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The history of general-purpose CPUs is a continuation of the earlier
history of computing hardware The history of computing hardware covers the developments from early simple devices to aid calculation to modern day computers. Before the 20th century, most calculations were done by humans. The first aids to computation were purely mechan ...
.


1950s: Early designs

In the early 1950s, each computer design was unique. There were no upward-compatible machines or computer architectures with multiple, differing implementations. Programs written for one machine would run on no other kind, even other kinds from the same company. This was not a major drawback then because no large body of software had been developed to run on computers, so starting programming from scratch was not seen as a large barrier. The design freedom of the time was very important because designers were very constrained by the cost of electronics, and only starting to explore how a computer could best be organized. Some of the basic features introduced during this period included
index register An index register in a computer's CPU is a processor register (or an assigned memory location) used for pointing to operand addresses during the run of a program. It is useful for stepping through strings and arrays. It can also be used for hol ...
s (on the
Ferranti Mark 1 The Ferranti Mark 1, also known as the Manchester Electronic Computer in its sales literature, and thus sometimes called the Manchester Ferranti, was produced by British electrical engineering firm Ferranti Ltd. It was the world's first commer ...
), a
return address In postal mail, a return address is an explicit inclusion of the address of the person sending the message. It provides the recipient (and sometimes authorized intermediaries) with a means to determine how to respond to the sender of the message i ...
saving instruction (
UNIVAC I The UNIVAC I (Universal Automatic Computer I) was the first general-purpose electronic digital computer design for business application produced in the United States. It was designed principally by J. Presper Eckert and John Mauchly, the invento ...
), immediate operands (
IBM 704 The IBM 704 is a large digital mainframe computer introduced by IBM in 1954. It was the first mass-produced computer with hardware for floating-point arithmetic. The IBM 704 ''Manual of operation'' states: The type 704 Electronic Data-Pro ...
), and detecting invalid operations (
IBM 650 The IBM 650 Magnetic Drum Data-Processing Machine is an early digital computer produced by IBM in the mid-1950s. It was the first mass produced computer in the world. Almost 2,000 systems were produced, the last in 1962, and it was the first ...
). By the end of the 1950s, commercial builders had developed factory-constructed, truck-deliverable computers. The most widely installed computer was the
IBM 650 The IBM 650 Magnetic Drum Data-Processing Machine is an early digital computer produced by IBM in the mid-1950s. It was the first mass produced computer in the world. Almost 2,000 systems were produced, the last in 1962, and it was the first ...
, which used
drum memory Drum memory was a magnetic data storage device invented by Gustav Tauschek in 1932 in Austria. Drums were widely used in the 1950s and into the 1960s as computer memory. For many early computers, drum memory formed the main working memory ...
onto which programs were loaded using either paper
punched tape Five- and eight-hole punched paper tape Paper tape reader on the Harwell computer with a small piece of five-hole tape connected in a circle – creating a physical program loop Punched tape or perforated paper tape is a form of data storage ...
or
punched card A punched card (also punch card or punched-card) is a piece of stiff paper that holds digital data represented by the presence or absence of holes in predefined positions. Punched cards were once common in data processing applications or to di ...
s. Some very high-end machines also included
core memory Core or cores may refer to: Science and technology * Core (anatomy), everything except the appendages * Core (manufacturing), used in casting and molding * Core (optical fiber), the signal-carrying portion of an optical fiber * Core, the central ...
which provided higher speeds.
Hard disk A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating platters coated with magnet ...
s were also starting to grow popular. A computer is an automatic
abacus The abacus (''plural'' abaci or abacuses), also called a counting frame, is a calculating tool which has been used since ancient times. It was used in the ancient Near East, Europe, China, and Russia, centuries before the adoption of the Hin ...
. The type of number system affects the way it works. In the early 1950s, most computers were built for specific numerical processing tasks, and many machines used decimal numbers as their basic number system; that is, the mathematical functions of the machines worked in base-10 instead of base-2 as is common today. These were not merely
binary-coded decimal In computing and electronic systems, binary-coded decimal (BCD) is a class of binary encodings of decimal numbers where each digit is represented by a fixed number of bits, usually four or eight. Sometimes, special bit patterns are used for ...
(BCD). Most machines had ten vacuum tubes per digit in each
processor register A processor register is a quickly accessible location available to a computer's processor. Registers usually consist of a small amount of fast storage, although some registers have specific hardware functions, and may be read-only or write-only. ...
. Some early
Soviet The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, ...
computer designers implemented systems based on
ternary logic In logic, a three-valued logic (also trinary logic, trivalent, ternary, or trilean, sometimes abbreviated 3VL) is any of several many-valued logic systems in which there are three truth values indicating ''true'', ''false'' and some indeterminate ...
; that is, a bit could have three states: +1, 0, or -1, corresponding to positive, zero, or negative voltage. An early project for the
U.S. Air Force The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Sign ...
,
BINAC BINAC (Binary Automatic Computer) was an early electronic computer designed for Northrop Aircraft Company by the Eckert–Mauchly Computer Corporation (EMCC) in 1949. Eckert and Mauchly, though they had started the design of EDVAC at the Univers ...
attempted to make a lightweight, simple computer by using binary arithmetic. It deeply impressed the industry. As late as 1970, major computer languages were unable to standardize their numeric behavior because decimal computers had groups of users too large to alienate. Even when designers used a binary system, they still had many odd ideas. Some used sign-magnitude arithmetic (-1 = 10001), or
ones' complement The ones' complement of a binary number is the value obtained by inverting all the bits in the binary representation of the number (swapping 0s and 1s). The name "ones' complement" (''note this is possessive of the plural "ones", not of a sing ...
(-1 = 11110), rather than modern
two's complement Two's complement is a mathematical operation to reversibly convert a positive binary number into a negative binary number with equivalent (but negative) value, using the binary digit with the greatest place value (the leftmost bit in big- endian ...
arithmetic (-1 = 11111). Most computers used six-bit character sets because they adequately encoded Hollerith
punched card A punched card (also punch card or punched-card) is a piece of stiff paper that holds digital data represented by the presence or absence of holes in predefined positions. Punched cards were once common in data processing applications or to di ...
s. It was a major revelation to designers of this period to realize that the data word should be a multiple of the character size. They began to design computers with 12-, 24- and 36-bit data words (e.g., see the
TX-2 The MIT Lincoln Laboratory TX-2 computer was the successor to the Lincoln TX-0 and was known for its role in advancing both artificial intelligence and human–computer interaction. Wesley A. Clark was the chief architect of the TX-2. Specific ...
). In this era,
Grosch's law Grosch's law is the following observation of computer performance, made by Herb Grosch in 1953: I believe that there is a fundamental rule, which I modestly call ''Grosch's law'', giving added economy only as the square root of the increase in spe ...
dominated computer design: computer cost increased as the square of its speed.


1960s: Computer revolution and CISC

One major problem with early computers was that a program for one would work on no others. Computer companies found that their customers had little reason to remain loyal to a given brand, as the next computer they bought would be incompatible anyway. At that point, the only concerns were usually price and performance. In 1962, IBM tried a new approach to designing computers. The plan was to make a family of computers that could all run the same software, but with different performances, and at different prices. As users' needs grew, they could move up to larger computers, and still keep all of their investment in programs, data and storage media. To do this, they designed one ''reference computer'' named ''
System/360 The IBM System/360 (S/360) is a family of mainframe computer systems that was announced by IBM on April 7, 1964, and delivered between 1965 and 1978. It was the first family of computers designed to cover both commercial and scientific applica ...
'' (S/360). This was a virtual computer, a reference instruction set, and abilities that all machines in the family would support. To provide different classes of machines, each computer in the family would use more or less hardware emulation, and more or less
microprogram In processor design, microcode (μcode) is a technique that interposes a layer of computer organization between the central processing unit (CPU) hardware and the programmer-visible instruction set architecture of a computer. Microcode is a lay ...
emulation, to create a machine able to run the full S/360
instruction set 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 by that ISA, such as a central processing unit (CPU), is called an ' ...
. For instance, a low-end machine could include a very simple processor for low cost. However this would require the use of a larger microcode emulator to provide the rest of the instruction set, which would slow it down. A high-end machine would use a much more complex processor that could directly process more of the S/360 design, thus running a much simpler and faster emulator. IBM chose consciously to make the reference
instruction set 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 by that ISA, such as a central processing unit (CPU), is called an ' ...
quite complex, and very capable. Even though the computer was complex, its ''
control store A control store is the part of a CPU's control unit that stores the CPU's microprogram. It is usually accessed by a microsequencer. A control store implementation whose contents are unalterable is known as a Read Only Memory (ROM) or Read Only Sto ...
'' holding the
microprogram In processor design, microcode (μcode) is a technique that interposes a layer of computer organization between the central processing unit (CPU) hardware and the programmer-visible instruction set architecture of a computer. Microcode is a lay ...
would stay relatively small, and could be made with very fast memory. Another important effect was that one instruction could describe quite a complex sequence of operations. Thus the computers would generally have to fetch fewer instructions from the main memory, which could be made slower, smaller and less costly for a given mix of speed and price. As the S/360 was to be a successor to both scientific machines like the 7090 and data processing machines like the
1401 Year 1401 ( MCDI) was a common year starting on Saturday (link will display the full calendar) of the Julian calendar. Events January–December * January 6 – Rupert, King of Germany, is crowned King of the Romans at Cologne. * ...
, it needed a design that could reasonably support all forms of processing. Hence the instruction set was designed to manipulate simple binary numbers, and text, scientific floating-point (similar to the numbers used in a calculator), and the
binary-coded decimal In computing and electronic systems, binary-coded decimal (BCD) is a class of binary encodings of decimal numbers where each digit is represented by a fixed number of bits, usually four or eight. Sometimes, special bit patterns are used for ...
arithmetic needed by accounting systems. Almost all following computers included these innovations in some form. This basic set of features is now called ''
complex instruction set computing A complex instruction set computer (CISC ) is a computer architecture in which single instructions can execute several low-level operations (such as a load from memory, an arithmetic operation, and a memory store) or are capable of multi-step o ...
'' (CISC, pronounced "sisk"), a term not invented until many years later, when ''
reduced instruction set computing In computer engineering, a reduced instruction set computer (RISC) is a computer designed to simplify the individual instructions given to the computer to accomplish tasks. Compared to the instructions given to a complex instruction set comput ...
'' (RISC) began to get market share. In many CISCs, an instruction could access either registers or memory, usually in several different ways. This made the CISCs easier to program, because a programmer could remember only thirty to a hundred instructions, and a set of three to ten
addressing mode Addressing modes are an aspect of the instruction set architecture in most central processing unit (CPU) designs. The various addressing modes that are defined in a given instruction set architecture define how the machine language instructions in ...
s rather than thousands of distinct instructions. This was called an ''
orthogonal instruction set In computer engineering, an orthogonal instruction set is an instruction set architecture where all instruction types can use all addressing modes. It is "orthogonal" in the sense that the instruction type and the addressing mode vary independentl ...
''. The
PDP-11 The PDP-11 is a series of 16-bit minicomputers sold by Digital Equipment Corporation (DEC) from 1970 into the 1990s, one of a set of products in the Programmed Data Processor (PDP) series. In total, around 600,000 PDP-11s of all models were sold, ...
and
Motorola 68000 The Motorola 68000 (sometimes shortened to Motorola 68k or m68k and usually pronounced "sixty-eight-thousand") is a 16/32-bit complex instruction set computer (CISC) microprocessor, introduced in 1979 by Motorola Semiconductor Products Sector ...
architecture are examples of nearly orthogonal instruction sets. There was also the ''
BUNCH Bunch may refer to: * Bunch (surname) * Bunch Davis (), American baseball player in the Negro leagues * BUNCH, nickname of five computer manufacturing companies, IBM's main competitors in the 1970s * Tussock (grass) or bunch grass, members of t ...
'' ( Burroughs,
UNIVAC UNIVAC (Universal Automatic Computer) was a line of electronic digital stored-program computers starting with the products of the Eckert–Mauchly Computer Corporation. Later the name was applied to a division of the Remington Rand company an ...
, NCR,
Control Data Corporation Control Data Corporation (CDC) was a mainframe and supercomputer firm. CDC was one of the nine major United States computer companies through most of the 1960s; the others were IBM, Burroughs Corporation, DEC, NCR, General Electric, Honeywel ...
, and
Honeywell Honeywell International Inc. is an American publicly traded, multinational conglomerate corporation headquartered in Charlotte, North Carolina. It primarily operates in four areas of business: aerospace, building technologies, performance ma ...
) that competed against IBM at this time; however, IBM dominated the era with S/360. The Burroughs Corporation (which later merged with Sperry/Univac to form
Unisys Unisys Corporation is an American multinational information technology (IT) services and consulting company headquartered in Blue Bell, Pennsylvania. It provides digital workplace solutions, cloud, applications, and infrastructure solutions, e ...
) offered an alternative to S/360 with their
Burroughs large systems The Burroughs Large Systems Group produced a family of large 48-bit mainframes using stack machine instruction sets with dense syllables.E.g., 12-bit syllables for B5000, 8-bit syllables for B6500 The first machine in the family was the B5000 in ...
B5000 series. In 1961, the B5000 had virtual memory, symmetric multiprocessing, a multiprogramming operating system (Master Control Program (MCP)), written in
ALGOL 60 ALGOL 60 (short for ''Algorithmic Language 1960'') is a member of the ALGOL family of computer programming languages. It followed on from ALGOL 58 which had introduced code blocks and the begin and end pairs for delimiting them, representing a k ...
, and the industry's first recursive-descent compilers as early as 1964.


1970s: Microprocessor revolution

The first commercial
microprocessor 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 circu ...
, the
binary-coded decimal In computing and electronic systems, binary-coded decimal (BCD) is a class of binary encodings of decimal numbers where each digit is represented by a fixed number of bits, usually four or eight. Sometimes, special bit patterns are used for ...
(BCD) based
Intel 4004 The Intel 4004 is a 4-bit central processing unit (CPU) released by Intel Corporation in 1971. Sold for US$60, it was the first commercially produced microprocessor, and the first in a long line of Intel CPUs. The 4004 was the first signific ...
, was released by
Intel Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California. It is the world's largest semiconductor chip manufacturer by revenue, and is one of the developers of the x86 seri ...
in 1971. In March 1972, Intel introduced a microprocessor with an
8-bit In computer architecture, 8-bit Integer (computer science), integers or other Data (computing), data units are those that are 8 bits wide (1 octet (computing), octet). Also, 8-bit central processing unit (CPU) and arithmetic logic unit (ALU) arc ...
architecture, the
8008 The Intel 8008 ("''eight-thousand-eight''" or "''eighty-oh-eight''") is an early byte-oriented microprocessor designed by Computer Terminal Corporation (CTC), implemented and manufactured by Intel, and introduced in April 1972. It is an 8-bit ...
, an integrated
pMOS logic PMOS or pMOS logic (from p-channel metal–oxide–semiconductor) is a family of digital circuits based on p-channel, enhancement mode metal–oxide–semiconductor field-effect transistors (MOSFETs). In the late 1960s and early 1970s, PMOS log ...
re-implementation of the
transistor–transistor logic Transistor–transistor logic (TTL) is a logic family built from bipolar junction transistors. Its name signifies that transistors perform both the logic function (the first "transistor") and the amplifying function (the second "transistor"), as opp ...
(TTL) based
Datapoint 2200 The Datapoint 2200 was a mass-produced programmable computer terminal usable as a computer, designed by Computer Terminal Corporation (CTC) founders Phil Ray and Gus Roche and announced by CTC in June 1970 (with units shipping in 1971). It was i ...
CPU. 4004 designers
Federico Faggin Federico Faggin (, ; born 1 December 1941) is an Italian physicist, engineer, inventor and entrepreneur. He is best known for designing the first commercial microprocessor, the Intel 4004. He led the 4004 (MCS-4) project and the design group du ...
and
Masatoshi Shima is a Japanese electronics engineer. He was one of the architects of the world's first microprocessor, the Intel 4004. In 1968, Shima worked for Busicom in Japan, and did the logic design for a specialized CPU to be translated into three-chip cu ...
went on to design the 8008's successor, the
Intel 8080 The Intel 8080 (''"eighty-eighty"'') is the second 8-bit microprocessor designed and manufactured by Intel. It first appeared in April 1974 and is an extended and enhanced variant of the earlier 8008 design, although without binary compatibil ...
, a slightly more
minicomputer A minicomputer, or colloquially mini, is a class of smaller general purpose computers that developed in the mid-1960s and sold at a much lower price than mainframe and mid-size computers from IBM and its direct competitors. In a 1970 survey, ...
-like microprocessor, largely based on customer feedback on the limited 8008. Much like the 8008, it was used for applications such as terminals, printers, cash registers and industrial robots. However, the more able 8080 also became the original target CPU for an early
de facto standard A ''de facto'' standard is a custom or convention that has achieved a dominant position by public acceptance or market forces (for example, by early entrance to the market). is a Latin phrase (literally " in fact"), here meaning "in practice b ...
personal computer A personal computer (PC) is a multi-purpose microcomputer whose size, capabilities, and price make it feasible for individual use. Personal computers are intended to be operated directly by an end user, rather than by a computer expert or tec ...
operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may also in ...
called
CP/M CP/M, originally standing for Control Program/Monitor and later Control Program for Microcomputers, is a mass-market operating system created in 1974 for Intel 8080/ 85-based microcomputers by Gary Kildall of Digital Research, Inc. Initial ...
and was used for such demanding control tasks as
cruise missile A cruise missile is a guided missile used against terrestrial or naval targets that remains in the atmosphere and flies the major portion of its flight path at approximately constant speed. Cruise missiles are designed to deliver a large warhe ...
s, and many other uses. Released in 1974, the 8080 became one of the first really widespread microprocessors. By the mid-1970s, the use of integrated circuits in computers was common. The decade was marked by market upheavals caused by the shrinking price of transistors. It became possible to put an entire CPU on one printed circuit board. The result was that minicomputers, usually with 16-bit words, and 4K to 64K of memory, became common. CISCs were believed to be the most powerful types of computers, because their microcode was small and could be stored in very high-speed memory. The CISC architecture also addressed the ''semantic gap'' as it was then perceived. This was a defined distance between the machine language, and the higher level programming languages used to program a machine. It was felt that compilers could do a better job with a richer instruction set. Custom CISCs were commonly constructed using ''bit slice'' computer logic such as the AMD 2900 chips, with custom microcode. A bit slice component is a piece of an
arithmetic logic unit In computing, an arithmetic logic unit (ALU) is a Combinational logic, combinational digital circuit that performs arithmetic and bitwise operations on integer binary numbers. This is in contrast to a floating-point unit (FPU), which operates on ...
(ALU), register file or microsequencer. Most bit-slice integrated circuits were 4 bits wide. By the early 1970s, the
16-bit 16-bit microcomputers are microcomputers that use 16-bit microprocessors. A 16-bit register can store 216 different values. The range of integer values that can be stored in 16 bits depends on the integer representation used. With the two mos ...
PDP-11 The PDP-11 is a series of 16-bit minicomputers sold by Digital Equipment Corporation (DEC) from 1970 into the 1990s, one of a set of products in the Programmed Data Processor (PDP) series. In total, around 600,000 PDP-11s of all models were sold, ...
minicomputer A minicomputer, or colloquially mini, is a class of smaller general purpose computers that developed in the mid-1960s and sold at a much lower price than mainframe and mid-size computers from IBM and its direct competitors. In a 1970 survey, ...
was developed, arguably the most advanced small computer of its day. In the late 1970's, wider-word
superminicomputer A superminicomputer, colloquially supermini, is a high-end minicomputer. The term is used to distinguish the emerging 32-bit architecture midrange computers introduced in the mid to late 1970s from the classical 16-bit systems that preceded the ...
s were introduced, such as the
32-bit In computer architecture, 32-bit computing refers to computer systems with a processor, memory, and other major system components that operate on data in 32-bit units. Compared to smaller bit widths, 32-bit computers can perform large calculation ...
VAX VAX (an acronym for Virtual Address eXtension) is a series of computers featuring a 32-bit instruction set architecture (ISA) and virtual memory that was developed and sold by Digital Equipment Corporation (DEC) in the late 20th century. The V ...
. IBM continued to make large, fast computers. However, the definition of large and fast now meant more than a megabyte of RAM, clock speeds near one megahertz, and tens of megabytes of disk drives. IBM's System 370 was a version of the 360 tweaked to run virtual computing environments. The
virtual computer In computing, a virtual machine (VM) is the virtualization/emulation of a computer system. Virtual machines are based on computer architectures and provide functionality of a physical computer. Their implementations may involve specialized hardw ...
was developed to reduce the chances of an unrecoverable software failure. The
Burroughs large systems The Burroughs Large Systems Group produced a family of large 48-bit mainframes using stack machine instruction sets with dense syllables.E.g., 12-bit syllables for B5000, 8-bit syllables for B6500 The first machine in the family was the B5000 in ...
(B5000, B6000, B7000) series reached its largest market share. It was a stack computer whose OS was programmed in a dialect of Algol. All these different developments competed for market share. The first single-chip
16-bit 16-bit microcomputers are microcomputers that use 16-bit microprocessors. A 16-bit register can store 216 different values. The range of integer values that can be stored in 16 bits depends on the integer representation used. With the two mos ...
microprocessor was introduced in 1975.
Panafacom Panafacom was a Japanese microprocessor design firm formed on 2 July 1973 by a consortium including Fujitsu, Fuji Electric and Matsushita (Panasonic). The company was formed to design and manufacture the MN1610, a 16-bit microprocessor. It was rel ...
, a conglomerate formed by Japanese companies
Fujitsu is a Japanese multinational information and communications technology equipment and services corporation, established in 1935 and headquartered in Tokyo. Fujitsu is the world's sixth-largest IT services provider by annual revenue, and the la ...
,
Fuji Electric , operating under the brand name FE, is a Japanese electrical equipment company, manufacturing pressure transmitters, flowmeters, gas analyzers, controllers, inverters, pumps, generators, ICs, motors, and power equipment. History Fuji Electric ...
, and Matsushita, introduced the MN1610, a commercial 16-bit microprocessor.PANAFACOM Lkit-16
Information Processing Society of Japan The Information Processing Society of Japan ("IPSJ") is a Japanese learned society for computing. Founded in 1960, it is headquartered in Tokyo, Japan. IPSJ publishes a magazine and several professional journals mainly in Japanese, and sponsors c ...
According to Fujitsu, it was "the world's first 16-bit
microcomputer A microcomputer is a small, relatively inexpensive computer having a central processing unit (CPU) made out of a microprocessor. The computer also includes memory and input/output (I/O) circuitry together mounted on a printed circuit board (PC ...
on a single chip". The Intel 8080 was the basis for the 16-bit Intel
8086 The 8086 (also called iAPX 86) is a 16-bit microprocessor chip designed by Intel between early 1976 and June 8, 1978, when it was released. The Intel 8088, released July 1, 1979, is a slightly modified chip with an external 8-bit data bus (allowi ...
, which is a direct ancestor to today's ubiquitous
x86 x86 (also known as 80x86 or the 8086 family) is a family of complex instruction set computer (CISC) instruction set architectures initially developed by Intel based on the Intel 8086 microprocessor and its 8088 variant. The 8086 was introd ...
family (including
Pentium Pentium is a brand used for a series of x86 architecture-compatible microprocessors produced by Intel. The original Pentium processor from which the brand took its name was first released on March 22, 1993. After that, the Pentium II and Pe ...
and
Core i7 The following is a list of Intel Core i7 brand microprocessors. Introduced in 2008, the Core i7 line of microprocessors are intended to be used by high-end users. Desktop processors Nehalem microarchitecture (1st generation) "Bloomfield" ...
). Every instruction of the 8080 has a direct equivalent in the large x86 instruction set, although the opcode values are different in the latter.


Early 1980s–1990s: Lessons of RISC

In the early 1980s, researchers at
UC Berkeley The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California) is a public university, public land-grant university, land-grant research university in Berkeley, California. Established in 1868 as the University of Californi ...
and IBM both discovered that most computer language compilers and interpreters used only a small subset of the instructions of
complex instruction set computing A complex instruction set computer (CISC ) is a computer architecture in which single instructions can execute several low-level operations (such as a load from memory, an arithmetic operation, and a memory store) or are capable of multi-step o ...
(CISC). Much of the power of the CPU was being ignored in real-world use. They realized that by making the computer simpler and less orthogonal, they could make it faster and less costly at the same time. At the same time, CPU calculation became faster in relation to the time for needed memory accesses. Designers also experimented with using large sets of internal registers. The goal was to
cache Cache, caching, or caché may refer to: Places United States * Cache, Idaho, an unincorporated community * Cache, Illinois, an unincorporated community * Cache, Oklahoma, a city in Comanche County * Cache, Utah, Cache County, Utah * Cache Count ...
intermediate results in the registers under the control of the compiler. This also reduced the number of
addressing mode Addressing modes are an aspect of the instruction set architecture in most central processing unit (CPU) designs. The various addressing modes that are defined in a given instruction set architecture define how the machine language instructions in ...
s and orthogonality. The computer designs based on this theory were called
reduced instruction set computing In computer engineering, a reduced instruction set computer (RISC) is a computer designed to simplify the individual instructions given to the computer to accomplish tasks. Compared to the instructions given to a complex instruction set comput ...
(RISC). RISCs usually had larger numbers of registers, accessed by simpler instructions, with a few instructions specifically to load and store data to memory. The result was a very simple core CPU running at very high speed, supporting the sorts of operations the compilers were using anyway. A common variant on the RISC design employs the
Harvard architecture The Harvard architecture is a computer architecture with separate storage and signal pathways for instructions and data. It contrasts with the von Neumann architecture, where program instructions and data share the same memory and pathways. ...
, versus
Von Neumann architecture The von Neumann architecture — also known as the von Neumann model or Princeton architecture — is a computer architecture based on a 1945 description by John von Neumann, and by others, in the ''First Draft of a Report on the EDVAC''. The ...
or stored program architecture common to most other designs. In a Harvard Architecture machine, the program and data occupy separate memory devices and can be accessed simultaneously. In Von Neumann machines, the data and programs are mixed in one memory device, requiring sequential accessing which produces the so-called ''
Von Neumann bottleneck The von Neumann architecture — also known as the von Neumann model or Princeton architecture — is a computer architecture based on a 1945 description by John von Neumann, and by others, in the ''First Draft of a Report on the EDVAC''. The ...
''. One downside to the RISC design was that the programs that run on them tend to be larger. This is because
compiler In computing, a compiler is a computer program that translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primarily used for programs that ...
s must generate longer sequences of the simpler instructions to perform the same results. Since these instructions must be loaded from memory anyway, the larger code offsets some of the RISC design's fast memory handling. In the early 1990s, engineers at Japan's
Hitachi () is a Japanese multinational corporation, multinational Conglomerate (company), conglomerate corporation headquartered in Chiyoda, Tokyo, Japan. It is the parent company of the Hitachi Group (''Hitachi Gurūpu'') and had formed part of the Ni ...
found ways to compress the reduced instruction sets so they fit in even smaller memory systems than CISCs. Such compression schemes were used for the instruction set of their
SuperH SuperH (or SH) is a 32-bit reduced instruction set computing (RISC) instruction set architecture (ISA) developed by Hitachi and currently produced by Renesas. It is implemented by microcontrollers and microprocessors for embedded systems. At t ...
series of microprocessors, introduced in 1992. The SuperH instruction set was later adapted for
ARM architecture ARM (stylised in lowercase as arm, formerly an acronym for Advanced RISC Machines and originally Acorn RISC Machine) is a family of reduced instruction set computer (RISC) instruction set architectures for computer processors, configured ...
's ''Thumb'' instruction set. In applications that do not need to run older binary software, compressed RISCs are growing to dominate sales. Another approach to RISCs was the
minimal instruction set computer Minimal instruction set computer (MISC) is a central processing unit (CPU) architecture, usually in the form of a microprocessor, with a very small number of basic operations and corresponding opcodes, together forming an instruction set. Such ...
(MISC), ''niladic'', or ''zero-operand'' instruction set. This approach realized that most space in an instruction was used to identify the operands of the instruction. These machines placed the operands on a push-down (last-in, first out)
stack Stack may refer to: Places * Stack Island, an island game reserve in Bass Strait, south-eastern Australia, in Tasmania’s Hunter Island Group * Blue Stack Mountains, in Co. Donegal, Ireland People * Stack (surname) (including a list of people ...
. The instruction set was supplemented with a few instructions to fetch and store memory. Most used simple caching to provide extremely fast RISC machines, with very compact code. Another benefit was that the interrupt latencies were very small, smaller than most CISC machines (a rare trait in RISC machines). The
Burroughs large systems The Burroughs Large Systems Group produced a family of large 48-bit mainframes using stack machine instruction sets with dense syllables.E.g., 12-bit syllables for B5000, 8-bit syllables for B6500 The first machine in the family was the B5000 in ...
architecture used this approach. The B5000 was designed in 1961, long before the term ''RISC'' was invented. The architecture puts six 8-bit instructions in a 48-bit word, and was a precursor to ''
very long instruction word 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 exe ...
'' (VLIW) design (see below: 1990 to today). The Burroughs architecture was one of the inspirations for
Charles H. Moore Charles Havice Moore II (born 9 September 1938), better known as Chuck Moore, is an American computer engineer and programmer, best known for inventing the Forth programming language in 1968. He cofounded FORTH, Inc., with Elizabeth Rather in ...
's programming language
Forth Forth or FORTH may refer to: Arts and entertainment * ''forth'' magazine, an Internet magazine * ''Forth'' (album), by The Verve, 2008 * ''Forth'', a 2011 album by Proto-Kaw * Radio Forth, a group of independent local radio stations in Scotla ...
, which in turn inspired his later MISC chip designs. For example, his f20 cores had 31 5-bit instructions, which fit four to a 20-bit word. RISC chips now dominate the market for 32-bit embedded systems. Smaller RISC chips are even growing common in the cost-sensitive 8-bit embedded-system market. The main market for RISC CPUs has been systems that need low power or small size. Even some CISC processors (based on architectures that were created before RISC grew dominant), such as newer
x86 x86 (also known as 80x86 or the 8086 family) is a family of complex instruction set computer (CISC) instruction set architectures initially developed by Intel based on the Intel 8086 microprocessor and its 8088 variant. The 8086 was introd ...
processors, translate instructions internally into a RISC-like instruction set. These numbers may surprise many, because the ''market'' is perceived as desktop computers. x86 designs dominate desktop and notebook computer sales, but such computers are only a tiny fraction of the computers now sold. Most people in industrialised countries own more computers in embedded systems in their car and house, than on their desks.


Mid-to-late 1980s: Exploiting instruction level parallelism

In the mid-to-late 1980s, designers began using a technique termed ''
instruction pipelining In computer engineering, instruction pipelining or ILP is a technique for implementing instruction-level parallelism within a single processor. Pipelining attempts to keep every part of the processor busy with some instruction by dividing inco ...
'', in which the processor works on multiple instructions in different stages of completion. For example, the processor can retrieve the operands for the next instruction while calculating the result of the current one. Modern CPUs may use over a dozen such stages. (Pipelining was originally developed in the late 1950s by International Business Machines (IBM) on their 7030 (Stretch) mainframe computer.)
Minimal instruction set computer Minimal instruction set computer (MISC) is a central processing unit (CPU) architecture, usually in the form of a microprocessor, with a very small number of basic operations and corresponding opcodes, together forming an instruction set. Such ...
s (MISC) can execute instructions in one cycle with no need for pipelining. A similar idea, introduced only a few years later, was to execute multiple instructions in parallel on separate
arithmetic logic unit In computing, an arithmetic logic unit (ALU) is a Combinational logic, combinational digital circuit that performs arithmetic and bitwise operations on integer binary numbers. This is in contrast to a floating-point unit (FPU), which operates on ...
s (ALUs). Instead of operating on only one instruction at a time, the CPU will look for several similar instructions that do not depend on each other, and execute them in parallel. This approach is called
superscalar A superscalar processor is a CPU that implements a form of parallelism called instruction-level parallelism within a single processor. In contrast to a scalar processor, which can execute at most one single instruction per clock cycle, a sup ...
processor design. Such methods are limited by the degree of
instruction level parallelism Instruction-level parallelism (ILP) is the parallel or simultaneous execution of a sequence of instructions in a computer program. More specifically ILP refers to the average number of instructions run per step of this parallel execution. Disc ...
(ILP), the number of non-dependent instructions in the program code. Some programs can run very well on superscalar processors due to their inherent high ILP, notably graphics. However, more general problems have far less ILP, thus lowering the possible speedups from these methods. Branching is one major culprit. For example, a program may add two numbers and branch to a different code segment if the number is bigger than a third number. In this case, even if the branch operation is sent to the second ALU for processing, it still must wait for the results from the addition. It thus runs no faster than if there was only one ALU. The most common solution for this type of problem is to use a type of
branch prediction In computer architecture, a branch predictor is a digital circuit that tries to guess which way a branch (e.g., an if–then–else structure) will go before this is known definitively. The purpose of the branch predictor is to improve the flow ...
. To further the efficiency of multiple functional units which are available in
superscalar A superscalar processor is a CPU that implements a form of parallelism called instruction-level parallelism within a single processor. In contrast to a scalar processor, which can execute at most one single instruction per clock cycle, a sup ...
designs, operand register dependencies were found to be another limiting factor. To minimize these dependencies,
out-of-order execution In computer engineering, out-of-order execution (or more formally dynamic execution) is a paradigm used in most high-performance central processing units to make use of instruction cycles that would otherwise be wasted. In this paradigm, a proce ...
of instructions was introduced. In such a scheme, the instruction results which complete out-of-order must be re-ordered in program order by the processor for the program to be restartable after an exception. Out-of-order execution was the main advance of the computer industry during the 1990s. A similar concept is
speculative execution Speculative execution is an optimization technique where a computer system performs some task that may not be needed. Work is done before it is known whether it is actually needed, so as to prevent a delay that would have to be incurred by doing t ...
, where instructions from one direction of a branch (the predicted direction) are executed before the branch direction is known. When the branch direction is known, the predicted direction and the actual direction are compared. If the predicted direction was correct, the speculatively executed instructions and their results are kept; if it was incorrect, these instructions and their results are erased. Speculative execution, coupled with an accurate branch predictor, gives a large performance gain. These advances, which were originally developed from research for RISC-style designs, allow modern CISC processors to execute twelve or more instructions per clock cycle, when traditional CISC designs could take twelve or more cycles to execute one instruction. The resulting instruction scheduling logic of these processors is large, complex and difficult to verify. Further, higher complexity needs more transistors, raising power consumption and heat. In these, RISC is superior because the instructions are simpler, have less interdependence, and make superscalar implementations easier. However, as Intel has demonstrated, the concepts can be applied to a
complex instruction set computing A complex instruction set computer (CISC ) is a computer architecture in which single instructions can execute several low-level operations (such as a load from memory, an arithmetic operation, and a memory store) or are capable of multi-step o ...
(CISC) design, given enough time and money.


1990 to today: Looking forward


VLIW and EPIC

The instruction scheduling logic that makes a superscalar processor is boolean logic. In the early 1990s, a significant innovation was to realize that the coordination of a multi-ALU computer could be moved into the
compiler In computing, a compiler is a computer program that translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primarily used for programs that ...
, the software that translates a programmer's instructions into machine-level instructions. This type of computer is called a ''
very long instruction word 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 exe ...
'' (VLIW) computer. Scheduling instructions statically in the compiler (versus scheduling dynamically in the processor) can reduce CPU complexity. This can improve performance, and reduce heat and cost. Unfortunately, the compiler lacks accurate knowledge of runtime scheduling issues. Merely changing the CPU core frequency multiplier will have an effect on scheduling. Operation of the program, as determined by input data, will have major effects on scheduling. To overcome these severe problems, a VLIW system may be enhanced by adding the normal dynamic scheduling, losing some of the VLIW advantages. Static scheduling in the compiler also assumes that dynamically generated code will be uncommon. Before the creation of
Java Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's List ...
and the
Java virtual machine A Java virtual machine (JVM) is a virtual machine that enables a computer to run Java programs as well as programs written in other languages that are also compiled to Java bytecode. The JVM is detailed by a specification that formally describes ...
, this was true. It was reasonable to assume that slow compiles would only affect software developers. Now, with
just-in-time compilation In computing, just-in-time (JIT) compilation (also dynamic translation or run-time compilations) is a way of executing computer code that involves compilation during execution of a program (at run time) rather than before execution. This may cons ...
(JIT) virtual machines being used for many languages, slow code generation affects users also. There were several unsuccessful attempts to commercialize VLIW. The basic problem is that a VLIW computer does not scale to different price and performance points, as a dynamically scheduled computer can. Another issue is that compiler design for VLIW computers is very difficult, and compilers, as of 2005, often emit suboptimal code for these platforms. Also, VLIW computers optimise for throughput, not low latency, so they were unattractive to engineers designing controllers and other computers embedded in machinery. The
embedded system An embedded system is a computer system—a combination of a computer processor, computer memory, and input/output peripheral devices—that has a dedicated function within a larger mechanical or electronic system. It is ''embedded'' as ...
s markets had often pioneered other computer improvements by providing a large market unconcerned about compatibility with older software. In January 2000,
Transmeta Corporation Transmeta Corporation was an American fabless semiconductor company based in Santa Clara, California. It developed low power x86 compatible microprocessors based on a VLIW core and a software layer called Code Morphing Software. Code Morphing So ...
took the novel step of placing a compiler in the central processing unit, and making the compiler translate from a reference byte code (in their case,
x86 x86 (also known as 80x86 or the 8086 family) is a family of complex instruction set computer (CISC) instruction set architectures initially developed by Intel based on the Intel 8086 microprocessor and its 8088 variant. The 8086 was introd ...
instructions) to an internal VLIW instruction set. This method combines the hardware simplicity, low power and speed of VLIW RISC with the compact main memory system and software reverse-compatibility provided by popular CISC.
Intel Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California. It is the world's largest semiconductor chip manufacturer by revenue, and is one of the developers of the x86 seri ...
's
Itanium Itanium ( ) is a discontinued family of 64-bit Intel microprocessors that implement the Intel Itanium architecture (formerly called IA-64). Launched in June 2001, Intel marketed the processors for enterprise servers and high-performance computin ...
chip is based on what they call an
explicitly parallel instruction computing Explicitly parallel instruction computing (EPIC) is a term coined in 1997 by the HP–Intel alliance to describe a computing paradigm that researchers had been investigating since the early 1980s. This paradigm is also called ''Independence'' a ...
(EPIC) design. This design supposedly provides the VLIW advantage of increased instruction throughput. However, it avoids some of the issues of scaling and complexity, by explicitly providing in each ''bundle'' of instructions information concerning their dependencies. This information is calculated by the compiler, as it would be in a VLIW design. The early versions are also backward-compatible with newer
x86 x86 (also known as 80x86 or the 8086 family) is a family of complex instruction set computer (CISC) instruction set architectures initially developed by Intel based on the Intel 8086 microprocessor and its 8088 variant. The 8086 was introd ...
software by means of an on-chip
emulator In computing, an emulator is Computer hardware, hardware or software that enables one computer system (called the ''host'') to behave like another computer system (called the ''guest''). An emulator typically enables the host system to run so ...
mode. Integer performance was disappointing and despite improvements, sales in volume markets continue to be low.


Multi-threading

Current designs work best when the computer is running only one program. However, nearly all modern
operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may also in ...
s allow running multiple programs together. For the CPU to change over and do work on another program needs costly
context switching In computing, a context switch is the process of storing the state of a process or thread, so that it can be restored and resume execution at a later point, and then restoring a different, previously saved, state. This allows multiple processes ...
. In contrast, multi-threaded CPUs can handle instructions from multiple programs at once. To do this, such CPUs include several sets of registers. When a context switch occurs, the contents of the ''working registers'' are simply copied into one of a set of registers for this purpose. Such designs often include thousands of registers instead of hundreds as in a typical design. On the downside, registers tend to be somewhat costly in chip space needed to implement them. This chip space might be used otherwise for some other purpose. Intel calls this technology "hyperthreading" and offers two threads per core in its current Core i3, Core i5, Core i7 and Core i9 Desktop lineup (as well as in its Core i3, Core i5 and Core i7 Mobile lineup), as well as offering up to four threads per core in high-end Xeon Phi processors.


Multi-core

Multi-core CPUs are typically multiple CPU cores on the same die, connected to each other via a shared L2 or L3 cache, an on-die
bus A bus (contracted from omnibus, with variants multibus, motorbus, autobus, etc.) is a road vehicle that carries significantly more passengers than an average car or van. It is most commonly used in public transport, but is also in use for cha ...
, or an on-die
crossbar switch In electronics and telecommunications, a crossbar switch (cross-point switch, matrix switch) is a collection of switches arranged in a matrix configuration. A crossbar switch has multiple input and output lines that form a crossed pattern of int ...
. All the CPU cores on the die share interconnect components with which to interface to other processors and the rest of the system. These components may include a
front-side bus A front-side bus (FSB) is a computer communication interface (bus) that was often used in Intel-chip-based computers during the 1990s and 2000s. The EV6 bus served the same function for competing AMD CPUs. Both typically carry data between the ...
interface, a
memory controller The memory controller is a digital circuit that manages the flow of data going to and from the computer's main memory. A memory controller can be a separate chip or integrated into another chip, such as being placed on the same die or as an int ...
to interface with
dynamic random access memory Dynamic random-access memory (dynamic RAM or DRAM) is a type of random-access semiconductor memory that stores each bit of data in a memory cell, usually consisting of a tiny capacitor and a transistor, both typically based on metal-oxid ...
(DRAM), a cache coherent link to other processors, and a non-coherent link to the southbridge and I/O devices. The terms ''
multi-core A multi-core processor is a microprocessor on a single integrated circuit with two or more separate processing units, called cores, each of which reads and executes program instructions. The instructions are ordinary CPU instructions (such a ...
'' and ''
microprocessor 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 circu ...
unit'' (MPU) have come into general use for one die having multiple CPU cores.


Intelligent RAM

One way to work around the
Von Neumann bottleneck The von Neumann architecture — also known as the von Neumann model or Princeton architecture — is a computer architecture based on a 1945 description by John von Neumann, and by others, in the ''First Draft of a Report on the EDVAC''. The ...
is to mix a processor and DRAM all on one chip. * The Berkeley IRAM Project *
eDRAM Embedded DRAM (eDRAM) is dynamic random-access memory (DRAM) integrated on the same die or multi-chip module (MCM) of an application-specific integrated circuit (ASIC) or microprocessor. eDRAM's cost-per-bit is higher when compared to equivalen ...
*
Computational RAM Computational RAM (C-RAM) is random-access memory with central processing unit, processing elements integrated on the same chip. This enables C-RAM to be used as a SIMD computer. It also can be used to more efficiently use memory bandwidth within ...
*
Memristor A memristor (; a portmanteau of ''memory resistor'') is a non-linear two-terminal electrical component relating electric charge and magnetic flux linkage. It was described and named in 1971 by Leon Chua, completing a theoretical quartet of fu ...


Reconfigurable logic

Another track of development is to combine reconfigurable logic with a general-purpose CPU. In this scheme, a special computer language compiles fast-running subroutines into a bit-mask to configure the logic. Slower, or less-critical parts of the program can be run by sharing their time on the CPU. This process allows creating devices such as software
radio Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmit ...
s, by using digital signal processing to perform functions usually performed by analog
electronics The field of electronics is a branch of physics and electrical engineering that deals with the emission, behaviour and effects of electrons using electronic devices. Electronics uses active devices to control electron flow by amplification ...
.


Open source processors

As the lines between hardware and software increasingly blur due to progress in design methodology and availability of chips such as
field-programmable gate array A field-programmable gate array (FPGA) is an integrated circuit designed to be configured by a customer or a designer after manufacturinghence the term '' field-programmable''. The FPGA configuration is generally specified using a hardware d ...
s (FPGA) and cheaper production processes, even
open source hardware Open-source hardware (OSH) consists of physical artifacts of technology designed and offered by the open-design movement. Both free and open-source software (FOSS) and open-source hardware are created by this open-source culture movement and a ...
has begun to appear. Loosely knit communities like
OpenCores OpenCores is a community developing digital open-source hardware through electronic design automation (EDA), with a similar ethos as the free software movement. OpenCores hopes to eliminate redundant design work and slash development costs. A nu ...
and
RISC-V RISC-V (pronounced "risk-five" where five refers to the number of generations of RISC architecture that were developed at the University of California, Berkeley since 1981) is an open standard instruction set architecture (ISA) based on estab ...
have recently announced fully open CPU architectures such as the
OpenRISC OpenRISC is a project to develop a series of open-source hardware based central processing units (CPUs) on established reduced instruction set computer (RISC) principles. It includes an instruction set architecture (ISA) using an open-source licen ...
which can be readily implemented on FPGAs or in custom produced chips, by anyone, with no license fees, and even established processor makers like
Sun Microsystems Sun Microsystems, Inc. (Sun for short) was an American technology company that sold computers, computer components, software, and information technology services and created the Java programming language, the Solaris operating system, ZFS, the ...
have released processor designs (e.g.,
OpenSPARC OpenSPARC is an open-source hardware project started in December 2005. The initial contribution to the project was Sun Microsystems' register-transfer level (RTL) Verilog code for a full 64-bit, 32- thread microprocessor, the UltraSPARC T1 processor ...
) under open-source licenses.


Asynchronous CPUs

Yet another option is a ''clockless'' or ''
asynchronous CPU Asynchronous circuit (clockless or self-timed circuit) is a sequential digital logic circuit that does not use a global clock circuit or signal generator to synchronize its components. Instead, the components are driven by a handshaking circu ...
''. Unlike conventional processors, clockless processors have no central clock to coordinate the progress of data through the pipeline. Instead, stages of the CPU are coordinated using logic devices called ''pipe line controls'' or ''FIFO sequencers''. Basically, the pipeline controller clocks the next stage of logic when the existing stage is complete. Thus, a central clock is unneeded. Relative to clocked logic, it may be easier to implement high performance devices in asynchronous logic: * In a clocked CPU, no component can run faster than the clock rate. In a clockless CPU, components can run at different speeds. * In a clocked CPU, the clock can go no faster than the worst-case performance of the slowest stage. In a clockless CPU, when a stage finishes faster than normal, the next stage can immediately take the results rather than waiting for the next clock tick. A stage might finish faster than normal because of the type of data inputs (e.g., multiplication can be very fast if it occurs by 0 or 1), or because it is running at a higher voltage or lower temperature than normal. Asynchronous logic proponents believe these abilities would have these benefits: * lower power dissipation for a given performance * highest possible execution speeds The biggest disadvantage of the clockless CPU is that most CPU design tools assume a clocked CPU (a
synchronous circuit In digital electronics, a synchronous circuit is a digital circuit in which the changes in the state of memory elements are synchronized by a clock signal. In a sequential digital logic circuit, data are stored in memory devices called flip-fl ...
), so making a clockless CPU (designing an
asynchronous circuit Asynchronous circuit (clockless or self-timed circuit) is a sequential digital logic circuit that does not use a global clock circuit or signal generator to synchronize its components. Instead, the components are driven by a handshaking circuit ...
) involves modifying the design tools to handle clockless logic and doing extra testing to ensure the design avoids
metastability In chemistry and physics, metastability denotes an intermediate Energy level, energetic state within a dynamical system other than the system's ground state, state of least energy. A ball resting in a hollow on a slope is a simple example of me ...
problems. Even so, several asynchronous CPUs have been built, including * the
ORDVAC The ORDVAC (''Ordnance Discrete Variable Automatic Computer)'', is an early computer built by the University of Illinois for the Ballistic Research Laboratory at Aberdeen Proving Ground. A successor to the ENIAC (along with EDVAC built earlier). ...
and the identical
ILLIAC I The ILLIAC I (Illinois Automatic Computer), a pioneering computer in the ILLIAC series of computers built in 1952 by the University of Illinois, was the first computer built and owned entirely by a United States educational institution. Computer ...
(1951) * the
ILLIAC II The ILLIAC II was a revolutionary super-computer built by the University of Illinois that became operational in 1962. Description The concept, proposed in 1958, pioneered Emitter-coupled logic (ECL) circuitry, pipelining, and transistor memory ...
(1962), then the fastest computer on Earth * The Caltech Asynchronous Microprocessor, the world-first asynchronous microprocessor (1988) * the
ARM In human anatomy, the arm refers to the upper limb in common usage, although academically the term specifically means the upper arm between the glenohumeral joint (shoulder joint) and the elbow joint. The distal part of the upper limb between the ...
-implementing
AMULET An amulet, also known as a good luck charm or phylactery, is an object believed to confer protection upon its possessor. The word "amulet" comes from the Latin word amuletum, which Pliny's ''Natural History'' describes as "an object that protects ...
(1993 and 2000) * the asynchronous implementation of
MIPS Technologies MIPS Technologies, Inc., formerly MIPS Computer Systems, Inc., was an American fabless semiconductor design company that is most widely known for developing the MIPS architecture and a series of RISC CPU chips based on it. MIPS provides proce ...
R3000 The R3000 is a 32-bit RISC microprocessor chipset developed by MIPS Computer Systems that implemented the MIPS I instruction set architecture (ISA). Introduced in June 1988, it was the second MIPS implementation, succeeding the R2000 as the flags ...
, named MiniMIPS (1998) * the SEAforth
multi-core A multi-core processor is a microprocessor on a single integrated circuit with two or more separate processing units, called cores, each of which reads and executes program instructions. The instructions are ordinary CPU instructions (such a ...
processor from
Charles H. Moore Charles Havice Moore II (born 9 September 1938), better known as Chuck Moore, is an American computer engineer and programmer, best known for inventing the Forth programming language in 1968. He cofounded FORTH, Inc., with Elizabeth Rather in ...


Optical communication

One promising option is to eliminate the
front-side bus A front-side bus (FSB) is a computer communication interface (bus) that was often used in Intel-chip-based computers during the 1990s and 2000s. The EV6 bus served the same function for competing AMD CPUs. Both typically carry data between the ...
. Modern vertical
laser diode file:Laser diode chip.jpg, The laser diode chip removed and placed on the eye of a needle for scale A laser diode (LD, also injection laser diode or ILD, or diode laser) is a semiconductor device similar to a light-emitting diode in which a di ...
s enable this change. In theory, an optical computer's components could directly connect through a holographic or phased open-air switching system. This would provide a large increase in effective speed and design flexibility, and a large reduction in cost. Since a computer's connectors are also its most likely failure points, a busless system may be more reliable. Further, as of 2010, modern processors use 64- or 128-bit logic. Optical wavelength superposition could allow data lanes and logic many orders of magnitude higher than electronics, with no added space or copper wires.


Optical processors

Another long-term option is to use light instead of electricity for digital logic. In theory, this could run about 30% faster and use less power, and allow a direct interface with quantum computing devices. The main problems with this approach are that, for the foreseeable future, electronic computing elements are faster, smaller, cheaper, and more reliable. Such elements are already smaller than some wavelengths of light. Thus, even waveguide-based optical logic may be uneconomic relative to electronic logic. As of 2016, most development effort is for electronic circuitry.


Ionic processors

Early experimental work has been done on using ion-based chemical reactions instead of electronic or photonic actions to implement elements of a logic processor.


Belt machine architecture

Relative to conventional
register machine In mathematical logic and theoretical computer science a register machine is a generic class of abstract machines used in a manner similar to a Turing machine. All the models are Turing equivalent. Overview The register machine gets its name from ...
or
stack machine In computer science, computer engineering and programming language implementations, a stack machine is a computer processor or a virtual machine in which the primary interaction is moving short-lived temporary values to and from a push down st ...
architecture, yet similar to Intel's
Itanium Itanium ( ) is a discontinued family of 64-bit Intel microprocessors that implement the Intel Itanium architecture (formerly called IA-64). Launched in June 2001, Intel marketed the processors for enterprise servers and high-performance computin ...
architecture, a temporal register addressing scheme has been proposed by Ivan Godard and company that is intended to greatly reduce the complexity of CPU hardware (specifically the number of internal registers and the resulting huge
multiplexer In electronics, a multiplexer (or mux; spelled sometimes as multiplexor), also known as a data selector, is a device that selects between several analog or digital input signals and forwards the selected input to a single output line. The sel ...
trees). While somewhat harder to read and debug than general-purpose register names, it aids understanding to view the belt as a moving ''
conveyor belt A conveyor belt is the carrying medium of a belt conveyor system (often shortened to belt conveyor). A belt conveyor system is one of many types of conveyor systems. A belt conveyor system consists of two or more pulleys (sometimes referred to ...
'' where the oldest values ''drop off'' the belt and vanish. It is implemented in the Mill architecture.


Timeline of events

* 1964. IBM release the 32-bit
IBM System/360 The IBM System/360 (S/360) is a family of mainframe computer systems that was announced by IBM on April 7, 1964, and delivered between 1965 and 1978. It was the first family of computers designed to cover both commercial and scientific applica ...
with memory protection. * 1969.
Intel 4004 The Intel 4004 is a 4-bit central processing unit (CPU) released by Intel Corporation in 1971. Sold for US$60, it was the first commercially produced microprocessor, and the first in a long line of Intel CPUs. The 4004 was the first signific ...
's initial design led by Intel's Ted Hoff and
Busicom was a Japanese company that manufactured and sold computer-related products headquartered in Taito, Tokyo. It owned the rights to Intel's first microprocessor, the Intel 4004, which they created in partnership with Intel in 1970. Busicom ask ...
's
Masatoshi Shima is a Japanese electronics engineer. He was one of the architects of the world's first microprocessor, the Intel 4004. In 1968, Shima worked for Busicom in Japan, and did the logic design for a specialized CPU to be translated into three-chip cu ...
.
Federico Faggin Federico Faggin (, ; born 1 December 1941) is an Italian physicist, engineer, inventor and entrepreneur. He is best known for designing the first commercial microprocessor, the Intel 4004. He led the 4004 (MCS-4) project and the design group du ...

The Making of the First Microprocessor
''IEEE Solid-State Circuits Magazine'', Winter 2009,
IEEE Xplore IEEE Xplore digital library is a research database for discovery and access to journal articles, conference proceedings, technical standards, and related materials on computer science, electrical engineering and electronics, and allied fields. It ...
* 1970. Intel 4004's design completed by Intel's
Federico Faggin Federico Faggin (, ; born 1 December 1941) is an Italian physicist, engineer, inventor and entrepreneur. He is best known for designing the first commercial microprocessor, the Intel 4004. He led the 4004 (MCS-4) project and the design group du ...
and Busicom's Masatoshi Shima. * 1971. IBM release the
IBM System/370 The IBM System/370 (S/370) is a model range of IBM mainframe computers announced on June 30, 1970, as the successors to the System/360 family. The series mostly maintains backward compatibility with the S/360, allowing an easy migration path f ...
successor to System/360. * 1971.
Intel Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California. It is the world's largest semiconductor chip manufacturer by revenue, and is one of the developers of the x86 seri ...
release the 4-bit
Intel 4004 The Intel 4004 is a 4-bit central processing unit (CPU) released by Intel Corporation in 1971. Sold for US$60, it was the first commercially produced microprocessor, and the first in a long line of Intel CPUs. The 4004 was the first signific ...
, the first commercial
microprocessor 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 circu ...
. * 1971.
NEC is a Japanese multinational corporation, multinational information technology and electronics corporation, headquartered in Minato, Tokyo. The company was known as the Nippon Electric Company, Limited, before rebranding in 1983 as NEC. It prov ...
release the μPD707 and μPD708, a two-chip 4-bit CPU. * 1972. IBM announce "System/370 Advanced Function", adding support for
virtual memory In computing, virtual memory, or virtual storage is a memory management technique that provides an "idealized abstraction of the storage resources that are actually available on a given machine" which "creates the illusion to users of a very l ...
with
demand paging In computer operating systems, demand paging (as opposed to anticipatory paging) is a method of virtual memory management. In a system that uses demand paging, the operating system copies a disk page into physical memory only if an attempt is mad ...
* 1972. NEC release single-chip 4-bit microprocessor, μPD700.1970年代 マイコンの開発と発展 ~集積回路Semiconductor History Museum of Japan
/ref>Jeffrey A. Hart & Sangbae Kim (2001)
The Defense of Intellectual Property Rights in the Global Information Order
International Studies Association, Chicago
* 1973. NEC release 4-bit μCOM-4 (μPD751), combining the μPD707 and μPD708 into a single microprocessor. * 1974. Intel release the
Intel 8080 The Intel 8080 (''"eighty-eighty"'') is the second 8-bit microprocessor designed and manufactured by Intel. It first appeared in April 1974 and is an extended and enhanced variant of the earlier 8008 design, although without binary compatibil ...
, an
8-bit In computer architecture, 8-bit Integer (computer science), integers or other Data (computing), data units are those that are 8 bits wide (1 octet (computing), octet). Also, 8-bit central processing unit (CPU) and arithmetic logic unit (ALU) arc ...
microprocessor, designed by
Federico Faggin Federico Faggin (, ; born 1 December 1941) is an Italian physicist, engineer, inventor and entrepreneur. He is best known for designing the first commercial microprocessor, the Intel 4004. He led the 4004 (MCS-4) project and the design group du ...
and
Masatoshi Shima is a Japanese electronics engineer. He was one of the architects of the world's first microprocessor, the Intel 4004. In 1968, Shima worked for Busicom in Japan, and did the logic design for a specialized CPU to be translated into three-chip cu ...
. * 1975.
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 mo ...
release the 8-bit
MOS Technology 6502 The MOS Technology 6502 (typically pronounced "sixty-five-oh-two" or "six-five-oh-two") William Mensch and the moderator both pronounce the 6502 microprocessor as ''"sixty-five-oh-two"''. is an 8-bit microprocessor that was designed by a small t ...
, the first integrated processor to have an affordable price of $25 when the 6800 rival was $175. * 1976.
Zilog Zilog, Inc. is an American manufacturer of microprocessors and 8-bit and 16-bit microcontrollers. It is also a supplier of application-specific embedded system-on-chip (SoC) products. Its most famous product is the Z80 series of 8-bit microp ...
introduce the 8-bit
Zilog Z80 The Z80 is an 8-bit microprocessor introduced by Zilog as the startup company's first product. The Z80 was conceived by Federico Faggin in late 1974 and developed by him and his 11 employees starting in early 1975. The first working samples wer ...
, designed by
Federico Faggin Federico Faggin (, ; born 1 December 1941) is an Italian physicist, engineer, inventor and entrepreneur. He is best known for designing the first commercial microprocessor, the Intel 4004. He led the 4004 (MCS-4) project and the design group du ...
and
Masatoshi Shima is a Japanese electronics engineer. He was one of the architects of the world's first microprocessor, the Intel 4004. In 1968, Shima worked for Busicom in Japan, and did the logic design for a specialized CPU to be translated into three-chip cu ...
. * 1977.
Digital Equipment Corporation Digital Equipment Corporation (DEC ), using the trademark Digital, was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president unt ...
introduced its first
32-bit In computer architecture, 32-bit computing refers to computer systems with a processor, memory, and other major system components that operate on data in 32-bit units. Compared to smaller bit widths, 32-bit computers can perform large calculation ...
VAX VAX (an acronym for Virtual Address eXtension) is a series of computers featuring a 32-bit instruction set architecture (ISA) and virtual memory that was developed and sold by Digital Equipment Corporation (DEC) in the late 20th century. The V ...
superminicomputer A superminicomputer, colloquially supermini, is a high-end minicomputer. The term is used to distinguish the emerging 32-bit architecture midrange computers introduced in the mid to late 1970s from the classical 16-bit systems that preceded the ...
, the
VAX-11 The VAX-11 is a discontinued family of 32-bit superminicomputers, running the Virtual Address eXtension (VAX) instruction set architecture (ISA), developed and manufactured by Digital Equipment Corporation (DEC). Development began in 1976. In a ...
/780. * 1978. Intel introduces the
Intel 8086 The 8086 (also called iAPX 86) is a 16-bit microprocessor chip designed by Intel between early 1976 and June 8, 1978, when it was released. The Intel 8088, released July 1, 1979, is a slightly modified chip with an external 8-bit data bus (allowi ...
and
Intel 8088 The Intel 8088 ("''eighty-eighty-eight''", also called iAPX 88) microprocessor is a variant of the Intel 8086. Introduced on June 1, 1979, the 8088 has an eight-bit external data bus instead of the 16-bit bus of the 8086. The 16-bit registers an ...
, the first x86 chips. * 1978.
Fujitsu is a Japanese multinational information and communications technology equipment and services corporation, established in 1935 and headquartered in Tokyo. Fujitsu is the world's sixth-largest IT services provider by annual revenue, and the la ...
releases the MB8843 microprocessor. * 1979.
Zilog Zilog, Inc. is an American manufacturer of microprocessors and 8-bit and 16-bit microcontrollers. It is also a supplier of application-specific embedded system-on-chip (SoC) products. Its most famous product is the Z80 series of 8-bit microp ...
release the
Zilog Z8000 The Z8000 ("''zee-'' or ''zed-eight-thousand''") is a 16-bit microprocessor introduced by Zilog in early 1979. The architecture was designed by Bernard Peuto while the logic and physical implementation was done by Masatoshi Shima, assisted by a ...
, a 16-bit microprocessor, designed by
Federico Faggin Federico Faggin (, ; born 1 December 1941) is an Italian physicist, engineer, inventor and entrepreneur. He is best known for designing the first commercial microprocessor, the Intel 4004. He led the 4004 (MCS-4) project and the design group du ...
and
Masatoshi Shima is a Japanese electronics engineer. He was one of the architects of the world's first microprocessor, the Intel 4004. In 1968, Shima worked for Busicom in Japan, and did the logic design for a specialized CPU to be translated into three-chip cu ...
. * 1979.
Motorola Motorola, Inc. () was an American Multinational corporation, multinational telecommunications company based in Schaumburg, Illinois, United States. After having lost $4.3 billion from 2007 to 2009, the company split into two independent p ...
introduce the
Motorola 68000 The Motorola 68000 (sometimes shortened to Motorola 68k or m68k and usually pronounced "sixty-eight-thousand") is a 16/32-bit complex instruction set computer (CISC) microprocessor, introduced in 1979 by Motorola Semiconductor Products Sector ...
, a 16/32-bit microprocessor. * 1981.
Stanford MIPS MIPS, an acronym for Microprocessor without Interlocked Pipeline Stages, was a research project conducted by John L. Hennessy at Stanford University between 1981 and 1984. MIPS investigated a type of instruction set architecture (ISA) now called ...
introduced, one of the first
reduced instruction set computing In computer engineering, a reduced instruction set computer (RISC) is a computer designed to simplify the individual instructions given to the computer to accomplish tasks. Compared to the instructions given to a complex instruction set comput ...
(RISC) designs. * 1982. Intel introduces the
Intel 80286 The Intel 80286 (also marketed as the iAPX 286 and often called Intel 286) is a 16-bit microprocessor that was introduced on February 1, 1982. It was the first 8086-based CPU with separate, non-multiplexed address and data buses and also the fi ...
, which was the first Intel processor that could run all the software written for its predecessors, the 8086 and 8088. * 1984.
Motorola Motorola, Inc. () was an American Multinational corporation, multinational telecommunications company based in Schaumburg, Illinois, United States. After having lost $4.3 billion from 2007 to 2009, the company split into two independent p ...
introduces the
Motorola 68020 The Motorola 68020 ("''sixty-eight-oh-twenty''", "''sixty-eight-oh-two-oh''" or "''six-eight-oh-two-oh''") is a 32-bit microprocessor from Motorola, released in 1984. A lower-cost version was also made available, known as the 68EC020. In keepin ...
, which enabled full 32-bit addressing, and the
68851 The Motorola 68851 is an external Memory Management Unit (MMU) which is designed to provide paged memory support for the 68020 using that processor's coprocessor interface. In theory it can be used with other processors such as the 68010 by simulat ...
memory management unit A memory management unit (MMU), sometimes called paged memory management unit (PMMU), is a computer hardware unit having all memory references passed through itself, primarily performing the translation of virtual memory addresses to physical ad ...
, which supported demand paging. * 1985. Intel introduces the
Intel 80386 The Intel 386, originally released as 80386 and later renamed i386, is a 32-bit microprocessor introduced in 1985. The first versions had 275,000 transistorsARM architecture ARM (stylised in lowercase as arm, formerly an acronym for Advanced RISC Machines and originally Acorn RISC Machine) is a family of reduced instruction set computer (RISC) instruction set architectures for computer processors, configured ...
introduced. * 1989. Intel introduces the
Intel 80486 The Intel 486, officially named i486 and also known as 80486, is a microprocessor. It is a higher-performance follow-up to the Intel 386. The i486 was introduced in 1989. It represents the fourth generation of binary compatible CPUs following the ...
. * 1992.
Hitachi () is a Japanese multinational corporation, multinational Conglomerate (company), conglomerate corporation headquartered in Chiyoda, Tokyo, Japan. It is the parent company of the Hitachi Group (''Hitachi Gurūpu'') and had formed part of the Ni ...
introduces
SuperH SuperH (or SH) is a 32-bit reduced instruction set computing (RISC) instruction set architecture (ISA) developed by Hitachi and currently produced by Renesas. It is implemented by microcontrollers and microprocessors for embedded systems. At t ...
architecture, which provides the basis for ARM's
Thumb The thumb is the first digit of the hand, next to the index finger. When a person is standing in the medical anatomical position (where the palm is facing to the front), the thumb is the outermost digit. The Medical Latin English noun for thumb ...
instruction set. * 1993. Intel launches the original
Pentium Pentium is a brand used for a series of x86 architecture-compatible microprocessors produced by Intel. The original Pentium processor from which the brand took its name was first released on March 22, 1993. After that, the Pentium II and Pe ...
microprocessor, the first processor with a x86 superscalar microarchitecture. * 1994. IBM introduce the first IBM mainframe models to use single-chip microprocessors as CPUs, the
IBM System/390 The IBM System/390 is a discontinued mainframe product family implementing the ESA/390, the fifth generation of the System/360 instruction set architecture. The first computers to use the ESA/390 were the Enterprise System/9000 (ES/9000) ...
9672 series. * 1994. ARM's
Thumb The thumb is the first digit of the hand, next to the index finger. When a person is standing in the medical anatomical position (where the palm is facing to the front), the thumb is the outermost digit. The Medical Latin English noun for thumb ...
instruction set introduced, based on
Hitachi () is a Japanese multinational corporation, multinational Conglomerate (company), conglomerate corporation headquartered in Chiyoda, Tokyo, Japan. It is the parent company of the Hitachi Group (''Hitachi Gurūpu'') and had formed part of the Ni ...
's
SuperH SuperH (or SH) is a 32-bit reduced instruction set computing (RISC) instruction set architecture (ISA) developed by Hitachi and currently produced by Renesas. It is implemented by microcontrollers and microprocessors for embedded systems. At t ...
instruction set. * 1995. Intel introduces the
Pentium Pro The Pentium Pro is a sixth-generation x86 microprocessor developed and manufactured by Intel and introduced on November 1, 1995. It introduced the P6 microarchitecture (sometimes termed i686) and was originally intended to replace the original P ...
which becomes the foundation for the
Pentium II The Pentium II brand refers to Intel's sixth-generation microarchitecture (" P6") and x86-compatible microprocessors introduced on May 7, 1997. Containing 7.5 million transistors (27.4 million in the case of the mobile Dixon with 256  KB ...
,
Pentium III The Pentium III (marketed as Intel Pentium III Processor, informally PIII or P3) brand refers to Intel's 32-bit x86 desktop and mobile CPUs based on the sixth-generation P6 microarchitecture introduced on February 28, 1999. The brand's initial p ...
,
Pentium M The Pentium M is a family of mobile 32-bit single-core x86 microprocessors (with the modified Intel P6 microarchitecture) introduced in March 2003 and forming a part of the Intel Carmel notebook platform under the then new Centrino brand. The '' ...
and
Intel Core Intel Core is a line of streamlined midrange consumer, workstation and enthusiast computer central processing units (CPUs) marketed by Intel Corporation. These processors displaced the existing mid- to high-end Pentium processors at the time ...
architectures. * 2000. IBM introduce
z/Architecture z/Architecture, initially and briefly called ESA Modal Extensions (ESAME), is IBM's 64-bit complex instruction set computer (CISC) instruction set architecture, implemented by its mainframe computers. IBM introduced its first z/Architecture-b ...
, the 64-bit version of their mainframe architecture. * 2000.
AMD Advanced Micro Devices, Inc. (AMD) is an American multinational semiconductor company based in Santa Clara, California, that develops computer processors and related technologies for business and consumer markets. While it initially manufactur ...
announced
x86-64 x86-64 (also known as x64, x86_64, AMD64, and Intel 64) is a 64-bit version of the x86 instruction set, first released in 1999. It introduced two new modes of operation, 64-bit mode and compatibility mode, along with a new 4-level paging mod ...
64-bit extension to the x86 microarchitecture. * 2000. AMD hits 1 GHz with its
Athlon Athlon is the brand name applied to a series of x86-compatible microprocessors designed and manufactured by Advanced Micro Devices (AMD). The original Athlon (now called Athlon Classic) was the first seventh-generation x86 processor and the fi ...
microprocessor. * 2000. Analog Devices introduces the
Blackfin The Blackfin is a family of 16-/32-bit microprocessors developed, manufactured and marketed by Analog Devices. The processors have built-in, fixed-point digital signal processor (DSP) functionality supplied by 16-bit multiply–accumulates (MA ...
architecture. * 2002. Intel released a
Pentium 4 Pentium 4 is a series of single-core CPUs for desktops, laptops and entry-level servers manufactured by Intel. The processors were shipped from November 20, 2000 until August 8, 2008. The production of Netburst processors was active from 2000 ...
with
hyper-threading Hyper-threading (officially called Hyper-Threading Technology or HT Technology and abbreviated as HTT or HT) is Intel's proprietary simultaneous multithreading (SMT) implementation used to improve parallelization of computations (doing multip ...
, the first modern desktop processor to implement
simultaneous multithreading Simultaneous multithreading (SMT) is a technique for improving the overall efficiency of superscalar CPUs with hardware multithreading. SMT permits multiple independent threads of execution to better use the resources provided by modern process ...
(SMT). * 2003. AMD released the
Athlon 64 The Athlon 64 is a ninth-generation, AMD64-architecture microprocessor produced by Advanced Micro Devices (AMD), released on September 23, 2003. It is the third processor to bear the name ''Athlon'', and the immediate successor to the Athlon XP. T ...
, the first
64-bit In computer architecture, 64-bit Integer (computer science), integers, memory addresses, or other Data (computing), data units are those that are 64 bits wide. Also, 64-bit central processing unit, CPUs and arithmetic logic unit, ALUs are those ...
consumer CPU. * 2003. Intel introduced the
Pentium M The Pentium M is a family of mobile 32-bit single-core x86 microprocessors (with the modified Intel P6 microarchitecture) introduced in March 2003 and forming a part of the Intel Carmel notebook platform under the then new Centrino brand. The '' ...
, a low power mobile derivative of the Pentium Pro architecture. * 2005. AMD announced the
Athlon 64 X2 The Athlon 64 X2 is the first native dual-core desktop central processing unit (CPU) designed by Advanced Micro Devices (AMD). It was designed from scratch as native dual-core by using an already multi-CPU enabled Athlon 64, joining it with anoth ...
, their first x86
dual-core A multi-core processor is a microprocessor on a single integrated circuit with two or more separate processing units, called cores, each of which reads and executes program instructions. The instructions are ordinary CPU instructions (such a ...
processor. * 2006. Intel introduces the
Core Core or cores may refer to: Science and technology * Core (anatomy), everything except the appendages * Core (manufacturing), used in casting and molding * Core (optical fiber), the signal-carrying portion of an optical fiber * Core, the central ...
line of CPUs based on a modified Pentium M design. * 2008. Over 10 billion Arm based CPUs shipped. * 2010. Intel introduced the
Core i3 Core or cores may refer to: Science and technology * Core (anatomy), everything except the appendages * Core (manufacturing), used in casting and molding * Core (optical fiber), the signal-carrying portion of an optical fiber * Core, the central ...
, i5, and i7, with 2, 4 and 4 cores respectively. * 2011. ARM release
ARMv8-A ARM (stylised in lowercase as arm, formerly an acronym for Advanced RISC Machines and originally Acorn RISC Machine) is a family of reduced instruction set computer (RISC) instruction set architectures for computer processors, configured ...
, supporting the 64-bit AAarch64 architecture. * 2011. AMD announced the world's first 8-core CPU for
desktop PCs A desktop computer (often abbreviated desktop) is a personal computer designed for regular use at a single location on or near a desk due to its size and power requirements. The most common configuration has a computer case, case that houses th ...
. * 2017. AMD announced
Ryzen Ryzen ( ) is a brand of multi-core x86-64 microprocessors designed and marketed by AMD for desktop, mobile, server, and embedded platforms based on the Zen microarchitecture. It consists of central processing units (CPUs) marketed for mainst ...
processors based on the
Zen Zen ( zh, t=禪, p=Chán; ja, text= 禅, translit=zen; ko, text=선, translit=Seon; vi, text=Thiền) is a school of Mahayana Buddhism that originated in China during the Tang dynasty, known as the Chan School (''Chánzong'' 禪宗), and ...
architecture, with up to 16 cores. * 2017. Intel 8th generation Core i3, Core i5, Core i7 and Core i9, increased to approximately 4, 6, 8 and 8 cores respectively. * 2017. Over 100 billion Arm based CPUs shipped. * 2020.
Fujitsu A64FX The A64FX is a 64-bit ARM architecture microprocessor designed by Fujitsu. The processor is replacing the SPARC64 V as Fujitsu's processor for supercomputer applications. It powers the Fugaku supercomputer, the fastest supercomputer in the wor ...
48-core (ARMv8.2) processors power Fugaku, the worlds most powerful supercomputer. * 2021. ARM release
ARMv9 ARM (stylised in lowercase as arm, formerly an acronym for Advanced RISC Machines and originally Acorn RISC Machine) is a family of reduced instruction set computer (RISC) instruction set architectures for central processing unit, computer ...
the first major upgrade in a decade, since Armv8 in 2011. * 2021. Over 200 billion Arm based CPUs shipped.


See also

*
Microprocessor chronology 1970s The first microprocessors were designed and manufactured in the 1970s. Intel's 4004 of 1971 is widely regarded as the first commercial microprocessor. Designers predominantly used MOSFET transistors with pMOS logic in the early 1970s, swi ...
*
General-purpose computing on graphics processing units General-purpose computing on graphics processing units (GPGPU, or less often GPGP) is the use of a graphics processing unit (GPU), which typically handles computation only for computer graphics, to perform computation in applications traditiona ...
(GPGPU)


References


External links


Great moments in microprocessor history by W. Warner, 2004


* ''Bit by Bit: An Illustrated History of Computers'', Stan Augarten, 1984
OCR with permission of the author
* Gallery of CPU and related PCBs (in Italian

{{CPU technologies Central processing unit History of computing hardware History of computing