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The OPL (FM Operator Type-L) series are a family of
sound chips 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 a ...
developed 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 ...
. The OPL series are low-cost sound chips providing
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 amplitude ...
for use in computing, music and video game applications.


Internal operation

The internal operation of the chips is completely digital. Each FM-tone is generated by a digital oscillator using a form of
direct digital synthesis Direct digital synthesis (DDS) is a method employed by frequency synthesizers used for creating arbitrary waveforms from a single, fixed-frequency reference clock. DDS is used in applications such as signal generation, local oscillators in communic ...
. A
low-frequency oscillator Low-frequency oscillation (LFO) is an electronic frequency that is usually below 20  Hz and creates a rhythmic pulse or sweep. This is used to modulate musical equipment such as synthesizers to create audio effects such as vibrato, tremol ...
and an
envelope generator In sound and music, an envelope describes how a sound changes over time. It may relate to elements such as amplitude (volume), frequencies (with the use of filters) or pitch. For example, a piano key, when struck and held, creates a near-im ...
drive an FM operator to produce floating-point output for the DAC. Decapsulation of the chips shows two look-up tables, one for calculating exponents and one for log-sine. This allows the FM operator to calculate its output without any multipliers, using the formula \exp log_\sin[\varphi_2_+_\exp_[\log_\sin_[\varphi_1+_A_1.html" ;"title="varphi_2_+_\exp_[\log_\sin_[\varphi_1.html" ;"title="log \sin[\varphi_2 + \exp [\log \sin [\varphi_1">log \sin[\varphi_2 + \exp [\log \sin [\varphi_1+ A_1">varphi_2_+_\exp_[\log_\sin_[\varphi_1.html" ;"title="log \sin[\varphi_2 + \exp [\log \sin [\varphi_1">log \sin[\varphi_2 + \exp [\log \sin [\varphi_1+ A_1 + A_2] and two 256-entry look-up tables. Both tables are stored as pairs of values rounded to the nearest whole number, with the second value represented as the difference between it and the first value. A quarter of the log-transformed sine waveform is stored as a sampled approximation in a 256-
word A word is a basic element of language that carries an semantics, objective or pragmatics, practical semantics, meaning, can be used on its own, and is uninterruptible. Despite the fact that language speakers often have an intuitive grasp of w ...
read-only memory Read-only memory (ROM) is a type of non-volatile memory used in computers and other electronic devices. Data stored in ROM cannot be electronically modified after the manufacture of the memory device. Read-only memory is useful for storing sof ...
(ROM) table, computed by 256\times -\log_2 \left(\sin\left(\frac\right)\right) for values of 0 to 255. The rest of the sine-waveform is extrapolated via its property of symmetry. Scaling the output of an oscillator to a wanted volume would normally be done by multiplication, but the YM3526 avoids multiplications by operating on log-transformed signals, which reduces multiplications into computationally cheaper additions. Another 256-word ROM stores the
exponential function The exponential function is a mathematical function denoted by f(x)=\exp(x) or e^x (where the argument is written as an exponent). Unless otherwise specified, the term generally refers to the positive-valued function of a real variable, a ...
as a lookup table, used to convert the logarithmic scale signal back to linear scale when required, as the final stage where the oscillator-outputs are summed together (just prior to the DAC-output bus), with the modulator waveform always delayed by one sample before the carrier waveform. This table is computed by \left(\frac-1\right)\times 1024 for values of 0 to 255. To compute the exponent, 1024 is added to the value at the index given by the
least significant byte In computing, bit numbering is the convention used to identify the bit positions in a binary number. Bit significance and indexing In computing, the least significant bit (LSB) is the bit position in a binary integer representing the binar ...
of input; this becomes the significand and the remaining bits of input become the exponent of the floating point output.


Chips in the series


OPL

The YM3526, introduced in 1984, was the first in the OPL family, providing a nine channel, two operator synthesizer. A very closely related chip is the Y8950, or ''MSX-AUDIO'', which was used as an MSX expansion. It is essentially a YM3526 with
ADPCM Adaptive differential pulse-code modulation (ADPCM) is a variant of differential pulse-code modulation (DPCM) that varies the size of the quantization step, to allow further reduction of the required data bandwidth for a given signal-to-noise ratio ...
recording and playback capability. The circuit has 244 different
write-only register In information technology, a write-only memory (WOM) is a memory location or register that can be written to but not read. In addition to its literal meaning, the term may be applied to a situation when the data written by one circuit can be read o ...
s. It can produce 9 channels of sound, each made of two oscillators or 6 channels with 5 percussion instruments available. Each oscillator can produce
sine wave A sine wave, sinusoidal wave, or just sinusoid is a curve, mathematical curve defined in terms of the ''sine'' trigonometric function, of which it is the graph of a function, graph. It is a type of continuous wave and also a Smoothness, smooth p ...
s and has its own
ADSR envelope generator In sound and music, an envelope describes how a sound changes over time. It may relate to elements such as amplitude (volume), frequencies (with the use of filters) or pitch. For example, a piano key, when struck and held, creates a near-immedi ...
. Its main method of synthesis is
frequency modulation 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 amplitude ...
, accomplished via
phase modulation Phase modulation (PM) is a modulation pattern for conditioning communication signals for transmission. It encodes a message signal as variations in the instantaneous phase of a carrier wave. Phase modulation is one of the two principal forms ...
of the phase of one channel's oscillators by the output of another. The YM3526's output, a sequence of
floating point In computing, floating-point arithmetic (FP) is arithmetic that represents real numbers approximately, using an integer with a fixed precision, called the significand, scaled by an integer exponent of a fixed base. For example, 12.345 can be ...
numbers clocked at a sampling frequency of approximately 49716 Hz, is sent to a separate
digital-to-analog converter In electronics, a digital-to-analog converter (DAC, D/A, D2A, or D-to-A) is a system that converts a digital signal into an analog signal. An analog-to-digital converter (ADC) performs the reverse function. There are several DAC architec ...
(DAC) chip, the YM3014B. Overview of a channel's registers: For the whole channel: * Main frequency (10 bits) * Octave (3 bits) * Note on/off * Synthesis mode (FM or just additive) * Feedback (0–7, the modulator modulating itself) For each one of the two oscillators: * Frequency multiply (can be set to , 1 to 10, 12 or 15) * Waveform (Sine) * Volume (0–63, logarithmic) * Attack, decay, sustain, release (4 bits each, logarithmic) *
Tremolo In music, ''tremolo'' (), or ''tremolando'' (), is a trembling effect. There are two types of tremolo. The first is a rapid reiteration: * Of a single Musical note, note, particularly used on String instrument#Bowing, bowed string instrument ...
(on or off) *
Vibrato Vibrato (Italian language, Italian, from past participle of "wikt:vibrare, vibrare", to vibrate) is a musical effect consisting of a regular, pulsating change of pitch (music), pitch. It is used to add expression to vocal and instrumental music. ...
(on or off) * Sustain (on or off) * Envelope scaling per key (on or off) * Volume scaling per key (0–3) There are also a few parameters that can be set for the whole chip: * Vibrato depth * Tremolo depth * Percussion mode (uses 3 channels to provide 5 percussion sounds) * Composite sine mode (see
Sinewave synthesis Sinewave synthesis, or sine wave speech, is a technique for synthesizing speech by replacing the formants (main bands of energy) with pure tone whistles. The first sinewave synthesis program (''SWS'') for the automatic creation of stimuli for perce ...
)


OPL2

In 1985, Yamaha created the YM3812, also known as the OPL2. It is backwards compatible with the YM3526. Another related chip is the
YM2413 The YM2413, a.k.a. 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 th ...
(OPLL), which is a cut down version. Yamaha YM3812.jpg, Yamaha YM3812 (OPL2 chip) YM3812 sticker overlay.jpg, Creative Labs and other companies often hid the original Yamaha labels YM3812-F.jpg, Yamaha YM3812-F SMD (surface mount OPL2 chip) Yamaha YM3812 audio IC decapsulated.jpg, Decapsulated YM3812, showing the
die Die, as a verb, refers to death, the cessation of life. Die may also refer to: Games * Die, singular of dice, small throwable objects used for producing random numbers Manufacturing * Die (integrated circuit), a rectangular piece of a semicondu ...
surface
Among its newly-added features is the ability to pick between four waveforms for each individual oscillator by setting a register. In addition to the original sine wave, three modified waveforms can be produced: half-sine waves (where the negative part of the sine is muted), absolute-sine waves (where the negative part is inverted), and pseudo-sawtooth waves (quarter sine waves upward only with silent sections in between). This odd way of producing waveforms give the YM3812 a characteristic sound. The YM3812 is used with the YM3014B external DAC chip to output its audio in analog form, like with the YM3526.


OPL3

YMF262-M.jpg, Yamaha YMF262 (OPL3 chip, manuf. year 1994) Yamaha YMF262 audio IC decapsulated.jpg, Decapsulated YMF262, showing the die surface An upgraded version of the OPL2, the YMF262 (a.k.a. OPL3), was released in 1988. It improved upon the feature-set of the YM3812, adding the following features: * twice as many channels (18 instead of 9) * simple stereo (hard left, center or hard right) * 4 channel sound output * 4 new waveforms (alternating-sine, "camel"-sine, square and logarithmic sawtooth) * 4 operator mode, pairing 2 channels together to create up to six 4 operator FM voices * reduced latency for host-register access (the OPL2 had much longer I/O access delays) * subtle differences in the sine-wave lookup table and envelope generator to YM3812 (e.g. the modulator waveform on YM3812 is delayed by one sample, whereas both carrier and modulator waveforms on OPL3 are properly synchronized) The YMF262 also removed support for the little-used CSM (Composite sine mode) mode, featured on the YM3812 and YM3526. The YMF262's FM synthesis mode can be configured in many different ways: * Its basic mode provides 18 two-operator FM channels. * One setting, common with the rest of the OPL line, converts 3 of the FM channels into a 5-channel percussion set. * Another setting, introduced with this chip, causes 12 of the channels to be paired up into six four-operator channels. This trades in polyphony for more complex sound formation. * These two settings above can be used separately or in conjunction, resulting in four total modes: ** 18 2-operator channels ** 15 2-operator channels + 5 drum channels (drum setting on) ** 6 2-operator channels + 6 4-operator channels (4-op setting on) ** 3 2-operator channels + 6 4-operator channels + 5 drum channels (both settings on) Like its predecessors, the OPL3 outputs audio in digital-I/O form, requiring an external DAC chip such as the YAC512. Competing sound chip vendors (such as ESS, OPTi, Crystal and others) designed their own OPL3-compatible audio chips, with varying degrees of faithfulness to the original OPL3.


Yamaha YMF289

Yamaha also produced a fully compatible, low-power variant of the YMF262 in 1995 called the YMF289 (OPL3-L), which targeted
PCMCIA The Personal Computer Memory Card International Association (PCMCIA) was a group of computer hardware manufacturers, operating under that name from 1989 to 2009. Starting with the PCMCIA card in 1990 (the name later simplified to ''PC Card''), i ...
sound cards and laptop computers. It was used in some
Sound Blaster 16 The Sound Blaster 16 is a series of sound cards by Creative Technology. They are add-on boards for IBM PC compatible, PCs with an industry standard architecture, ISA or conventional PCI, PCI slot. Sound Blaster 16 Sound Blaster 16 (June 1992 ...
sound cards made by
Creative Technology Creative Technology Ltd. is a Singaporean multinational technology company headquartered with overseas offices in Shanghai, Tokyo, Dublin, and Silicon Valley (where in the US it is known as Creative Labs). The principal activities of the compa ...
. The YMF289B is paired with a YAC513 or YAC516 companion floating-point DAC chip. The YMF289 is fully register-compatible with and retains the feature-set of the YMF262, with a number of differences: * Supports 5 or 3.3 volt operation. * The registers can be read or written by the host CPU, whereas on the YMF262 they are write-only. * 44,100 Hz (44.1 kHz) output sample rate. * A power-down mode is added. * Somewhat smaller overall footprint, including DAC, compared to a full YMF262 implementation. * 33.868 MHz input clock, compared to the 14.32 MHz input clock used for the YMF262. * Internal linear interpolator. YMF289_and_YAC516.jpg, Yamaha YMF289B and companion YAC516 DAC


ESS ESFM

ESS Technology ESS Technology Incorporated is a private manufacturer of computer multimedia products, Audio DACs and ADCs based in Fremont, California with R&D centers in Kelowna, BC, Canada and Beijing, China. It was founded by Forrest Mozer in 1983. Robe ...
's in-house developed derivative, termed ''ESFM'', is an enhanced, 20-voice, 72-operator, OPL3-compatible clone incorporating two operating modes, a Native mode and a Legacy mode, which controls its feature-set and behavior. In Native mode, ESFM allows more than six 4-operator FM voices to be mapped, potentially allowing for a significant increase in the complexity of tones generated. The drivers for Windows 9x incorporate their own custom instrument patches which make use of this extended mode. Conversely, Legacy mode provides full backward-compatibility with Yamaha's YMF262. ESFM's output in this mode is moderately faithful to the YMF262 overall, but some tones are rendered quite differently, resulting in unique distortions in the sound and music of some games. ESFM is available in ESS sound chips starting with the ISA-based ES1688 AudioDrive, up to the PCI-based ES1946 Solo-1E, whereas earlier chips required an external FM synthesizer chip (typically a Yamaha YMF262). ESS's Maestro series of PCI-based sound chips rely on a software implementation of FM synthesis that lacks ESFM's special features. Compaq ES 1869 Audio Feature Board - Model X071 - ESS Technology ES1869F-0312.jpg, The ES1869F is one of several ESS-developed sound chips which incorporate their unique ESFM function.


OPL3-SA, DS-XG, OPL4

Yamaha's later PC audio controllers, including the
YMF278 The Yamaha YMF278B, also known as the OPL4 (OPL is an acronym for ''FM Operator Type-L''), is a sound chip that incorporates both frequency modulation synthesis, FM synthesis and sample-based synthesis (often incorrectly called "wavetable synthesis" ...
(OPL4), the single-chip Yamaha YMF718/719S, and the PCI YMF724/74x family, included the YMF262's FM synthesis block for backward compatibility with legacy software. See
YMF7xx There have been various families of Yamaha audio controllers labelled as YMF7xx. OPL3-SA families *YMF701 (OPL3-SA): Incorporates OPL3 and OPL3-L features, 16-bit stereo CODEC, MPU-401-compatible MIDI interface, game port, Plug and Play ISA inter ...
for more information. Toshiba Satellite 220CS - motherboard FVNSS2 - Yamaha OPL YMF715B-S-3548.jpg, Yamaha OPL YMF715B-S chipset


Products using the OPL series

The YM3526 was notably used in a
Commodore 64 The Commodore 64, also known as the C64, is an 8-bit home computer introduced in January 1982 by Commodore International (first shown at the Consumer Electronics Show, January 7–10, 1982, in Las Vegas). It has been listed in the Guinness ...
expansion, the ''Sound Expander'', as well as several
arcade game An arcade game or coin-op game is a coin-operated entertainment machine typically installed in public businesses such as restaurants, bars and amusement arcades. Most arcade games are presented as primarily games of skill and include arcade v ...
s, such as ''
Terra Cresta is a vertically scrolling shooter arcade video game released by Nichibutsu in 1985. The player controls a flying craft to destroy the Mandler army before they destroy all of humanity. Gameplay involves shooting enemies and collecting different ...
'' and ''
Bubble Bobble is a 1986 platform video game, platform arcade game developed and published by Taito. It was distributed in the United States by Romstar, and in Europe by Electrocoin. Players control Bub and Bob, two dragons that set out to save their girlfrien ...
''. The YM3812 saw wide use in
IBM PC The IBM Personal Computer (model 5150, commonly known as the IBM PC) is the first microcomputer released in the IBM PC model line and the basis for the IBM PC compatible de facto standard. Released on August 12, 1981, it was created by a team ...
-based
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 i ...
s such as the
AdLib Ad Lib, Inc. was a Canadian manufacturer of sound cards and other computer equipment founded by Martin Prevel, a former professor of music and vice-dean of the music department at the Université Laval. The company's best known product, the ''Ad ...
,
Sound Blaster Sound Blaster is a family of sound cards designed by Singaporean technology company Creative Technology (known in the US as Creative Labs). Sound Blaster sound cards were the de facto standard for consumer audio on the IBM PC compatible system pl ...
and Pro AudioSpectrum (8bit), as well as several arcade games by
Nichibutsu was a Japanese video game developer and publisher headquartered in Kita, Osaka. In the past they had also manufactured and sold yachts. The main video game brand of the company was Nichibutsu (日物、ニチブツ), with adult video games (ma ...
,
Toaplan was a Japanese video game developer based in Tokyo responsible for the creation of a wide array of Shoot 'em up#Scrolling shooters, scrolling shooters and other arcade games. The company was founded in 1979 but its gaming division was establis ...
and others. The YM2413 was used in the FM Sound Unit expansion for the Sega Mark III and the Japanese model
Sega Master System The is an 8-bit third-generation home video game console manufactured by Sega. It was originally a remodeled export version of the Sega Mark III, the third iteration of the SG-1000 series of consoles, which was released in Japan in 1985 and ...
, as well as various MSX sound enhancement cards. The YMF262 was used in many IBM PC-based
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 i ...
s, including the popular Sound Blaster Pro 2 and Sound Blaster 16 ASP, as well as the Pro AudioSpectrum (16bit). Later models of the Sound Blaster 16 and Sound Blaster AWE series integrated the OPL3 with other chips, with Creative Labs using an OPL3 clone chip, the CQM, integral with other chips in later models from late 1995. It is also used in several arcade games by
Tecmo , was a Japanese video game corporation founded in 1967. It had its headquarters in Kudankita, Chiyoda, Tokyo, Chiyoda, Tokyo. Its subsidiary, Tecmo Inc, was located in Torrance, California. Tecmo was formerly known as Tehkan. Tecmo is known for ...
. The YMF278 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 ...
card for the MSX, as well as the SoundEdge card by Yamaha for IBM PC compatibles.


Synthesizers

Synthesizers that use the YM3812: * Yamaha PSR-11 49-keys 16-sounds (1986) * Yamaha PSR-12 49-keys 32-sounds (1987) * Yamaha PSR-21 49-keys 16-sounds, 2 steps sliders (1986) * Yamaha PSR-22 49-keys 32-sounds, 2 steps sliders (1987) * Yamaha PSR-31 61-keys 16-sounds, additional YM3301 chip for drums (1991) * Yamaha PSR-32 61-keys 32-sounds, additional YM3301 chip for drums (1987) * Yamaha PSS-360 49 mini-keys 21-sounds, 5 steps sliders, low-cost mono version of PSS-460 (1986) * Yamaha PSS-460 49 mini-keys 21-sounds, 5 steps sliders (1986) * Yamaha PSS-470 49 mini-keys 21-sounds, 5 steps sliders (1987) * Yamaha PSS-560 49 mini-keys 21-sounds, 5 steps sliders, additional YM3301 chip for drums (1986) * Yamaha PSS-570 49 mini-keys 21-sounds, 5 steps sliders, additional YM3301 chip for drums (1987) Synthesizers that use the YM2413 (cost reduced YM3812): * Yamaha PSR-6 49-keys 100-sounds (1994) * Yamaha PSS-140 37 mini-keys 100-sounds (1988) * Yamaha PSS-170 44 mini-keys 100-sounds (1986) * Yamaha PSS-270 49 mini-keys 100-sounds (1986)


Variants and derivatives

An
open-source Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use the source code, design documents, or content of the product. The open-source model is a decentralized sof ...
RTL implementation of the OPL3 was written in
SystemVerilog SystemVerilog, standardized as IEEE 1800, is a hardware description and hardware verification language used to model, design, simulate, test and implement electronic systems. SystemVerilog is based on Verilog and some extensions, and since 200 ...
and adapted to an
FPGA A field-programmable gate array (FPGA) is an integrated circuit designed to be configured by a customer or a designer after manufacturinghence the term '' field-programmable''. The FPGA configuration is generally specified using a hardware de ...
in 2015.


See also

*
List of sound chips Sound chips come in different forms and use a variety of techniques to generate audio signals. This is a list of sound chips that were produced by a certain company or manufacturer, categorized by the sound generation of the chips. Programmable sou ...
*
List of Yamaha products This is a list of products made by Yamaha Corporation. This does not include products made by Bösendorfer, which has been a wholly owned subsidiary of Yamaha Corporation since February 1, 2008. For products made by Yamaha Motor Company, see the ...
* Yamaha Y8950 *
Yamaha YM2413 The YM2413, a.k.a. 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 t ...
*
Yamaha YMF278 The Yamaha YMF278B, also known as the OPL4 (OPL is an acronym for ''FM Operator Type-L''), is a sound chip that incorporates both FM synthesis and sample-based synthesis (often incorrectly called "wavetable synthesis") by Yamaha. Sample-based synth ...


References


External links

* http://www.oplx.com/ OPL series programming info
MIDIbox FM
a YMF262-based DIY synthesizer
AdlibTracker.net
Adlib Tracker II (YMF262-Tracker)
RAD
Reality Adlib Tracker (YMF262-Tracker) * A
YMF262 emulator
with an online player for OPL3 music.
OPLx decapsulated (a reverse engineering report)

OPL3_FPGA GitHub
Reverse engineered OPL3 in an FPGA
Analysis of the OPL3 math
{{Yamaha soundchips Computer-related introductions in 1985
YM3812 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 operation ...
YM3526
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 ...
Sound chips Video game music technology