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PostPosted: Tue May 21, 2019 5:26 pm 
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I want to start a general info thread about this thing just because I picked up one of the RAM cartridges for it recently, but the whole thing isn't very well-known or documented at this point.

Basically, the "Game Processor" was some kind of system developed by Nintendo to allow people to develop simple SNES games using a point-and-click interface on specialized hardware, which wrote the games onto SRAM-based cartridges for play on regular SNES/SFC consoles. I'm not aware of the system itself ever appearing "in the wild", but it's described fairly in-depth in this 1994 US patent along with some mockups of the so-called "Mario Factory" game creation software that would run on it, as well as details about the "Game Processor RAM Cassette" cartridges used for storing users' games.

There have been a few of these cartridges popping up on auction sites every once in a while, but without a lot of context behind them. There's at least one (badly corrupted) dump of one of these floating around, but given that mine was manufactured all the way out in 1999 and the battery was completely dead by the time I got it, it's probably safe to assume (sadly) that these are basically all toast by now.

An old dump of a RAM cartridge by d4s circa 2008: https://project.satellaview.org/snes/gpc4m.zip (note: it's basically unplayable due to bit rot)
Some images of the game contained on it: https://twitter.com/LuigiBlood/status/1 ... 0699585536

Interestingly, kukun kun's recent treasure trove of Satellaview broadcast videos have included footage of an event in 1995 where some of these games were made available as downloads via Satellaview, with the presenters mentioning the system by name at least a couple of times over the course of the broadcast. I'm not sure how much they actually talk about the specifics of it, though, or what the actual circumstances of this event were (if anyone could pick out some choice info to translate from these videos that would be awesome!)

Video 1: https://www.youtube.com/watch?v=ez79CMBcFe8 (featuring "Easy Racer" and "Sweet Honey Action")
Video 2: https://www.youtube.com/watch?v=5fokITLC8F8 (featuring "Puzzle & Bread" and "Flower")
Video 3: https://www.youtube.com/watch?v=UJStIhjTgRA (featuring "ラジパズ" ("Radio Puzzle" or something) and "Wonderful My Race")

I've also seen speculation in the past that this system was used at Digipen at some point, which might explain why Nintendo filed patents for it in both the US and Japan (for contrast, the Satellaview only has a Japanese patent).

Hardware-wise, the cart contains 4Mbit of battery-backed SRAM (in place of ROM) and some additional ICs for memory mapping and write protection. The RAM itself is mapped like a normal HiROM/mode 21 cart would be. The SRAM is normally write-protected; this is controlled by a 4-bit counter mapped to $6000-7FFF and $E000-FFFF in banks $20-3F (that is, any address with A23=0, A22=0, A21=1, A14=1, A13=1). Maxing out the counter by writing any value to these addresses 15 times will make the RAM writeable; writing to the counter again will overflow it and re-enable write protection. There's also a jumper (CL5) to keep the SRAM permanently writeable, and unused footprints for a write-enable indicator LED near the battery.

Programming the cartridge, in short:
  • Write any value to $206000 fifteen times (timing doesn't matter)
  • Write your program to $C00000-C7FFFF
  • Write to $206000 again to re-enable write protection

Basically everything on the cart (the SRAM chips and other logic) is also protected by a 74LS123 multivibrator which takes in the SNES master clock signal and turns it into a constant high input to SRAM chip enables and parts of the write-enable logic. This is to allow safely removing/hot-swapping the carts from the Game Processor unit while it's powered on, since disconnecting MCK would disable both the write-enable circuitry and all four SRAM chips. This also means that if you want to read/write anything from the cartridges you'll need something that can actually supply the master clock (I used a Super UFO for testing purposes). None of the other expansion pins are connected to anything.

Cart/board photos: https://imgur.com/a/hvK1ohX
Partial chip pinouts: https://docs.google.com/spreadsheets/d/ ... sp=sharing


Last edited by Revenant on Fri Jun 14, 2019 2:43 pm, edited 1 time in total.

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PostPosted: Tue May 21, 2019 8:23 pm 
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Emphasis mine:
Revenant wrote:
Basically, the "Game Processor" was some kind of system developed by Nintendo to allow people to develop simple SNES games using a point-and-click interface on specialized hardware, which wrote the games onto SRAM-based cartridges for play on regular SNES/SFC consoles.

Do we have any details on this part of the setup? Photos, technical details, or even best guesses (even things like "gut feeling the SNES mouse may have started here")?


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PostPosted: Tue May 21, 2019 9:00 pm 
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The mouse interaction is described rather thoroughly in the patent that I linked in the OP, along with drawings of the unit itself and mockups of the system software. (Throughout the body of the patent, the words "mouse" and "click" appear 38 and 46 times, respectively). I didn't really want to quote the relevant parts directly in the post just because it's so verbose and spread out through the entire document, but there's a pretty intriguing amount of info to be found about that part of it in particular.

(The SNES mouse certainly already existed at this point; the patent is from two years after Mario Paint was released)


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