Martin, The Matrix runs slow enough so it should work. The only advantage to the 28Cxxx series is if you want to change the firmware quickly. Also in today's SMD world it's getting harder to find eeproms in DIP format.

--- In oberheim@yahoogroups.com , Martin Ator wrote:
>
> Would a 28C256 work Then you wouldn't need a UV eraser, although I have had timing issues with some older stuff that didn't like EEPROM. Might have to stick with 27C256.