GitHub Repository: cogliano/Fruit_Jam_ColecoVision_Cartridge_Reader
(Note: KiCAD files coming soon).
I have always loved the Colecovision Game System. Released in 1982, it was a step above from the then popular Atari 2600 Game System, with improved sound and graphics nearly matching arcade quality games. With popular arcade games available for the system, like the included “Donkey Kong” game, my college dorm room became a popular hangout for friends craving the video arcade game experience without leaving the campus.
Fun Fact: “Donkey Kong” on the Colecovision was the first time “Mario” appeared on any home video game, although the name “Mario” wasn’t official until the release of the sequel “Donkey Kong Jr.”.
Adafruit’s Fruit Jam microcomputer came out in 2025. Based on the powerful Raspberry Pi 2350 chip, it has proven popular with emulating computers and video game consoles from the 1980s. Although a Colecovision emulator is not available for the Fruit Jam (yet), and a bit tough to tackle as a first project, I thought I could create a game cartridge reader for the Fruit Jam, where a game cartridge is inserted and then read and written to an SD card.
My inspiration was a project on Instructables (https://www.instructables.com/Arduino-ColecoVision-Cartridge-Reader/) by MatthewH that used an Arduino connected to a PC to copy a Colecovision game cartridge. There were a few shortcomings for me with this project, and I had a few enhancements that I wanted to add:
- Ability to run standalone (without a PC host) and write to an SD card
- Read the cartridge using CircuitPython instead of Arduino
- No loose wires!
The last item was important for me: with 30 connections required to read a Colecovision cartridge, I didn’t want to have a rat’s nest of wires that could pull out easily.
The Fruit Jam could easily support the first two items. To remove the loose wires I needed to create a PCB shield. No shields yet existed for the Fruit Jam, so this was something new!
The PCB Shield Design
This shield needed to be able to address the 30 pins of the Colecovision cartridge. Although the Fruit Jam has 32 pins available, there are several duplicate power pins on the Fruit Jam, so the 32 pins was not enough. I needed to find more pins. I was able to accomplish this with 2 shift registers. With 8 addressable pins each, this gave me 16 additional pins to utilize.
I was able to map all 30 pins of the cartridge with no vias. The through hole design of the PCB helped, which allowed me to choose either the top or bottom layer when routing a wire. It did make it a little confusing later when mapping the wires in the code.
CircuitPython Code
Writing the code for the shift registers was a breeze since there was already a CircuitPython library for it.
The code was written so it could run connected to a computer with a connected terminal or in standalone mode. When running standalone mode, the NeoPixel colors determine what is happening with the code.
Additional Components
Once the shield was connected to the Fruit Jam, it was apparent the shield sat higher than the original cover plate due to the housing within the header pins on the shield. This added 5 mm in height, which meant additional components were needed to compensate for the height. This included additional stand-offs to fill the gap between the 3 corner stand-offs on the Fruit Jam and the shield.
Button “extenders” were designed and 3D printed to extend the buttons and the on-off switch. Otherwise, you will need a toothpick or some other thin pointy device to press the buttons or turn the Fruit Jam on or off using the switch. An optional NeoPixel tunnel STL file was also created to isolate the NeoPixels. This is similar to one designed by Mikey Sklar but is taller to fit the additional height of the shield. STL files are included in the GitHub Project.
Parts List
| Item | Part # | Quantity | URL |
| 2×16 header pin (32 pins, 2.54 mm) | DigiKey:732-5307-ND | 1 | https://www.digikey.com/en/products/detail/w%C3%BCrth-elektronik/61303221121/4846875 |
| Edge Connector (Sullins Connector Solutions) | DigiKey:S3305-ND | 1 | https://www.digikey.com/en/products/detail/sullins-connector-solutions/EBC15DCWN/927257 |
| 74HC595 Shift Register | Adafruit:450 | 2 (comes in 3 pack) | https://www.adafruit.com/product/450 |
| HEX STANDOFF M3X0.5 STEEL 5MM | 732-10381-ND | 3 | https://www.digikey.com/en/products/detail/w%C3%BCrth-elektronik/971050321/6174600 |
Next Steps
With a Colecovision cartridge reader now working on a Fruit Jam, could a Colecovision emulator be next? That is something I’m looking into. The other neat thing to have would be a custom 3D printed case for the Fruit Jam, designed in the spirit of the original Colecovision Game System.