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's Neo 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
- Two interval timers
- A low frequency oscillator (LFO)
The YM2610B variant added two extra FM channels for a total of six, but was identical in every other feature. It was used in Taito's arcade boards, such as the Taito Z System, amongst others.