CV Homebrew Cartridge PCB (bare)

The ColecoVision Homebrew Cartridge PCB (Bare)—designed by Pixels Past (Joe Grand) and distributed via AtariAge—is the raw unpopulated circuit board option in this development series.

It is designed for experienced builders who want complete control over their components, allowing them to solder their own logic chips, capacitors, and sockets rather than buying a pre-assembled board.

Component Bill of Materials (BOM):

To populate this bare PCB into a fully functioning cartridge for the ColecoVision or Coleco ADAM system, you must source and solder the following components yourself:

• IC1 (Main ROM Slot): A 28-pin low-profile DIP socket or a direct-soldered non-volatile memory chip, such as a standard 27C256 EPROM or a 28C256 EEPROM.
• IC2 (Address Decoder): A 14-pin DIP socket or a direct-soldered 74LS21 dual 4-input positive-AND gate logic chip. This chip reads inputs from the system's address pins to map the game data accurately.
• C1 (Bypass Capacitor): One 0.1µF ceramic disc or axial capacitor (typically 25V or 50V) to filter power supply noise and maintain signal stability across the ICs.

Core Technical Rules

• 32 KB Address Bound: The linear, unmapped routing path natively supports game files up to 32 KB. Advanced modern homebrew configurations that exceed 32 KB (like 128 KB MegaCart files or titles requiring NVRAM save states) will not work on this basic layout.
• Binary Padding: When deploying smaller classic game sizes—such as an 8 KB or 16 KB binary—the raw file must be padded or mirrored to completely fill out the 32 KB target memory chip space (using tools like Bin Wizard). Leaving the extra chip space blank causes address selection failures, resulting in a black screen on boot.