Yamaha YM2413

Yamaha YM2413

The YM2413, aka OPLL, is a cost-reduced FM synthesis sound chip manufactured by Yamaha Corporation and based on their YM3812 (OPL2). To make the chip cheaper to manufacture, many of the internal registers were removed. The result of this is that the YM2413 can only play one user-defined instrument at a time; the other 15 instrument settings are hard-coded and cannot be altered by the user. There were other cost-cutting modifications: the number of waveforms was reduced to two, and the channels are not mixed using an adder; instead, the chip's DAC uses time-division multiplexing to play short segments of each channel in sequence, as also done in the YM2612.

List of YM2413 Applications

• The YM2413 was used in the FM Sound Unit, an 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.
• The YM2413 was used in an arcade board design produced by SNK and Alpha Denshi in the late 1980s for a number of their games. Games using the design include Time Soldiers, Sky Soldiers, and Gang Wars.
• The YM2413 was used in the Yamaha PSS-170 and PSS-270 keyboards in 1986.
• The YM2413 was used in the Yamaha PSS-140 in 1988.
• The YM2413 was used in the Yamaha PSR-6 keyboard in 1994.
• The YM2413 was used in 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.^[1]

Variants and clones

• Konami's VRC7 MMC contains a YM2413 derivative, used exclusively on the Family Computer game Lagrange Point. It has 6 FM channels instead of 9 and lacks the rhythm channels. The hard-coded sound bank is also different.
• Yamaha YMF281 is another YM2413 derivative. It has the same pinout and register set, but a different sound bank.
• Yamaha YM2423 is yet another YM2413 derivative. Like the YMF281, it has the same pinout and register map, but a different sound bank.
• UMC U3567 is a 100% software compatible chip with a slightly different pinout, requiring a pin-to-pin adapter in order to be used on a YM2413 socket.
• UMC UM3567 is a 100% software compatible chip, with the same pinout as the U3567 but a slightly enhanced DAC output. It requires the same pin-to-pin adapter, but the different DAC output will also require the two pull-down resistors of the audio output pins to be removed from the motherboard.

References

External links

• MSX-Music
• d'Osvualdo, G. (2008), Luppes, E., Martin, C., Brychkov, E. (2013) "FM-Pak without SRAM". AGE Labs, 2013-12-29. Accessed on 2013-12-31.