Introduction to the Roland M-64C:

The M-64C is the "big brother" to the more common Roland M-16Cmemory Cartridge. This cartridge can be used with the Alpha Juno 2, GR-700, GR-77B, MKS-10, MKS-20, MKS-30, MKS-70, MKS-80, TR-707, TR-727, TR-909, JX-3P, JX-8P, JX-10.

The M-64C was part of a trio of memory cartridges. Along with the M-64C there is the very rare M-32C, and the M-16C. Inside the M-64C are four Toshiba TC5517AFL 8 x 2K static RAM chips with a lithium battery to power the chip and protect the memory contents.

The original projected life span of the battery was five years, but many of these batteries are still at work twenty-five years later. However, I have seen a few M-64Cs, with dead batteries. Replacing the battery is a bit of work, you will need some desoldering tools, and patience getting the pins lined up when installing the new battery.

M-64C - Compatible with Synths and Drum Machines Designed for the M-16C:

My experience has been that while the M-64C has four times the memory capacity of the M-16C, it is "backwards" compatible. You can use a M-64C in a synth that accepts the M-16C. However, you do not get any additional memory. The synth still "sees" the M-64C as a M-16C. The additional memory capacity of the M-64C remains unused.

Another interesting example is the Roland JX-10. It has a modest on-board sequencer. Using the M-16C, 400 notes of sequencer data can be stored. Using the M-64C, 1600 notes can be stored, or four times the amount of note data.

The M-64C can also be used with a modified Roland GR-700 to increase the external memory by means of a switching circuit.