The

MOS Technology MOS Technology, Inc. ("MOS" being short for Metal Oxide Semiconductor), later known as CSG (Commodore Semiconductor Group) and GMT Microelectronics, was a semiconductor design and fabrication company based in Audubon, Pennsylvania. It is ...

6581/8580 SID (Sound Interface Device) is the built-in

programmable sound generator A programmable sound generator (PSG) is a sound chip that generates (or synthesizes) 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 m ...

chip of the Commodore CBM-II,

Commodore 64 The Commodore 64, also known as the C64, is an 8-bit computing, 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 ...

Commodore 128 The Commodore 128, also known as the C128, is the last 8-bit home computer that was commercially released by Commodore Business Machines (CBM). Introduced in January 1985 at the CES in Las Vegas, it appeared three years after its predecessor, t ...

, and

MAX Machine MAX Machine (or simply MAX), also known as Ultimax in the United States and Canada and VC-10 in Germany, is a home computer designed and sold by Commodore International in Japan, beginning in November of 1982, a cousin to the popular Commodore 64 ...

home computer Home computers were a class of microcomputers that entered the market in 1977 and became common during the 1980s. They were marketed to consumers as affordable and accessible computers that, for the first time, were intended for the use of a s ...

s. Together with the VIC-II graphics chip, the SID was instrumental in making the C64 the best-selling home computer in history, and is partly credited for initiating the

demoscene The demoscene () is an international computer art subculture focused on producing demos: self-contained, sometimes extremely small, computer programs that produce audiovisual presentations. The purpose of a demo is to show off computer programmi ...

History

The SID was devised by engineer Bob Yannes, who later co-founded the

Ensoniq Ensoniq Corp. was an American electronics manufacturer, best known throughout the mid-1980s and 1990s for its musical instruments, principally Sampler (musical instrument), samplers and synthesizers. History In spring 1983, former MOS Technol ...

digital

synthesizer A synthesizer (also synthesiser or synth) is an electronic musical instrument that generates audio signals. Synthesizers typically create sounds by generating waveforms through methods including subtractive synthesis, additive synthesis a ...

and sampler company. Yannes headed a team that included himself, two technicians and a CAD operator, who designed and completed the chip in five months in the latter half of 1981. Yannes was inspired by previous work in the synthesizer industry and was not impressed by the current state of computer sound chips. Instead, he wanted a high-quality instrument chip, which is the reason why the SID has features like the

envelope generator In sound and music, an envelope describes how a sound changes over time. For example, a piano key, when struck and held, creates a near-immediate initial sound which gradually decreases in volume to zero. An envelope may relate to elements such ...

, previously not found in home computer sound chips. Emphasis during chip design was on high-precision frequency control, and the SID was originally designed to have 32 independent voices, sharing a common wavetable lookup scheme that would be time multiplexed. However, these features could not be finished in time, so instead the mask work for a certain working oscillator was simply replicated three times across the chip's surface, creating three voices each with its own oscillator. Another feature that was not incorporated in the final design was a frequency look-up table for the most common musical notes, a feature that was dropped because of space limitations. The support for an audio input pin was a feature Yannes added without asking, which in theory would have allowed the chip to be used as a simple effect processor. The masks were produced in 7- micrometer technology to gain a high yield; the state of the art at the time was 6-micrometer technologies. The chip, like the first product using it (the Commodore 64), was finished in time for the

Consumer Electronics Show CES (; formerly an initialism for Consumer Electronics Show) is an annual trade show organized by the Consumer Technology Association (CTA). Held in January at the Las Vegas Convention Center in Winchester, Nevada, United States, the event typi ...

in the first weekend of January 1982. Even though Yannes was partly displeased with the result, his colleague Charles Winterble said: "This thing is already 10 times better than anything out there and 20 times better than it needs to be." The specifications for the chip were not used as a blueprint. Rather, they were written as the development work progressed, and not all planned features made it into the final product. Yannes claims he had a feature-list of which three quarters made it into the final design. The later revision (8580) was revised to more closely match the specifications. For example, the 8580 slightly improved upon the ability to perform a binary AND between two waveforms, which the SID can only do in an odd and illogical manner that results in messy, and in some cases nearly silent, waveforms. Wave combinations on the 8580 result in cleaner waveforms than on the 6581, although irregularities are still present. Another feature that differs between the two revisions is the filter, as the 6581 version is far away from the specification.

Design

6581/6582/8580R5 Pin configuration The SID is a

mixed-signal integrated circuit A mixed-signal integrated circuit is any integrated circuit that has both analog circuits and digital circuits on a single semiconductor die.variable duty cycle), triangle wave, sawtooth wave, and pseudorandom noise (called

white noise In signal processing, white noise is a random signal having equal intensity at different frequencies, giving it a constant power spectral density. The term is used with this or similar meanings in many scientific and technical disciplines, i ...

in documentation). Multiple waveform types may be selected simultaneously, which produces certain complex/combined waveforms. The oscillators of each voice are built on a 24-bit phase accumulator. A voice playing a triangle waveform may be ring-modulated with one of the other voices, where the triangle waveform's bits are inverted when the MSB of the modulating voice's accumulator is set, producing a discontinuity and inversion of direction with the triangle's ramp. Voices may also be hard-synced to each other, where the synced voice's oscillator is reset whenever the MSB of the syncing voice's accumulator is increased. If both ring modulation and hard-sync are set to affect the same voice, the two effects are combined. The voice that ring modulates and/or syncs a given affected voice is determined by the following pattern: voice 1 affects voice 2, voice 2 affects voice 3, and voice 3 affects voice 1. Each voice may be routed into a common, digitally controlled analog multimode filter, which is constructed with aid of external capacitors to the chip. The filter has lowpass, bandpass and highpass outputs, which can be individually selected for final output amplification via the master volume register. Filter modes can also be combined. For example, using a combined state of lowpass and highpass results in a notch (or inverted bandpass) output. The programmer may vary the filter's cutoff frequency and resonance. An external audio-in port enables external audio to be passed through the filter. The ring modulation, filter, and programming techniques such as arpeggio (rapid cycling between frequencies to make chord-like sounds) together produce the characteristic feel and sound of SID music. Due to imperfect manufacturing technologies of the time and poor separation between the analog and digital parts of the chip, the 6581's output (before the amplifier stage) was always slightly biased from the zero level. Each time the volume register was altered, an audible click was produced. By quickly adjusting the amplifier's gain through the main 4-bit volume register, this bias could be modulated as

PCM Pulse-code modulation (PCM) is a method used to Digital signal (signal processing), digitally represent analog signals. It is the standard form of digital audio in computers, compact discs, digital telephony and other digital audio application ...

, resulting in a "virtual" fourth channel allowing 4-bit digital sample playback. The glitch was known and used from an early point on, first by Electronic Speech Systems to produce sampled speech in games such as '' Impossible Mission'' (1984,

Epyx Epyx, Inc. was a video game developer and video game publisher active in the late 1970s and 1980s. The company was founded in 1978 as Automated Simulations by Jim Connelley and Jon Freeman, publishing a series of tactical combat games. The Epyx ...

) and ''

Ghostbusters ''Ghostbusters'' is a 1984 American supernatural comedy film directed by Ivan Reitman and written by Dan Aykroyd and Harold Ramis. It stars Bill Murray, Aykroyd, and Ramis as Peter Venkman, Ray Stantz, and Egon Spengler, three eccentric ...

'' (1984,

Activision Activision Publishing, Inc. is an American video game publisher based in Santa Monica, California. It serves as the publishing business for its parent company, Activision Blizzard, and consists of several subsidiary studios. Activision is one o ...

). The first instance of samples being used in actual musical compositions was by

Martin Galway Martin Galway (born 3 January 1966, Belfast, Northern Ireland) is one of the best known composers of chiptune video game music for the Commodore 64 and the ZX Spectrum. His works include '' Rambo: First Blood Part II'', '' Comic Bakery'' and ...

in ''

Arkanoid is a 1986 Block kuzushi, block breaker arcade game developed and published by Taito. In North America, it was published by Romstar. Controlling a paddle-like craft known as the Vaus, the player is tasked with clearing a formation of colorful blo ...

'' (1987, Imagine), although he had copied the idea from an earlier drum synthesizer package called Digidrums. The length of sampled sound playback was limited first by memory and later technique. Kung Fu Fighting (1986), a popular early sample, has a playback length measured in seconds. c64mp3 (2010) and Cubase64 (2010) demonstrate playback lengths measured in minutes. Also, it was hugely CPU intensive - one had to output the samples very fast (in comparison to the speed of the 6510 CPU). The better manufacturing technology in the 8580 used in the later revisions of Commodore 64C and the Commodore 128 DCR caused the bias to almost entirely disappear, causing the digitized sound samples to become very quiet. Fortunately, the volume level could be mostly restored with either a hardware modification (biasing the audio-in pin), or more commonly a software trick involving using the Pulse waveform to intentionally recreate the required bias. The software trick generally renders one voice temporarily unusable, although clever musical compositions can make this problem less noticeable. An excellent example of this quality improvement noticeably reducing a sampled channel can be found in the introduction to Electronic Arts' game Skate or Die (1987). The guitar riff played is all but missing when played on the Commodore 64c or the Commodore 128. At the X'2008 demo party, a completely new method of playing digitized samples was unveiled. The method allows for an unprecedented four (software-mixed) channels of 8-bit samples with optional filtering on top of all samples, as well as two ordinary SID sound channels. The method works by resetting the oscillator using the waveform generator test bit, quickly ramping up the new waveform with the Triangle waveform selected, and then disabling all waveforms, resulting in the DAC continuing to output the last value---which is the desired sample. This continues for as long as two scanlines, which is ample time for glitch-free, arbitrary sample output. It is however more CPU-intensive than the 4-bit volume register DAC trick described above. Because the filtering in a SID chip is applied after the waveform generators, samples produced this way can be filtered normally. The original manual for the SID mentions that if several waveforms are enabled at the same time, the result will be a binary AND between them. What happens in reality is that the input to the waveform DAC pins receives several waveforms at once. For instance, the Triangle waveform is made with a separate XOR circuit and a shift-to-left circuit. The top bit drives whether the XOR circuit inverts the accumulator value seen by the DAC. Thus, enabling triangle and sawtooth simultaneously causes adjacent accumulator bits in the DAC input to mix. (The XOR circuit does not come to play because it is always disabled whenever the sawtooth waveform is selected.) The pulse waveform is built by joining all the DAC bits together via a long strip of polysilicon, connected to the pulse control logic that digitally compares current accumulator value to the pulse width value. Thus, selecting the pulse waveform together with any other waveform causes every bit on the DAC to partially mix, and the loudness of the waveform is affected by the state of the pulse. The noise generator is implemented as a 23-bit-length Fibonacci LFSR (Feedback polynomial: x^22+x^17+1). When using noise waveform simultaneously with any other waveform, the pull-down via waveform selector tends to quickly reduce the XOR shift register to 0 for all bits that are connected to the output DAC. As the zeroes shift in the register when the noise is clocked, and no 1-bits are produced to replace them, a situation can arise where the XOR shift register becomes fully zeroed. Luckily, the situation can be remedied by using the waveform control test bit, which in that condition injects one 1-bit into the XOR shift register. Some musicians are also known to use noise's combined waveforms and test bit to construct unusual sounds. The 6581 and 8580 differ from each other in several ways. The original 6581 was manufactured using the older NMOS process, which used 12V DC to operate. The 6581 is very sensitive to static discharge and if they weren't handled properly the filters would stop working, explaining the large number of dead 6581s in the market. The 8580 was made using the HMOS-II process, which requires less power (9V DC), and therefore makes the IC run cooler. The 8580 is thus far more durable than the 6581. Also, due to more stable waveform generators, the bit-mixing effects are less noticeable and thus the combined waveforms come close to matching the original SID specification (which stated that they will be combined as a binary AND). The filter is also very different between the two models. The 6581 cutoff range resembles a

sigmoid function A sigmoid function is any mathematical function whose graph of a function, graph has a characteristic S-shaped or sigmoid curve. A common example of a sigmoid function is the logistic function, which is defined by the formula :\sigma(x ...

on a log scale and varies wildly between chips, while the cutoff range on the 8580 is a straight line on a linear scale and is both more consistent between chips and close to the designers' actual specifications. The 8580 filter can achieve higher resonances as well. Additionally, a better separation between the analog and the digital circuits made the 8580's output less noisy and distorted. The noise in 6xxx-series systems can be reduced by disconnecting the audio-in pin. The consumer version of the 8580 was rebadged the 6582, even though the die on the chip is identical to a stock 8580 chip, including the '8580R5' mark. Dr. Evil Laboratories used it in their SID Symphony expansion cartridge (sold to Creative Micro Designs in 1991), and it was used in a few other places as well, including one PC sound-card. Despite its documented shortcomings, many SID musicians prefer the flawed 6581 chip over the corrected 8580 chip, some even seeing the flaws as actual 'features' that made the SID chip distinct from other sound chips at the time. The main reason for this is that the filter produces strong distortion that is sometimes used to produce simulation of instruments such as a distorted electric guitar. Also, the highpass component of the filter was mixed in 3 dB attenuated compared to the other outputs, making the sound more bassy. In addition to nonlinearities in filter, the D/A circuitry used in the waveform generators produces yet more additional distortion that made its sound richer in character.

Features

* Three separately programmable independent audio

oscillators Oscillation is the repetitive or periodic variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states. Familiar examples of oscillation include a swinging pendulum ...

(able to produce 65,535 equally spaced frequencies on a linear scale, 0.0625–4095.9375 Hz range on a 1 MHz clock) * Four distinct

waveform In electronics, acoustics, and related fields, the waveform of a signal is the shape of its Graph of a function, graph as a function of time, independent of its time and Magnitude (mathematics), magnitude Scale (ratio), scales and of any dis ...

s per audio oscillator (

triangle A triangle is a polygon with three corners and three sides, one of the basic shapes in geometry. The corners, also called ''vertices'', are zero-dimensional points while the sides connecting them, also called ''edges'', are one-dimension ...

, sawtooth,

pulse In medicine, the pulse refers to the rhythmic pulsations (expansion and contraction) of an artery in response to the cardiac cycle (heartbeat). The pulse may be felt ( palpated) in any place that allows an artery to be compressed near the surfac ...

noise Noise is sound, chiefly unwanted, unintentional, or harmful sound considered unpleasant, loud, or disruptive to mental or hearing faculties. From a physics standpoint, there is no distinction between noise and desired sound, as both are vibrat ...

). Any combination of triangle, sawtooth, and pulse may be selected at the same time to produce additional waveforms. * One multi mode filter featuring

low-pass A low-pass filter is a filter that passes signals with a frequency lower than a selected cutoff frequency and attenuates signals with frequencies higher than the cutoff frequency. The exact frequency response of the filter depends on the filt ...

, high-pass and

band-pass A band-pass filter or bandpass filter (BPF) is a device that passes frequencies within a certain range and rejects ( attenuates) frequencies outside that range. It is the inverse of a '' band-stop filter''. Description In electronics and s ...

outputs with 6 dB/oct (bandpass) or 12 dB/

octave In music, an octave (: eighth) or perfect octave (sometimes called the diapason) is an interval between two notes, one having twice the frequency of vibration of the other. The octave relationship is a natural phenomenon that has been referr ...

(lowpass/highpass) rolloff. The different filter modes may be combined to produce additional timbres, for instance a notch-reject filter. * Three attack/decay/sustain/release ( ADSR) volume envelope controls, one for each audio oscillator * Three ring modulators *

Oscillator sync Oscillator sync is a feature in some synthesizers with two or more VCOs, DCOs, or "virtual" oscillators. As one oscillator finishes a cycle, it resets the period of another oscillator, forcing the latter to have the same base frequency. This can ...

for each audio oscillator * Two

8-bit In computer architecture, 8-bit integers or other data units are those that are 8 bits wide (1 octet). Also, 8-bit central processing unit (CPU) and arithmetic logic unit (ALU) architectures are those that are based on registers or data bu ...

analog-to-digital converter In electronics, an analog-to-digital converter (ADC, A/D, or A-to-D) is a system that converts an analog signal, such as a sound picked up by a microphone or light entering a digital camera, into a Digital signal (signal processing), digi ...

s (typically used for game control paddles, but later also used for a

mouse A mouse (: mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus'' ...

) * External audio input (for sound mixing with external signal sources) *

Random number A random number is generated by a random (stochastic) process such as throwing dice. Individual numbers cannot be predicted, but the likely result of generating a large quantity of numbers can be predicted by specific mathematical series and st ...

/modulation generator (via reading the state of the 3rd oscillator or 3rd envelope generator)

Revisions

No instances reading "6581 R1" ever reached the market. In fact, Yannes has stated that " heSID chip came out pretty well the first time, it made sound. Everything we needed for the show was working after the second pass." High-resolution photos of Charles Winterble's prototype C64 show the markings "MOS 6581 2082", the last number being a date code indicating that his prototype SID chip was produced during the 20th week of 1982, which would be within 6 days of May 17, 1982. These are the known revisions of the various SID chips: (date codes are in WWYY w=week y=year format) The SID (Sound Interface Device) chip, notable for its fusion of digital and analog technologies, was a cornerstone in the system architecture of the Commodore 64 amongst other models. The chip boasted three distinct voices each with precise and varying waveform options—it also included a 12 dB/octave multimode filter. Over the years, the design of this filter differed with each subsequent chip revision, lending each its unique sonic fingerprint. One of the earliest models of the SID chip, the 6581, initially found its way into Commodore 64 computers between 1982 and around 1986. This model underwent several notable revisions including the 6581 R1, a prototype model which was only seen on CES machines and development prototypes and had a date code of 4981 to 0882. This model was renowned for its full 12-bit filter cutoff range and while the precise number of models produced remains unknown, it is estimated to be between 50 and 100 chips, being packaged in ceramic. Following the R1, were the 6581 R2, 6581 R3, 6581 R4 AR, and finally, the 6581 R4. The evolution of the 6581 iterations saw minor changes to the protection/buffering of the input pins, adjustment of the silicon grade, and changes to its packaging. However, no substantial alterations were made to the filter section throughout these progressions. Moving to the latter models, the updated 8580 SID chipped marked its introduction in newer versions of the Commodore 64 machines. Technically compatible with the 6581 software, the 8580 brought with it a unique sound character due to specific adjustments in the filter structure. The sonic differences noticed between the two models, 6581 and 8580, were attributed broadly to the nuances in the analog filters, and intrinsic design distortions. These sound characteristics were heavily influenced by updates in the circuitry and quality differences in the material batches used in the various production runs of the chips. The SID chip encompassed an ongoing journey of specifications that evolved in tandem with the chip design process. Not all initial features made it into the final blueprint. However, subsequent iterations like the 8580 model were meticulously revised to match more closely with the original specifications, specifically focusing on waveform combinations and filter functionality. Some of these chips are marked "CSG" (Commodore Semiconductor Group) with the Commodore logo, while others are marked "MOS". This includes chips produced during the same week (and thus, receiving the same date code), indicating that at least two different factory lines were in operation during that week. The markings of chips varied by factory, and even by line within a factory, throughout most of the manufacturing run of the chip.

Remarking and forgery

Since 6581 and 8580 SID ICs are no longer produced, they have become highly sought after. In late 2007, various defective chips started appearing on eBay as supposedly "new". Some of these remarked SIDs have a defective filter, but some also have defective channels/noise generators, and some are completely dead. Fake SID chips have also been supplied to unwitting buyers from unscrupulous manufacturers in China; the supplied chips are laser-etched with completely bogus markings, and the chip inside the package is not a SID at all.

Uses

Game audio

The majority of games produced for the Commodore 64 made use of the SID chip, with sounds ranging from simple clicks and beeps to complex musical extravaganzas or even entire digital audio tracks. Due to the technical mastery required to implement music on the chip, and its versatile features compared to other sound chips of the era, composers for the Commodore 64 have described the SID as a musical instrument in its own right. Most software did not use the full capabilities of SID, however, because the incorrect published specifications caused programmers to only use well-documented functionality. Some early software, by contrast, relied on the specifications, resulting in inaudible sound effects. Well known composers of game music for this chip are Rob Hubbard, known for titles such as ''

Commando A commando is a combatant, or operative of an elite light infantry or special operations force, specially trained for carrying out raids and operating in small teams behind enemy lines. Originally, "a commando" was a type of combat unit, as oppo ...

'', '' Monty on the run'', '' International Karate'', '' Sanxion'', ''

Skate or Die! ''Skate or Die!'' is a skateboarding video game released by Electronic Arts (EA) in 1987 for the Commodore 64. It is EA's first internally developed game. Versions for the Apple II, MS-DOS, Amstrad CPC, and ZX Spectrum followed. It was por ...

'', and

, known for '' Wizball'', ''

'' and '' Times of Lore''. Other noteworthies include David Whittaker ('' Lazy Jones'', '' Speedball'', '' Glider Rider'', '' Amaurote''), Jeroen Tel (''Cybernoid'', '' Turbo Outrun'', ''Robocop 3'' and ''Myth''), Ben Daglish (''

The Last Ninja ''The Last Ninja'' is an action-adventure game developed and published by System 3 (company), System 3 in 1987 for the Commodore 64. It was converted to the Apple IIGS, MS-DOS, BBC Micro and Acorn Electron in 1988, the Apple II in 1989, the Amig ...

'', '' Jack the Nipper'', ''Firelord'', '' Gauntlet''), David Dunn ('' Finders Keepers'' and ''Flight Path 737''), and Chris Hülsbeck (''

R-Type is a horizontally scrolling shooter arcade video game developed and released by Irem in 1987 and the first game in the ''R-Type'' series. The player controls a star ship, the R-9 "Arrowhead", in its efforts to destroy the Bydo, a powerful a ...

'', ''

Turrican ''Turrican'' is a 1990 video game developed by Manfred Trenz. It was developed for the Commodore 64 by Rainbow Arts, and was Video game port, ported to other systems later. In addition to concept design and character creation, Trenz programmed ' ...

'' and '' The Great Giana Sisters'').

Recordings

The fact that many enthusiasts prefer the real chip sound over software emulators has led to several recording projects aiming to preserve the authentic sound of the SID chip for modern hardware. The sid.oth4 project has over 380 songs of high quality MP3 available recorded on hardsid hardware and the SOASC= project has the entire High Voltage SID Collection (HVSC) released with 49 (over 35,000 songs) recorded from real Commodore 64s in a high quality

MP3 MP3 (formally MPEG-1 Audio Layer III or MPEG-2 Audio Layer III) is a coding format for digital audio developed largely by the Fraunhofer Society in Germany under the lead of Karlheinz Brandenburg. It was designed to greatly reduce the amount ...

file. Both projects emphasize the importance of preserving the authentic sound of the SID chip. In 2016, the Unepic Stoned High SID Collection (USHSC) was launched. It is a

YouTube YouTube is an American social media and online video sharing platform owned by Google. YouTube was founded on February 14, 2005, by Steve Chen, Chad Hurley, and Jawed Karim who were three former employees of PayPal. Headquartered in ...

channel with over 50,000 SID tunes uploaded as single videos. The USHSC is based on both the SOASC= and HVSC, but also uploads recordings of recent SID music released at the Commodore Scene Database (CSDb) site. The channel features playlists containing roughly 5000 tunes each.

Reimplementations and derivatives

Emulation

* In 1989 on the Amiga computer, the demo "The 100 Most Remembered C64 Tunes" and later the PlaySID application was released, developed by Per Håkan Sundell and Ron Birk. This was one of the first attempts to emulate the SID in software only, and also introduced the file format for representing songs made on the C64 using the SID chip. This later spawned the creation of similar applications for other platforms as well as the creation of a community of people fascinated by SID music, resulting in ''The High Voltage SID Collection'' which contains over 57,000 SID tunes. A SID file contains the 6510 program code and associated data needed to replay the music on the SID. The SID files have the

MIME A mime artist, or simply mime (from Greek language, Greek , , "imitator, actor"), is a person who uses ''mime'' (also called ''pantomime'' outside of Britain), the acting out of a story through body motions without the use of speech, as a the ...

media type audio/prs.sid. The actual file format of a SID file has had several versions. The older standard is PSID (current version V4). The newer standard, RSID, is intended for music that requires a more complete emulation of the Commodore 64 hardware. The SID file format is not a native format used on the Commodore 64 or 128, but a format specifically created for emulator-assisted music players such as ''PlaySID '', ''Sidplay'' and ''JSidplay2''. However, there are loaders like ''RealSIDPlay'' and converters such as ''PSID64'' that make it possible to play a substantial portion of SID files on original Commodore computers. * SIDPlayer, developed by Christian Bauer and released in 1996 for the

BeOS BeOS is a discontinued operating system for personal computers that was developed by Be Inc. It was conceived for the company's BeBox personal computer which was released in 1995. BeOS was designed for multitasking, multithreading, and a graph ...

operating system, was the first SID emulator to replicate the filter section of the SID chip using a second-order

Infinite impulse response Infinite impulse response (IIR) is a property applying to many linear time-invariant systems that are distinguished by having an impulse response h(t) that does not become exactly zero past a certain point but continues indefinitely. This is in ...

filter as an approximation. * In June 1998, a cycle-based SID emulator engine called reSID became available. The all-software emulator, available with C++

source code In computing, source code, or simply code or source, is a plain text computer program written in a programming language. A programmer writes the human readable source code to control the behavior of a computer. Since a computer, at base, only ...

, is licensed under the GPL by the author, Dag Lem. In 2008, Antti Lankila significantly improved the filter and distortion simulation in reSID. The improvements were included in

VICE A vice is a practice, behaviour, Habit (psychology), habit or item generally considered morally wrong in the associated society. In more minor usage, vice can refer to a fault, a negative character trait, a defect, an infirmity, or a bad or unhe ...

version 2.1 as well. * In 2007 the JSidplay2 project was released, a pure Java based SID player developed by Ken Händel.

Hardware using the SID chip

* In 1989 Innovation Computer developed the Innovation Sound Standard SSI-2001, an

IBM PC compatible An IBM PC compatible is any personal computer that is hardware- and software-compatible with the IBM Personal Computer (IBM PC) and its subsequent models. Like the original IBM PC, an IBM PC–compatible computer uses an x86-based central p ...

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 ...

with a SID chip and a

game port The game port is a device port that was found on IBM PC compatible and other computer systems throughout the 1980s and 1990s. It was the traditional connector for joystick input, and occasionally MIDI devices, until made obsolete by USB in the ...

MicroProse MicroProse is an American video game publisher and video game developer, developer founded by Bill Stealey, Sid Meier, and Andy Hollis in 1982. It developed and published numerous games, including starting the ''Civilization (series), Civilizat ...

promised software support for the card, and Commodore BASIC programs that used SID required little conversion to run on

GW-BASIC GW-BASIC is a dialect of the BASIC programming language developed by Microsoft from IBM BASICA. Functionally identical to BASICA, its BASIC interpreter is a fully self-contained executable and does not need the Cassette BASIC ROM found in the ori ...

. * In 1997, an

electronic musical instrument An electronic musical instrument or electrophone is a musical instrument that produces sound using electronics, electronic circuitry. Such an instrument sounds by outputting an electrical, electronic or digital audio signal that ultimately is ...

utilizing the SID chip as its synthesis engine was released. It is called the

SidStation The Elektron SidStation is a musical synthesizer sound module, built around the MOS Technology SID mixed-mode integrated circuit, mixed-mode synthesizer chip originally used in the Commodore 64 home computer. It was produced by the Sweden, Swedish ...

, built around the 6581 model SID chip (as opposed to the newer 8580), and it's produced by Swedish company Elektron. As the SID chip had been discontinued for years, Elektron allegedly bought up almost all of the remaining stock. In 2004, Elektron released the Monomachine pattern-based sequencer with optional keyboard. The Monomachine contains several synthesis engines, including an emulated 6581 oscillator using a DSP. * In 1999 HardSID, another PC sound card, was released. The card uses from one to four SID chips and allows a PC to utilize the sound capabilities of the chip directly, instead of by emulation via generic sound cards (e.g. SoundBlaster). * The Catweasel from

German German(s) may refer to: * Germany, the country of the Germans and German things **Germania (Roman era) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizenship in Germany, see also Ge ...

company Individual Computers, a PCI + Zorro multiformat

floppy disk A floppy disk or floppy diskette (casually referred to as a floppy, a diskette, or a disk) is a type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined with a ...

controller and digital joystick adapter for PCs, Macs, and

Amiga Amiga is a family of personal computers produced by Commodore International, Commodore from 1985 until the company's bankruptcy in 1994, with production by others afterward. The original model is one of a number of mid-1980s computers with 16-b ...

s, includes a hardware SID option, i.e. an option to insert one or two real SID chips in a socket for use when playing .MUS files. * The MIDIbox SID is a

MIDI Musical Instrument Digital Interface (; MIDI) is an American-Japanese technical standard that describes a communication protocol, digital interface, and electrical connectors that connect a wide variety of electronic musical instruments, ...

-controlled synthesizer which can contain up to eight SID chips. It is a free

open source Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use and view the source code, design documents, or content of the product. The open source model is a decentrali ...

project using a

PIC microcontroller PIC (usually pronounced as /pɪk/) is a family of microcontrollers made by Microchip Technology, derived from the PIC1640 originally developed by General Instrument's Microelectronics Division. The name PIC initially referred to ''Peripher ...

. Control of the synthesizer is realized with software or via a control panel with knobs, LEDs,

LCD A liquid-crystal display (LCD) is a flat-panel display or other electronically modulated optical device that uses the light-modulating properties of liquid crystals combined with polarizers to display information. Liquid crystals do not em ...

, etc., which may optionally be mounted on a keyboardless Commodore 64 body. * The Prophet64 is a cartridge for the Commodore 64. It features four separate music applications, mimicking everything from modern sequencers to the

Roland TB-303 The Roland TB-303 Bass Line (also known as the 303) is a bass synthesizer released by Roland Corporation in 1981. Designed to simulate bass guitars, it was a commercial failure and was discontinued in 1984. However, cheap second-hand units we ...

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series. With an optional User Port peripheral, the Prophet64 may synchronized to other equipment using

DIN Sync DIN sync, also called Sync24, is a synchronization interface for electronic musical instruments. It was introduced in 1980 by Roland Corporation and has been superseded by MIDI. Definition and history DIN sync was introduced in 1980 by Ro ...

standard (SYNC 24). The website now states "Prophet64 has been replaced with the MSSIAH." * The MSSIAH is a cartridge for the Commodore 64 that replaces the Prophet64. * Artist/hacker Paul Slocum developed the Cynthcart cartridge that enables you to turn your C64 into an analogue synthesizer. Its successor, Cynthcart 2, added MIDI in, out and thru ports. * The Parallel Port SID Interface allows those with very slim budgets to connect the SID chip to a PC. *In 2003 a SID interface (and software to play Commodore 64 tunes) was released for the

Z80 The Zilog Z80 is an 8-bit microprocessor designed by Zilog that played an important role in the evolution of early personal computing. Launched in 1976, it was designed to be software-compatible with the Intel 8080, offering a compelling altern ...

based Sam Coupé computer supporting both the 6581 and the 8580. * In May 2009 the SID chip was interfaced to the

BBC Micro The BBC Microcomputer System, or BBC Micro, is a family of microcomputers developed and manufactured by Acorn Computers in the early 1980s as part of the BBC's Computer Literacy Project. Launched in December 1981, it was showcased across severa ...

and

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range of computers via the 1 MHz bus allowing music written for the SID chip on the Commodore 64 to be ported and played on the BBC Micro. * In October 2009 thrashbarg's project interfaced an SID chip to an ATmega8 to play MIDI files on a MOS 6581 SID. * In March 2010 STG published the SIDBlaster/USB - an open source, open hardware implementation of the SID that connects to (and is powered by) a

USB port The initial versions of the USB standard specified connectors that were easy to use and that would have high life spans; revisions of the standard added smaller connectors useful for compact portable devices. Higher-speed development of the USB ...

, using an FTDI chip for the

USB Universal Serial Bus (USB) is an industry standard, developed by USB Implementers Forum (USB-IF), for digital data transmission and power delivery between many types of electronics. It specifies the architecture, in particular the physical ...

interface and a PIC to interface the SID. * In August 2010 SuperSoniqs published the Playsoniq, a cartridge for

MSX MSX is a standardized home computer architecture, announced by ASCII Corporation on June 16, 1983. It was initially conceived by Microsoft as a product for the Eastern sector, and jointly marketed by Kazuhiko Nishi, the director at ASCII Corpo ...

computers, with (in addition to other features) a real SID on it, ready to use on any MSX machine. * In May 2015 Gianluca Ghettini developed SidBerry, an open source, open hardware board to interface a MOS 6581 SID chip to a RaspberryPi and play standard SID music files * In 2016 Thibaut Varene published exSID, a USB audio device that can control a real 6581 and 8580 SID chip and natively playback most SID tunes.

Hardware reimplementations

* In 2008 the HyperSID project was released. HyperSID is a VSTi which acts like a MIDI controller for HyperSID hardware unit (synthesizer based on SID chip) and developed by HyperSynth company. * The SwinSID is hardware emulation of the SID using an Atmel AVR processor, also featuring a real SID player based on the Atmel AVR processor. * The V-SID 1.0 project (code name SID 6581D, 'D' for digital) from David was born in 2005. This project is a hardware emulation of the SID chip from the Bob Yannes's interview, datasheets. The V-SID 1.0 engine had been implemented in a

FPGA A field-programmable gate array (FPGA) is a type of configurable integrated circuit that can be repeatedly programmed after manufacturing. FPGAs are a subset of logic devices referred to as programmable logic devices (PLDs). They consist of a ...

EP1C12 Cyclone from ALTERA, on an ALTIUM development board, and emulates all the characteristics of the original SID, except the filter which is a digital version (IIR filter controlled by a CPU). * The PhoenixSID 65X81 project (2006) aimed to faithfully create the SID sound using modern hardware. The workings of a SID chip were recreated on an

, based on interviews with the SID's creator, original datasheets, and comparisons with real SID chips. It was distinguished from similar attempts by its use of real analog circuitry instead of emulation for the legendary SID filter. However, the project was discontinued, because George Pantazopoulos, who was the head of this project, died on April 23, 2007, at the age of 29. * The C64 Direct-to-TV emulates large portions the SID hardware, minus certain features such as (most notably) the filters. It reduces the entire C64 to a small circuit that fits into a joystick while sacrificing some compatibility. * The SIDcog is a software SID emulator running on the

Parallax Propeller The Parallax P8X32A Propeller is a multi-core processor parallel computer architecture microcontroller chip with eight 32-bit reduced instruction set computer (RISC) central processing unit (CPU) cores. Introduced in 2006, it is designed and so ...

. All three channels can be emulated on one of the Propeller's eight COG's. * The ARMSID is a "plug & play" replacement of the MOS 6581 and MOS 8580 with analog inputs support. * The FPGASID is a FPGA based SID replica providing high reproduction quality of the original device including all features such as the audio filters and the paddle registers. The device is a full featured stereo solution and can replace two SID chips in a single SID socket. Hardware base is an Altera MAX10 FPGA.

References

External links

SID in-depth information page

The 6581 SID Datasheet

SID programming info

{{MOS Video/Sound MOS Technology integrated circuits Sound chips Commodore 64 Commodore 64 music Video game music file formats Video game music technology