N64 DX256 5min mod: Use originals, backups Nintendo 64 Bung Super Game Saver Doctor V64jr jr512 CD64

N64 DX256 5min mod: Use originals / backups Nintendo 64 Super Game Saver Bung Enterprises Doctor V64 V64jr jr512 backup unit

The DX256 Super Game Saver from Bung Enterprises was primarily intended for use with backup units, though Bung would never admit that. Indeed, Bung’s regional distributors usually configured them as Emulation Adapters and bundled them with V64 and V64jr backup units AKA “consumer devkit and piracy device.” ;) DX256 units configured that way wouldn’t even work for original games!

The pirates needed a way to play games that expect to save to an EEPROM built-in to the original cartridge. They typically only owned one or two original cartridges just to bypass the console’s security lock-out, but they couldn’t save progress for dozens of pirated games on a few originals without a lot of tedium (backup and restore to PC, Controller Pak, etc). The DX256 solved this by giving them 256 banks of simulated EEPROM save slots with a single cartridge inserted (255 if that was a non-EEPROM cart).

Actual game developers did occasionally use these backup units as budget development kits but they were marketed to consumers just as much. Devs could also use the DX256 to replicate Nintendo’s 4k EEPROM when developing a game that uses it.

The Emulation Adapter function disables the inserted game’s program ROM while passing through the EEPROM and security chip (CIC) so that the console can boot a copied game from the console’s EXT port instead. To use the DX256 with an original game you usually have to open it up and make a couple small changes to disable the Emulation Adapter function, restoring access to the program ROM.

If you can’t boot a game through the DX256, take it apart and check J1 + R1. You will probably find a trace cut at J1 with silkscreened text saying “Open for Emu.” J1 = Jumper 1 and the entire point of that jumper is that you can add solder to close it and restore the trace. Unfortunately, there is no helpful silkscreen instruction at R1, which must be disconnected. You can remove the resistor or leave it attached on one side. It doesn’t really matter if you lose it since the value is silkscreened on the board (10k Ω).

Voila! You can now multiply the save memory slots on loads of Nintendo 64 games that use 4k EEPROM save. This includes including Super Mario 64, Mario Kart 64, Goldeneye 007, and several dozen others. There are literally more slots on the DX256 than there are games that can use it!

Yeah, not much of a mod since it was intended for both configurations but what else am I going to call it?