Archive of the former Yahoo!Groups mailing list: Yamaha CS80

Duplicating the logic is easy.  The big pain is the voltage.  The Yamaha uses 4000-series CMOS and runs all the digital logic at +8.5 / -6.5 -> 15 volt supply.  It’s offset above/below zero to interface with the analog circuits that run off +/- 15 volt.  No modern chips run at this high voltage.  Even 5-volt is history and 3.3-volt is only kept around for interfacing with older parts.  All the chip guts these days are running around 1-volt.   So, you end up needing tons of level-shifting chips to connect the Ardiuno (or FPGA) to the rest of the logic.  Most circuits I’ve seen use chips that were intended for converting RS-232 (also fairly extinct) like the MAX232.  The chips that were most commonly used won’t work anymore since they convert to +5v TTL.

 David