Firstly I'd like to say that this doesn't seem like the right "forum" for this question as it actually doesn't relate directly to the development of games.

As this is my first post on 'game development', I cannot include more links - sorry.

I recently obtained a Game Doctor SF7 ("Professor SF2" in the US I believe) backup unit for the Super Nintendo, and I'd like to add battery backup to it.

Quick background

This first model (SF1) unit was designed by Bung Enterprises starting in 1994. It was placed on top of the SNES (interfacing with it via the standard cartridge slot) and allowed backup of SNES cartridges to floppy disk and PC(via a straight-through DB-25 M/M cable).

The unit can store the cartridge ROM, SRAM ("Save" RAM - used by many cartridges to store save games) as well as complete SNES RAM onto its own (expandable) RAM so that one can later dump this to floppy/PC, or to simply keep the games retained in memory for quick recall during development/gaming.

More interestingly, it can download ROM and SRAM data from a PC on most modern platforms thanks to the ucon64 project; this is of course of great interest if you want to actually do some SNES development on real hardware (which I do)!


The main kink is that the unit does not have any battery backup - if you cut power to the unit, RAM is lost. This wouldn't have been much of a bother in '94 when floppy disks were the bees knees, but nowadays it's very frustrating!


The idea is to add battery backup functionality to the unit. I've tried to find people who have made similar (or any!) modifications to the unit, Unfortunately as the machine is very old (and has more modern, "non-programming" everyday alternatives) it's very hard to find any information at all - most of the websites I've found which do have some information have been on archive.org!

Finding information

There are a number of reasons for it being exceptionally frustrating to find information about the unit. Firstly, Nintendo(and others) basically forced Bung out of business about ten years ago, so none of the original sites exist. Secondly, the unit series has different names in the US as compared to Japan - it's called the game doctor sf7 in Japan, and professor SF2 in the US. Thirdly, the majority of the userbase used the unit for the sole purpose of "game backups" and not development/hardware mods.

So, Has anyone performed such a feat before, got information about it, or simply the hardware know-how to get me on the right track? Am I perhaps thinking this might be easy when it might actually be quite hard (difficulty in retaining power to the RAM versus the entire unit, unforeseen issues, etc)?

Thanks for taking the time!

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    \$\begingroup\$ Unfortunately you are correct in that this is not the right place for this question; game development stack exchange is for the development of games, whether software (video games) or ideas (game design) or even traditional (board) games. I believe you will find better help at gaming.stackexchange.com, though they are aimed towards game players and gameplay questions, so it may also not be a great place to ask. Your question seems like something that would be posted on hackaday.com but they aren't a question-answering site... I would try to find a different forum though. \$\endgroup\$ – Ricket Aug 18 '10 at 21:37
  • \$\begingroup\$ Thanks for the links and tips, I'll keep on looking. Perhaps I could also try a more general approach; looking for commonalities in generally applying battery backup to stuff...I have some ideas now anyhow! \$\endgroup\$ – gamen Aug 18 '10 at 22:59
  • \$\begingroup\$ Interesting and well thought out question, but as Ricket said it is inappropriate for this particular community. I recommend gaming, or electronics. electronics.stackexchange.com \$\endgroup\$ – Jesse Dorsey Dec 23 '10 at 13:50
  • \$\begingroup\$ Just realized how old this was. How did this get bumped up. \$\endgroup\$ – Jesse Dorsey Dec 23 '10 at 15:48

Just because your question doesn't really belong here, doesn't mean I won't try to give you an answer! :)

If you are set on hacking this thing and adding a battery, that's fine. But might I suggest obtaining an alternative instead? The everything2 post on SNES Backup Units lists several others, some of which do retain their memory through a poweroff:

Ahh yes. The Super Nintendo Backup Systems... Anybody remember the Pro Fighter? Multi Game Hunter? Game Doctor SF? Or the ever popular Super Wild Card DX?

Or you could always take a spare computer and run an emulator (ZSNES or Snes9x) on it, and then get a USB SNES controller or a USB SNES controller adapter (plugs into USB and has 2 plugs for any SNES controllers).

If you have a Game Boy or Nintendo DS, there are a number of homebrew cartridges that will play SNES games as well. I have been extremely pleased with my recent purchase of a DSTWO as recommended by Lifehacker, and the Nintendo DS gamepad layout is extremely similar to that of the SNES so it hardly takes away from the feel of playing the games.

Remember of course that it's only legal to play ROMs of games that you own.

Edit: Ah, my apologies, I missed one of the key parts of your question when I first read it:

this is of course of great interest if you want to actually do some SNES development on real hardware (which I do)!

Hopefully, then, the first part of my answer might at least help lead you to better alternates to the Game Doctor.

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  • \$\begingroup\$ Thanks for the response! I am aware that there are many other units(like the DX2) and solutions(including very fine emulators) but as you said I'm "set on hacking this thing", for historical reasons really (and the actually useful result!); the entire fun of it being to use this old hardware once again for some serious coding! \$\endgroup\$ – gamen Aug 18 '10 at 22:55

From the HW point of view, you need to take lithium battery, and connect it to power in this module through a diode. This diode will protect the battery while AC power is on, and will provice power to retain state in standby. If you are lucky it would be that simple.

Be careful with - and + as wrong polarity might explode the battery.

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