'Abacus' was the earliest known device to record computations.
It dates back to ancient times and was invented by the Chinese. Ten
beads were strung onto wires attached to a frame. Addition and
subtraction were read from the final positions of the beads. It was
considered the first manual tool used in calculating answers to problems
that provided information and in a primitive way storing the results.
First Generation Computers (1940s – 1950s):
First electronic computers used vacuum tubes, and they were huge and
complex. The first general purpose electronic computer was the ENIAC. It took up 167 square meters, weighed 27 tons, and consuming 150
kilowatts of power. It used thousands of vacuum tubes, crystal diodes,
relays, resistors, and capacitors.
The first non-general purpose computer was ABC (Atanasoff–Berry Computer), and other similar computers of this era included german Z3, ten British Colossus computers, LEO, Harvard Mark I, and UNIVAC.
Second Generation Computers (1955 – 1960):
The second generation of computers were built using transistors, which consumed far less power, produced
far less heat, and were much smaller compared to the first generation,
albeit still big by today’s standards.
The first transistor computer was created at the University of Manchester in 1953. The most popular of transistor computers was IBM 1401. IBM also created the first disk drive in 1956, the IBM 350 RAMAC.
Third Generation Computers (1960s):
The invention of the integrated circuits (ICs), also known as microchips (made by integrating a large number of transistors), paved the way for computers as we know them today. They were much smaller, and cheaper than first and second generation of computers.
Fourth Generation Computers (1971 – present):
First microchips-based central processing units consisted of multiple
microchips for different CPU components. The drive for ever greater
integration and miniaturization led towards single-chip CPUs, where all
of the necessary CPU components were put onto a single microchip, called
a Microprocessor. The first single-chip CPU, or a microprocessor, was
Intel 4004.
The advent of the microprocessor spawned the evolution of the microcomputers, the kind that would eventually become personal computers that we are familiar with today.
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