The ColecoVision Homebrew Cartridge PCB (Assembled, No EPROM)—designed by Pixels Past (Joe Grand) and distributed by AtariAge—is a high-quality, newly manufactured circuit board built for the homebrew and game preservation community.
It allows enthusiasts to assemble physical, playable cartridges of homebrew software, custom hacks, or unreleased prototypes for both the standalone ColecoVision console and the integrated Coleco ADAM system. By using a brand-new board, developers can avoid the destructive practice of scavenging and harvesting original 1980s retail game cartridges just to reuse their vintage PCBs.
Hardware Architecture & Logic
The layout is specifically optimized for high electrical reliability and easy, solderless chip configurations:
- The Socket Configuration: This specific "Assembled, No EPROM" tier features a pre-soldered, low-profile Dual In-line Package (DIP) IC retention socket. This allows you to pop programmed memory chips in and out instantly for rapid testing. It completely eliminates the risk of overheating delicate, aging motherboard traces with a soldering iron during data revision cycles.
- Target EPROMs: The board paths map natively to universally accessible non-volatile memory chips, specifically the 27C256 EPROM or standard EEPROM variants.
- Maximum File Size: The board supports linear, unmapped game binaries up to 256 Kilobits, which translates exactly to a maximum file capacity of 32 KB.
- Address Decoding Circuitry: To properly replicate classic 1980s cartridge banking, the PCB pairs the primary memory socket with a secondary logic slot running a 74LS21 dual 4-input positive-AND gate or a custom-configured PLD (Programmable Logic Device). This secondary component parses inputs from the host system's address line pins to accurately mirror the data tracks across the console's memory map blocks.
Shell and Cartridge Fitment
The external board boundaries, edge connector dimensions, and internal screw-hole positions are cut strictly to the original 1982 factory blueprints. It drops cleanly into standard, genuine Coleco retail plastic cartridge shells, as well as high-quality, archival-grade 3D-printed replica cartridge casings.
Crucial Software Compilation Rules
Because the board relies on static address selection rather than dynamic page mappers, developers must follow specific binary guidelines:
- No Bank-Switching: The base design tops out at a 32 KB file limit. Complex modern homebrews that exceed 32 KB (such as massive 128 KB MegaCart layouts or software requiring non-volatile NVRAM saves) are not natively supported by this unmapped PCB configuration.
- Padding Smaller Binaries: If you are deploying smaller vintage game files—such as an 8 KB or 16 KB game (e.g., BurgerTime)—the raw binary cannot be flashed as-is onto a 32 KB chip. You must use a file concatenation program or a tool like Bin Wizard to duplicate the code blocks until they perfectly fill out the 32 KB target length. This ensures the system address bus routes properly and prevents the console from locking up on a blank screen on boot.
