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Evolution of Computing

From Centralized to Distributed Systems

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Evolution of Computing

The nature and structure of computer networks havechanged in conjunction with hardware and softwaretechnology

Computers and networks have evolved from the highly

centralized mainframe systems of the 1950s and 1960sto the distributed systems of the 1960 and into thenew millennium

Todays enterprise networks include a variety ofcomputing devices such as terminals ,PCs,workstations,minicomputers,mainframes and supercomputers.

These devices can be connected via a number ofnetworking technologies like LAN,MAN,WAN

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Types of Computing Models

Mainframes

Mini Computers

Personnel Computer Client/Server Model

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Mainframe

The Parent of all computers is theMainframe

The first mainframe computer weredeveloped in 1940s, but they wereonly confined research anddevelopment uses.

By the late 1950s governemnt andsome corporate environments wereusing these computers

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Mainframe Systems

These are very huge in size and inprice.

Together with connected I/O devicesthey occupied entire rooms.

These are highly specialized :theywere designed for specific tasks suchas military applications.

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Execution in mainframes

Using punched cards and paper tapes.

Batch processing was implemented in

this era. Now IBM is still the leading vendor of

mainframes. With System/390 modeland SNA.

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1950s Mainframe Systems

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Mini Computer

In the early 1960s individual departmentsmaintain a separate computer called SuperComputer.

This Super Computer was first developedby Digital Equipment Corporation(DEC)(PDP5) in 1963.

It has the same basic components ofmainframes but occupied very small space.

It is smaller , less powerful , and lessexpensive.

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Distributed Mini Computer

Mini computer started the evolutionfrom centralized to distributedcomputing in which no centralauthority ; all are same.

Companies such as banks and retailpurchased used this distributed mini

computer.

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Mini Computer

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Personal Computer

In 1981 IBM released its first personalcomputer .These PCs sometimes called asMicroComputers since they are used microchips.

PCs are small ,low cost desktop systemswhich are appeared in every corporate andpersonal environment.

From this era so many software's arereleased for general purposes such as wordprocessing, spread sheets , graphicspackages, and games.

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Personal Computer