SEGA Genesis Multi Cart

TESTED! The board works. However, the multi game function of that cart may not work properly depending on which games you use because of how the Genesis hardware works. The cart works as intended when used for only a single game.

Thanks to HD Retrovision for sharing their Genesis cart (you can find it on OSH Park here ). I cheated and used the board outline instead of starting from scratch. : )

This can be used as a basic Genesis cart with a max ROM size of 8Mib. Or with the 74161 installed, you can use this as a 2-in-1 or 4-in-1 multi cart (combined ROMs can be a max of 8Mib). Games are switched by console reset button.

There are jumpers for the A18 and A17 address lines that will have to be set depending on how many games will be on the cart and what size memory you are using. For either jumper, closing positions 1 and 2 will allow the console to control that address line. Closing positions 2 and 3 will allow the 161 to control that address line. View the tables below to see how to set the jumpers when using 29F800 or 29F400 memory.

Memory = 29F800

Memory = 29F400

More options are possible, but will require jumper wires and/or cutting traces. There are solder pads for +5V, GND, A18, A17, A16, the reset line, and all four outputs of the 161. There are too many possibilities to list them all, but to name a few… You can make an 8-in-1 cart consisting of eight 1Mib games on a 29F800, or a 4-in-1 using a 29F400, you can wire in a mechanical switch to select games instead of using the reset line, you can wire in LEDs to indicate which game is currently selected.

BOM:

*If you are only installing one game on the cart, leave U2 and C3 unpopulated.

**R1 value is determined by the LED that you use. If you use another LED than the one listed above, then you may have to change the value of R1. Digi-Key has a calculator to make it easy. If you do not use an LED, you can leave R1 unpopulated.

***Jumper pads are spaced for 0 ohm 0805 resistors, but they are not necessary. You can simply use a blob or solder, or a bit of wire, or the trimmed legs from C1.

LED is 1206 package to make it easy if you wish to use a through hole LED instead of surface mount (it has the benefit of standing tall in the cart shell).