As well as its far more advanced successors: the YM2608 (also known as OPNA) which retained all previous features and greatly expanded upon those, the YM2612 (also known as OPN2) which was a cut-down YM2608 and removed many features including the YM2149 sound channels and I/O ports, and the YM2610 (OPNB) which added other features and retained the YM2149 sound but not the I/O ports.