A Brief History of Computing between 1940 and 1949

1940 - January

At Bell Labs, Samuel Williams and Stibitz complete a calculator which can operate on complex numbers, and give it the imaginative name of the "Complex Number Calculator"; it is later known as the "Model I Relay Calculator". It uses telephone switching parts for logic: 450 relays and 10 crossbar switches. Numbers are 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 is provided with three remote keyboards, at various places in the building, in the form of teletypes. Only one can be used at a time, and the output is automatically displayed on the same one. In September 1940, a teletype is set up at a mathematical conference in Hanover, New Hampshire, with a connection to New York, and those attending the conference can use the machine remotely.

1941 - Summer

Atanasoff and Berry complete a special-purpose calculator for solving systems of simultaneous linear equations, later called the "ABC" ("Atanasoff-Berry Computer"). This has 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 is 60 Hz, and an addition takes 1 second. For secondary memory it uses punch cards, moved around by the user. The holes are not actually punched in the cards, but burned. The punch card system's error rate is never reduced beyond 0.001%, and this isn't really good enough. (Atanasoff will leave Iowa State after the US enters the war, and this will end his work on digital computing machines.)

1941 - December

Now working with limited backing from the DVL (German Aero- nautical Research Institute), Zuse completes the "V3" (later "Z3"): the first operational programmable calculator. It works with floating point numbers having a 7-bit exponent, 14-bit mantissa (with a "1" bit automatically prefixed unless the number is 0), and a sign bit. The memory holds 64 of these words and therefore requires over 1400 relays; there are 1200 more in the arithmetic and control units. The program, input, and output are implemented as described above for the Z1. Conditional jumps are not available. The machine can do 3-4 additions per second, and takes 3-5 seconds for a multiplication. It is a marginal decision whether to call the Z3 a prototype; with its small memory it is certainly not very useful on the equation- solving problems that the DVL was mostly interested in.

1943

Computers between 1943 and 1959 (or thereabouts - some say this era did not start until UNIVAC-1 in 1951) usually regarded as 'first generation' and are based on valves and wire circuits. The are characterised by the use of punched cards and vacuum valves. All programming was done in machine code. A typical machine of the era was UNIVAC, see 1951.

1943

"I think there is a world market for maybe five computers.", Thomas Watson, chairman of IBM.

1943 - January

The Harvard Mark I (originally ASCC Mark I, Harvard-IBM Automatic Sequence Controlled Calculator) was built at Harvard University by Howard H. Aiken (1900-1973) and his team, partly financed by IBM - it became the first program controlled calculator. The whole machine is 51 feet long, weighs 5 tons, and incorporates 750,000 parts. It used 3304 electromechanical relays as on-off switches, had 72 accumulators (each with it's own arithmentic unit) as well as mechanical register with a capacity of 23 digits plus sign. The arithmetic is fixed-point, with a plugboard setting determining the number of decimal places. I/O facilities include card readers, a card punch, paper tape readers, and typewriters. There are 60 sets of rotary swithces, each of which can be used as a constant register - sort of mechanical read-only memory. The program is read from one paper tape; data can be read from the other tapes, or the card readers, or from the constant registers. Conditional jumps are not available. However, in later years the machine is modified to support multiple paper tape readers for the program, with the transfer from one to another being conditional, sort of like a conditional subroutine call. Another addition allows the provision of plugboard-wired subroutines callable from the tape. Used to create ballistics tables for the US Navy.

1943 - April

Max Newman, Wynn-Williams, and their team at the secret Government Code and Cypher School, Bletchley Park, Bletchley, England, complete the "Heath Robinson". This is a specialized machine for cipher-breaking, not a general-purpose calculator or computer but some sort of logic device, using a combination of electronics and relay logic. It reads 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 fore-runner of Colossus, see December 1943. (Turing was a student of Newman's.) (The secrecy that surrounded this machine and its successors at Bletchley Park will still be partially in effect at the time of writing, hence the vague description. Newman knew Turing from Cambridge, and had been the first person to see a draft of Turing's 1937 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 for London stores with "Robinson" in their names!)

1943 - September

Williams and Stibitz complete the "Relay Interpolator", later called the "Model II Relay Calculator". This is a programmable calculator; again, the program and data are read from paper tapes. An innovative feature is that, for greater reliability, numbers are 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 will use the biquinary notation for the digits of floating-point numbers.)

1943 - December

The earliest Programmable Electronic Computer first ran (in Britain), it contained 2400 Vacuum tubes for logic, and was called the Colossus. It was built, by Thomas Flowers, to crack the German coding 'Enigma' machines and used at Bletchly Park during WWII - as a successor to April's 'Robinson's. It translated an amazing 5000 characters a second, and used punched tape for input. Although 10 were eventually built, unfortunately they were destroyed immediately after they had finished their work - it was so advanced that there was to be no possibility of it's design falling into the wrong hands (presumably the Russians). One of the early engineers wrote an emulation on a Pentium - that ran at ½ the rate!

1946

ENIAC (Electronic Numerical Integrator and Computer): One of the first totally electronic, valve driven, digital, computers. Development started in 1943 and finished in 1946, 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 25kW of electrical power - widely recognised as the first Universal Electronic Computer. It could do around 100,000 calculations a second. It was used for calculating Ballistic trajectories and testing theories behind the Hydrogen bomb.

1947 - end

Invention of Transistor at The Bell Laboratories, USA, by William B. Shockley, John Bardeen and Walter H. Brattain.

1948

Manchester University - Mark I, completed, the first computer to use stored programs.

1949

EDSAC Wilkes and a team at Cambridge University build a stored program computer. It used paper tape I/O.

1949

EDVAC (electronic discrete variable computer) - First computer to use Magnetic Tape. This was a breakthrough as all previous computers had to be re-programmed by re-wiring them whereas EDVAC could have new programs loaded off of the tape. Proposed by John von Neumann, it was completed in 1952 at the Institute for Advance Study, Princeton, USA.

1949

"Computers in the future may weigh no more than 1.5 tons.", Popular Mechanics, forecasting the relentless march of science.