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75-462: SOASC may refer to: Stone Oakvalley's Authentic SID Collection Sultan Omar Ali Saifuddien College , a secondary school in Brunei Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title SOASC . If an internal link led you here, you may wish to change the link to point directly to

150-410: A big-endian orientation. Disregarding the boundary effects at both ends of the register, arithmetic and logical shift operations behave the same, and a shift by 8 bit positions transports the bit pattern by 1 byte position in the following way: In an arithmetic shift , the bits that are shifted out of either end are discarded. In a left arithmetic shift, zeros are shifted in on the right; in

225-463: 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. The SID

300-450: 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

375-472: 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

450-407: A binary AND). The filter is also very different between the two models. The 6581 cutoff range resembles a sigmoid function 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,

525-451: A bit pattern containing 1 only in the second bit: Because the result 0010 is non-zero, we know the second bit in the original pattern was set. This is often called bit masking . (By analogy, the use of masking tape covers, or masks , portions that should not be altered or portions that are not of interest. In this case, the 0 values mask the bits that are not of interest.) The bitwise AND may be used to clear selected bits (or flags ) of

600-495: A bitwise AND with the pattern that has a zero only in the third bit: Because of this property, it becomes easy to check the parity of a binary number by checking the value of the lowest valued bit. Using the example above: Because 6 AND 1 is zero, 6 is divisible by two and therefore even. A bitwise OR is a binary operation that takes two bit patterns of equal length and performs the logical inclusive OR operation on each pair of corresponding bits. The result in each position

675-473: A bitwise XOR with a bit pattern containing 1 in the second and fourth positions: This technique may be used to manipulate bit patterns representing sets of Boolean states. Assembly language programmers and optimizing compilers sometimes use XOR as a short-cut to setting the value of a register to zero. Performing XOR on a value against itself always yields zero, and on many architectures this operation requires fewer clock cycles and less memory than loading

750-636: 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. 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

825-510: 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. No instances reading "6581 R1" ever reached the market. In fact, Yannes has stated that "[the] SID chip came out pretty well

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900-439: A graph as a downward line that effectively "flips" an increasing range from 0 to 255, to a decreasing range from 255 to 0. A simple but illustrative example use is to invert a grayscale image where each pixel is stored as an unsigned integer. A bitwise AND is a binary operation that takes two equal-length binary representations and performs the logical AND operation on each pair of the corresponding bits. Thus, if both bits in

975-462: 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

1050-407: A register in which each bit represents an individual Boolean state . This technique is an efficient way to store a number of Boolean values using as little memory as possible. For example, 0110 (decimal 6) can be considered a set of four flags numbered from right to left, where the first and fourth flags are clear (0), and the second and third flags are set (1). The third flag may be cleared by using

1125-457: A right arithmetic shift, the sign bit (the MSB in two's complement) is shifted in on the left, thus preserving the sign of the operand. This example uses an 8-bit register, interpreted as two's complement: In the first case, the leftmost digit was shifted past the end of the register, and a new 0 was shifted into the rightmost position. In the second case, the rightmost 1 was shifted out (perhaps into

1200-477: A substantial portion of SID files on original Commodore computers. Bitwise operation#AND In computer programming , a bitwise operation operates on a bit string , a bit array or a binary numeral (considered as a bit string) at the level of its individual bits . It is a fast and simple action, basic to the higher-level arithmetic operations and directly supported by the processor . Most bitwise operations are presented as two-operand instructions where

1275-511: A zero value and saving it to the register. If the set of bit strings of fixed length n (i.e. machine words ) is thought of as an n -dimensional vector space F 2 n {\displaystyle {\bf {F}}_{2}^{n}} over the field F 2 {\displaystyle {\bf {F}}_{2}} , then vector addition corresponds to the bitwise XOR. Assuming ⁠ x ≥ y {\displaystyle x\geq y} ⁠ , for

1350-418: Is 32 , and 32 is outside the range 0–31 inclusive. A second try might result in where the shift amount is tested to ensure that it does not introduce undefined behavior. However, the branch adds an additional code path and presents an opportunity for timing analysis and attack, which is often not acceptable in high-integrity software. In addition, the code compiles to multiple machine instructions, which

1425-495: Is 0 if both bits are 0, while otherwise the result is 1. For example: The bitwise OR may be used to set to 1 the selected bits of the register described above. For example, the fourth bit of 0010 (decimal 2) may be set by performing a bitwise OR with the pattern with only the fourth bit set: A bitwise XOR is a binary operation that takes two bit patterns of equal length and performs the logical exclusive OR operation on each pair of corresponding bits. The result in each position

1500-443: Is 1 if only one of the bits is 1, but will be 0 if both are 0 or both are 1. In this we perform the comparison of two bits, being 1 if the two bits are different, and 0 if they are the same. For example: The bitwise XOR may be used to invert selected bits in a register (also called toggle or flip). Any bit may be toggled by XORing it with 1. For example, given the bit pattern 0010 (decimal 2) the second and fourth bits may be toggled by

1575-526: Is a mixed-signal integrated circuit , featuring both digital and analog circuitry. All control ports are digital, while the output ports are analog. The SID features three voices, with four types of waveforms able to be selected per voice: pulse wave (with variable duty cycle ), triangle wave, sawtooth wave, and pseudorandom noise (called white noise in documentation). Multiple waveform types may be selected simultaneously, which produces certain complex/combined waveforms. The oscillators of each voice are built on

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1650-421: Is an arithmetic right-shift. For this reason, some microcontrollers such as low end PICs just have rotate and rotate through carry , and don't bother with arithmetic or logical shift instructions. Rotate through carry is especially useful when performing shifts on numbers larger than the processor's native word size , because if a large number is stored in two registers, the bit that is shifted off one end of

1725-497: 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

1800-478: 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

1875-501: Is implementation-defined and not recommended by good coding practice; the result of left-shifting a signed value is undefined if the result cannot be represented in the result type. In C#, the right-shift is an arithmetic shift when the first operand is an int or long. If the first operand is of type uint or ulong, the right-shift is a logical shift. The C-family of languages lack a rotate operator (although C++20 provides std::rotl and std::rotr ), but one can be synthesized from

1950-436: Is larger than the number of bits (usually 8) of the smallest addressable unit, frequently called byte, the shift operations induce an addressing scheme from the bytes to the bits. Thereby the orientations "left" and "right" are taken from the standard writing of numbers in a place-value notation , such that a left shift increases and a right shift decreases the value of the number ― if the left digits are read first, this makes up

2025-513: 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

2100-559: Is often less efficient than the processor's native instruction. To avoid the undefined behavior and branches under GCC and Clang , the following is recommended. The pattern is recognized by many compilers, and the compiler will emit a single rotate instruction: There are also compiler-specific intrinsics implementing circular shifts , like _rotl8, _rotl16 , _rotr8, _rotr16 in Microsoft Visual C++ . Clang provides some rotate intrinsics for Microsoft compatibility that suffers

2175-421: Is shifted out (on the other end) becomes the new value of the carry flag. A single rotate through carry can simulate a logical or arithmetic shift of one position by setting up the carry flag beforehand. For example, if the carry flag contains 0, then x RIGHT-ROTATE-THROUGH-CARRY-BY-ONE is a logical right-shift, and if the carry flag contains a copy of the sign bit, then x RIGHT-ROTATE-THROUGH-CARRY-BY-ONE

2250-626: 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. 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

2325-403: The carry flag ), and a new 1 was copied into the leftmost position, preserving the sign of the number. Multiple shifts are sometimes shortened to a single shift by some number of digits. For example: A left arithmetic shift by n is equivalent to multiplying by 2 (provided the value does not overflow ), while a right arithmetic shift by n of a two's complement value is equivalent to taking

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2400-432: The floor of division by 2 . If the binary number is treated as ones' complement , then the same right-shift operation results in division by 2 and rounding toward zero . In a logical shift , zeros are shifted in to replace the discarded bits. Therefore, the logical and arithmetic left-shifts are exactly the same. However, as the logical right-shift inserts value 0 bits into the most significant bit, instead of copying

2475-508: The ones' complement of the given binary value. Bits that are 0 become 1, and those that are 1 become 0. For example: The result is equal to the two's complement of the value minus one. If two's complement arithmetic is used, then NOT x = -x − 1 . For unsigned integers , the bitwise complement of a number is the "mirror reflection" of the number across the half-way point of the unsigned integer's range. For example, for 8-bit unsigned integers, NOT x = 255 - x , which can be visualized on

2550-414: 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

2625-495: The C64 the best-selling home computer in history, and is partly credited for initiating the demoscene . The SID was devised by engineer Bob Yannes , who later co-founded the Ensoniq digital synthesizer 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

2700-530: 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,

2775-452: 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 12 dB/octave multimode filter, which

2850-461: The Nipper , Firelord , Gauntlet ), David Dunn ( Finders Keepers and Flight Path 737 ), David Whittaker ( Speedball , BMX Simulator , Glider Rider ) and Chris Hülsbeck ( R-Type , Turrican and The Great Giana Sisters ). 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

2925-456: 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 file. Both projects emphasize the importance of preserving the authentic sound of the SID chip. In 2016,

3000-583: The Unepic Stoned High SID Collection (USHSC) was launched. It is a YouTube 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. A SID file contains the 6510 program code and associated data needed to replay

3075-415: 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

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3150-400: 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

3225-569: 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

3300-407: The compared position are 1, the bit in the resulting binary representation is 1 (1 × 1 = 1); otherwise, the result is 0 (1 × 0 = 0 and 0 × 0 = 0). For example: The operation may be used to determine whether a particular bit is set (1) or cleared (0). For example, given a bit pattern 0011 (decimal 3), to determine whether the second bit is set we use a bitwise AND with

3375-406: The digits are moved, or shifted , to the left or right. Registers in a computer processor have a fixed width, so some bits will be "shifted out" of the register at one end, while the same number of bits are "shifted in" from the other end; the differences between bit shift operators lie in how they determine the values of the shifted-in bits. If the width of the register (frequently 32 or even 64)

3450-420: 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

3525-456: 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

3600-415: The first register must come in at the other end of the second. With rotate-through-carry, that bit is "saved" in the carry flag during the first shift, ready to shift in during the second shift without any extra preparation. In C and C++ languages, the logical shift operators are " << " for left shift and " >> " for right shift. The number of places to shift is given as the second argument to

3675-608: 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,

3750-469: The intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=SOASC&oldid=799051753 " Category : Disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages MOS Technology SID#Emulation Together with the VIC-II graphics chip, the SID was instrumental in making

3825-464: 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

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3900-528: 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

3975-503: 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

4050-667: The music on the SID. The SID files have the MIME 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

4125-409: The non-negative integers, the bitwise operations can be written as follows: There are 16 possible truth functions of two binary variables ; this defines a truth table . Here is the bitwise equivalent operations of two bits P and Q: The bit shifts are sometimes considered bitwise operations, because they treat a value as a series of bits rather than as a numerical quantity. In these operations,

4200-413: The operator. For example, assigns x the result of shifting y to the left by two bits, which is equivalent to a multiplication by four. Shifts can result in implementation-defined behavior or undefined behavior , so care must be taken when using them. The result of shifting by a bit count greater than or equal to the word's size is undefined behavior in C and C++. Right-shifting a negative value

4275-454: 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

4350-715: The problems above. GCC does not offer rotate intrinsics. Intel also provides x86 intrinsics . In Java , all integer types are signed, so the " << " and " >> " operators perform arithmetic shifts. Java adds the operator " >>> " to perform logical right shifts, but since the logical and arithmetic left-shift operations are identical for signed integer, there is no " <<< " operator in Java. More details of Java shift operators: JavaScript uses bitwise operations to evaluate each of two or more units place to 1 or 0. In Pascal, as well as in all its dialects (such as Object Pascal and Standard Pascal ),

4425-444: 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

4500-402: The reduced use of resources. In the explanations below, any indication of a bit's position is counted from the right (least significant) side, advancing left. For example, the binary value 0001 (decimal 1) has zeroes at every position but the first (i.e., the rightmost) one. The bitwise NOT , or bitwise complement , is a unary operation that performs logical negation on each bit, forming

4575-487: The result replaces one of the input operands. On simple low-cost processors, typically, bitwise operations are substantially faster than division, several times faster than multiplication, and sometimes significantly faster than addition. While modern processors usually perform addition and multiplication just as fast as bitwise operations due to their longer instruction pipelines and other architectural design choices, bitwise operations do commonly use less power because of

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4650-403: The right during a left-shift is whatever value was shifted out on the left, and vice versa for a right-shift operation. This is useful if it is necessary to retain all the existing bits, and is frequently used in digital cryptography . Rotate through carry is a variant of the rotate operation, where the bit that is shifted in (on either end) is the old value of the carry flag, and the bit that

4725-419: The shift operators. Care must be taken to ensure the statement is well formed to avoid undefined behavior and timing attacks in software with security requirements. For example, a naive implementation that left-rotates a 32-bit unsigned value x by n positions is simply However, a shift by 0 bits results in undefined behavior in the right-hand expression (x >> (32 - n)) because 32 - 0

4800-400: The sign bit, it is ideal for unsigned binary numbers, while the arithmetic right-shift is ideal for signed two's complement binary numbers. Another form of shift is the circular shift , bitwise rotation or bit rotation . In this operation, sometimes called rotate no carry , the bits are "rotated" as if the left and right ends of the register were joined. The value that is shifted into

4875-570: The specifications, resulting in inaudible sound effects. Well known composers of game music for this chip are Martin Galway , known for many titles, including Wizball , and Times of Lore , Rob Hubbard , known for titles such as ACE 2 , Commando , Delta , International Karate , IK+ , and Monty on the Run . Other noteworthies include Jeroen Tel ( Cybernoid , Turbo Outrun , Robocop 3 and Myth ), Ben Daglish ( The Last Ninja , Jack

4950-519: 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 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

5025-446: 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

5100-577: 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 , 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 ) and Ghostbusters (1984, Activision ). The first instance of samples being used in actual musical compositions

5175-403: 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,

5250-466: Was by Martin Galway in Arkanoid (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

5325-410: 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

5400-556: 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 , previously not found in home computer sound chips. I thought the sound chips on the market, including those in the Atari computers, were primitive and obviously had been designed by people who knew nothing about music. Emphasis during chip design

5475-404: 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;

5550-429: 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

5625-439: 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

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