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.
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!
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!