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Basics of Computer

Introduction
Data: It is the collection of raw facts, figures & symbols. Ex : Names of students and their marks in different subjects listed in random order.
Information: It is the data that is processed and presented in an organized manner. Ex : When the names of students are arranged in alphabetical order, total and average marks are calculated & presented in a tabular form, it is information
Program: Set of instructions that enable a computer to perform a given task.

Computer basics

computer is not an acronym and sometimes abbreviated as comp or ‘puter. The term “computer” was originally given to humans (human computers) who performed numerical calculations using mechanical calculators, such as the abacus and slide rule. The term was later given to a mechanical device as they began replacing the human computers. Today’s computers are electronic devices that accept data as input,  process that data, produce an output, and store the results.   You may already know that you can use a computer for many purposes. Fore example: to type documents, send email, play games, and browse the Web. You can also use it to edit or create spreadsheets, presentations, and even …

History of Computing

  • The earliest mechanical computing device was the Abacus, named after the Chinese scientist Abacus, during 1200 A.D.
  • Later during 1614 a Scottish nobleman John Napier developed a tool called Napier’s bones as an aid for multiplication.
  • By 1642, the French philosopher and mathematician, Blaise Pascal developed a rotating wheel calculator, the predecessor of the later desk calculator.
  • During the period 1792 – 1871, a British mathematician and engineer, who is considered to be the Father of today’s computer – Charles Babbage built a working model of a machine – the Difference Engine. Later the design of the Difference Engine was developed as Analytical Engine.
  • During 1880s, a statistician Herman Hollerith designed and developed Hollerith machine for processing the census data. The Hollerith machines used punched cards for data processing.
  • The first Electronic Calculator was developed by John Vincent Atanasoff in the late 1930s and along with Clifford Berry a prototype of the Atanasoff-Berry computer was constructed during 1939.
  • A fully electronic computer, the ENIAC (Electronic Numerical Integrator And Calculator) was built during 1943 to 1946 at the University of Pennsylvania.
  • In 1953, IBM announced a medium sized computer, IBM650.
  • In the Middle of 1960s, the Digital Equipment Corporation released its first PDP-1 (The PDP-1 is the first computer in Digital Equipment Corporation’s PDP series and was first produced in 1959. It is famous for being the computer most important in the creation of hacker culture at MIT, BBN and elsewhere) computer.

Characteristics of Computers
High speed: Computers have the ability to perform routine tasks at a greater speed than human beings. They can perform millions of calculations in seconds.
 Accuracy: Computers are used to perform tasks in a way that ensures accuracy.
Storage: Computers can store large amount of information. Any item of data or any instruction stored in the memory can be retrieved by the computer at lightning speeds.
Accuracy: Computer is capable of performing its task more accurately. It never commit mistake by itself. If it is provided with incorrect input it may generate wrong output or unable to output. We use the term GIGO (Garbage In Garbage Out).
Automation: Computers can be instructed to perform complex tasks automatically (Which increases the productivity)?
Diligence/Reliability: Computers can perform the same task repeatedly without getting tired.
Versatility: Computers are flexible to perform both simple and complex task
Types of Computers
Computers have come long way since the first operational computer in 1940s.  Divisions among the types are increasing as technology improves.  Let us classify the computers into three major categories as given below

  1. Based on the purpose of application
  2. Based on the operation of computers
  3. Based on the capacity and size of the microprocessor

1. Based on the operation of computers:
Based on the application of computers for various purpose the computers can be classified into three types.

  • Analog computers
  • Digital computers
  • Hybrid computers

a) Analog Computers
Computers that use analog signals for calculating and transmitting data are called Analog computers.  It can be defined as “A device that operates on data in the form of continuously varying physical quantities”. The values of the analog signals are continuously changing with states in between high and low.  Analog data is calculated using the concept of “measuring values” like magnitude in terms of voltage, length, current.  The analog data is transmitted in a continuous form that closely resembles the information it represents.  Electrical signals on a telephone line are nothing but analog data representing the original voice.

Eg. Thermometer, Voltmeter, Speedometer, Gasoline pump are examples of analog computers.

  • They are special purpose computers and have limited accuracy.

b) Digital Computers
The computers that use digital signals to calculate and transmit data are called Digital Computers.  The word digital is derived from the word “digit”.  The word digit simply means numeral.  The digital signal has only two states in which it can be represented.  They are ON and OFF or HIGH and LOW or 1 and 0.  Digital data is calculated using the concept of “counting values”. These computers manipulate digital data and perform arithmetic and logical operations.  Eg. Abacus, Desktop, laptop, palmtop.

  • They have higher accuracy and speed than the analog computer.

To facilitate the performance of digital computers intermediate languages such as BASIC, COBOL, FORTRAN, PASCAL, C, C++, JAVA etc., has been developed.

c) Hybrid Computers
Computer systems that use both analog and digital mechanisms are called Hybrid Computers.  Desirable features of analog and digital computers are combined to develop a hybrid computer.  In a hospital, the intensive care unit, an analog device measures a patient’s heart function, temperature and other vital signs, these measurements are then converted into numbers and supplied to a digital component that monitors the patient’s vital signs and signals to a nurse’s station

2. Based on the purpose of application: Computers can be categorized in to two sub groups. Those are:

a) General purpose computers
A general purpose computer is one that has the ability to store different programs of instructions. it Performs a variety of operations

  • It is designed to do a wide variety of jobs rather than perform a specific activity.
  • It is also called personal computers (PC’s)
  • They are Digital computers.

b) Special purpose computers

  • Designed to perform one specific task
  • Instructions is built into, or permanently stored in the machine
  • Specialization results in the given task being performed very quickly and efficiently
  • It is inflexible and cannot be easily used to perform other operations.
  • They are Analog computers. Eg. Pocket calculator, ticket machine, public telephone box, Traffic control system.

Now-a-days, for example, new cars have such devices installed to monitor and control fuel, ignition and other system

3.  Classification by Capacity and size of Microprocessor
Computers are also classified into different types mainly based on processing and storage capacity.  A Computer that is capable and used for general purpose business applications like billing, accounting, maintaining stock information ,……. cannot be used for very advanced applications like forecasting and analysis of weather phenomena, oil exploration, aircraft design etc.  And those computers used for the latter purpose mentioned above are not necessary to be used for the former purpose, for the reason, they are highly advanced and very expensive.  Hence, the computers can be classified as given below

  • Microcomputers
  • Minicomputers
  • Mainframe computers
  • Super computers

a) Microcomputers: are the smallest categories of computer and also called as Personal Computers (PCs). Computers that can either fit next to a desk (called the Desktop) or can be carried around (called the Laptop and Notebook). Microcomputers use microprocessor as its important device.   Microprocessor is a chip used to perform arithmetic and logical operations.  These computers can be used either as a standalone machine or connected to a network.  Microcomputers are used for general purpose business applications such as invoicing, accounting etc.

b) Minicomputers: are bigger in size, faster in speed, have more memory capacity and expensive when compared to the microcomputers. Minicomputers can be used for general purpose applications and as a server for small networks. Sometimes called mid range server. These computers are relatively small but expensive computer with somewhat limited input and output capabilities.  Minicomputers use large hard-disk units as online secondary storage.

c) Mainframe computers are more powerful in processing, faster in speed, have large memory, and very expensive when compared to the micro and mini computers. The word mainframe refers to mean the “Central Processor”. Their size varies depending on how many concurrent users they are serving – from a few hundreds to thousands when used in networks and has the capacity to support many powerful peripheral devices. Mainframe computers are used by multinational companies or by companies have many branches all over the country like banks, airlines, insurance, etc.

d) Super computers are the largest, fastest, most expensive and very powerful computers available when compared to the types of computers discussed earlier.  They occupy specially designed air-conditioned rooms and are often used for research, defense and to process complex scientific applications like weather forecasting, oil exploration, aircraft design, automobile design, launching missiles, mathematical research etc.  Unlike microcomputers, which generally have only one CPU, super computers have hundreds of processors.  CRAY-1 (The Cray-1 was a supercomputer designed, manufactured and marketed by Cray Research. Announced in 1975, the first Cray-1 system was installed at Los Alamos National Laboratory in 1976.)  is an example of super computer.