Generally, the computers built during the World War II era are known as the first generation computers.
These are considered the first computers, and were extremely different from the computers we see today. Because the first generation computers were extremely difficult to program, they were designed for a specific task, and they never made it to the general market.
These primitive computers relied on vacuum tubes and magnetic drums. Vacuum tubes process data by allowing the passage of electrons while magnetic drums use magnetic material to store data. The 1st generation computers were also extremely slow. However, despite their great number of downfalls, these computers have gradually evolved into computers, as we know them today.
1939-1942: Atanasoff-Barry Computer
The Atanasoff-Barry Computer (ABC) was the first electronic computer. It was developed by physics and mathematics professor John Atanasoff and his graduate student, Clifford Barry. This computer used the binary system found in modern computers and its method for storing data is quite similar to that of the modern computer. However, in 1942, Atanasoff was recruited to the Naval Ordnance Laboratory to help with war research, and the ABC was never properly put into working order.
1941: Konrad Zuse-Z3A
German named Konrad Zuse invented the Z3, a computer used to design airplanes and missiles. It was the first program-controlled processor.
Built in December of 1943 in Bletchly Park (a research center a few miles north of London), Colossus is a computer specifically designed for code breaking. It was used by the British during World War II to break German coded messages.
Howard Aiken proposes the idea of a fully automatic computer in 1937. With the help of IBM, Aiken was able to develop the Mark I by 1944. The Mark I was about 50 feet wide and 8 feet tall, and it was able to handle 23 digit numbers. In addition to the four basic operations, addition, subtraction, multiplication, and division, the Mark I was also able to perform trigonometric and probability functions. To input data and instructions, the computer used paper tapes, which were merely toilet-paper-like rolls of punch cards. For output, the Mark I printed the results using two electric typewriters. The Mark I could perform simple addition problems in less than a second and simple multiplication problems in a second or so. However, for more complicated problems, the computer would require as long as a whole minute. The Mark I was known for being the first automatic computer. It used electromagnetic signals to move mechanical parts. Later, predecessors of the Mark I were introduced to the world, such as the Mark II and the Mark III.
1944: Harvard Mark I
In April of 1943, the building of the Electronic Numerical Integrator Analyzer and Computer (ENIAC) commenced. Developed by colleagues John Mauchley and J. Presper Eckert Junior and built at the University of Pennsylvania's Moore School of Electrical Engineering, ENIAC was the first general-purpose, all-electronic, programmable digital computer. It cost $400,000 to build and it occupied 50 feet by 30 feet of floor space. This humongous computer consisted of 18,000 vacuum tubes (used to process data), 70,000 resistors (used to resist the flow of electric current), 10,000 capacitors (the part of an electrical circuit used to store charge), 6,000 switches, and 1,500 relays (used to activate switches when changes in voltages occur). In addition, it weighed 30 tons and used up 160 kilowatts of electrical power. That's nearly enough to dim every single light in a city as big as Philadelphia! The initial purpose of the ENIAC was to compute the values for artillery range tables, but its first actual task was to make certain calculations for the construction of a hydrogen bomb. The giant computer made use of plug boards, through which its instructions were entered, and it also made use of conditional branching. Conditional branching gave the ENIAC flexibility, allowing it to execute instructions in different orders, based on the value of the data. The ENIAC also contained accumulators, special registers used to store data, and in addition the computer used a digital number system rather than the binary system used in modern computers today. Furthermore, the computer operated at extremely fast speeds and had the capability to perform 5,000 operations per second.
Although the ENIAC was a major breakthrough in the computing world, it also had its problems. For one thing, once a certain task was completed, it would take days to reprogram the computer so that another task could be performed. Every time the computer was completed an operation, it had to be re-wired and its program had to be changed. Because of the great complexities of the ENIAC, this could take many hours, and even days. Another liability of the ENIAC was that because there were so many tubes and components, there were many potential sources of breakdowns. It had to be continuously serviced, and it usually spent one-third of its time down for maintenance. The ENIAC was used from February 1946 until October 1955.
John von Neumann (1903-1957), a mathematician and physicist at the Institute for Advanced Study in Princeton, played a key role in the development of the Electronic Discrete Variable Automatic Computer (EDVAC). The EDVAC was a successor to the ENIAC, and it had been designed to hopefully correct the weaknesses and problems of its predecessor. The EDVAC had a memory, which held the stored information and data. It was this stored memory that allowed for the EDVAC to be stopped and resumed at various times. The EDVAC also had a central processing unit (CPU), which can be found in many modern computers. The CPU of a computer is analogous to the brain of a person. Some of its duties include executing instructions and performing operations.
Plankalkul ("Plan Calculus"), developed by Konrad Zuse, was the first real programming language. Plankalkul made use of structured data, in which the records in the database was, a mixture of alphabetic and numeric data. It also used conditional statements, which modified the execution of a program. However, Plankalkul was not generally known outside of Germany.
Transistors were first developed in 1947 by Bell Telephone laboratories. They replaced vacuum tubes, which were big, bulky, costly, and unreliable. Transistors are most often used to regulate the flow of an electrical current and to switch electricity on and off.
The Selective Sequence Electronic Calculator (SSEC) was developed by IBM. It occupied space 25 feet by 40 feet and used punch cards, punched tape, vacuum tubes, and relays. It could do 50 multiplications per second, but it was not successful because of its high cost. However, it was of some use. In 1969, it produced tables that were used to plot the course of the spaceship Apollo's flight to the moon.
Maurice Wilkes was a mathematician and a physicist at Cambridge University in 1959 when, inspired by the creation of EDVAC, he designed the Electronic Delay Storage Automatic Calculator (EDSAC). The EDSAC was the first practical stored-program computer (a computer using its memory for the storage of data), although by today's standards, it would certainly be anything but practical. The EDSAC was humongous (it was smaller than the ENIAC though) and it contained 3000 tubes and used up 30 kilowatts of electric power.
The Whirlwind computer is the result of a project conducted by Jay Forrester and Robert Everrett at MIT. Started in 1945, it took six years before the Whirlwind would be completed in 1951. Whirlwind was used as an aircraft trainer and flight simulator. Using a concept known as real-time control, Whirlwind was able to simulate flight conditions and to respond accurately to changes such as airspeed, altitude, as well as various other conditions.
The UNIVAC, or the Universal Automatic Computer, was developed in 1951 by John Mauchley and J. Presper Eckert Junior, the creators of the ENIAC. It was a commercial data-processing computer and was generally sold to governments or other commercial businesses, such as the United States Census Bureau and General Electric. In all, 48 of the machines were sold. Although not as big as the ENIAC, the UNIVAC was still humongous compared to today's computers. It weighed approximately 8 tons and occupied a space 14.5 feet by 7.5 feet by 9 feet. The machine was a stored-program computer and could store up to 12000 digits in its mercury delay line tubes. The UNIVAC had an operator keyboard and a console typewriter for input, and could print its results by a tape printer. One of the computer's first major achievements was its prediction of the outcome of the 1952 United States presidential election. The UNIVAC was right in predicting that Dwight D. Eisenhower would become the United State's next president.
1953: IBM 701
The IBM 701 was the first electrical computer. In three years, 19 of these machines were sold.
1954: IBM 650
The IBM 650 was the first mass-produced computer. Despite the fact that only 450 of these were sold in one year, a small number compared to today's statistics, far more of these were sold than any other machine before it. The 650 made use of magnetic drums, which allowed for fast access to stored material.