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First generation computers were normally based around wired
circuits containing vacuum valves and used punched cards as the
main non-volatile storage medium. Another general purpose
computer of this era was ENIAC Electronic Numerical Integrator and
Computer which was completed in 1946. It was typical of first
generation computers, it weighed 30 tones contained 18,000
electronic valves and consumed around 25KW of electrical power. It
was, however, capable of an amazing 100,000 calculations a second.
The next major step in the history of computing was the
invention of the transistor in 1947. This replaced the inefficient
valves with a much smaller and more reliable component.
Transistorized computers are normally referred to as Second
Generation and dominated the late 1950s and early 1960s. Despite
using transistors and printed circuits these computers were still bulky
and strictly the domain of Universities and governments.
The explosion in the use of computers began with Third
Generation computers. These relied Jack St. Claire Kirby’s invention
— the integrated circuit or microchip; the first integrated circuit was
produced in September 1958 but computers using them didn’t begin
to appear until 1963. While large mainframes such as the I.B.M. 360
increased storage and processing capabilities further, the integrated
circuit allowed the development of Minicomputers that began to
bring computing into many smaller businesses. Large scale
integration of circuits led to the development of very small
processing units, an early example of this is the processor used for
analyzing flight data in the US Navy’s F14A `TomCat fighter jet.
This processor was developed by Steve Geller, Ray Holt and a team
from AiResearch and American Microsystems.
On November 15th, 1971, Intel released the world’s first
commercial microprocessor, the 4004. Fourth generation computers
were developed, using a microprocessor to locate much of the
computers processing abilities on a single small chip. Coupled with
one of Intel’s inventions — the RAM chip Kilobits of memory on a
single chip — the microprocessor allowed fourth generation

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