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“Model K” AdderBell Laboratories scientist George Stibitz uses relays for a demonstration adder
Called the “Model K” Adder because he built it on his “Kitchen” table, this simple demonstration circuit provides proof of concept for applying Boolean logic to the design of computers, resulting in construction of the relay-based Model I Complex Calculator in 1939. That same year in Germany, engineer Konrad Zuse built his Z2 computer, also using telephone company relays. -
The Complex Number Calculator (CNC) is completed
In 1939, Bell Telephone Laboratories completes this calculator, designed by scientist George Stibitz. In 1940, Stibitz demonstrated the CNC at an American Mathematical Society conference held at Dartmouth College. Stibitz stunned the group by performing calculations remotely on the CNC (located in New York City) using a Teletype terminal connected via to New York over special telephone lines. This is likely the first example of remote access computing. -
The Zuse Z3 ComputerKonrad Zuse finishes the Z3 Computer
The Z3, an early computer built by German engineer Konrad Zuse working in complete isolation from developments elsewhere, uses 2,300 relays, performs floating point binary arithmetic, and has a 22-bit word length. The Z3 was used for aerodynamic calculations but was destroyed in a bombing raid on Berlin in late 1943. Zuse later supervised a reconstruction of the Z3 in the 1960s, which is currently on display at the Deutsches Museum in Munich. -
The first Bombe is completed
Built as an electromechanical mechanical means of decrypting Nazi ENIGMA-based military communications during World War II, the British Bombe is conceived of by computer pioneer Alan Turing and Harold Keen of the British Tabulating Machine Company. Hundreds of bombes were built, their purpose to ascertain the daily rotor start positions of Enigma cipher machines, which in turn allowed the Allies to decrypt German messages -
The Atanasoff-Berry ComputerThe Atanasoff-Berry Computer (ABC) is completed
After successfully demonstrating a proof-of-concept prototype in 1939, Professor John Vincent Atanasoff receives funds to build a full-scale machine at Iowa State College (now University). The machine was designed and built by Atanasoff and graduate student Clifford Berry between 1939 and 1942. The ABC was at the center of a patent dispute related to the invention of the computer, which was resolved in 1973 when it was shown that ENIAC co-designer John Mauchly had seen the ABC shortly after it b -
George Stibitz circa 1940Bell Labs Relay Interpolator is completed
The US Army asked Bell Laboratories to design a machine to assist in testing its M-9 gun director, a type of analog computer that aims large guns to their targets. Mathematician George Stibitz recommends using a relay-based calculator for the project. The result was the Relay Interpolator, later called the Bell Labs Model II. The Relay Interpolator used 440 relays, and since it was programmable by paper tape, was used for other applications following the war. -
Curt Herzstark designs Curta calculator
Curt Herzstark was an Austrian engineer who worked in his family’s manufacturing business until he was arrested by the Nazis in 1943. While imprisoned at Buchenwald concentration camp for the rest of World War II, he refines his pre-war design of a calculator featuring a modified version of Leibniz’s “stepped drum” design. After the war, Herzstark’s Curta made history as the smallest all-mechanical, four-function calculator ever built. -
Project Whirlwind begins
During World War II, the US Navy approached the Massachusetts Institute of Technology (MIT) about building a flight simulator to train bomber crews. The team first builds a large analog computer, but found it inaccurate and inflexible. After designers saw a demonstration of the ENIAC computer, they decided instead on using a digital approach, while the project slowly changed from a flight simulator to an air defense system. By the time Whirlwind was completed in 1951, the Navy had lost interest -
Harvard Mark 1 is completed
Conceived by Harvard physics professor Howard Aiken, and designed and built by IBM, the Harvard Mark 1 is a room-sized, relay-based calculator. The machine had a fifty-foot long camshaft running the length of machine that synchronized the machine’s thousands of component parts and used 3,500 relays. The Mark 1 produced mathematical tables but was soon superseded by electronic stored-program computers. -
The Colossus at work at Bletchley ParkFirst Colossus operational at Bletchley Park
Designed by British engineer Tommy Flowers, the Colossus is designed to break the complex Lorenz ciphers used by the Nazis during World War II. A total of ten Colossi were delivered, each using as many as 2,500 vacuum tubes. A series of pulleys transported continuous rolls of punched paper tape containing possible solutions to a particular code. Colossus reduced the time to break Lorenz messages from weeks to hours. Most historians believe that the use of Colossus machines significantly shortene -
John von Neumann writes First Draft of a Report on the EDVAC
In a widely circulated paper, mathematician John von Neumann outlines the architecture of a stored-program computer, including electronic storage of programming information and data -- which eliminates the need for more clumsy methods of programming such as plugboards, punched cards and paper. Hungarian-born von Neumann demonstrated prodigious expertise in hydrodynamics, ballistics, meteorology, game theory, statistics, and the use of mechanical devices for computation. After the war, he concent -
Public unveiling of ENIAC
Started in 1943, the ENIAC computing system was built by John Mauchly and J. Presper Eckert at the Moore School of Electrical Engineering of the University of Pennsylvania. Because of its electronic, as opposed to electromechanical, technology, it is over 1,000 times faster than any previous computer. ENIAC used plugboards and switches for programming, occupied more than 1,000 square feet, used about 18,000 vacuum tubes and weighed 30 tons. It was believed that ENIAC had done more calculation ov -
Moore School lectures take place
An inspiring summer school on computing at the University of Pennsylvania´s Moore School of Electrical Engineering stimulates construction of stored-program computers at universities and research institutions in the US, France, the UK, and Germany. Among the lecturers were early computer designers like John von Neumann, Howard Aiken, J. Presper Eckert and John Mauchly, as well as mathematicians including Derrick Lehmer, George Stibitz, and Douglas Hartree. Students included future computing pion -
First Computer Program to Run on a Computer
University of Manchester researchers Frederic Williams, Tom Kilburn, and Geoff Toothill develop the Small-Scale Experimental Machine (SSEM), better known as the Manchester Baby. The Baby was built to test a new memory technology developed by Williams and Kilburn -- soon known as the Williams Tube – which was the first electronic random access memory for a computer. The first program, consisting of seventeen instructions and written by Kilburn, ran on June 21st, 1948. This was the first program t -
Plans to build the Simon 1 relay logic machine are published
The hobbyist magazine Radio Electronics publishes Edmund Berkeley's design for the Simon 1 relay computer from 1950 to 1951. The Simon 1 used relay logic and cost about $600 to build. In his book Giant Brains, Berkeley noted - “We shall now consider how we can design a very simple machine that will think. Let us call it Simon, because of its predecessor, Simple Simon... Simon is so simple and so small in fact that it could be built to fill up less space than a grocery-store box; about four cubic -
Grimsdale and Webb build early transistorized computer
Working under Tom Kilburn at England’s Manchester University, Richard Grimsdale and Douglas Webb demonstrate a prototype transistorized computer, the "Manchester TC", on November 16, 1953. The 48-bit machine used 92 point-contact transistors and 550 diodes. -
MIT researchers build the TX-0
The TX-0 (“Transistor eXperimental - 0”) is the first general-purpose programmable computer built with transistors. For easy replacement, designers placed each transistor circuit inside a "bottle," similar to a vacuum tube. Constructed at MIT´s Lincoln Laboratory, the TX-0 moved to the MIT Research Laboratory of Electronics, where it hosted some early imaginative tests of programming, including writing a Western movie shown on television, 3-D tic-tac-toe, and a maze in which a mouse found martin -
Digital Equipment Corporation (DEC) founded
DEC is founded initially to make electronic modules for test, measurement, prototyping and control markets. Its founders were Ken and Stan Olsen, and Harlan Anderson. Headquartered in Maynard, Massachusetts, Digital Equipment Corporation, took over 8,680 square foot leased space in a nineteenth century mill that once produced blankets and uniforms for soldiers who fought in the Civil War. General Georges Doriot and his pioneering venture capital firm, American Research and Development, invested -
IBM StretchIBM 7030 (“Stretch”) completed
IBM´s 7000 series mainframes are the company´s first transistorized computers. At the top of the line sat the 7030, also known as the "Stretch." Nine of the computers, which featured dozens of advanced design innovations later re-discovered by later generations of computer designers were sold, mainly to national laboratories and major scientific users. The knowledge and technologies developed for the Stretch project played a major role in the design of the later IBM System/360. -
DEC PDP-1 introduced
The typical PDP-1 computer system, which sells for about $120,000, includes a cathode ray tube graphic display, paper tape input/output, needs no air conditioning and requires only one operator; all of which become standards for minicomputers. Its large scope intrigued early hackers at MIT, who wrote the first computerized video game, SpaceWar!, as well as programs to play music. More than 50 PDP-1s were sold. -
IBM 1401IBM Introduces 1400 series
The 1401 mainframe, the first in the series, replaces earlier vacuum tube technology with smaller, more reliable transistors. Demand called for more than 12,000 of the 1401 computers, and the machine´s success made a strong case for using general-purpose computers rather than specialized systems. By the mid-1960s, nearly half of all computers in the world were IBM 1401s. -
MIT LINC introduced
The LINC is an early and important example of a ‘personal computer,’ that is, a computer designed for only one user. It was designed by MIT Lincoln Laboratory engineer Wesley Clark. Under the auspices of a National Institutes of Health (NIH) grant, biomedical research faculty from around the United States came to a workshop at MIT to build their own LINCs, and then bring them back to their home institutions where they would be used. For research, Digital Equipment Corporation (DEC) supplied the -
The Atlas Computer debuts
A joint project of England’s Manchester University, Ferranti Computers, and Plessey, Atlas comes online nine years after Manchester’s computer lab begins exploring transistor technology. Atlas was the fastest computer in the world at the time and introduced the concept of “virtual memory,” that is, using a disk or drum as an extension of main memory. System control was provided through the Atlas Supervisor, which some consider to be the first true operating system. -
CDC 6600 supercomputer introduced
The Control Data Corporation (CDC) 6600 performs up to 3 million instructions per second —three times faster than that of its closest competitor, the IBM 7030 supercomputer. The 6600 retained the distinction of being the fastest computer in the world until surpassed by its successor, the CDC 7600, in 1968. Part of the speed came from the computer´s design, which used 10 small computers, known as peripheral processing units, to offload the workload from the central processor.
