HOME

TheInfoList




A digital signal processor (DSP) is a specialized
microprocessor A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip ...

microprocessor
chip, with its architecture optimized for the operational needs of
digital signal processing Digital signal processing (DSP) is the use of digital processing Digital usually refers to something using digits, particularly binary digits. Technology and computing Hardware *Digital electronics Digital electronics is a field of electro ...
. DSPs are fabricated on
MOS integrated circuit file:MOSFET Structure.png, upright=1.6, MOSFET, showing metal gate, gate (G), body (B), source (S) and drain (D) terminals. The gate is separated from the body by an gate oxide, insulating layer (pink). The metal–oxide–semiconductor field-eff ...
chips. They are widely used in
audio signal processing Audio signal processing is a subfield of that is concerned with the electronic manipulation of s. Audio signals are electronic representations of s—s which travel through air, consisting of compressions and rarefactions. The energy contained ...
,
telecommunications Telecommunication is the transmission of information by various types of technologies over , radio, , or other systems. It has its origin in the desire of humans for communication over a distance greater than that feasible with the , but with ...
,
digital image processing Digital image processing is the use of a digital computer A computer is a machine A machine is a man-made device that uses power to apply forces and control movement to perform an action. Machines can be driven by animals and people ...
,
radar Radar (radio detection and ranging) is a detection system that uses radio waves to determine the distance (''ranging''), angle, or velocity of objects. It can be used to detect aircraft, Marine radar, ships, spacecraft, guided missiles, motor ...

radar
,
sonar Sonar (sound navigation and ranging) is a technique that uses sound In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, ...

sonar
and
speech recognition Speech recognition is an interdisciplinary subfield of computer science and computational linguistics that develops Methodology, methodologies and technologies that enable the recognition and translation of spoken language into text by computers ...

speech recognition
systems, and in common
consumer electronic Consumer electronics or home electronics are electronic ( analog or digital) equipment intended for everyday use, typically in private homes. Consumer electronics include devices used for entertainment Entertainment is a form of activi ...
devices such as
mobile phones A mobile phone, cellular phone, cell phone, cellphone, handphone, or hand phone, sometimes shortened to simply mobile, cell or just phone, is a portable telephone A telephone is a telecommunications Appliance (disambiguation), devic ...

mobile phones
,
disk drives Data Data (; ) are individual facts A fact is something that is truth, true. The usual test for a statement of fact is verifiability—that is whether it can be demonstrated to correspond to experience. Standard reference works a ...
and
high-definition television High-definition television (HD or HDTV) describes a television system providing a substantially higher image resolution Image resolution is the detail an holds. The term applies to s, film images, and other types of images. Higher resolution m ...
(HDTV) products. The goal of a DSP is usually to measure, filter or compress continuous real-world
analog signals An analog signal is any continuous signalIn mathematical dynamics, discrete time and continuous time are two alternative frameworks within which to model variables that evolve over time. Discrete time Discrete sampled signal Discrete time ...
. Most general-purpose microprocessors can also execute digital signal processing algorithms successfully, but may not be able to keep up with such processing continuously in real-time. Also, dedicated DSPs usually have better power efficiency, thus they are more suitable in portable devices such as
mobile phone A mobile phone, cellular phone, cell phone, cellphone, handphone, or hand phone, sometimes shortened to simply mobile, cell or just phone, is a portable telephone A telephone is a telecommunication Telecommunication is the tra ...

mobile phone
s because of power consumption constraints. DSPs often use special
memory architecture Memory architecture describes the methods used to implement electronic computer data storage in a manner that is a combination of the fastest, most reliable, most durable, and least expensive way to store and retrieve information. Depending on the s ...
s that are able to fetch multiple data or instructions at the same time. DSPs often also implement
data compression In signal processing Signal processing is an electrical engineering subfield that focuses on analysing, modifying, and synthesizing signals such as audio signal processing, sound, image processing, images, and scientific measurements. Signal ...
technology, with the
discrete cosine transform A discrete cosine transform (DCT) expresses a finite sequence of data points In statistics Statistics is the discipline that concerns the collection, organization, analysis, interpretation, and presentation of data. In applying statistics ...
(DCT) in particular being a widely used compression technology in DSPs.


Overview

Digital signal processing(DSP)
algorithm In and , an algorithm () is a finite sequence of , computer-implementable instructions, typically to solve a class of problems or to perform a computation. Algorithms are always and are used as specifications for performing s, , , and other ...

algorithm
s typically require a large number of mathematical operations to be performed quickly and repeatedly on a series of data samples. Signals (perhaps from audio or video sensors) are constantly converted from analog to digital, manipulated digitally, and then converted back to analog form. Many DSP applications have constraints on
latency Latency or latent may refer to: Science and technology * Latent heat, energy released or absorbed, by a body or a thermodynamic system, during a constant-temperature process * Latent variable, a variable that is not directly observed but inferred i ...
; that is, for the system to work, the DSP operation must be completed within some fixed time, and deferred (or batch) processing is not viable. Most general-purpose microprocessors and operating systems can execute DSP algorithms successfully, but are not suitable for use in portable devices such as mobile phones and PDAs because of power efficiency constraints. A specialized DSP, however, will tend to provide a lower-cost solution, with better performance, lower latency, and no requirements for specialised cooling or large batteries. Such performance improvements have led to the introduction of digital signal processing in commercial
communications satellite A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a Transponder (satellite communications), transponder; it creates a communication channel between a source transmitter and a Radi ...
s where hundreds or even thousands of analog filters, switches, frequency converters and so on are required to receive and process the
uplink In a telecommunications network A telecommunications network is a group of nodes interconnected by links that are used to exchange messages between the nodes. The links may use a variety of technologies based on the methodologies of circuit sw ...
ed signals and ready them for
downlink In a telecommunications network A telecommunications network is a group of nodes In general, a node is a localized swelling (a "knot") or a point of intersection (a Vertex (graph theory), vertex). Node may refer to: In mathematics *Vertex (gra ...
ing, and can be replaced with specialised DSPs with significant benefits to the satellites' weight, power consumption, complexity/cost of construction, reliability and flexibility of operation. For example, the SES-12 and SES-14 satellites from operator
SES SES, S.E.S., Ses and similar variants can refer to: Business and economics * Socioeconomic status * Scottish Economic Society, a learned society in Scotland * SES, callsign of the TV station SES/RTS (Mount Gambier, South Australia) * SES S.A., a ...
launched in 2018, were both built by
Airbus Defence and Space Airbus Defence and Space is a division of Airbus Airbus SE (; ; ; ) is a European multinational aerospace corporation. Airbus designs, manufactures and sells civil and military aerospace Aerospace is a term used to collectively refer t ...
with 25% of capacity using DSP. The architecture of a DSP is optimized specifically for digital signal processing. Most also support some of the features as an applications processor or microcontroller, since signal processing is rarely the only task of a system. Some useful features for optimizing DSP algorithms are outlined below.


Architecture


Software architecture

By the standards of general-purpose processors, DSP instruction sets are often highly irregular; while traditional instruction sets are made up of more general instructions that allow them to perform a wider variety of operations, instruction sets optimized for digital signal processing contain instructions for common mathematical operations that occur frequently in DSP calculations. Both traditional and DSP-optimized instruction sets are able to compute any arbitrary operation but an operation that might require multiple ARM or x86 instructions to compute might require only one instruction in a DSP optimized instruction set. One implication for software architecture is that hand-optimized assembly-code routines (assembly programs) are commonly packaged into libraries for re-use, instead of relying on advanced compiler technologies to handle essential algorithms. Even with modern compiler optimizations hand-optimized assembly code is more efficient and many common algorithms involved in DSP calculations are hand-written in order to take full advantage of the architectural optimizations.


Instruction sets

* multiply–accumulates (MACs, including
fused multiply–add Fuse or FUSE may refer to: Devices * Fuse (electrical), a device used in electrical systems to protect against excessive current ** Fuse (automotive), a class of fuses for vehicles * Fuse (hydraulic), a device used in hydraulic systems to protect ...
, FMA) operations **used extensively in all kinds of
matrix Matrix or MATRIX may refer to: Science and mathematics * Matrix (mathematics), a rectangular array of numbers, symbols, or expressions * Matrix (logic), part of a formula in prenex normal form * Matrix (biology), the material in between a eukaryoti ...
operations ***
convolution In mathematics Mathematics (from Ancient Greek, Greek: ) includes the study of such topics as quantity (number theory), mathematical structure, structure (algebra), space (geometry), and calculus, change (mathematical analysis, analysis). ...
for filtering ***
dot product In mathematics, the dot product or scalar productThe term ''scalar product'' is often also used more generally to mean a symmetric bilinear form, for example for a pseudo-Euclidean space. is an algebraic operation that takes two equal-length seque ...
***
polynomial evaluation In mathematics, especially in the field of algebra, a polynomial ring or polynomial algebra is a ring (mathematics), ring (which is also a commutative algebra (structure), commutative algebra) formed from the Set (mathematics), set of polynomial ...
**Fundamental DSP algorithms depend heavily on multiply–accumulate performance *** FIR filters ***
Fast Fourier transform A fast Fourier transform (FFT) is an algorithm that computes the discrete Fourier transform (DFT) of a sequence, or its inverse (IDFT). Fourier analysis converts a signal from its original domain (often time or space) to a representation in t ...
(FFT) *related instructions: **
SIMD Single instruction, multiple data (SIMD) is a type of parallel computer, parallel processing in Flynn's taxonomy. SIMD can be internal (part of the hardware design) and it can be directly accessible through an instruction set architecture (IS ...

SIMD
**
VLIW Very long instruction word (VLIW) refers to instruction set architectures designed to exploit instruction level parallelism (ILP). Whereas conventional central processing units (CPU, processor) mostly allow programs to specify instructions to exec ...
*Specialized instructions for modulo addressing in and bit-reversed addressing mode for
FFT A fast Fourier transform (FFT) is an algorithm of an algorithm (Euclid's algorithm) for calculating the greatest common divisor (g.c.d.) of two numbers ''a'' and ''b'' in locations named A and B. The algorithm proceeds by successive subtract ...
cross-referencing *DSPs sometimes use time-stationary encoding to simplify hardware and increase coding efficiency. *Multiple arithmetic units may require
memory architecture Memory architecture describes the methods used to implement electronic computer data storage in a manner that is a combination of the fastest, most reliable, most durable, and least expensive way to store and retrieve information. Depending on the s ...
s to support several accesses per instruction cycle – typically supporting reading 2 data values from 2 separate data buses and the next instruction (from the instruction cache, or a 3rd program memory) simultaneously. *Special loop controls, such as architectural support for executing a few instruction words in a very tight loop without overhead for instruction fetches or exit testing -- such as zero-overhead looping and hardware loop buffers.


Data instructions

*
Saturation arithmeticSaturation arithmetic is a version of arithmetic in which all operations such as addition and multiplication are limited to a fixed range between a minimum and maximum value. If the result of an operation is greater than the maximum, it is set ("Cla ...
, in which operations that produce overflows will accumulate at the maximum (or minimum) values that the register can hold rather than wrapping around (maximum+1 doesn't overflow to minimum as in many general-purpose CPUs, instead it stays at maximum). Sometimes various sticky bits operation modes are available. *
Fixed-point arithmetic In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithm of an algorithm (Euclid's algorithm) for calculating the greatest comm ...
is often used to speed up arithmetic processing *Single-cycle operations to increase the benefits of
pipeliningPipelining may refer to: * Pipeline (computing) In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes and development o ...


Program flow

*
Floating-point In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithm of an algorithm (Euclid's algorithm) for calculating the greatest com ...
unit integrated directly into the
datapathA datapath is a collection of functional unit Functional may refer to: * Movements in architecture: ** Functionalism (architecture) ** Form follows function * Functional group, combination of atoms within molecules * Medical conditions without curre ...
*
Pipelined Pipeline may refer to: Electronics, computers and computing * Pipeline (computing), a chain of data-processing stages or a CPU optimization found on ** Instruction pipelining, a technique for implementing instruction-level parallelism within a si ...
architecture *Highly parallel multiplier–accumulators (MAC units) *Hardware-controlled looping, to reduce or eliminate the overhead required for looping operations


Hardware architecture

In engineering, hardware architecture refers to the identification of a system's physical components and their interrelationships. This description, often called a hardware design model, allows hardware designers to understand how their components fit into a system architecture and provides to software component designers important information needed for software development and integration. Clear definition of a hardware architecture allows the various traditional engineering disciplines (e.g., electrical and mechanical engineering) to work more effectively together to develop and manufacture new machines, devices and components. Hardware is also an expression used within the computer engineering industry to explicitly distinguish the (electronic computer) hardware from the software that runs on it. But hardware, within the automation and software engineering disciplines, need not simply be a computer of some sort. A modern automobile runs vastly more software than the Apollo spacecraft. Also, modern aircraft cannot function without running tens of millions of computer instructions embedded and distributed throughout the aircraft and resident in both standard computer hardware and in specialized hardware components such as IC wired logic gates, analog and hybrid devices, and other digital components. The need to effectively model how separate physical components combine to form complex systems is important over a wide range of applications, including computers, personal digital assistants (PDAs), cell phones, surgical instrumentation, satellites, and submarines.


Memory architecture

DSPs are usually optimized for streaming data and use special memory architectures that are able to fetch multiple data or instructions at the same time, such as the
Harvard architecture The Harvard architecture is a computer architecture with separate computer storage, storage and signal pathways for Machine code, instructions and data. It contrasts with the von Neumann architecture, where program instructions and data share ...

Harvard architecture
or Modified
von Neumann architecture The von Neumann architecture — also known as the von Neumann model or Princeton architecture — is a computer architecture In computer engineering Computer engineering (CoE or CpE) is a branch of engineering Engineering is ...

von Neumann architecture
, which use separate program and data memories (sometimes even concurrent access on multiple data buses). DSPs can sometimes rely on supporting code to know about cache hierarchies and the associated delays. This is a tradeoff that allows for better performance. In addition, extensive use of DMA is employed.


=Addressing and virtual memory

= DSPs frequently use multi-tasking operating systems, but have no support for
virtual memory In computing, virtual memory, or virtual storage is a Memory management (operating systems), memory management technique that provides an "idealized abstraction of the storage resources that are actually available on a given machine" which "cre ...

virtual memory
or memory protection. Operating systems that use virtual memory require more time for
context switching In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes and development of both computer hardware , hardware and softwa ...
among
processes A process is a series or set of Action (philosophy), activities that interact to produce a result; it may occur once-only or be recurrent or periodic. Things called a process include: Business and management *Business process, activities that pro ...
, which increases latency. *Hardware modulo addressing **Allows
circular buffer In computer science Computer science deals with the theoretical foundations of information, algorithms and the architectures of its computation as well as practical techniques for their application. Computer science is the study of Algo ...

circular buffer
s to be implemented without having to test for wrapping *Bit-reversed addressing, a special
addressing mode Addressing modes are an aspect of the instruction set architecture In computer science, an instruction set architecture (ISA), also called computer architecture, is an abstract model of a computer. A device that executes instructions described b ...
**useful for calculating FFTs *Exclusion of a
memory management unit MMU could be used with the Motorola 68010 The Motorola MC68010 processor is a 16/32-bit microprocessor A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit, or a s ...
*
Address generation unit The address generation unit (AGU), sometimes also called address computation unit (ACU), is an execution unit inside central processing unit A central processing unit (CPU), also called a central processor, main processor or just processor ...


History


Background

Prior to the advent of stand-alone digital signal processor (DSP)
chips ''CHiPs'' is an American crime drama Crime films, in the broadest sense, is a film genre inspired by and analogous to the crime fiction literary genre. Films of this genre generally involve various aspects of crime and its detection. Stylist ...

chips
, early
digital signal processing Digital signal processing (DSP) is the use of digital processing Digital usually refers to something using digits, particularly binary digits. Technology and computing Hardware *Digital electronics Digital electronics is a field of electro ...
applications were typically implemented using
bit-slice Bit slicing is a technique for constructing a central processing unit, processor from modules of processors of smaller bit width, for the purpose of increasing the word length; in theory to make an arbitrary n-bit CPU. Each of these component mod ...
chips. The AMD 2901 bit-slice chip with its family of components was a very popular choice. There were reference designs from AMD, but very often the specifics of a particular design were application specific. These bit slice architectures would sometimes include a peripheral multiplier chip. Examples of these multipliers were a series from
TRWTRW may refer to: * TRW Inc., former US aerospace and automotive company, purchased by Northrop Grumman ** TRW Automotive, spun off from TRW Inc., later ZF TRW Automotive Holdings Corp. * The Real World (TV series), ''The Real World'' (TV series), a ...
including the TDC1008 and TDC1010, some of which included an accumulator, providing the requisite multiply–accumulate (MAC) function. Electronic
signal processing Signal processing is an electrical engineering Electrical engineering is an engineering discipline concerned with the study, design, and application of equipment, devices, and systems which use electricity, electronics, and electromagnetis ...

signal processing
was revolutionized in the 1970s by the wide adoption of the
MOSFET The metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET), also known as the metal–oxide–silicon transistor (MOS transistor, or MOS), is a type of insulated-gate field-effect transistor that is fabricated by th ...

MOSFET
(metal-oxide-semiconductor field-effect transistor, or MOS transistor),
MOS integrated circuit file:MOSFET Structure.png, upright=1.6, MOSFET, showing metal gate, gate (G), body (B), source (S) and drain (D) terminals. The gate is separated from the body by an gate oxide, insulating layer (pink). The metal–oxide–semiconductor field-eff ...
technology was the basis for the first single-chip
microprocessors A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit, or a small number of integrated circuits. The microprocessor contains the arithmetic, logic, and control circuitr ...
and
microcontrollers A microcontroller (MCU for ''microcontroller unit'') is a small computer on a single MOSFET, metal-oxide-semiconductor (MOS) integrated circuit (IC) chip. A microcontroller contains one or more Central processing unit, CPUs (processor cores) alo ...
in the early 1970s, and then the first single-chip DSPs in the late 1970s. Another important development in digital signal processing was
data compression In signal processing Signal processing is an electrical engineering subfield that focuses on analysing, modifying, and synthesizing signals such as audio signal processing, sound, image processing, images, and scientific measurements. Signal ...
.
Linear predictive coding Linear predictive coding (LPC) is a method used mostly in audio signal processing and speech processing for representing the spectral envelope of a Digital data, digital signal (information theory), signal of Speech communication, speech in data co ...
(LPC) was first developed by
Fumitada Itakura is a Japanese scientist A scientist is a person who conducts Scientific method, scientific research to advance knowledge in an Branches of science, area of interest. In classical antiquity, there was no real ancient analog of a modern scientist. ...
of
Nagoya University , abbreviated to or NU, is a Japanese national research university A research university is a university A university ( la, universitas, 'a whole') is an educational institution, institution of higher education, higher (or Tertiary educatio ...
and Shuzo Saito of
Nippon Telegraph and Telephone , commonly known as NTT, is a Japanese telecommunications Telecommunication is the transmission of information by various types of technologies over , radio, , or other systems. It has its origin in the desire of humans for communication o ...
(NTT) in 1966, and then further developed by Bishnu S. Atal and Manfred R. Schroeder at
Bell Labs Nokia Bell Labs (formerly named Bell Labs Innovations (1996–2007), AT&T Bell Laboratories (1984–1996) and Bell Telephone Laboratories (1925–1984)) is an American industrial research and scientific development company A company, ab ...
during the early-to-mid-1970s, becoming a basis for the first
speech synthesizer Speech synthesis is the artificial production of human speech Speech is human vocal communication using language. Each language uses Phonetics, phonetic combinations of vowel and consonant sounds that form the sound of its words (that is, all ...
DSP chips in the late 1970s. The
discrete cosine transform A discrete cosine transform (DCT) expresses a finite sequence of data points In statistics Statistics is the discipline that concerns the collection, organization, analysis, interpretation, and presentation of data. In applying statistics ...
(DCT) was first proposed by Nasir Ahmed in the early 1970s, and has since been widely implemented in DSP chips, with many companies developing DSP chips based on DCT technology. DCTs are widely used for
encoding In communication Communication (from Latin ''communicare'', meaning "to share") is the act of developing Semantics, meaning among Subject (philosophy), entities or Organization, groups through the use of sufficiently mutually understood sign ...

encoding
, decoding,
video coding A video coding format (or sometimes video compression format) is a content representation format for storage or transmission of digital Digital usually refers to something using digits, particularly binary digits. Technology and computing Har ...
,
audio coding An audio coding format (or sometimes audio compression format) is a content representation format for storage or transmission of digital audio Digital audio is a representation of sound recorded in, or converted into, Digital signal (signal ...
,
multiplexing In telecommunications Telecommunication is the transmission of information by various types of technologies over , radio, , or other systems. It has its origin in the desire of humans for communication over a distance greater than that ...
, control signals,
signaling In signal processing Signal processing is an electrical engineering subfield that focuses on analysing, modifying, and synthesizing signals such as audio signal processing, sound, image processing, images, and scientific measurements. Sig ...
, analog-to-digital conversion, formatting
luminance Luminance is a photometricPhotometry can refer to: * Photometry (optics), the science of measurement of visible light in terms of its perceived brightness to human vision * Photometry (astronomy), the measurement of the flux or intensity of an ...

luminance
and color differences, and color formats such as YUV444 and YUV411. DCTs are also used for encoding operations such as
motion estimation Motion estimation is the process of determining ''motion vector In video compression In signal processing Signal processing is an electrical engineering subfield that focuses on analysing, modifying, and synthesizing signals such as a ...
,
motion compensation Motion compensation is an algorithmic technique used to predict a frame in a video, given the previous and/or future frames by accounting for motion of the camera and/or objects in the video. It is employed in the encoding of video data for video ...
,
inter-frame An inter frame is a frame in a video compression In signal processing, data compression, source coding, or bit-rate reduction is the process of encoding information using fewer bits than the original representation. Any particular compression i ...
prediction, quantization, perceptual weighting,
entropy encoding In information theory, an entropy coding (or entropy encoding) is a lossless compression , lossless data compression scheme that is independent of the specific characteristics of the medium. One of the main types of entropy coding creates and assi ...
, variable encoding, and
motion vector In video compression In signal processing Signal processing is an electrical engineering subfield that focuses on analysing, modifying, and synthesizing signals such as audio signal processing, sound, image processing, images, and scienti ...
s, and decoding operations such as the inverse operation between different color formats (
YIQ An image along with its Y, I, and Q components. YIQ is the color space A color space is a specific organization of colors. In combination with color profiling supported by various physical devices, it supports reproducible representations of co ...
,
YUV YUV is a color encoding system typically used as part of a color image pipelineAn image pipeline or video pipeline is the set of components commonly used between an image source (such as a camera, a scanner, or the rendering engine in a compute ...
and
RGB s The RGB color model is an additive color, additive color model A color model is an abstract mathematical model describing the way colors can be represented as tuples of numbers, typically as three or four values or color components. When ...

RGB
) for display purposes. DCTs are also commonly used for
high-definition television High-definition television (HD or HDTV) describes a television system providing a substantially higher image resolution Image resolution is the detail an holds. The term applies to s, film images, and other types of images. Higher resolution m ...
(HDTV) encoder/decoder chips.


Development

In 1976, Richard Wiggins proposed the Speak & Spell concept to Paul Breedlove, Larry Brantingham, and Gene Frantz at
Texas Instruments Texas Instruments Incorporated (TI) is an America The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America North America is a ...
' Dallas research facility. Two years later in 1978, they produced the first Speak & Spell, with the technological centerpiece being the TMS5100, the industry's first digital signal processor. It also set other milestones, being the first chip to use linear predictive coding to perform
speech synthesis Speech synthesis is the artificial production of human speech. A computer system used for this purpose is called a speech computer or speech synthesizer, and can be implemented in software or Computer hardware, hardware products. A text-to-speech ...
. The chip was made possible with a 7µm PMOS
fabrication process Semiconductor device fabrication is the process used to manufacture semiconductor devices, typically the metal–oxide–semiconductor (MOS) devices used in the integrated circuit (IC) chips such as modern computer processors, microcontrollers ...
. In 1978,
American Microsystems ON Semiconductor is a semiconductors supplier company, formerly in the Fortune 500, but dropping into the Fortune 1000 (ranked 512) in 2020 . Products include power and signal management, logic, discrete, and custom devices for automotive, communic ...
(AMI) released the S2811. The AMI S2811 "signal processing peripheral", like many later DSPs, has a hardware multiplier that enables it to do multiply–accumulate operation in a single instruction. The S2281 was the first
integrated circuit An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuit 200px, A circuit built on a printed circuit board (PCB). An electronic circuit is composed of indiv ...

integrated circuit
chip specifically designed as a DSP, and fabricated using
VMOS A VMOS () transistor is a type of MOSFET The metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET), also known as the metal–oxide–silicon transistor (MOS transistor, or MOS), is a type of insulated-gate fi ...
(V-groove MOS), a technology that had previously not been mass-produced. It was designed as a microprocessor peripheral, for the
Motorola 6800 The 6800 ("''sixty-eight hundred''") is an 8-bit microprocessor designed and first manufactured by Motorola in 1974. The MC6800 microprocessor was part of the M6800 Microcomputer System that also included serial and parallel interface integrated c ...

Motorola 6800
, and it had to be initialized by the host. The S2811 was not successful in the market. In 1979,
Intel Intel Corporation is an American multinational corporation A multinational company (MNC) is a corporate A corporation is an organization—usually a group of people or a company A company, abbreviated as co., is a Legal personalit ...

Intel
released the 2920 as an "analog signal processor". It had an on-chip ADC/DAC with an internal signal processor, but it didn't have a hardware multiplier and was not successful in the market. In 1980, the first stand-alone, complete DSPs –
Nippon Electric Corporation is a Japanese multinational Multinational may refer to: * Multinational corporation, a corporate organization operating in multiple countries * Multinational force, a military body from multiple countries * Multinational state, a sovereign stat ...
's NEC µPD7720 and AT&T Corporation, AT&T's AT&T DSP1, DSP1 – were presented at the International Solid-State Circuits Conference '80. Both processors were inspired by the research in public switched telephone network (PSTN) telecommunications. The µPD7720, introduced for voiceband applications, was one of the most commercially successful early DSPs. The Altamira DX-1 was another early DSP, utilizing quad integer pipelines with delayed branches and branch prediction. Another DSP produced by Texas Instruments (TI), the Texas Instruments TMS320, TMS32010 presented in 1983, proved to be an even bigger success. It was based on the Harvard architecture, and so had separate instruction and data memory. It already had a special instruction set, with instructions like load-and-accumulate or multiply-and-accumulate. It could work on 16-bit numbers and needed 390 ns for a multiply–add operation. TI is now the market leader in general-purpose DSPs. About five years later, the second generation of DSPs began to spread. They had 3 memories for storing two operands simultaneously and included hardware to accelerate tight loops; they also had an addressing unit capable of loop-addressing. Some of them operated on 24-bit variables and a typical model only required about 21 ns for a MAC. Members of this generation were for example the AT&T DSP16A or the Motorola 56000. The main improvement in the third generation was the appearance of application-specific units and instructions in the data path, or sometimes as coprocessors. These units allowed direct hardware acceleration of very specific but complex mathematical problems, like the Fourier-transform or matrix operations. Some chips, like the Motorola MC68356, even included more than one processor core to work in parallel. Other DSPs from 1995 are the TI TMS320C541 or the TMS 320C80. The fourth generation is best characterized by the changes in the instruction set and the instruction encoding/decoding. SIMD extensions were added, and VLIW and the superscalar architecture appeared. As always, the clock-speeds have increased; a 3 ns MAC now became possible.


Modern DSPs

Modern signal processors yield greater performance; this is due in part to both technological and architectural advancements like lower design rules, fast-access two-level cache, (E) DMA circuitry and a wider bus system. Not all DSPs provide the same speed and many kinds of signal processors exist, each one of them being better suited for a specific task, ranging in price from about US$1.50 to US$300.
Texas Instruments Texas Instruments Incorporated (TI) is an America The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America North America is a ...
produces the TMS320C6000, C6000 series DSPs, which have clock speeds of 1.2 GHz and implement separate instruction and data caches. They also have an 8 MiB 2nd level cache and 64 EDMA channels. The top models are capable of as many as 8000 MIPS (millions of instructions per second), use VLIW (very long instruction word), perform eight operations per clock-cycle and are compatible with a broad range of external peripherals and various buses (PCI/serial/etc). TMS320C6474 chips each have three such DSPs, and the newest generation C6000 chips support floating point as well as fixed point processing. Freescale produces a multi-core DSP family, the MSC81xx. The MSC81xx is based on StarCore Architecture processors and the latest MSC8144 DSP combines four programmable SC3400 StarCore DSP cores. Each SC3400 StarCore DSP core has a clock speed of 1 GHz. XMOS produces a multi-core multi-threaded line of processor well suited to DSP operations, They come in various speeds ranging from 400 to 1600 MIPS. The processors have a multi-threaded architecture that allows up to 8 real-time threads per core, meaning that a 4 core device would support up to 32 real time threads. Threads communicate between each other with buffered channels that are capable of up to 80 Mbit/s. The devices are easily programmable in C and aim at bridging the gap between conventional micro-controllers and FPGAs CEVA, Inc. produces and licenses three distinct families of DSPs. Perhaps the best known and most widely deployed is the CEVA-TeakLite DSP family, a classic memory-based architecture, with 16-bit or 32-bit word-widths and single or dual Multiply–accumulate operation, MACs. The CEVA-X DSP family offers a combination of VLIW and SIMD architectures, with different members of the family offering dual or quad 16-bit MACs. The CEVA-XC DSP family targets Software-defined radio, Software-defined Radio (SDR) modem designs and leverages a unique combination of VLIW and Vector architectures with 32 16-bit MACs. Analog Devices produce the Super Harvard Architecture Single-Chip Computer, SHARC-based DSP and range in performance from 66 MHz/198 MFLOPS (million floating-point operations per second) to 400 MHz/2400 MFLOPS. Some models support multiple binary multiplier, multipliers and Arithmetic logic unit, ALUs,
SIMD Single instruction, multiple data (SIMD) is a type of parallel computer, parallel processing in Flynn's taxonomy. SIMD can be internal (part of the hardware design) and it can be directly accessible through an instruction set architecture (IS ...

SIMD
instructions and audio processing-specific components and peripherals. The Blackfin family of embedded digital signal processors combine the features of a DSP with those of a general use processor. As a result, these processors can run simple operating systems like μCLinux, velocity and Nucleus RTOS while operating on real-time data. NXP Semiconductors produce DSPs based on TriMedia (mediaprocessor), TriMedia
VLIW Very long instruction word (VLIW) refers to instruction set architectures designed to exploit instruction level parallelism (ILP). Whereas conventional central processing units (CPU, processor) mostly allow programs to specify instructions to exec ...
technology, optimized for audio and video processing. In some products the DSP core is hidden as a fixed-function block into a System-on-a-chip, SoC, but NXP also provides a range of flexible single core media processors. The TriMedia media processors support both fixed-point arithmetic as well as floating-point arithmetic, and have specific instructions to deal with complex filters and entropy coding. CSR plc, CSR produces the Quatro family of SoCs that contain one or more custom Imaging DSPs optimized for processing document image data for scanner and copier applications. Microchip Technology produces the PIC24 based dsPIC line of DSPs. Introduced in 2004, the dsPIC is designed for applications needing a true DSP as well as a true microcontroller, such as motor control and in power supplies. The dsPIC runs at up to 40MIPS, and has support for 16 bit fixed point MAC, bit reverse and modulo addressing, as well as DMA. Most DSPs use fixed-point arithmetic, because in real world signal processing the additional range provided by floating point is not needed, and there is a large speed benefit and cost benefit due to reduced hardware complexity. Floating point DSPs may be invaluable in applications where a wide dynamic range is required. Product developers might also use floating point DSPs to reduce the cost and complexity of software development in exchange for more expensive hardware, since it is generally easier to implement algorithms in floating point. Generally, DSPs are dedicated integrated circuits; however DSP functionality can also be produced by using field-programmable gate array chips (FPGAs). Embedded general-purpose RISC processors are becoming increasingly DSP like in functionality. For example, the Texas Instruments OMAP, OMAP3 processors include an ARM Cortex-A8 and C6000 DSP. In Communications a new breed of DSPs offering the fusion of both DSP functions and H/W acceleration function is making its way into the mainstream. Such Modem processors include ASOCS ModemX and CEVA's XC4000. In May 2018, Huarui-2 designed by Nanjing Research Institute of Electronics Technology of China Electronics Technology Group passed acceptance. With a processing speed of 0.4 TFLOPS, the chip can achieve better performance than current mainstream DSP chips. The design team has begun to create Huarui-3, which has a processing speed in TFLOPS level and a support for artificial intelligence.


See also

* Digital signal controller * Graphics processing unit *System on a chip *Hardware acceleration * Vision processing unit * MDSP – a multiprocessor DSP * OpenCL


References


External links


DSP Online Book
{{Hardware acceleration Digital signal processing Digital signal processors, * Computer engineering Integrated circuits Coprocessors Hardware acceleration