Here are some simple instructions for making a JGM cartridge. If you're careful, you won't hurt yourself and nothing will be ruined. In the event that you hurt yourself or break something, call 911 or Radio Shack – don't call me.
Making a new cartridge requires soldering skills, a 2732 EPROM, an old Odyssey² cartridge and access to a EPROM programmer.
Program the 2732 with the JGMUNCH.BIN image.
Disassemble the Odyssey² Cartridge.
The pinout of the 2732 is very close to that of the Odyssey² ROM.
The above image assumes you are using a 2K cartridge (I used one of my many Speedway!/Spinout!/Crypto-Logic! carts). You will have to cut an additional trace and add an additional wire to convert a 4K cartridge since the 2732 uses a different pin for A11. If you really want to waste a 4K cartridge, (or 8K), then use the address pinouts (along with 2732 pinouts) to figure out how to hook it up.
Cut the red traces marked 1 and 2.
The first cut frees A11 on the 2732 from vcc.
The second cut allows pad B (Used by the voice) to float.
Solder a wire (Blue 3) from pin 21 of the 2732 to pad A11 on the circuit board.
The pad marked A11 is used for the most-significant address. Try to solder it at the very top since the lower 3/4 of the pad must make good contact with the O² edge connector.
Reassemble the Cartridge.
There! A monkey could do it – A VERY SMART MONKEY – but then again, that could be said about just about anything.