LuigiBlood's Blog

Here are my research about the SNES Playstation / SNES CD / SuperDisc.

First of all, aside from the CD drive part on the console, this is nothing more than your regular Super Nintendo. No glorified chips that adds power to the machine itself. You could compare it to the homemade MSU1 enhancement, it’s not too far from it.

Second, I should mention that I’m not in any way an expert on hardware stuff, I know a bit of how things work but I’m not the guy to ask about that.

As you can probably see, the board is divided into several parts, but the ones we are interested about are SFX and CD-ROM. SFX is the Super Famicom part of the PCB.

SFX contains everything of your typical Super Famicom, including the CIC. Interestingly, the sound chips (S-DSP & S-SMP) has their actual IDs on them, which is unusual.

The CD-ROM part has the CD interface & the DSP, not unusual.
It happens that the Playstation as we know it uses chips with similar IDs (SONY CXD1815Q, SONY CXD2510Q) and for similar uses as well.

If you are wondering about the other side of the PCB…

To the right side is the SFX part, there’s only the RAM for the PPU and the SMP/DSP.

The CDROM part only has CXK58257AM-70L… which is CMOS Memory. A very similar chip was used for the Playstation: CXK58257ASP-70L. Both provides 32Kx8 of SRAM.

No traces of a powerful chip, it would have been bigger, and we would have noticed it at this point even if we couldn’t see the ID.

One of the most interesting part is the cartridge that came with it. This is indeed the Super Disc System Cartridge (that’s the official name).

It contains the BIOS ROM (version 0.95), 8Kx8 of SRAM, and two S-WRAM chips. Considering the SNES only has one and it is known to have 128KB of WRAM, we can assume this cartridge brings 256KB of WRAM for CD drive use.

You can’t directly run a game from a disc, you need to pull the data from it to memory first and then you can be able to run the code. You have a total of 384KB of WRAM (Cartridge + SNES) for running a SuperDisc game. 128KB is the equivalent of 2 full memory banks (7E-7F), meaning you have 6 full memory banks to work with.

Also, people seemed to think that the console has a SuperDisc BIOS in it. There are no BIOS ROMs in the console, else I would have mentioned it.

So the only enhancement is brought by the cartridge, which has the BIOS (for CD drive functions), and more RAM. And the CD drive on the system, of course, which isn’t used without the cartridge. Not too shabby.

Also, it means it cannot run any Playstation games. That shouldn’t even be a question. This hardware is from 1991. The Sony Playstation was released in 1994.

Image sources (check these out, they’re nice articles):
http://www.engadget.com/2015/11/06/nintendo-playstation-is-real-and-it-works/
http://www.hkgolden.com/articles/article.aspx?id=20279&catid=33