Computer System

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Computer System

Introduction & Definitions
— Computer is an electronic device that is used to solve various

problems according to a set of instructions given to it
— A computer is a programmable machine that receives input, stores and manipulates data, and provides output in a useful format

Brief History of Computer
— The first use of the word "computer" was recorded in 1613,

referring to a person who carried out calculations, or
computations, and word continued to be used in that sense until middle of 20th century
— From end of 19th century onwards though, word began to take on its more familiar meaning, describing a machine that carries out computations
— The history of computer development is often referred to in reference to different generations of computing devices
— Each generation of computer is characterized by a major
technological development that fundamentally changed way
computers operate, resulting in increasingly smaller, cheaper, more powerful and more efficient and reliable devices

Computer Generations
First Generation (1940-1956 )
— The first computers used vacuum tubes for circuitry and
magnetic drums for memory, and were often enormous,
taking up entire rooms
— They were very expensive to operate and in addition to using a great deal of electricity, generated a lot of heat, which was often the cause of malfunctions
— First generation computers relied on machine language,
lowest-level programming language understood by
computers, to perform operations, and they could only solve
one problem at a time

Computer Generations
First Generation (1940-1956 )
— Input was based on punched cards and paper tape, and output was displayed on printouts
— The UNIVAC and ENIAC computers are examples of firstgeneration computing devices — The UNIVAC was the first commercial computer delivered
to a business client, the U.S. Census Bureau in 1951

Computer Generations
Second Generation (1956-1963 )
— Transistors replaced vacuum tubes and ushered in the second generation of computers
— The transistor was invented in 1947 but did not see
widespread use in computers until the late 1950s
— The transistor was far superior to the vacuum tube, allowing computers to become smaller, faster, cheaper, more energyefficient and more reliable than their first-generation predecessors
— Though the transistor still generated a great deal of heat that subjected the computer to damage, it was a vast
improvement over the vacuum tube

Computer Generations
Second Generation (1956-1963 )
— Second-generation computers still relied on punched cards for

input and printouts for output

— Second-generation computers moved from cryptic binary

machine language to symbolic, or assembly, languages, which
allowed programmers to specify instructions in words
— High-level programming languages were also being
developed at this time, such as early versions of COBOL and
— These were also the first computers that stored their
instructions in their memory, which moved from a magnetic
drum to magnetic core technology.

Computer Generations
Third Generation (1964 -1971)
— The development of the integrated circuit was the hallmark of the third generation of computers
— Transistors were miniaturized and placed on silicon chips, called semiconductors, which drastically increased the speed and
efficiency of computers
— Instead of punched cards and printouts, users interacted with third generation computers through keyboards and monitors and
interfaced with an operating system
— which allowed the device to run many different applications at one time with a central program that monitored the memory
— Computers for the first time became accessible to a mass audience because they were smaller and cheaper than their predecessors.

Computer Generations
Fourth Generation (1971-Present)
— The microprocessor brought fourth generation of computers, as thousands of integrated circuits...
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