Computer
The first lecture
Dr. Jameela Alkrimi
University of Babylon
College of Dentistry
The development of digital computers is rooted in the early mechanical calculating devices; Charles Babbage is credited with the design of the first modern computer, the "analytical engine," during the 1830s. Vanevar Bush built a mechanically operated device, called a differential analyzer
First Generation Computers 1951-1959
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Characterized by vacuum tubes which burned out very rapidly.
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The first generation of computers used machine language or 0s and 1s.
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This generation also used magnetic tape.
The Second Generation (1959 to 1963)
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The second generation of computers used transistors for the internal operations.
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They used magnetic core for the memory.
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These machines used assembly language.
The Third Generation (1963 to 1975)
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These computers used integrated circuits on silicon chips.
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They were characterized with high-level programming languages which required logic such as BASIC, Pascal, C, COBOL, and Fortran
Fourth Generation 1975-Today
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These computers use microprocessor chips.
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Object-Oriented Programming (OOP) Languages such as Visual Basic, and JAVA are characteristic of this computer generation.
5th Generation Still Being Developed
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Natural Language
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This language is designed to give people a more human connection with computers.
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Uses multi-media has also defined this generation.
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There is a great deal of “bundled software” with this generation.
Types of Computers
There are many types of computers including
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Supercomputers are used to process very large amounts of information including processing information to predict hurricanes, satellite images and navigation, and process military war scenarios.
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Mainframes are used by government and businesses to process very large amounts of information.
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Mini-Computers are similar to mainframes...they are used by business and government to process large amounts of information.
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Personal Computers also known as PC’s are smaller and less powerful than the others. They are used in homes, schools, and small businesses. There are 3 main types of PCs
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Desktop
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Portable (Notebook/Laptop)
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When portable (notebook/laptop). They weighed around 100 lbs., and were carried in a large luggage suitcase. The creators of the portable (notebook/laptop) computer dreamed that one day it would be the size a notebook or pocket dictionary. With today’s technology, we have been able to accomplish this goal and more..
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Hand-Held
Classification of Computer
Computing machines can be classified in many ways and these classifications depend on their functions and definitions. They can be classified by the technology from which they were constructed, the uses to which they are put, their capacity or size, the era in which they were used, their basic operating principle and by the kinds of data they process. Some of these classification techniques are discussed as follows:
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Classification by Technology
Classification by Technology This classification is a historical one and it is based on what performs the computer operation, or the technology behind the computing skill. This classification really does not apply to developments in the last sixty years because several kinds of new electro technological devices have been used thereafter
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Classification by Capacity
Classification by Capacity Computers can be classified according to their capacity. The term ‘capacity’ refers to the volume of work or the data processing capability a computer can handle. Their performance is determined by the amount of data that can be stored in memory, speed of internal operation of the computer, number and type of peripheral devices, amount and type of software available for use with the computer.
The capacity of early generation computers was determined by their physical size - the larger the size, the greater the volume. Recent computer technology however is tending to create smaller machines, making it possible to package equivalent speed and capacity in a smaller format. Computer capacity is currently measured by the number of applications that it can run rather than by the volume of data it can process. This classification is therefore done as follows:
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Microcomputers have the lowest level capacity. The machine has memories that are generally made of semiconductors fabricated on silicon chips. Large-scale production of silicon chips began in 1971 and this has been of great use in the production of microcomputers. The microcomputer is a digital computer system that is controlled by a stored program that uses a microprocessor, a programmable read-only memory (ROM) and a random-access memory (RAM). The ROM defines the instructions to be executed by the computer while RAM is the functional equivalent of computer memory
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Supercomputers are used to process very large amounts of information including processing information to predict hurricanes, satellite images and navigation, and process military war scenarios.
-
Mainframes are used by government and businesses to process very large amounts of information.
-
Mini-Computers are similar to mainframes...they are used by business and government to process large amounts of information.
-
Personal Computers also known as PC’s are smaller and less powerful than the others. They are used in homes, schools, and small businesses. There are 3 main types of PCs
-
Desktop
-
Portable (Notebook/Laptop)
-
When portable (notebook/laptop). They weighed around 100 lbs., and were carried in a large luggage suitcase. The creators of the portable (notebook/laptop) computer dreamed that one day it would be the size a notebook or pocket dictionary. With today’s technology, we have been able to accomplish this goal and more..
-
Classification by their basic operating principle
Classification by their basic operating principle Using this classification technique, computers can be divided into Analog, Digital and Hybrid systems. They are explained as follows
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Analog Computers
Analog computers are used to process continuous data. Analog computers represent variables by physical quantities. Thus any computer which solve problem by translating physical conditions such as flow, temperature, pressure, angular position or voltage into related mechanical or electrical related circuits as an analog for the physical phenomenon being investigated in general it is a computer which uses an analog quantity and produces analog values as output. Thus an analog computer measures continuously. Analog computers are very much speedy. They produce their results very fast. But their results are approximately correct. All the analog computers are special purpose computers.
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Digital Computers
Digital computer represents physical quantities with the help of digits or numbers. These numbers are used to perform Arithmetic calculations and also make logical decision to reach a conclusion, depending on, the data they receive from the user.
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Hybrid Computers
Various specifically designed computers are with both digital and analog characteristics combining the advantages of analog and digital computers when working as a system. Hybrid computers are being used extensively in process control system where it is necessary to have a close representation with the physical world. The hybrid system provides the good precision that can be attained with analog computers and the greater control that is possible with digital computers, plus the ability to accept the input data in either form.
Networks
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A network is a group of computers that share information and hardware.
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The computers are connected together using copper phone wires, fiber optic cables, or radio waves.
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The internet is many networks around the world that are all connected together to make 1 huge network.
The Internet
A collection of computing devices connected in order to communicate and share resources. Connections between computing devices can be physical using wires or cables or wireless using radio waves or infrared signals. Computer networks have opened up an entire frontier in the world of computing called the client/server model
Elements of internet
Protocol: A set of rules that defines how data is formatted and processed on a network
File server : A computer dedicated to storing and managing files for network users
Web server: A computer dedicated to responding to requests for web pages
P2P model: A decentralized approach that shares resources and responsibilities among many “peer” computers
Network Types
Computer networks vary in shape and size depending on usage.
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Wide Area Network (WAN)
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A WAN exist over a large area
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Data travels through telephone or cable lines
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Usually requires a Modem
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The world’s largest Wide Area Network in the Internet
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A Local Area Network LAN
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ALN spans a relatively small area
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LAN are usually confined to one building or a group of buildings
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Data travel between network devices via network cables.
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The most common type of Local Area Network is called Ethernet
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Peer to Peer
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Usually very small networks
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Each workstation has equivalent capabilities and responsibilities
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Does not require a switch or a hub.
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These types of networks do not perform well under heavy data loads
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