Yamaha YM2413

The YM2413, a.k.a. OPLL, is a 9-voice FM synthesissound chip manufactured by Yamaha Corporation. It is related to Yamaha's OPL family of FM synthesis chips, being a cost-reduced version of the YM3812 (OPL2). It has nine concurrent FM channels with two operators per channel, and features a percussion mode (or rhythm mode) that turns the last three channels into percussion/rhythm channels to produce 5 percussion/rhythm sounds.

The YM2413 was used in many devices, including:

• the FM Sound Unit add-on for the Sega Mark III sold exclusively in Japan, that improved the sound quality of all compatible games. The Japanese model of the Master System came with this add-on built-in;
• an arcade board design produced by SNK and Alpha Denshi in the late 1980s for a number of their games, including Time Soldiers, Sky Soldiers, and Gang Wars;
• the Atari GamesRampart arcade game;
• the Yamaha PSS-170 and PSS-270 keyboards in 1986;
• the Yamaha SHS-10 shoulder keyboard in 1987, and the Yamaha PSS-140 and Yamaha SHS-200 in 1988;
• the Yamaha PSR-6 keyboard in 1988;
• several sound enhancement cartridges for MSX computers. It is also built into select MSX2 and MSX2+ systems, and all MSX Turbo R machines, as part of the MSX-Music standard; and
• JTES Japanese teletext receivers.