Electronic digital computation
The era of modern computing began with a flurry of development before and during World War II, as electronic circuit elements replaced mechanical equivalents, and digital calculations replaced analog calculations. Machines such as the Z3(SONY Vaio VGN-FW11S Battery), the Atanasoff–Berry Computer, the Colossus computers, and the ENIAC were built by hand using circuits containing relays or valves (vacuum tubes), and often used punched cards or punched paper tape for input and as the main (non-volatile) storage medium(SONY Vaio VGN-FW11M Battery). Defining a single point in the series as the "first computer" misses many subtleties (see the table "Defining characteristics of some early digital computers of the 1940s" below).
Alan Turing's 1936 paper proved enormously influential in computing and computer science in two ways(SONY Vaio VGN-FW11 Battery). Its main purpose was to prove that there were problems (namely the halting problem) that could not be solved by any sequential process. In doing so, Turing provided a definition of a universal computer which executes a program stored on tape(SONY VAIO VGN-FZ21J Battery). This construct came to be called a Turing machine. Except for the limitations imposed by their finite memory stores, modern computers are said to be Turing-complete, which is to say, they have algorithmexecution capability equivalent to a universal Turing machine(SONY VAIO VGN-FZ21Z Battery).
For a computing machine to be a practical general-purpose computer, there must be some convenient read-write mechanism, punched tape, for example. With knowledge of Alan Turing's theoretical 'universal computing machine' John von Neumann defined an architecture which uses the same memory both to store programs and data(SONY VAIO VGN-FZ21E Battery): virtually all contemporary computers use this architecture (or some variant). While it is theoretically possible to implement a full computer entirely mechanically (as Babbage's design showed), electronics made possible the speed and later the miniaturization that characterize modern computers(SONY Vaio VGN-FW31M Battery).
There were three parallel streams of computer development in the World War II era; the first stream largely ignored, and the second stream deliberately kept secret. The first was the German work of Konrad Zuse(SONY Vaio VGN-FW465J Battery). The second was the secret development of the Colossus computers in the UK. Neither of these had much influence on the various computing projects in the United States. The third stream of computer development, Eckert and Mauchly's ENIAC and EDVAC, was widely publicized.
George Stibitz is internationally recognized as one of the fathers of the modern digital computer(SONY Vaio VGN-FW139E/H Battery). While working at Bell Labs in November 1937, Stibitz invented and built a relay-based calculator that he dubbed the "Model K" (for "kitchen table", on which he had assembled it), which was the first to calculate using binary form(SONY Vaio VGN-FW139E Battery).
Zuse
Working in isolation in Germany, Konrad Zuse started construction in 1936 of his first Z-series calculators featuring memory and (initially limited) programmability. Zuse's purely mechanical, but already binary Z1, finished in 1938, never worked reliably due to problems with the precision of parts(SONY Vaio VGN-FW31E Battery).
Zuse's later machine, the Z3, was finished in 1941. It was based on telephone relays and did work satisfactorily. The Z3 thus became the first functional program-controlled, all-purpose, digital computer(SONY Vaio VGN-FW17W Battery). In many ways it was quite similar to modern machines, pioneering numerous advances, such as floating point numbers. Replacement of the hard-to-implement decimal system (used in Charles Babbage's earlier design) by the simpler binary system meant that Zuse's machines were easier to build and potentially more reliable, given the technologies available at that time(SONY Vaio VGN-FW32J Battery).
Programs were fed into Z3 on punched films. Conditional jumps were missing, but since the 1990s it has been proved theoretically that Z3 was still a universal computer(as always, ignoring physical storage limitations) (SONY Vaio VGN-FW31J Battery). In two 1936 patent applications, Konrad Zuse also anticipated that machine instructions could be stored in the same storage used for data—the key insight of what became known as the von Neumann architecture, first implemented in the British SSEM of 1948(SONY VGN-CR42E battery). Zuse also claimed to have designed the first higher-level programming language, which he named Plankalkül, in 1945 (published in 1948) although it was implemented for the first time in 2000 by a team around Raúl Rojas at the Free University of Berlin—five years after Zuse died(SONY VGN-CR42S battery).
Zuse suffered setbacks during World War II when some of his machines were destroyed in the course of Allied bombing campaigns. Apparently his work remained largely unknown to engineers in the UK and US until much later, although at least IBM was aware of it as it financed his post-war startup company in 1946 in return for an option on Zuse's patents(SONY VGN-CR42Z battery).
Colossus
During World War II, the British at Bletchley Park (40 miles north of London) achieved a number of successes at breaking encrypted German military communications. The German encryption machine, Enigma, was attacked with the help of electro-mechanical machines called bombes(SONY VGN-CR42ZR battery). The bombe, designed by Alan Turing and Gordon Welchman, after the Polish cryptographic bombaby Marian Rejewski (1938), came into productive use in 1941. They ruled out possible Enigma settings by performing chains of logical deductions implemented electrically(SONY VGN-CR41SR battery). Most possibilities led to a contradiction, and the few remaining could be tested by hand.
The Germans also developed a series of teleprinter encryption systems, quite different from Enigma. The Lorenz SZ 40/42 machine was used for high-level Army communications, termed "Tunny" by the British(SONY VGN-CR41E battery). The first intercepts of Lorenz messages began in 1941. As part of an attack on Tunny, Professor Max Newman and his colleagues helped specify the Colossus. The Mk I Colossus was built between March and December 1943 by Tommy Flowers and his colleagues at the Post Office Research Station at Dollis Hill in London and then shipped to Bletchley Park in January 1944(SONY VGN-CR41S battery).
Colossus was the world's first electronic programmable computing device. It used a large number of valves (vacuum tubes). It had paper-tape input and was capable of being configured to perform a variety of boolean logical operations on its data(SONY VGN-CR41Z battery), but it was not Turing-complete. Nine Mk II Colossi were built (The Mk I was converted to a Mk II making ten machines in total). Details of their existence, design, and use were kept secret well into the 1970s. Winston Churchill personally issued an order for their destruction into pieces no larger than a man's hand(SONY VGN-CR31Z battery), to keep secret that the British were capable of cracking Lorenz during the oncoming cold war. As a result the machines were not included in many histories of computing. A reconstructed copy of one of the Colossus machines is now on display at Bletchley Park(SONY VGN-CR31E battery).
American developments
In 1937, Claude Shannon showed there is a one-to-one correspondence between the concepts of Boolean logic and certain electrical circuits, now called logic gates, which are now ubiquitous in digital computers(SONY VGN-CR31S battery). In his master's thesis at MIT, for the first time in history, Shannon showed that electronic relays and switches can realize the expressions of Boolean algebra. Entitled A Symbolic Analysis of Relay and Switching Circuits(SONY VGN-CR31SR battery), Shannon's thesis essentially founded practical digital circuit design. George Stibitz completed a relay-based computer he dubbed the "Model K" at Bell Labs in November 1937. Bell Labs authorized a full research program in late 1938 with Stibitz at the helm. Their Complex Number Calculator, completed January 8, 1940(SONY VGN-CR21SR battery), was able to calculate complex numbers. In a demonstration to theAmerican Mathematical Society conference at Dartmouth College on September 11, 1940, Stibitz was able to send the Complex Number Calculator remote commands over telephone lines by a teletype. It was the first computing machine ever used remotely, in this case over a phone line(SONY VGN-CR21Z battery). Some participants in the conference who witnessed the demonstration were John von Neumann, John Mauchly, and Norbert Wiener, who wrote about it in their memoirs.
In 1939, John Vincent Atanasoff and Clifford E. Berry of Iowa State University developed the Atanasoff–Berry Computer (ABC) (SONY VGN-CR21S battery), The Atanasoff-Berry Computer was the world's first electronic digital computer. The design used over 300 vacuum tubes and employed capacitors fixed in a mechanically rotating drum for memory. Though the ABC machine was not programmable(SONY VGN-CR21E battery), it was the first to use electronic tubes in an adder. ENIAC co-inventor John Mauchly examined the ABC in June 1941, and its influence on the design of the later ENIAC machine is a matter of contention among computer historians(SONY VGN-CR11E battery). The ABC was largely forgotten until it became the focus of the lawsuit Honeywell v. Sperry Rand, the ruling of which invalidated the ENIAC patent (and several others) as, among many reasons, having been anticipated by Atanasoff's work(SONY VGN-CR11M battery).
In 1939, development began at IBM's Endicott laboratories on the Harvard Mark I. Known officially as the Automatic Sequence Controlled Calculator, the Mark I was a general purpose electro-mechanical computer built with IBM financing and with assistance from IBM personnel(SONY VGN-CR11S battery), under the direction of Harvard mathematician Howard Aiken. Its design was influenced by Babbage's Analytical Engine, using decimal arithmetic and storage wheels and rotary switches in addition to electromagnetic relays(SONY VGN-CR11Z battery). It was programmable via punched paper tape, and contained several calculation units working in parallel. Later versions contained several paper tape readers and the machine could switch between readers based on a condition(SONY VGN-CR11SR battery). Nevertheless, the machine was not quite Turing-complete. The Mark I was moved to Harvard University and began operation in May 1944.
ENIAC
The US-built ENIAC (Electronic Numerical Integrator and Computer) was the first electronic general-purpose computer. It combined, for the first time, the high speed of electronics with the ability to be programmed for many complex problems(SONY VAIO VGN-NR110E/W battery). It could add or subtract 5000 times a second, a thousand times faster than any other machine. (Colossus couldn't add). It also had modules to multiply, divide, and square root. High speed memory was limited to 20 words (about 80 bytes). Built under the direction ofJohn Mauchly and J. Presper Eckert at the University of Pennsylvania(SONY VAIO VGN-NR110E/S battery), ENIAC's development and construction lasted from 1943 to full operation at the end of 1945. The machine was huge, weighing 30 tons, and contained over 18,000 vacuum tubes. One of the major engineering feats was to minimize tube burnout(SONY VAIO VGN-NR110E/T battery), which was a common problem at that time. The machine was in almost constant use for the next ten years.
ENIAC was unambiguously a Turing-complete device. It could compute any problem (that would fit in memory). A "program" on the ENIAC, however, was defined by the states of its patch cables and switches(SONY VAIO VGN-NR110E battery), a far cry from the stored program electronic machines that evolved from it. Once a program was written, it had to be mechanically set into the machine. Six women did most of the programming of ENIAC. (Improvements completed in 1948 made it possible to execute stored programs set in function table memory, which made programming less a "one-off" effort, and more systematic) (SONY VAIO VGN-NR11S battery).
First-generation machines
Even before the ENIAC was finished, Eckert and Mauchly recognized its limitations and started the design of a stored-program computer, EDVAC. John von Neumann was credited with a widely circulated report describing the EDVAC design in which both the programs and working data were stored in a single(SONY VAIO VGN-NR11Z battery), unified store. This basic design, denoted the von Neumann architecture, would serve as the foundation for the worldwide development of ENIAC's successors. In this generation of equipment, temporary or working storage was provided by acoustic delay lines, which used the propagation time of sound through a medium such as liquid mercury (Sony VAIO PCG-5K1L battery) (or through a wire) to briefly store data. A series of acoustic pulses is sent along a tube; after a time, as the pulse reached the end of the tube, the circuitry detected whether the pulse represented a 1 or 0 and caused the oscillator to re-send the pulse. Others used Williams tubes(Sony VAIO PCG-6W2L battery), which use the ability of a small cathode-ray tube (CRT) to store and retrieve data as charged areas on the phosphor screen. By 1954, magnetic core memory was rapidly displacing most other forms of temporary storage, and dominated the field through the mid-1970s(Sony VAIO PCG-7112L battery).
EDVAC was the first stored-program computer designed; however it was not the first to run. Eckert and Mauchly left the project and its construction floundered. The first working von Neumann machine was the Manchester "Baby" or Small-Scale Experimental Machine, developed by Frederic C(Sony VAIO PCG-8Z1L battery). Williams and Tom Kilburn at the University of Manchester in 1948 as a test bed for the Williams tube; it was followed in 1949 by the Manchester Mark 1 computer, a complete system, using Williams tube and magnetic drum memory, and introducing index registers(Sony VAIO PCG-8Z2L battery). The other contender for the title "first digital stored-program computer" had been EDSAC, designed and constructed at the University of Cambridge. Operational less than one year after the Manchester "Baby", it was also capable of tackling real problems. EDSAC was actually inspired by plans for EDVAC (Sony VAIO PCG-8Y2L battery) (Electronic Discrete Variable Automatic Computer), the successor to ENIAC; these plans were already in place by the time ENIAC was successfully operational. Unlike ENIAC, which used parallel processing, EDVAC used a single processing unit(Sony VAIO PCG-8Y1L battery). This design was simpler and was the first to be implemented in each succeeding wave of miniaturization, and increased reliability. Some view Manchester Mark 1 / EDSAC / EDVAC as the "Eves" from which nearly all current computers derive their architecture(Sony VAIO PCG-7Z2L battery). Manchester University's machine became the prototype for the Ferranti Mark 1. The first Ferranti Mark 1 machine was delivered to the University in February, 1951 and at least nine others were sold between 1951 and 1957(Sony VAIO PCG-7Z1L battery).
The first universal programmable computer in the Soviet Union was created by a team of scientists under direction of Sergei Alekseyevich Lebedev from Kiev Institute of Electrotechnology, Soviet Union (nowUkraine) (Sony VAIO PCG-7133L battery). The computer MESM (МЭСМ, Small Electronic Calculating Machine) became operational in 1950. It had about 6,000 vacuum tubes and consumed 25 kW of power. It could perform approximately 3,000 operations per second(Sony VAIO PCG-7113L battery). Another early machine was CSIRAC, an Australian design that ran its first test program in 1949. CSIRAC is the oldest computer still in existence and the first to have been used to play digital music(Sony VAIO PCG-6W3L battery).
Commercial computers
The first commercial computer was the Ferranti Mark 1, which was delivered to the University of Manchester in February 1951. It was based on the Manchester Mark 1. The main improvements over the Manchester Mark 1 were in the size of the primary storage (using random accessWilliams tubes), secondary storage (using a magnetic drum) (Sony VAIO PCG-7111L battery), a faster multiplier, and additional instructions. The basic cycle time was 1.2 milliseconds, and a multiplication could be completed in about 2.16 milliseconds. The multiplier used almost a quarter of the machine's 4,050 vacuum tubes (valves) (Sony VAIO PCG-6W1L battery). A second machine was purchased by theUniversity of Toronto, before the design was revised into the Mark 1 Star. At least seven of these later machines were delivered between 1953 and 1957, one of them to Shell labs in Amsterdam(Sony VAIO PCG-6V1L battery).
In October 1947, the directors of J. Lyons & Company, a British catering company famous for its teashops but with strong interests in new office management techniques, decided to take an active role in promoting the commercial development of computers(Sony VAIO PCG-6S3L battery). The LEO I computer became operational in April 1951 and ran the world's first regular routine office computer job. On 17 November 1951, the J. Lyons company began weekly operation of a bakery valuations job on the LEO (Lyons Electronic Office). This was the first business application to go live on a stored program computer(Sony VAIO PCG-6S2L battery).
In June 1951, the UNIVAC I (Universal Automatic Computer) was delivered to the U.S. Census Bureau. Remington Rand eventually sold 46 machines at more than $1 million each ($8.46 million as of 2011). UNIVAC was the first "mass produced" computer. It used 5,200 vacuum tubes and consumed 125 kW of power(Sony VAIO PCG-5L1L battery). Its primary storage was serial-access mercury delay lines capable of storing 1,000 words of 11 decimal digits plus sign (72-bit words). A key feature of the UNIVAC system was a newly invented type of metal magnetic tape, and a high-speed tape unit(Sony VAIO PCG-5K2L battery), for non-volatile storage. Magnetic media are still used in many computers. In 1952, IBM publicly announced the IBM 701 Electronic Data Processing Machine, the first in its successful 700/7000 series and its first IBM mainframe computer. The IBM 704, introduced in 1954(Sony VAIO PCG-5J2L battery), used magnetic core memory, which became the standard for large machines. The first implemented high-level general purpose programming language, Fortran, was also being developed at IBM for the 704 during 1955 and 1956 and released in early 1957(Sony VAIO PCG-5J1L battery). (Konrad Zuse's 1945 design of the high-level language Plankalkül was not implemented at that time.) A volunteer user group, which exists to this day, was founded in 1955 to share their software and experiences with the IBM 701(Sony VAIO PCG-5G3L battery).
IBM introduced a smaller, more affordable computer in 1954 that proved very popular. The IBM 650 weighed over 900 kg, the attached power supply weighed around 1350 kg and both were held in separate cabinets of roughly 1.5 meters by 0.9 meters by 1.8 meters(Sony VAIO PCG-5G2L battery). It cost $500,000 ($4.09 million as of 2011) or could be leased for $3,500 a month ($30 thousand as of 2011). Its drum memory was originally 2,000 ten-digit words, later expanded to 4,000 words. Memory limitations such as this were to dominate programming for decades afterward(Sony VGP-BPS21A/B battery). The program instructions were fetched from the spinning drum as the code ran. Efficient execution using drum memory was provided by a combination of hardware architecture: the instruction format included the address of the next instruction(Sony VGP-BPS21/S battery); and software: the Symbolic Optimal Assembly Program, SOAP, assigned instructions to the optimal addresses (to the extent possible by static analysis of the source program). Thus many instructions were, when needed, located in the next row of the drum to be read and additional wait time for drum rotation was not required(Sony VGP-BPS21B battery).
In 1955, Maurice Wilkes invented microprogramming, which allows the base instruction set to be defined or extended by built-in programs (now called firmware ormicrocode). It was widely used in the CPUs and floating-point units of mainframe and other computers, such as the Manchester Atlas and the IBM 360 series(Sony VGP-BPS21 battery).
IBM introduced its first magnetic disk system, RAMAC (Random Access Method of Accounting and Control) in 1956. Using fifty 24-inch (610 mm) metal disks, with 100 tracks per side, it was able to store 5 megabytes of data at a cost of $10,000 per megabyte ($80 thousand as of 2011) (Sony VGN-FW31J battery).
Second generation: transistors
The bipolar transistor was invented in 1947. From 1955 onwards transistors replaced vacuum tubes in computer designs, giving rise to the "second generation" of computers. Initially the only devices available were germanium point-contact transistors(Sony VGP-BPS13A/S battery), which although less reliable than the vacuum tubes they replaced had the advantage of consuming far less power. The first transistorised computer was built at the University of Manchester and was operational by 1953; a second version was completed there in April 1955(Sony VGP-BPS13B/S battery). The later machine used 200 transistors and 1,300 solid-state diodes and had a power consumption of 150 watts. However, it still required valves to generate the clock waveforms at 125 kHz and to read and write on the magnetic drum memory(Sony VGP-BPS13S battery), whereas the Harwell CADET operated without any valves by using a lower clock frequency, of 58 kHz when it became operational in February 1955. Problems with the reliability of early batches of point contact and alloyed junction transistors meant that the machine's mean time between failures was about 90 minutes, but this improved once the more reliable bipolar junction transistorsbecame available(Sony VGP-BPS13AS battery).
Compared to vacuum tubes, transistors have many advantages: they are smaller, and require less power than vacuum tubes, so give off less heat. Silicon junction transistors were much more reliable than vacuum tubes and had longer(Sony VGP-BPS13/B battery), indefinite, service life. Transistorized computers could contain tens of thousands of binary logic circuits in a relatively compact space(Sony VGP-BPS13/S battery). Transistors greatly reduced computers' size, initial cost, and operating cost. Typically, second-generation computers were composed of large numbers of printed circuit boards such as the IBM Standard Modular System each carrying one to four logic gates or flip-flops(Sony VGP-BPS13A/B battery).
A second generation computer, the IBM 1401, captured about one third of the world market. IBM installed more than ten thousand 1401s between 1960 and 1964.
Transistorized electronics improved not only the CPU (Central Processing Unit), but also the peripheral devices(Sony VGP-BPS13B/B battery). The IBM 350 RAMAC was introduced in 1956 and was the world's first disk drive. The second generation disk data storage units were able to store tens of millions of letters and digits. Next to the fixed disk storage units(Sony VGN-FZ11E battery), connected to the CPU via high-speed data transmission, were removable disk data storage units. A removable disk stack can be easily exchanged with another stack in a few seconds. Even if the removable disks' capacity is smaller than fixed disks(Sony VGN-FZ430E battery), their interchangeability guarantees a nearly unlimited quantity of data close at hand.Magnetic tape provided archival capability for this data, at a lower cost than disk(Sony Vaio VGN-FZ31J battery ).
Many second-generation CPUs delegated peripheral device communications to a secondary processor. For example, while the communication processor controlled card reading and punching(Sony Vaio VGN-FZ31B battery), the main CPU executed calculations and binary branch instructions. One databus would bear data between the main CPU and core memory at the CPU's fetch-execute cycle rate, and other databusses would typically serve the peripheral devices. On the PDP-1(Sony VGN-FZ18L battery), the core memory's cycle time was 5 microseconds; consequently most arithmetic instructions took 10 microseconds (100,000 operations per second) because most operations took at least two memory cycles; one for the instruction, one for the operand data fetch(Sony VGN-FW11M battery).
During the second generation remote terminal units (often in the form of teletype machines like a Friden Flexowriter) saw greatly increased use. Telephone connections provided sufficient speed for early remote terminals and allowed hundreds of kilometers separation between remote-terminals and the computing center(Sony Vaio VGN-FZ18S battery). Eventually these stand-alone computer networks would be generalized into an interconnected network of networks—the Internet.
Post-1960: third generation and beyond
The explosion in the use of computers began with "third-generation" computers, making use of Jack St. Clair Kilby's and Robert Noyce'sindependent invention of theintegrated circuit (or microchip) (Sony Vaio VGN-FZ210CE battery), which led to the invention of the microprocessor, by Ted Hoff, Federico Faggin, and Stanley Mazor at Intel. The integrated circuit in the image on the right, for example, an Intel 8742, is an 8-bit microcontrollerthat includes a CPU running at 12 MHz, 128 bytes of RAM, 2048 bytes of EPROM, and I/O in the same chip(Sony Vaio VGN-FZ21S battery).
During the 1960s there was considerable overlap between second and third generation technologies.[84] IBM implemented its IBM Solid Logic Technology modules inhybrid circuits for the IBM System/360 in 1964. As late as 1975, Sperry Univac continued the manufacture of second-generation machines such as the UNIVAC 494(Sony Vaio VGN-FZ21E battery ). TheBurroughs large systems such as the B5000 were stack machines, which allowed for simpler programming. These pushdown automatons were also implemented in minicomputers and microprocessors later, which influenced programming language design. Minicomputers served as low-cost computer centers for industry, business and universities(Sony VGN-FZ18 battery). It became possible to simulate analog circuits with the simulation program with integrated circuit emphasis, or SPICE (1971) on minicomputers, one of the programs for electronic design automation (EDA). The microprocessor led to the development of the microcomputer(Sony VGN-FZ190E battery), small, low-cost computers that could be owned by individuals and small businesses. Microcomputers, the first of which appeared in the 1970s, became ubiquitous in the 1980s and beyond.
In April 1975 at the Hannover Fair, was presented the P6060 produced by Olivetti, the world's first personal with built-in floppy disk(Sony VGN-FZ190 battery): Central Unit on two plates, code names PUCE1/PUCE2, TTL components made, 8" single or double floppy disk driver, 32 alphanumeric characters plasma display, 80 columns graphical thermal printer, 48 Kbytes of RAM, Basic language, 40 kilograms of weight. He was in competition with a similar product by IBM but with an external floppy disk(Sony VGP-BPS9/B battery).
Steve Wozniak, co-founder of Apple Computer, is sometimes erroneously credited with developing the first mass-market home computers. However, his first computer, the Apple I(Sony VGN-FZ15G battery), came out some time after the MOS Technology KIM-1 and Altair 8800, and the first Apple computer with graphic and sound capabilities came out well after the Commodore PET. Computing has evolved with microcomputer architectures, with features added from their larger brethren, now dominant in most market segments(Sony VGN-FZ11L battery).
Systems as complicated as computers require very high reliability. ENIAC remained on, in continuous operation from 1947 to 1955, for eight years before being shut down. Although a vacuum tube might fail(Sony Vaio VGN-FZ31S battery), it would be replaced without bringing down the system. By the simple strategy of never shutting down ENIAC, the failures were dramatically reduced. The vacuum-tube SAGE air-defense computers became remarkably reliable – installed in pairs(Sony Vaio VGN-FZ38M battery), one off-line, tubes likely to fail did so when the computer was intentionally run at reduced power to find them. Hot-pluggable hard disks, like the hot-pluggable vacuum tubes of yesteryear, continue the tradition of repair during continuous operation(Sony VGN-FZ19VN battery). Semiconductor memories routinely have no errors when they operate, although operating systems like Unix have employed memory tests on start-up to detect failing hardware. Today, the requirement of reliable performance is made even more stringent when server farms are the delivery platform(Sony Vaio VGN-FZ31Z battery). Google has managed this by using fault-tolerant software to recover from hardware failures, and is even working on the concept of replacing entire server farms on-the-fly, during a service event.
In the 21st century, multi-core CPUs became commercially available(Sony Vaio VGN-FZ31M battery). Content-addressable memory (CAM) has become inexpensive enough to be used in networking, although no computer system has yet implemented hardware CAMs for use in programming languages. Currently, CAMs (or associative arrays) in software are programming-language-specific(Sony VGN-FZ11M battery). Semiconductor memory cell arrays are very regular structures, and manufacturers prove their processes on them; this allows price reductions on memory products. During the 1980s, CMOS logic gates developed into devices that could be made as fast as other circuit types(Sony VGN-FZ11Z battery); computer power consumption could therefore be decreased dramatically. Unlike the continuous current draw of a gate based on other logic types, a CMOS gate only draws significant current during the 'transition' between logic states, except for leakage(Sony VGN-FZ220E battery).
This has allowed computing to become a commodity which is now ubiquitous, embedded in many forms, from greeting cards and telephones to satellites. Computing hardware and its software have even become a metaphor for the operation of the universe(Sony VGN-FZ29VN battery). Although DNA-based computing and quantum qubit computing are years or decades in the future, the infrastructure is being laid today, for example, with DNA origamion photolithography and with quantum antennae for transferring information between ion traps(Sony VGN-FZ290 battery). Fast digital circuits (including those based on Josephson junctions and rapid single flux quantum technology) are becoming more nearly realizable with the discovery of nanoscale superconductors.
Fiber-optic and photonic devices, which already have been used to transport data over long distances, are now entering the data center(Sony VGP-BPL7 battery), side by side with CPU and semiconductor memory components. This allows the separation of RAM from CPU by optical interconnects(Sony VGP-BPL12 battery).
An indication of the rapidity of development of this field can be inferred by the history of the seminal article. By the time that anyone had time to write anything down, it was obsolete. After 1945, others read John von Neumann's First Draft of a Report on the EDVAC, and immediately started implementing their own systems. To this day, the pace of development has continued, worldwide(Sony VGP-BPS12 battery).
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