Computers: Eniac through Minicomputers

Computers: ENIAC through minicomputers

Wartime needs:

need for ballistics calculations led to the building of the Harvard Mark I and II.
Meanwhile in England Alan M. Turing , author of a famous paper in 1936 entitled "Can a Machine Think" was building a specialized vacuum tube machine called the Colossus for codebreaking--became operational in 1943. The program was built into the machine.

Colossus

ENIAC :

Meanwhile John Brainard at the University of Pennsylvania's Moore School of Electrical Engineering had been doing ballistic calculations with an analog computer, and each table took 30 days of machine time. Brainard proposed to build a multipurpose electronic digital computer to compute ballistic tables, and he got a contract from the Army Ordinance Dept. (not OSRD) in 1943
the army correctly judged that this technology was so experimental that it was not likely to be completed in time to be useful in the war.
with the help of ideas from John Mauchly and engineering by J. P. Eckert, Brainard built his machine and named it the Electronic Numerical Integrator and Computer, or ENIAC for short
some of the original ideas had been developed by John Atanasoff , a physicist at Iowa State College. Maunchly visited in 1941 and asked permission to use some of the features. Atanosoff asked for time to file a patent application, but didn't get around to it because his wartime assignment to work on analog computers took precedence. In 1973 the courts did overthrow Maunchly's patent on the basis of Atanosoff's precedence.

ENIAC U.S. Army Photo

When it was completed in late 1945, ENIAC contained 18,000 vacuum tubes, was 100 feet long, 10 feet high, and 3 feet deep and it consumed 140 kilowatts of electricity in operation. At first it spend 50% of the time under repair, but they got to a more acceptable one tube failure every two days by leaving it on all the time (failures had been happening mostly when during warm-up and cool-down). It had been budgeted at $150,000 but ended up costing nearly $500,000.

Programming ENIAC (US Army Photo)

ENIAC was 1000 times faster than the electromechanical machines but it had only 20 words of storage and it had to be programmed with wires (plugboards) and switches.
The first real problem programmed on ENIAC was a mathematical model of a hydrogen bomb from the Los Alamos atomic weapons lab--thousands of steps and data on 1 million punched cards. The results showed several problems with the proposed H-bomb design.
Grace Hopper was hired from Harvard to lead the development of programming. Most of the programming was done by the women who had supervised the human calculators for two reasons: programming the machine was not that different from parceling out a complex series of calculations among a group of people each of whom did one simple task, and the engineers were slow to realize that programming was interesting and challenging.

This led to a series of vacuum tube computers.

In 1948 the first stored-program computer was built in Manchester, England, confusingly called the Mark 1 .
the next one at Penn was the Electronic Discrete Variable Automatic Computer (EDVAC) built between 1947 and 1950, also with the ability to store programs electronically. A copy in Cambridge, England, actually operated first, and was described as the first stored-program electronic computer with any serious computational ability.
Eckert and Mauchley also built a commercial computer for the Census Bureau --the Universal Automatic Computer (UNIVAC )--eventually 48 Univac 1 computers were sold. In November 1952 a UNIVAC computer was used to correctly predict presidential election results, generating much publicity. In England at about the same time Ferranti built a commercial computer that became operational a few months before UNIVAC and sold eight.

John Von Neumann

John von Neumann, a Hungarian immigrant working at Princeton's Insititute for Advanced Studies, began to collaborate with the Penn group in 1944, in particular formulating the stored program concept. He then developed a major research program at Princeton.
Whirlwind was built in 1944 and 1945 by Jay Forrester at MIT's Lincoln Laboratory for the Air Force to simulate flight. Forrester in 1949 introduced magnetic core storage for Whirlwind.
In 1955 IBM began producing computers designed for business data-processing, building on existing technology using punched cards.

Vacuum tubes could take you only so far

but in research between 1945 and 1948, John Bardeen, Walter Brattain, and William Shockley of Bell Labs had invented the point-contact transistor.
In the 1950s IBM , Univac and others used this new technology to produce medium to large-scale systems--mainframe computers. IBM introduced the first disk storage system in 1957. By 1960 they had an effective business system; they produced 12,000 of the transistor based IBM 1401 computers, most rented but the equivalent purchase price would have been $150,000 each. They were popular partly because they came with the best printer on the market. IBM beat out its competitors by a decision in 1962 to go to a completely new product line, the system 360. They spend $500,000 on research and ten times as much on development, including retooling factories and retraining staff
these mainframe computers cost hundreds of thousands to millions of dollars, required special housing and air conditioning, and users submitted jobs on paper tape or punched cards for batch processing. Remote job entry (feed the cards into a card reader away from the mainframe itself) was introduced in the 1960s.

punching cards

Programming languages ( follow this link for a diagram of the history of programming languages ):

the earliest computers were programmed in machine language--instructions and data input in binary form. This was so awkward that it was fairly quickly replaced by assembly language, which gave the computer its actual instructions but allowed decimal numbers and relative addressing
In 1954 John Backus of IBM published the first version of Fortran (Formula Translator)--the first higher-level language. By the mid-1960s 90% of all scientific and engineering programs were written in Fortran.
In 1959 COBOL was developed under the urging of DoD as a standardized higher-level language for business use.
these languages were essential to the wider use of mainframe computers because they made programming easier, but everything was still custom programmed.
In 1961 MIT demonstrated a model time-sharing system, and by the mid-1960s this had become a commercial service. Terminals were Teletypes--already mass produced and inexpensive for message communication, so you got your output on paper, not on a screen.

a teletype with typewriter keyboard and roll of paper

teletype ASR33 used in timesharing

PDP-8

an early microcomputer--8 books take up about half the top

Integrated circuits and programming languages for non-scientists

mini-computers like the Vax introduced by Digital Equipment in 1963 taking advantage of integrated circuits. The first one marketed, the PDP-5 sold for $27,000 and two years later the PDP-8 was more powerful and smaller and sold for $18,000. The PDP-8 was the first mass-produced computer.
BASIC , introduced in 1964, was designed for time-sharing on minicomputers. Designed to be an easy-to-learn language, compared to the technical knowledge presumed by Fortran.
Pascal was released in 1971 as a language for teaching programming and became a rival to BASIC
mini-computers and BASIC meant that computers could for the first time be used by people who were not professional computer programers. The first applications were developed for mini-computers.

	technology	languages & applications	how computers were used
1	vacuum tubes	wires, assembly language	military research, census, weather forecasting
2	transistor	higher level languages--Fortran , Cobol	scientific research, mathematical problems , recordkeeping by big businesses and government
3	integrated circuit	BASIC, first word processors for offices (on special purpose minicomputers)	timesharing, text based games , still mostly programs to make calculations
4	microprocessor	applications become the usual way of using computers, instead of programming	games (but videogame machines are cheaper), small businesses, education