- Yamaha YM2151 (OPM) 4 operator FM sound chip
- Supports MIDI CCs.
"OPM chip was popular in the 1980s
and early 1990s. Videogame fans will most likely be
familiar with the
Sega Genesis (Megadrive), whose sound chip is
a slight variation on the OPM - the OPN. The chip
has also been used in countless arcade games
including Paperboy, Outrun, Metal Slugs 1-5, and
Street Fighter II."
VOPM is free, open source.