YM2610, aka OPNB, is a fifteen-channel sound chip developed by Yamaha. It's a member of Yamaha's OPN family of FM synthesis chips, and related to the YM2608. It was most notably used in SNK'sNeo Geo arcade and home game systems, along with other arcade game systems. The YM2610 was used in conjunction with a YM3016 stereo DAC.
The YM2610 has the following features:
Four concurrent FM channels (voices), four operators per channel
Three SSG channels
One programmable noise channel
ADPCM-A: Six ADPCM channels, 18.5kHz sampling rate
ADPCM-B: One ADPCM channel, 1.8–55.5kHz sampling rate