The Yamaha YM2413B is a variant of the YM2413 FM synthesis sound chip (also known as OPLL - FM Operator Type-LL), produced by Yamaha. Like the original YM2413, it was primarily utilized in 8-bit and 16-bit computers (especially the MSX), consoles, and arcade machines during the late 1980s and early 1990s to generate music and sound effects. It's a cost-effective and simplified alternative to the more complex YM3812 (OPL2) chip.

Applications

• MSX Computers: The YM2413B, like its predecessor, was a standard sound chip in many MSX home computers.
• Arcade Games: It found its way into some arcade game boards for generating both music and sound effects.
• Electronic Keyboards: Used in some budget-friendly electronic keyboards for sound generation.
• Sound Cards (Early): In some instances, it was used on early PC sound cards, providing basic FM synthesis capability.

Features

• FM Synthesis: Generates sounds through frequency modulation (FM).
• 9 Channels: Offers nine simultaneous melodic channels for creating polyphonic music.
• Preset Instruments: Includes a collection of pre-programmed instrument sounds (typically 15), like piano, organ, guitar, etc.
• Custom Instrument Programming: Allows users to define their own instrument sounds by tweaking FM parameters.
• Low Power: Designed for use in systems with limited power resources, including battery-operated devices.
• Simplified Interface: Relatively easy to integrate with microprocessors and other digital circuits, making it accessible for developers.

Benefits

• Improved Audio: Enhances the audio output compared to basic tone generators, offering richer and more complex sounds.
• Sound Versatility: Provides a wide range of sound possibilities, from instrument emulations to synthesized sound effects.
• Cost-Effective: Its low cost allowed for the wider adoption of FM synthesis in consumer electronic devices.
• Easy Programming: Simpler to program and use compared to more elaborate sound chips with more operators.
• Nostalgia Factor: Remains popular due to its association with the sounds of classic video games and computer music.

The “B” suffix indicates a revision or slightly modified version of the original YM2413. There are often subtle differences in the manufacturing process, and potentially some improvements in the signal to noise ratio. The YM2413B employs a 2-operator FM synthesis engine, which is less complex than the OPL2 (YM3812) and OPL3 (YMF262) chips, leading to a simpler programming model but also limiting the complexity of sounds it can create. However, the chip still allowed for the creation of remarkably diverse and interesting music, and remains popular with retro-computing enthusiasts.