't seem to be any read-protect feature, so dumping should work without problems; with that PROM dumped one could probably even build a hardware clone with new components if the original boards cannot be repaired).

Is there somebody with some electronic skills having access to the console whom one could talk to?

byuu
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Re: SuperDisc What exactly doesn't work with the prototype?

Post by byuu » Thu Mar 10, 2016 9:41 pm

With all due respect, this hardware landed in the hands of people who have absolutely no business owning it. Again, no disrespect: it'd be like me stumbling across a Stradivarius in a pawn shop for $75 (what they paid.) Doesn't mean I'm an idiot, but there is no reason I should own such a priceless instrument. Likewise them and this system. Is that a statement of jealousy? Yes, you're damn right it is. But it's also a very bad thing for trying to reverse engineer the secrets of this thing.

Thankfully, they are generous people that have shared the BIOS dump. But even that, they did with a standard SNES copier. We're never going to know for sure where all the cartridge data mirrors to without a proper analysis of the entire 16MiB address bus, but they aren't going to send the cart to me because it's priceless. So we can only place RAM where we see the BIOS accessing it.

To them, this is their 15 minutes of fame in life. It's extremely unlikely they're going to allow someone to desolder that NEC PROM to dump for us. Yes, even though the system is dead right now. There are those who'd rather this sit in a glass case at a museum untouched while the actual data bitrots away forever.

Even in the miraculous case that we get this system up and running, it took like 8+ months just to get a copier imaging of the BIOS, and the only reason we have it right now is because his friend leaked it. My pessimistic side thinks that maybe he didn't want it to be made public, but now that it is, he's saying that was his intention. That's the shitty part about keeping things like this secret ... now we'll never know which is true.

As far as making a new hardware clone, very unlikely. The skill level would be absolutely monumental, we don't know if the CXD1196 is a drop-in replacement for the CXD1800, and we have no idea what the 36-pin unmarked IC is on the board. And that's not even getting into the prototype hell mess of wires jumping connections all over the board, or all of the trace lines hidden by chips that they're never going to desolder for us to see under.

But yes, a truly dedicated absolute wizard of engineering could probably recreate a board (I really doubt such a person would bother with there being no software for this system.) But it'd be about as accurate as our emulation would be. Tons of guesswork without being able to run our own diagnostics on the original hardware.

ccovell
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Re: SuperDisc What exactly doesn't work with the prototype?

Post by ccovell » Thu Mar 10, 2016 11:33 pm

byuu wrote:My pessimistic side thinks that maybe he didn't want it to be made public...
When leaking stuff from major companies (Nintendo, Sony...) a little bit of ass-covering is always wise. Perhaps he's doing that? "No, that ROM dump didn't come from me; I never dumped it," is the safer thing to say.

byuu
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Re: SuperDisc What exactly doesn't work with the prototype?

Post by byuu » Thu Mar 10, 2016 11:46 pm

> When leaking stuff from major companies (Nintendo, Sony...) a little bit of ass-covering is always wise. Perhaps he's doing that? "No, that ROM dump didn't come from me; I never dumped it," is the safer thing to say.

I would have thought that, but he gave the ROM to LuigiBlood once the leak was known. The leaker had only sent it to a couple of gaming news sites, and left out any emulator authors or promiment ROM hackers from the list of recipients.

Most likely he would have shared the ROM at some point in the future, but again, there's no way to know now when or if that would have happened without the leak.

nocash
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Re: SuperDisc What exactly doesn't work with the prototype?

Post by nocash » Thu Mar 10, 2016 11:59 pm

Rare stuff never ends up where you want it to end up, that's fine. But in this case, assuming that owner might want it to get repaired by some skilled hardware hacker... pretty much everything could happen. Just be optimistic.
At the moment I would be happy to know if the owner is already in touch with somebody who could separate a diode from a resistor and who could answer some basic questions.

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LuigiBlood
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Re: SuperDisc What exactly doesn't work with the prototype?

Post by LuigiBlood » Fri Mar 11, 2016 3:56 am

nocash wrote:Video just shows "We'll need you to do this in order to continue using Google services" preceeded by some non-legible text (probably requesting to eat animals or to buy something new for continuing to use the internet). Anyways, if the video just shows nothing to happen when pushing Eject then it's probably not too interesting. I hope they tried the cdrom eject button (not the inviting big round cartridge eject button). Selftest shows OK or NG on the different tests?
So basically the guy booted up the console with the cartridge on it. "NO CD-ROM SYSTEM" appears on screen.
They pressed the Eject on the front of the console, nothing happens.
They accessed the Self-Check, which the first part is all OK (logical since it's all SNES, no sound though at the Sound Check), and the second part, only the RAM checks are OK. CD-ROM DECODER and I/F are NG.

Sik
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Re: SuperDisc What exactly doesn't work with the prototype?

Post by Sik » Fri Mar 11, 2016 6:02 am

Actually, considering the DECODER test only needs IRQs to fire to pass (from what I've seen?), doesn't that mean that it's not a mechanical failure, but that particular chip? (although it could be just a loose connection too) Unless that's a red herring and I misunderstood something.

byuu
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Re: SuperDisc What exactly doesn't work with the prototype?

Post by byuu » Fri Mar 11, 2016 10:15 am

> doesn't that mean that it's not a mechanical failure, but that particular chip?

It appears the NEC chip isn't operational either. And that doesn't even require an IRQ, just a simple response to the "status request." Any status result will do. But I don't think both would fail independently, unless something catastrophic happened, like pumping in way too much power and frying all the chips on the CD-drive side.

Plus, there's the CD-ROM door that won't open. So I'm inclined to agree with nocash in that it's most likely a power issue. Because if it truly isn't, then the system is most likely shot for good.

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