Description

What is it?

This opensource PCB by James Hagerman replicates the Ensoniq writeable patch cartridges used by the ESQ-1 and SQ-80 synthesizer released in the 1980s which used 64kb EEPROMs and stored 2 banks of 40 patches each.

The PCB is designed to support AT28C64 and AT28C256 (or similar) EEPROM’s. The larger EEPROM option can be controlled using 2 switches. The cartridge can also be configured as a “read-only” cartridge with some reducion in parts count.

Why did you make it?

Both vintage cartridges and many modern, “upgraded” alternatives are now selling for nearly the same price as what owners of these synthesizers originally paid for the entire synth!

A cheaper, more democratized option was required to keep these 36+ year old synthesizers operational and functional.

What makes it special?

This PCB was designed from the ground up based on an original ROM cartridge and publicly available information.

Along with the optional features described above, these PCBs may also help allow intrepid synth hackers to more easily write custom firmware for these 6809-based synths and achieve things that were not originally possible when Ensoniq released them.

Note: After assembly, you have to “initialize” the cartridge before using it. You can do this by saving the synths internal patches to EEPROM. Here are some steps:

Power up the synth
Plug in the cartridge
Press “STORAGE”
Press the button under “CARTRIDGE”
Press the button for “INT TO CART A” or “INT TO CART B”
Press the button for “YES”

Important notes:

This includes only the PCB, no components or 3D print housing.

This PCB is open-source and more info about the project and BOM can be found here:
https://github.com/JamesHagerman/Ensoniq-ESQ-1-EEPROM-Cartridge