The Yamaha YMF278B, also known as the OPL4 (OPL is an

acronym An acronym is a word or name formed from the initial components of a longer name or phrase. Acronyms are usually formed from the initial letters of words, as in ''NATO'' (''North Atlantic Treaty Organization''), but sometimes use syllables, as ...

for ''FM Operator Type-L''), is a

sound chip A sound chip is an integrated circuit (chip) designed to produce audio signals through digital, analog or mixed-mode electronics. Sound chips are typically fabricated on metal–oxide–semiconductor (MOS) mixed-signal chips that process ...

that incorporates both

FM synthesis Frequency modulation synthesis (or FM synthesis) is a form of sound synthesis whereby the frequency of a waveform is changed by modulating its frequency with a modulator. The frequency of an oscillator is altered "in accordance with the amplitud ...

and

sample-based synthesis Sample-based synthesis is a form of audio synthesis that can be contrasted to either subtractive synthesis or additive synthesis. The principal difference with sample-based synthesis is that the seed waveforms are sampled sounds or instruments ...

(often incorrectly called "

wavetable synthesis Wavetable synthesis is a sound synthesis technique used to create quasi-periodic waveforms often used in the production of musical tones or notes. Development Wavetable synthesis was invented by Max Mathews in 1958 as part of MUSIC II. ...

") by

Yamaha Yamaha may refer to: * Yamaha Corporation, a Japanese company with a wide range of products and services, established in 1887. The company is the largest shareholder of Yamaha Motor Company (below). ** Yamaha Music Foundation, an organization estab ...

Sample-based synthesis component

The sample synthesis part is based on

pulse-code modulation Pulse-code modulation (PCM) is a method used to digitally represent sampled analog signals. It is the standard form of digital audio in computers, compact discs, digital telephony and other digital audio applications. In a PCM Stream (comp ...

(PCM). It features: * Up to 24 simultaneous sounds (voices) * Output sampling frequency of 44.1 kHz (it can also accept 22.05-kHz samples – they are up-sampled to 44.1 kHz before output) * Waveform data lengths of 8, 12, or 16

bit The bit is the most basic unit of information in computing and digital communications. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represente ...

s * Stereo output (with a 4-bit/16-level pan for each voice) The PCM synthesizer part accepts: * Up to 4 MB of external memory for wave data * Up to 512 samples * External

ROM Rom, or ROM may refer to: Biomechanics and medicine * Risk of mortality, a medical classification to estimate the likelihood of death for a patient * Rupture of membranes, a term used during pregnancy to describe a rupture of the amniotic sac * ...

or SRAM memory. If SRAM is connected, then wave data can be downloaded from the OPL4. * Chip select signals for 128 KB, 512 KB, 1 MB, or 2 MB memory can be output.

Frequency modulation synthesis component

The FM part is essentially a ''

YMF262 The OPL (FM Operator Type-L) 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. Internal operation The internal operatio ...

'' (OPL3) block; thus, it is also backwards-compatible with the '' YM3526'' (OPL) and the '' YM3812'' (OPL2). Like the OPL3, it can operate in one of four ways: * 18 two-operator FM channels * 6 four-operator FM channels + 6 two-operator FM channels * 15 two-operator FM channels + 5 FM drums * 6 four-operator FM channels + 3 two-operator FM channels + 5 FM drums Four-operator FM allows more complex sounds but reduces polyphony. Eight waveforms are available for the FM synthesis: * simple sine * half sine * absolute sine * quarter sine (pseudo-sawtooth) * alternating sine * "camel" sine * square * logarithmic sawtooth Unlike the OPL3, which has four channels for sound output, the OPL4 features six channels.

Connectivity

For ROM wave data access, the Yamaha YRW801 2MB ROM chip can be connected to the OPL4. It holds approximately 330 samples, mostly 22.05-kHz 12-bit samples with some drums at 44.1 kHz. It is compatible with the

General MIDI General MIDI (also known as GM or GM 1) is a standardized specification for electronic musical instruments that respond to MIDI messages. GM was developed by the American MIDI Manufacturers Association (MMA) and the Japan MIDI Standards Committe ...

standard (128 melody sounds, 47 percussion sounds). For sound effects, the OPL4 can be connected to the Yamaha YSS225 effects processor (EP), which adds various sound effects. Like all its predecessors, the OPL4 outputs audio in digital-I/O form, thus requiring an external DAC chip. For this purpose, the Yamaha YAC513 DAC was designed.

Variants

YMW258-F (Sega MultiPCM)

A stripped-down version of the ''YMF278B'' (removing the FM synthesis section) was built for Sega as the MultiPCM. Yamaha internally identifies the chip as the YMW258-F, also known as the GEW8, or FA1005, whereas Sega uses the part number 315-5560. This version of the chip was used in conjunction with the YM3438 which provided sound timer controls. The YMW258-F is capable of producing up to 28 channels of both FM synthesis and Advanced Wave Memory (AWM) sampling. It supports sampling rates up to 44.1 kHz and supports 16-bit audio.

Applications

The ''YMF278B'' was used in the

Moonsound Moonsound is the name of a sound card released for the MSX home-computer system at the Tilburg Computer Fair in 1995. It was designed by electronic engineer Henrik Gilvad and produced by Sunrise Swiss on a semi-hobby basis. It arrived after the U ...

MSX

sound card A sound card (also known as an audio 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 ...

and in Yamaha's SoundEdge sound card for IBM PC and compatibles. As with the YMW258-F, it is used in various Yamaha

electronic musical instruments Electronic may refer to: *Electronics, the science of how to control electric energy in semiconductor * ''Electronics'' (magazine), a defunct American trade journal * Electronic storage, the storage of data using an electronic device * Electronic ...

, including the Yamaha MU5 and TG-100

sound modules A sound module is an electronic musical instrument without a human-playable interface such as a piano-style musical keyboard. Sound modules have to be operated using an externally connected device, which is often a MIDI controller, of which the ...

, Yamaha Portasound

electronic keyboards An electronic keyboard, portable keyboard, or digital keyboard is an electronic musical instrument, an electronic derivative of keyboard instruments. Electronic keyboards include synthesizers, digital pianos, stage pianos, electronic organs ...

(PSS-51, PSR-200, PSR-210, PSR-215, PSR-300, PSR-310, PSR-400, PSR-410, PSR-500, PSR-510 and PSR-600), QR-10 music accompaniment player, and QY-20

music workstation A music workstation is an electronic musical instrument providing the facilities of: *a sound module, *a music sequencer and *(usually) a musical keyboard. It enables a musician to compose electronic music using just one piece of equipment. Origi ...

References

OPL4 YMF278B Application Manual

External links

Yamaha SoundEdge Owner's Manual
{{Yamaha soundchips YMF278