This PCB attempts to replicate the Ensoniq writeable patch cartridges used by the ESQ-1 and SQ-80 synthesizer from the 1980s that used 64kb EEPROMs and stored 2 banks of 40 patches each. Both vintage cartridges and many modern, “upgraded” alternatives are selling for the same prices as many of these synthesizers themselves and a cheaper, more democratized option was required.

Designed with the AT28C64B in mind (28 pin DIP), it can be configured as a read-only or read/write cartridge. Instructions are on the PCB.

Optionally, the AT28C256 EEPROMs can be used with extra components at the top of the board and external switches to provide 4 original carts worth of storage (320 patches).

Latest PCB revision is available for purchase through Tindie: https://www.tindie.com/products/zensynth/oshdiy-ensoniq-esq-1sq-80-eeprom-cartridge/

And Reverb: https://reverb.com/item/62807297-ensoniq-esq-1-sq-80-eeprom-cartridge-pcb-direct-from-pcb-designer

Latest schematic designs along with CAD files for a 3D printed enclosure are now available on GitHub: https://github.com/JamesHagerman/Ensoniq-ESQ-1-EEPROM-Cartridge