The quest to get a unique SNES CD-ROM prototype working again

Since a prototype of the fabled, unreleased SNES-CD (aka the "Nintendo PlayStation") was first found and disassembled last year, we've learned enough about this one-of-a-kind piece of hardware to actually emulate homebrew games as if they were running on its CD-ROM drive. The prototype console itself, though, has never been fully functional—it couldn't generate sound, the CD-ROM drive wouldn't spin up, and, after a recent trip to Hong Kong, it actually stopped generating a picture.

That's when the prototype's owners, Terry and Dan Diebold, went to famed gaming hardware hacker Ben Heck. They want this piece of gaming history up and running again. Heck documented his efforts in a fascinating two-part YouTube series that reveals a lot about the system and what makes it tick.

Terry Diebold starts off talking about how he first discovered the prototype SNES while boxing up an estate sale, where it was sold in a lot alongside CDs, cups, saucers, and other knickknacks. After paying $75 for the entire lot, Diebold recalls, "if you break it down to everything I did buy, I probably paid a nickel for it."

Examining the outside of the "remarkably finished-looking" prototype, Heck finds some interesting design touches. The eject button that would remove SNES cartridges, for instance, becomes locked so it won't engage when the power is on. The system also has a powered "RF multi-out" plug in the back similar to many '90s Sony camcorders. On the bottom, there's an additional expansion port, apparently just in case Nintendo released any other additions to the SNES family.

Inside, the SNES-CD looks a lot like a standard SNES on a chip-to-chip basis, Heck said. The major difference is the CD-ROM drive and a cartridge with 256KB of RAM, likely used to store data being loaded from the optical discs.

After the hardware analysis, part two of Heck's efforts focuses on trying to get the machine in good working order again. After hacking together a new 7.5 Volt plug that will fit the system, Heck removed some extraneous connecting wires, replaced a few jumpers, and actually blew in that expansion cartridge to try to get the system to recognize it again (he also used some rubbing alcohol, but why ruin a good urban myth?).

Still, the CD-ROM drive itself wouldn't spin up, and a system check mode failed on the "CD I/F" test. The system was sending commands to the CD drive but not receiving any responses back. "Looks like whether or not the CD-ROM is attached, it fails in the same way, so whatever is causing the CD-ROM not to work is pretty catastrophic," Heck said. This led Heck to theorize that the CD-ROM drive may have been disabled intentionally before being given to its original owner, much in the same way that "if you want to put a tank in a park, you obviously take out the guns," as Heck put it.

Finally, after removing some more wires leading to the CD controller and cleaning out some aging capacitors, Heck and his team got the CD-ROM drive spinning (and the associated sound chip outputting audio signals again). Of course, there's no actual known SNES-CD software to test the hardware with, and the on-unit controls for a plain old audio CD don't seem to work at the moment. But Heck relayed a vague but tantalizing possibility that Terry Diebold "might have [SNES-CD discs] in the attic or like in a box of stuff."

In any case, the now repaired system works fine as a standard SNES, and it might even be able to soon test some of that homebrew software via the now-spinning CD-ROM drive. If you have the time, both videos are worth a watch for their insight into how to reverse engineer and troubleshoot classic hardware with little-to-no documentation. Here's hoping Heck and the Diebolds will be able to unlock even more secrets from this unique piece of gaming arcanum.