Timeline of computing hardware before 1950

This article presents a detailed timeline of events in the history of computing hardware: from prehistory until 1949. For narratives explaining the overall developments, see History of computing.

Prehistory–1640

Date	Event
80,000 BC	Two notched rib bones may have been used for counting but they could have been merely decorative.
18,000 BC	The Ishango bone, may indicate that – even so early – material objects were used for simple arithmetical operations, and it may provide evidence of some knowledge of prime numbers (although this is disputed).
c. 2400 BC	The abacus – the first known calculator, was probably invented by the Babylonians as an aid to simple arithmetic around this time period. This laid the foundations for positional notation and later computing developments.
c. 1115 BC	The south-pointing chariot was invented in ancient China. It was the first known geared mechanism to use a differential gear. The chariot was a two-wheeled vehicle, upon which is a pointing figure connected to the wheels by means of differential gearing. Through careful selection of wheel size, track and gear ratios, the figure atop the chariot always pointed in the same direction.
c. 500 BC	First known use of zero by mathematicians in ancient India around this date.
c. 500 BC	Indian grammarian Pāṇini formulated the grammar of Sanskrit (in 3959 rules) known as the Ashtadhyayi which was highly systematised and technical. Pāṇini used metarules, transformations, and recursions with such sophistication that his grammar had the computing power equivalent to a Turing machine. Pāṇini's work was the forerunner to modern formal language theory, and a precursor to its use in modern computing. The Panini-Backus form used to describe most modern programming languages is also significantly similar to Pāṇini's grammar rules.
c. 300 BC	Indian mathematician/scholar/musician Pingala first described the binary number system which is now used in the design of essentially all modern computing equipment. He also conceived the notion of a binary code similar to the Morse code.
c. 200 BC	The Chinese invented the suanpan (Chinese abacus) which was widely used until the invention of the modern calculator, and continues to be used in some cultures today.
c. 125 BC	The Antikythera mechanism: A clockwork, analog computer believed to have been designed and built in the Corinthian colony of Syracuse. The mechanism contained a differential gear and was capable of tracking the relative positions of all then-known heavenly bodies.
c. 100 BC	Chinese mathematicians first used negative numbers.
c. 60 AD	Heron of Alexandria made numerous inventions, including "Sequence Control" in which the operator of a machine set a machine running, which then follows a series of instructions in a deterministic fashion. This was, essentially, the first program. He also made numerous innovations in the field of automata, which are important steps in the development of robotics.
c. 200	Indian Jaina mathematicians invented logarithms.
c. 600	Indian mathematician Brahmagupta was the first to describe the modern place-value numeral system (Hindu numeral system).
724	Chinese inventor Liang Lingzan built the world's first fully mechanical clock; water clocks, some of them extremely accurate, had been known for centuries previous to this. This was an important technological leap forward; the earliest true computers, made a thousand years later, used technology based on that of clocks.
820	Persian mathematician, Muḥammad ibn Mūsā al-Khwārizmī, described the rudiments of modern algebra whose name is derived from his book Al-Kitāb al-muḫtaṣar fī ḥisāb al-ğabr wa-l-muqābala. The word algorithm is derived from al-Khwarizmi's Latinized name Algoritmi.
c. 850	Arab mathematician, Al-Kindi (Alkindus), was a pioneer of cryptography. He gave the first known recorded explanation of cryptanalysis in A Manuscript on Deciphering Cryptographic Messages. In particular, he is credited with developing the frequency analysis method whereby variations in the frequency of the occurrence of letters could be analyzed and exploited to break encryption ciphers (i.e. crypanalysis by frequency analysis). The text also covers methods of cryptanalysis, encipherments, cryptanalysis of certain encipherments, and statistical analysis of letters and letter combinations in Arabic.
850	The Banū Mūsā brothers, in their Book of Ingenious Devices, invented "the earliest known mechanical musical instrument", in this case a hydropowered organ which played interchangeable cylinders automatically. This "cylinder with raised pins on the surface remained the basic device to produce and reproduce music mechanically until the second half of the nineteenth century." They also invented an automatic flute player which appears to have been the first programmable machine.
996	Persian astronomer, Abū Rayhān al-Bīrūnī, invented the first geared mechanical astrolabe, featuring eight gear-wheels. This can be considered as an ancestor of the mechanical clocks.
c. 1000	Abū Rayhān al-Bīrūnī invented the Planisphere, an analog computer. He also invented the first mechanical lunisolar calendar which employed a gear train and eight gear-wheels. This was an early example of a fixed-wired knowledge processing machine.
1015	Arab astronomer, Abū Ishāq Ibrāhīm al-Zarqālī (Arzachel) of al-Andalus, invented the Equatorium, a mechanical analog computer device used for finding the longitudes and positions of the Moon, Sun and planets without calculation, using a geometrical model to represent the celestial body's mean and anomalistic position.
1020	The mechanical geared astrolabe earlier developed by Abū Rayhān al-Bīrūnī perfected by Ibn Samh. This can be considered an ancestor of the mechanical clock.
c. 1100	Arab astronomer, Jabir ibn Aflah (Geber), invented the Torquetum, an observational instrument and mechanical analog computer device used to transform between spherical coordinate systems. It was designed to take and convert measurements made in three sets of coordinates: horizon, equatorial, and ecliptic.
1206	Arab engineer, Al-Jazari, invented numerous automata and made numerous other technological innovations. One of these is a design for a programmable humanoid-shaped mannequin: this seems to have been the first serious, scientific (as opposed to magical) plan for a robot. He also invented the "castle clock", an astronomical clock which is considered to be the earliest programmable analog computer. It displayed the zodiac, the solar and lunar orbits, a crescent moon-shaped pointer travelling across a gateway causing automatic doors to open every hour, and five robotic musicians who play music when struck by levers operated by a camshaft attached to a water wheel. The length of day and night could be re-programmed every day in order to account for the changing lengths of day and night throughout the year.
1235	Persian astronomer Abi Bakr of Isfahan invented a brass astrolabe with a geared calendar movement based on the design of Abū Rayhān al-Bīrūnī's mechanical calendar analog computer. Abi Bakr's geared astrolabe uses a set of gear-wheels and is the oldest surviving complete mechanical geared machine in existence.
1300	Ramon Llull invented the Lullian Circle: a notional machine for calculating answers to philosophical questions (in this case, to do with Christianity) via logical combinatorics. This idea was taken up by Leibniz centuries later, and is thus one of the founding elements in computing and information science
c. 1400	Kerala school of astronomy and mathematics in South India invented the floating point number system.
c. 1400	Jamshīd al-Kāshī invented the Plate of Conjunctions, an analog computer instrument used to determine the time of day at which planetary conjunctions will occur, and for performing linear interpolation. He also invented a mechanical "planetary computer" which he called the Plate of Zones, which could graphically solve a number of planetary problems, including the prediction of the true positions in longitude of the Sun and Moon, and the planets; the latitudes of the Sun, Moon, and planets; and the ecliptic of the Sun. The instrument also incorporated an alhidade and ruler.
c. 1400	Ahmad al-Qalqashandi gives a list of ciphers in his Subh al-a'sha which include both substitution and transposition, and for the first time, a cipher with multiple substitutions for each plaintext letter. He also gives an exposition on and worked example of cryptanalysis, including the use of tables of letter frequencies and sets of letters which can not occur together in one word.
1492	Leonardo da Vinci produced drawings of a device consisting of interlocking cog wheels which can be interpreted as a mechanical calculator capable of addition and subtraction. A working model inspired by this plan was built in 1968 but it remains controversial whether Leonardo really had a calculator in mind. Da Vinci also made plans for a mechanical man: an early design for a robot.
1588	Joost Buerghi discovered natural logarithms.
1614	Scotsman John Napier reinvented a form of logarithms and an ingenious system of movable rods (referred to as Napier's Rods or Napier's bones). These rods were based on the lattice or gelosia multiplication algorithm and allowed the operator to multiply, divide and calculate square and cube roots by moving the rods around and placing them in specially constructed boards.
1622	William Oughtred developed slide rules based on natural logarithms as developed by John Napier.
1623	German polymath Wilhelm Schickard drew a device that he called a Calculating Clock on two letters that he sent to Johannes Kepler; one in 1623 and the other in 1624. A fire later destroyed the machine as it was being built in 1624 and he decided to abandon his project. This machine became known to the world only in 1957 when the two letters were discovered. Some replicas were built in 1961. This machine had no impact on the development of mechanical calculators.

1641-1850

Date	Place	Event
1642		French polymath Blaise Pascal invented the mechanical calculator. Called machine arithmétique, Pascal's calculator and eventually Pascaline, its public introduction in 1645 started the development of mechanical calculators first in Europe and then in the rest of the world. It was the first machine to have a controlled carry mechanism. Pascal built 50 prototypes before releasing his first machine (eventually twenty machines were built). The Pascaline inspired the works of Gottfried Leibniz (1671), Thomas de Colmar (1820) and Dorr E. Felt (1887).
1668		Sir Samuel Morland (1625–1695), of England, produced a non-decimal adding machine, suitable for use with English money. Instead of a carry mechanism, it registered carries on auxiliary dials, from which the user re-entered them as addends.
1671		German mathematician, Gottfried Leibniz designed a machine which multiplied, the 'Stepped Reckoner'. It could multiply numbers of up to 5 and 12 digits to give a 16 digit result. Two machines were built, one in 1694 (it was discovered in an attic in 1879), and one in 1706.
1685		In an article titled "Machina arithmetica in qua non additio tantum et subtractio sed et multiplicatio nullo, diviso vero paene nullo animi labore peragantur", Gottfried Leibniz described a machine that used wheels with movable teeth which, when coupled to a Pascaline, could perform all four mathematical operations. There is no evidence that Leibniz ever constructed this pinwheel machine.
1709		Giovanni Poleni was the first to build a calculator that used a pinwheel design. It was made of wood and was built in the shape of a calculating clock.
1726		Jonathan Swift described (satirically) a machine ("engine") in his Gulliver's Travels. The "engine" consisted of a wooden frame with wooden blocks containing parts of speech. When the engine's 40 levers are simultaneously turned, the machine displayed grammatical sentence fragments.
1774		Philipp Matthäus Hahn, in what is now Germany, made a successful portable calculator able to perform all four mathematical operations.
1775		Charles Stanhope, 3rd Earl Stanhope, of England, designed and constructed a successful multiplying calculator similar to Leibniz's.
1786		J. H. Müller, an engineer in the Hessian army, first conceived of the idea of a difference engine.
1801		Joseph-Marie Jacquard developed an automatic loom controlled by punched cards.
1820		Charles Xavier Thomas de Colmar invented the 'Arithmometer' which after thirty more years of development became, in 1851, the first mass-produced mechanical calculator. An operator could perform long multiplications and divisions quickly and effectively by using a movable accumulator for the result. This machine was based on the earlier works of Pascal and Leibniz.
1822		Charles Babbage designed his first mechanical computer, the first prototype of the decimal difference engine for tabulating polynomials.
1832		Semen Korsakov proposed the usage of punched cards for information storage and search. He designed several machines to demonstrate his ideas, including the so-called linear homeoscope.
1832		Babbage and Joseph Clement produced a prototype segment of his difference engine, which operated on 6-digit numbers and second-order differences (i.e., it could tabulate quadratic polynomials). The complete engine, which would have been room-sized, was planned to operate both on sixth-order differences with numbers of about 20 digits, and on third-order differences with numbers of 30 digits. Each addition would have been done in two phases, the second one taking care of any carries generated in the first. The output digits were to be punched into a soft metal plate, from which a printing plate might have been made. But there were various difficulties, and no more than this prototype piece was ever finished.
1834		Babbage conceived, and began to design, his decimal 'Analytical Engine'. A program for it was to be stored on read-only memory, in the form of punched cards. Babbage continued to work on the design for years, though after about 1840 design changes seem to have been minor. The machine would have operated on 40-digit numbers; the 'mill' (CPU) would have had 2 main accumulators and some auxiliary ones for specific purposes, while the 'store' (memory) would have held a thousand 50-digit numbers. There would have been several punched card readers, for both programs and data; the cards were to be chained and the motion of each chain reversible. The machine would have performed conditional jumps. There would also have been a form of microcoding: the meaning of instructions were to depend on the positioning of metal studs in a slotted barrel, called the "control barrel". The machine envisioned would have been capable of an addition in 3 seconds and a multiplication or division in 2–4 minutes. It was to be powered by a steam engine. In the end, no more than a few parts were actually built.
1835		Joseph Henry invented the electromechanical relay.
1842		Timoleon Maurel patented the Arithmaurel, a mechanical calculator with a very intuitive user interface, especially for multiplying and dividing numbers because the result was displayed as soon as the operands were entered. It received a gold medal at the French national show in Paris in 1849. Unfortunately its complexity and the fragility of its design prevented it from being manufactured.
1842		Construction of Babbage's difference engine was cancelled as an official project. The cost overruns had been considerable (£17,470 was spent, which, in 2004 money, would be about £1,000,000 ).
1843		Per Georg Scheutz and his son Edvard produced a third-order difference engine with printer; the Swedish government agrees to fund their next development.
1847		Babbage designed an improved, simpler difference engine (the Difference Engine No.2), a project which took 2 years. The machine would have operated on 7th-order differences and 31-digit numbers, but nobody was found to pay to have it built. In 1989-1991 a team at London's Science Museum did build one from the surviving plans. They built components using modern methods, but with tolerances no better than Clement could have provided... and, after a bit of tinkering and detail-debugging, they found that the machine works properly. In 2000, the printer was also completed.
1848		British Mathematician George Boole developed binary algebra (Boolean algebra) which has been widely used in binary computer design and operation, beginning about a century later. See 1939.

1851–1930

Date	Place	Event
1851		After 30 years of development, Thomas de Colmar launched the mechanical calculator industry by starting the manufacturing of a much simplified Arithmometer (invented in 1820). Aside from its clones, which started thirty years later, it was the only calculating machine available anywhere in the world for forty years (Dorr E. Felt only sold one hundred comptometers and a few comptographs from 1887 to 1890). Its simplicity made it the most reliable calculator to date. It was a big machine (a 20 digit arithmometer was long enough to occupy most of a desktop). Even though the arithmometer was only manufactured until 1915, twenty European companies manufactured improved clones of its design until the beginning of WWII ; they were Burkhardt, Layton, Saxonia, Gräber, Peerless, Mercedes-Euklid, XxX, Archimedes, etc...
1853		To Babbage's delight, the Scheutzes completed the first full-scale difference engine, which they called a Tabulating Machine. It operated on 15-digit numbers and 4th-order differences, and produced printed output just as Babbage's would have. A second machine was later built to the same design by the firm of Bryan Donkin of London.
1858		The first Tabulating Machine (see 1853) was bought by the Dudley Observatory in Albany, New York, and the second by the British government. The Albany machine was used to produce a set of astronomical tables; but the Observatory's director was fired for this extravagant purchase, and the machine never seriously used again, eventually ending up in a museum. The second machine had a long and useful life.
1869		The first practical logic machine was built by William Stanley Jevons.
1871		Babbage produced a prototype section of the Analytical Engine's mill and printer.
1875		Martin Wiberg produced a reworked difference-engine-like machine intended to prepare logarithmic tables.
1878		Ramon Verea, living in New York City, invented a calculator with an internal multiplication table; this was much faster than the shifting carriage, or other digital methods of the time. He wasn't interested in putting it into production, however; it seems he just wanted to show that a Spaniard could invent as well as an American.
1879		A committee investigated the feasibility of completing the Analytical Engine, and concluded that it would be impossible now that Babbage was dead. The project was then largely forgotten, except by a very few; Howard Aiken was a notable exception.
1884		Dorr Felt, of Chicago, developed his Comptometer. This was the first calculator in which operands are entered by pressing keys rather than having to be, for example, dialled in. It was feasible because of Felt's invention of a carry mechanism fast enough to act while the keys return from being pressed. Felt and Tarrant started a partnership to manufacture the comptometer in 1887.
1885		A multiplying calculator more compact than the Arithmometer entered mass production. The design was the independent, and more or less simultaneous, invention of Frank S. Baldwin, of the United States, and Willgodt Theophil Odhner, a Swede living in Russia. Fluted drums were replaced by a "variable-toothed gear" design: a disk with radial pegs that could be made to protrude or retract from it.
1886		Herman Hollerith developed the first version of his tabulating system in the Baltimore Department of Health.
1889		Dorr Felt invented the first printing desk calculator.
1890		The 1880 US census had taken 7 years to complete since all processing had been done by hand from journal sheets. The increasing population suggested that by the 1890 census, data processing would take longer than the 10 years before the next census —so a competition was held to find a better method. It was won by a Census Department employee, Herman Hollerith, who went on to found the Tabulating Machine Company, later to become IBM. He invented the recording of data on a medium that could then be read by a machine. Prior uses of machine readable media had been for control (Automatons, Piano rolls, looms, ...), not data. "After some initial trials with paper tape, he settled on punched cards..." His machines used mechanical relays to increment mechanical counters. This method was used in the 1890 census. The net effect of the many changes from the 1880 census: the larger population, the data items to be collected, the Census Bureau headcount, the scheduled publications, and the use of Hollerith's electromechanical tabulators, was to reduce the time required to process the census from eight years for the 1880 census to six years for the 1890 census. The inspiration for this invention was Hollerith's observation of railroad conductors during a trip in the western US; they encoded a crude description of the passenger (tall, bald, male) in the way they punched the ticket.
1892		William S. Burroughs of St. Louis, invented a machine similar to Felt's (see 1884) in 1885 but unlike the comptometer it was a 'key-set' machine which only processed each number after a crank handle was pulled. The true manufacturing of this machine started in 1892 even though Burroughs had started his American Arithmometer Company in 1886 (it later became Burroughs Corporation and is now called Unisys).
1896		Herman Hollerith introduced an Integrating Tabulator that could add numbers encoded on punched cards to one of several 7-digit counters. His earlier tabulators simply incremented counters based on whether a hole was punched or not.
1901		The Standard Adding Machine Company released the first 10-key adding machine in between 1901 and 1903. The inventor, William Hopkins, filed his first patent on October 4, 1892. The 10 keys were set on a single row.
1902		Remington advertised the Dalton adding machine as the first 10-key printing adding machine. The 10 keys were set on two rows. Six machines had been manufactured by the end of 1906
1906		Henry Babbage, Charles's son, with the help of the firm of R. W. Munro, completed the 'mill' from his father's Analytical Engine, to show that it would have worked. It does. The complete machine was not produced.
1906		Vacuum tube (or thermionic valve) invented by Lee De Forest.
1906		Herman Hollerith introduces a tabulator with a plugboard that can be rewired to adapt the machine for different applications. Plugboards were widely used to direct machine calculations until displaced by stored programs in the 1950s.
1919		William Henry Eccles and F. W. Jordan published the first flip-flop circuit design.
1924		Walther Bothe built an AND logic gate - the coincidence circuit, for use in physics experiments, for which he received the Nobel Prize in Physics 1954. Digital circuitries of all kinds make heavy use of this technique.
1926		Westinghouse AC Calculating board. A Network analyzer (AC power) used for electrical transmission line simulations up until the 1960s.
1928		IBM standardizes on punched cards with 80 columns of data and rectangular holes. Widely known as IBM Cards, they dominate the data processing industry for almost half a century.
1930		Vannevar Bush built a partly electronic difference engine capable of solving differential equations.
1930		Welsh physicist C. E. Wynn-Williams, at Cambridge, England, used a ring of thyratron tubes to construct a binary digital counter that counted emitted Alpha particles.

1931–1940

Date	Place	Event
1931		Kurt Gödel of Vienna University, Austria, published a paper on a universal formal language based on arithmetic operations. He used it to encode arbitrary formal statements and proofs, and showed that formal systems such as traditional mathematics are either inconsistent in a certain sense, or contain unprovable but true statements. This result is often called the fundamental result of theoretical computer science.
1931		IBM introduced the IBM 601 Multiplying Punch, an electromechanical machine that could read two numbers, up to 8 digits long, from a card and punch their product onto the same card.
1934		Wallace Eckert of Columbia University connects an IBM 285 Tabulator, an 016 Duplicating Punch and an IBM 601 Multiplying Punch with a cam-controlled sequencer switch that he designed. The combined system was used to automate the integration of differential equations.
1936		Alan Turing of Cambridge University, England, published a paper on 'computable numbers' which reformulated Kurt Gödel's results (see related work by Alonzo Church). His paper addressed the famous 'Entscheidungsproblem' whose solution was sought in the paper by reasoning (as a mathematical device) about a simple and theoretical computer, known today as a Turing machine. In many ways, this device was more convenient than Gödel's arithmetics-based universal formal system.
1937		George Stibitz of the Bell Telephone Laboratories (Bell Labs), New York City, constructed a demonstration 1-bit binary adder using relays. This was one of the first binary computers, although at this stage it was only a demonstration machine; improvements continued leading to the Complex Number Calculator of January 1940.
1937		Claude E. Shannon published a paper on the implementation of symbolic logic using relays as his MIT Master's thesis.
1938		Konrad Zuse of Berlin, completed the 'Z1', the first mechanical binary programmable computer. It was based on Boolean Algebra and had some of the basic ingredients of modern machines, using the binary system and floating-point arithmetic. Zuse's 1936 patent application (Z23139/GMD Nr. 005/021) also suggested a 'von Neumann' architecture (re-invented about 1945) with program and data modifiable in storage. Originally the machine was called the 'V1' but retroactively renamed after the war, to avoid confusion with the V-1 flying bomb. It worked with floating point numbers (7-bit exponent, 16-bit mantissa, and sign bit). The memory used sliding metal parts to store 16 such numbers, and worked well; but the arithmetic unit was less successful, occasionally suffering from certain mechanical engineering problems. The program was read from holes punched in discarded 35 mm movie film. Data values could have been entered from a numeric keyboard, and outputs were displayed on electric lamps. The machine was not a general purpose computer (i.e., Turing complete) because it lacked loop capabilities.
1939		William Hewlett and David Packard established the Hewlett-Packard Company in Packard's garage in Palo Alto, California with an initial investment of $538; this was considered to be the symbolic founding of Silicon Valley. HP would grow to become one of the largest technology companies in the world today.
1939 Nov		John Vincent Atanasoff and graduate student Clifford Berry of Iowa State College (now the Iowa State University), Ames, Iowa, completed a prototype 16-bit adder. This was the first machine to calculate using vacuum tubes.
1939		Konrad Zuse completed the 'Z2' (originally 'V2'), which combined the Z1's existing mechanical memory unit with a new arithmetic unit using relay logic. Like the Z1, the Z2 lacked loop capabilities. The project was interrupted for a year when Zuse was drafted, but continued after he was released.
1939		Helmut Schreyer completed a prototype 10-bit adder using vacuum tubes, and a prototype memory using neon lamps.
1940 Jan		At Bell Labs, Samuel Williams and George Stibitz completed a calculator which could operate on complex numbers, and named it the 'Complex Number Calculator'; it was later known as the 'Model I Relay Calculator'. It used telephone switching parts for logic: 450 relays and 10 crossbar switches. Numbers were represented in 'plus 3 BCD'; that is, for each decimal digit, 0 is represented by binary 0011, 1 by 0100, and so on up to 1100 for 9; this scheme requires fewer relays than straight BCD. Rather than requiring users to come to the machine to use it, the calculator was provided with three remote keyboards, at various places in the building, in the form of teletypes. Only one could be used at a time, and the output was automatically displayed on the same one. On 9 September 1940, a teletype was set up at a Dartmouth College in Hanover, New Hampshire, with a connection to New York, and those attending the conference could use the machine remotely.
1940 April 1		In 1940 Zuse presented the Z2 to an audience of the [Deutsche Versuchsanstalt für Luftfahrt] Error: {{Lang}}: text has italic markup (help) ("German Laboratory for Aviation") in Berlin-Adlershof.

1941–1949

Date	Place	Event
1941 May 11		Now working with limited backing from the DVL (German Aeronautical Research Institute), Konrad Zuse completed the 'Z3' (originally 'V3'): the first operational programmable computer. One major improvement over Charles Babbage's non-functional device is the use of Leibniz's binary system (Babbage and others unsuccessfully tried to build decimal programmable computers). Zuse's machine also featured floating point numbers with a 7-bit exponent, 14-bit mantissa (with a '1' bit automatically prefixed unless the number is 0), and a sign bit. The memory held 64 of these words and therefore required over 1400 relays; there were 1200 more in the arithmetic and control units. It also featured parallel adders. The program, input, and output were implemented as described above for the Z1. Although conditional jumps were not available, it has been shown that Zuse's Z3 is, in principle, capable of functioning as a universal computer. The machine could do 3-4 additions per second, and took 3–5 seconds for a multiplication. The Z3 was destroyed in 1943 during an Allied bombardment of Berlin, and had no impact on computer technology in America and England.
1942 Summer		Atanasoff and Berry completed a special-purpose calculator for solving systems of simultaneous linear equations, later called the 'ABC' ('Atanasoff–Berry Computer'). This had 60 50-bit words of memory in the form of capacitors (with refresh circuits —the first regenerative memory) mounted on two revolving drums. The clock speed was 60 Hz, and an addition took 1 second. For secondary memory it used punched cards, moved around by the user. The holes were not actually punched in the cards, but burned. The punched card system's error rate was never reduced beyond 0.001%, and this was inadequate. Atanasoff left Iowa State after the U.S. entered the war, ending his work on digital computing machines.
1942		Helmut Hölzer built an analog computer to calculate and simulateV-2 rocket trajectories.
1942		Konrad Zuse developed the S1, the world's first process computer, used by Henschel to measure the surface of wings.
1943 Apr		Max Newman, Wynn-Williams and their team at the secret Government Code and Cypher School ('Station X'), Bletchley Park, Bletchley, England, completed the 'Heath Robinson'. This was a specialized counting machine used for cipher-breaking, not a general-purpose calculator or computer, but a logic device using a combination of electronics and relay logic. It read data optically at 2000 characters per second from 2 closed loops of paper tape, each typically about 1000 characters long. It was significant since it was the forerunner of Colossus. Newman knew Turing from Cambridge (Turing was a student of Newman's), and had been the first person to see a draft of Turing's 1936 paper. Heath Robinson is the name of a British cartoonist known for drawings of comical machines, like the American Rube Goldberg. Two later machines in the series will be named after London stores with 'Robinson' in their names.
1943 Sep		Williams and Stibitz completed the 'Relay Interpolator', later called the 'Model II Relay Calculator'. This was a programmable calculator; again, the program and data were read from paper tapes. An innovative feature was that, for greater reliability, numbers were represented in a biquinary format using 7 relays for each digit, of which exactly 2 should be "on": 01 00001 for 0, 01 00010 for 1, and so on up to 10 10000 for 9. Some of the later machines in this series would use the biquinary notation for the digits of floating-point numbers.
1943 Dec		The Colossus was built, by Dr Thomas Flowers at The Post Office Research Laboratories in London, to crack the German Lorenz (SZ42) cipher. It contained 2400 vacuum tubes for logic and applied a programmable logical function to a stream of input characters, read from punched tape at a rate of 5000 characters a second. Colossus was used at Bletchley Park during World War II —as a successor to the unreliable Heath Robinson machines. Although 10 were eventually built, most were destroyed immediately after they had finished their work to maintain the secrecy of the work.
1944 August 7		The IBM Automatic Sequence Controlled Calculator was turned over to Harvard University, which called it the Harvard Mark I. It was designed by Howard Aiken and his team, financed and built by IBM —it became the second program controlled machine (after Konrad Zuse's). The whole machine was 51 feet (16 m) long, weighed 5 (short) tons (4.5 tonnes), and incorporated 750,000 parts. It used 3304 electromechanical relays as on-off switches, had 72 accumulators (each with its own arithmetic unit), as well as a mechanical register with a capacity of 23 digits plus sign. The arithmetic was fixed-point and decimal, with a control panel setting determining the number of decimal places. Input-output facilities include card readers, a card punch, paper tape readers, and typewriters. There were 60 sets of rotary switches, each of which could be used as a constant register —sort of mechanical read-only memory. The program was read from one paper tape; data could be read from the other tapes, or the card readers, or from the constant registers. Conditional jumps were not available. However, in later years, the machine was modified to support multiple paper tape readers for the program, with the transfer from one to another being conditional, rather like a conditional subroutine call. Another addition allowed the provision of plug-board wired subroutines callable from the tape. Used to create ballistics tables for the US Navy.
1945		Konrad Zuse developed Plankalkül, the first higher-level programming language. He also presented the Z4 in March.
1945		Vannevar Bush developed the theory of the memex, a hypertext device linked to a library of books and films.
1945		John von Neumann drafted a report describing the future computer eventually built as the EDVAC (Electronic Discrete Variable Automatic Computer). First Draft of a Report on the EDVAC includes the first published description of the design of a stored-program computer, giving rise to the term von Neumann architecture. It directly or indirectly influenced nearly all subsequent projects, especially EDSAC. The design team included John W. Mauchly and J. Presper Eckert.
1946 February 14		ENIAC (Electronic Numerical Integrator and Computer): One of the first totally electronic, valve driven, digital, program-controlled computers was unveiled although it was shut down on 9 November 1946 for a refurbishment and a memory upgrade, and was transferred to Aberdeen Proving Ground, Maryland in 1947. Development had started in 1943 at the Ballistic Research Laboratory, USA, by John W. Mauchly and J. Presper Eckert. It weighed 30 tonnes and contained 18,000 electronic valves, consuming around 160 kW of electrical power. It could do 50,000 basic calculations a second. It was used for calculating ballistic trajectories and testing theories behind the hydrogen bomb.
1946 February 19		ACE (Automatic Computing Engine): Alan Turing presented a detailed paper to the National Physical Laboratory (NPL) Executive Committee, giving the first reasonably complete design of a stored-program computer. However, because of the strict and long-lasting secrecy around his wartime work at Bletchley Park, he was prohibited (having signed the Official Secrets Act) from explaining that he knew that his ideas could be implemented in an electronic device.
1946		The trackball was invented as part of a radar plotting system named Comprehensive Display System (CDS) by Ralph Benjamin when working for the British Royal Navy Scientific Service. Benjamin's project used analog computers to calculate the future position of target aircraft based on several initial input points provided by a user with a joystick. Benjamin felt that a more elegant input device was needed and invented a ball tracker system called the roller ball for this purpose in 1946. The device was patented in 1947, but only a prototype was ever built and the device was kept as a secret outside military.
1947 December 16		Invention of the transistor at Bell Laboratories, USA, by William B. Shockley, John Bardeen and Walter Brattain.
1947		Howard Aiken completed the Harvard Mark II.
1947		The Association for Computing Machinery (ACM), was founded as the world's first scientific and educational computing society. It remains to this day with a membership currently around 78,000. Its headquarters are in New York City.
1948 January 27		IBM finished the SSEC (Selective Sequence Electronic Calculator). It was the first computer to modify a stored program. "About 1300 vacuum tubes were used to construct the arithmetic unit and eight very high-speed registers, while 23000 relays were used in the control structure and 150 registers of slower memory."
1948 June 21		SSEM, Small-Scale Experimental Machine or 'Baby' was built at the University of Manchester. It ran its first program on this date. It was the first computer to store both its programs and data in RAM, as modern computers do. By 1949 the 'Baby' had grown, and acquired a magnetic drum for more permanent storage, and it became the Manchester Mark 1.
1948		ANACOM from Westinghouse was an AC-energized electrical analog computer system used up until the early 1990s for problems in mechanical and structural design, fluidics, and various transient problems.
1948		IBM introduced the '604', the first machine to feature Field Replaceable Units (FRUs), which cut downtime as entire pluggable units can simply be replaced instead of troubleshot.
1948		The first Curta handheld mechanical calculator was sold. The Curta computed with 11 digits of decimal precision on input operands up to 8 decimal digits. The Curta was about the size of a handheld pepper grinder.
1949 Mar		John Presper Eckert and John William Mauchly construct the BINAC for Northrop.
1949 May 6		This is considered the birthday of modern computing. Maurice Wilkes and a team at Cambridge University executed the first stored program on the EDSAC computer, which used paper tape input-output. Based on ideas from John von Neumann about stored program computers, the EDSAC was the first complete, fully functional von Neumann architecture computer.
1949 Oct		The Manchester Mark 1 final specification is completed; this machine was notably in being the first computer to use the equivalent of base/index registers, a feature not entering common computer architecture until the second generation around 1955.
1949		CSIR Mk I (later known as CSIRAC), Australia's first computer, ran its first test program. It was a vacuum tube based electronic general purpose computer. Its main memory stored data as a series of acoustic pulses in 5 ft (1.5 m) long tubes filled with mercury.
1949		MONIAC (Monetary National Income Analogue Computer) also known as the Phillips Hydraulic Computer, was created in 1949 to model the national economic processes of the United Kingdom. The MONIAC consisted of a series of transparent plastic tanks and pipes. It is thought that twelve to fourteen machines were built.
1949		Computers in the future may weigh no more than 1.5 tons. — Popular Mechanics, forecasting the relentless march of science.

Computing timeline

• Timeline of computing
  • 1950–1979
  • 1980–1989
  • 1990–1999
  • 2000-2009
  • 2010-present

References

• Marguin, Jean (1994). Histoire des instruments et machines à calculer, trois siècles de mécanique pensante 1642-1942 (in French). Hermann. ISBN 978-2-7056-6166-3.
• Ginsburg, Jekuthiel (2003). Scripta Mathematica (Septembre 1932-Juin 1933). Kessinger Publishing, LLC. ISBN 978-0-7661-3835-3.
• Gladstone-Millar, Lynne (2003). John Napier: Logarithm John. National Museums Of Scotland. ISBN 978-1-901663-70-9.
• Taton, René (1969). Histoire du calcul. Que sais-je ? n° 198. Presses universitaires de France.
• Swedin, Eric G.; Ferro, David L. (2005). Computers: The Life Story of a Technology. Greenwood. ISBN 978-0-313-33149-7.
• Taton, René (1963). Le calcul mécanique (in French). Paris: Presses universitaires de France.
• Smith, David Eugene (1929). A Source Book in Mathematics. New York and London: McGraw-Hill Book Company, Inc.

External links

• A Brief History of Computing, by Stephen White. An excellent computer history site; the present article is a modified version of his timeline, used with permission.
• The Evolution of the Modern Computer (1934 to 1950): An Open Source Graphical History, article from Virtual Travelog
• Timeline: exponential speedup since first automatic calculator in 1623 by Jürgen Schmidhuber, from "The New AI: General & Sound & Relevant for Physics, In B. Goertzel and C. Pennachin, eds.: Artificial General Intelligence, p. 175-198, 2006."
• Computing History Timeline, a photographic gallery on computing history