Yamaha YM2612

Last updated
Yamaha YM2612 Yamaha YM2612 chip.jpg
Yamaha YM2612

The YM2612, a.k.a. OPN2, is a sound chip developed by Yamaha. It is a member of Yamaha's OPN family of FM synthesis chips, and is derived from the YM2203. [1]

Contents

The YM2612 is a six-channel FM synthesizer used in several game and computer systems, most notably in Sega's Mega Drive/Genesis video game console [2] as well as Fujitsu's FM Towns computer series. [3]

As with the YM3438, it was used by Sega in later models of the Mega Drive/Genesis (integrated into an ASIC) as well as in various arcade game systems, including the Mega-Play and Sega System 32.

Features

The YM2612 has the following features: [1]

Technical details

The YM2612's FM synthesis block is an extended version of the FM block featured in the YM2203, adding three FM channels and integrating a stereo output DAC. [1] The YM2612 removes the SSG component (although retaining its envelope generators) and I/O ports found in the YM2203, YM2608 and YM2610. [1] It was also available in CMOS form as the YM3438, a.k.a. OPN2C. [1] The YM2612 was also often erroneously referred to as being based on the YM2608 due to its similarities to the latter, only lacking the latter's ADPCM channels among other aforementioned changes.

Whereas the high-end OPN chips such as the YM2608 have dedicated ADPCM channels for playing sampled audio, the YM2612 does not. However, its sixth channel can act as a basic PCM channel by means of the 'DAC Enable' register, disabling FM output for that channel but allowing it to play 8-bit pulse-code modulation sound samples. [1] Unlike the other OPNs with ADPCM, the YM2612 does not provide any timing or buffering of samples, so all frequency control and buffering must be done in software by the host processor. [2]

Low volume distortion of the built-in DAC

An example (from the Mega Drive game Beyond Oasis ) of low volume distortion created by the peculiar qualities of the YM2612's built-in DAC
In some cases, this low volume distortion can affect the loudness, and to some degree the timbres, of certain sounds. This sample is from the Mega Drive game Streets of Rage 2 .

Unlike most Yamaha FM chips which require an external floating-point DAC, the YM2612 features a built-in 9-bit DAC, which uses time-division multiplexing to play one sample of each channel in sequence, similar to the YM2413.

Due to an error with the amplitude voltage in the original chip design, a peculiar form of crossover distortion known as low volume distortion (and historically known as the "ladder effect" or "TDM distortion") is introduced in the output. Any output that is sufficiently low in volume undergoes an exaggerated quantization, including any usage of fades in video game music. Some early Mega Drive/Genesis games such as After Burner II had their music written around this distortion, and as a result, the music sounds too quiet on later Mega Drive/Genesis consoles that uses the integrated YM3438 chip on the ASIC. Also, because of the reduced dynamic range of the built-in DAC, additional distortion may be generated when playing sounds with a very high volume. [1]

In recent years, the low volume distortion bug in the YM2612 has been successfully emulated in software and has been implemented as a feature in many Mega Drive/Genesis emulators since. Other YM2612 variants that have fixed the low volume distortion bug such as the YM3438 are also emulated and have been implemented in many Mega Drive/Genesis emulators as well.

Variants

Yamaha YM3438

The YM3438, [1] a.k.a. OPN2C, is a modified CMOS version of the YM2612, commonly used in Sega's arcade system boards. This version has an improved built-in DAC that fixed the low volume distortion bug that was present in the YM2612 while also improving the dynamic range of the DAC to prevent clipping at very high volumes. It is not a direct, drop-in replacement for the YM2612 however, as the sound outputs have higher impedance.

Yamaha YMF276

The YMF276, [5] a.k.a. OPN2L, is a low-power version of the YM3438, used in the Fujitsu FM Towns II. It came in a smaller 24-pin SOP package. Unlike the YM2612 and YM3438, the YMF276 requires an external DAC chip like most other Yamaha FM chips. The YM3433 external DAC chip was made specifically for the YMF276.

Sega Mega Drive/Genesis ASICs made by Yamaha (FC1004, FF1004, FJ3002 and FQ8007)

The YM3438 core was integrated in custom ASICs [6] used in the final revision of the Model 1 version and most revisions of the Model 2 version of the Sega Mega Drive/Genesis, as well as the Genesis 3 released by Majesco.

Game audio

Used in conjunction with the Texas Instruments SN76489 PSG as the main sound generators of the Sega Mega Drive/Genesis console, the YM2612 was prominently utilized by numerous prolific video game music composers, most notably Yuzo Koshiro. [4] [7]

See also

Related Research Articles

<span class="mw-page-title-main">Sound card</span> Expansion card that provides input and output of audio signals

A sound card is an internal expansion card that provides input and output of audio signals to and from a computer under the control of computer programs. The term sound card is also applied to external audio interfaces used for professional audio applications.

<span class="mw-page-title-main">Sound Blaster</span> Family of sound cards by Creative Technology

Sound Blaster is a family of sound cards and audio peripherals designed by Singaporean technology company Creative Technology. The first Sound Blaster card was introduced in 1989.

<span class="mw-page-title-main">Texas Instruments SN76489</span>

The SN76489 Digital Complex Sound Generator (DCSG) is a TTL-compatible programmable sound generator chip from Texas Instruments. Its main application was the generation of music and sound effects in game consoles, arcade video games, and home computers, competing with the similar General Instrument AY-3-8910.

<span class="mw-page-title-main">Yamaha DX7</span> Synthesizer

The Yamaha DX7 is a synthesizer manufactured by the Yamaha Corporation from 1983 to 1989. It was the first successful digital synthesizer and is one of the best-selling synthesizers in history, selling more than 200,000 units.

The digital sound revolution refers to the widespread adoption of digital audio technology in the computer industry beginning in the 1980s.

<span class="mw-page-title-main">Covox Speech Thing</span> External digital-to-analog audio converter

The Covox Speech Thing is an external digital-to-analog converter (DAC) that plugs into the parallel printer port of a PC. It converts 8-bit digital sound using a simple R-2R resistor ladder into an analog signal output.

<span class="mw-page-title-main">Yamaha YM2413</span> FM synthesis sound chip by Yamaha

The YM2413, a.k.a. OPLL, is a cost-reduced FM synthesis sound chip manufactured by Yamaha Corporation and based on their YM3812 (OPL2).

<span class="mw-page-title-main">General Instrument AY-3-8910</span> Sound generation IC

The AY-3-8910 is a 3-voice programmable sound generator (PSG) designed by General Instrument (GI) in 1978, initially for use with their 16-bit CP1610 or one of the PIC1650 series of 8-bit microcomputers. The AY-3-8910 and its variants were used in many arcade games—Konami's Gyruss contains five—and Bally pinball machines as well as being the sound chip in the Intellivision and Vectrex video game consoles, and the Amstrad CPC, Oric-1, Colour Genie, Elektor TV Games Computer, MSX, Tiki 100 and later ZX Spectrum home computers. It was also used in the Mockingboard and Cricket sound cards for the Apple II and the Speech/Sound Cartridge for the TRS-80 Color Computer.

OPN may stand for:

<span class="mw-page-title-main">Sound Blaster Live!</span>

Sound Blaster Live! is a PCI add-on sound card from Creative Technology Limited for PCs. Moving from ISA to PCI allowed the card to dispense with onboard memory, storing digital samples in the computer's main memory and then accessing them in real time over the bus. This allowed for a much wider selection of, and longer playing, samples. It also included higher quality sound output at all levels, quadrophonic output, and a new MIDI synthesizer with 64 sampled voices. The Live! was introduced on August 11, 1998 and variations on the design remained Creative's primary sound card line into the early 2000's.

<span class="mw-page-title-main">Yamaha YM2151</span>

The Yamaha YM2151, also known as OPM is an eight-channel, four-operator sound chip. It was Yamaha's first single-chip FM synthesis implementation, being created originally for some of the Yamaha DX series of keyboards. Yamaha also used it in some of their budget-priced electric pianos, such as the YPR-7, -8, and -9.

Music of the <i>Streets of Rage</i> series Video game discography

The music of the Streets of Rage series of beat 'em up games, released in the early 1990s, was primarily produced by Yuzo Koshiro.

A programmable sound generator (PSG) is a sound chip that generates audio wave signals built from one or more basic waveforms, and often some kind of noise. PSGs use a relatively simple method of creating sound compared to other methods such as frequency modulation synthesis or pulse-code modulation.

<span class="mw-page-title-main">Yamaha YM2203</span> Sound chip

The YM2203, a.k.a. OPN, is a six-channel sound chip developed by Yamaha. It was the progenitor of Yamaha's OPN family of FM synthesis chips used in many video game and computer systems throughout the 1980s and early 1990s. It was used in a variety of NEC computers, along with various arcade game machines.

<span class="mw-page-title-main">Yamaha YM2608</span>

The YM2608, a.k.a. OPNA, is a sound chip developed by Yamaha. It is a member of Yamaha's OPN family of FM synthesis chips, and is the successor to the YM2203. It was notably used in NEC's PC-8801/PC-9801 series computers.

<span class="mw-page-title-main">Yamaha YM2610</span> Sound chip developed by Yamaha

The YM2610, a.k.a. OPNB, is a sound chip developed by Yamaha. It is a member of Yamaha's OPN family of FM synthesis chips, and related to the YM2608.

<span class="mw-page-title-main">Yamaha YMF292</span>

The YMF292, aka SCSP is a multi-function sound chip developed by Yamaha for the Sega Saturn, and was also used in Sega's arcade version of the Saturn, the ST-V, along with the Model 2 and Model 3.

The Yamaha YMZ280B, also known as PCMD8, is a sound chip produced by Yamaha Corporation. It is an eight-channel PCM/ADPCM sample-based synthesizer designed for use with video game machines, packaged in a 64-pin QFP.

The OPL series are a family of sound chips developed by Yamaha. The OPL series are low-cost sound chips providing FM synthesis for use in computing, music and video game applications.

References

  1. 1 2 3 4 5 6 7 8 YM3438 Application Manual (Japanese)
  2. 1 2 Sega Genesis Technical Manual - YM2612 section (updated with errors corrected)
  3. Purcaru, Bogdan Ion (13 March 2014). Games vs. Hardware. The History of PC video games: The 80's. p. 527. Retrieved 14 December 2017.
  4. 1 2 "Super Sonic: Creating the new sound of Sega's hedgehog hit". TheGuardian.com . 13 February 2020.
  5. Undocumented Sound Chips - Yamaha YMF276
  6. Sega Genesis 2 / Sega Mega Drive II Service Manual
  7. "Sega Mega Drive Mini review – a legacy truly honoured". TheGuardian.com . 19 September 2019.