The SC-55mkII
A minor upgrade to the original SC-55, the Roland SC-55mkII has increased polyphony (28 voices), more patches, raising the total number to 354 instruments and extended, and improved audio-circuitry in the form of 18-bit audio (versus 16-bit in the original SC 55.)
The SC-55mkII added a serial port as an alternative interface to the MPU-401.
Read more about this topic: Roland SC-55