INTRODUCTION TO COMPUTER

WHAT IS COMPUTER ?

• A computer is an electronic device which takes input from the user,
  processes it and gives the output as per user’s requirement.
• The word “computer” is comes from the word “TO COMPUTE” means to
  calculate.
• The fact that computer process data is so fundamental that many people have
  started calling as “Data Processor”.
  
• A computer first it gets the Data, does Process on it and then produces
  Information.
  

CHARACTERISTICS

Automatic:

• Computers are automatic machines because it works by itself without
  human intervention.
  
• Once it started on a job they carry on until the job is finished.
  Computer cannot start themselves.

Accuracy:

• The accuracy of a computer is very high.
• The degree of accuracy of a particular computer depends upon its design.
  
• Errors can occur by the computer. But these are due to human weakness,
  due to incorrect data, but not due to the technological weakness.

Speed:

• Computer is a very fact device. It can perform the amount of work in fewseconds for which a human can take an entire year.
• While talking about computer speed we do not talk in terms of seconds
  and milliseconds but in microseconds.
  
• A powerful computer is capable of performing several billion (109) simplearithmetic operations per second.

Versatility:

• It is one of the most wonderful features about the computer.
• One moment it is preparing the results of a particular examination, the
  next moment it is busy with preparing electricity bills and in between it
  may be helping an office secretary to trace an important letter in seconds.

DATA PROCESSING OF COMPUTER

• The computer Data Processing is any process that a computer program does to
  enter data & summarise, analyse or convert data into useable information.
• The process may be automated & run on a computer.
• It involves recording, analysing, storing, summarising & storing data.
  
• Because data are most useful when it is well presented & informative.

• Data Processing cycle described all activities which are common to all data
  processing systems from manual to electronic systems.
• These activities can be grouped in four functional categories, viz., data input,
  data processing, data output and storage, constituting what is known as a data
  processing cycle.
• The main aim of data processing cycle is to convert the data into meaningful
  information.
  
• Data processing system are often referred to as Information System.

CLASSIFICATION OF THE COMPUTER

• The computers are divided mainly three types on the based on data processed:
  1. Analog computers
  2. Digital computers
  3. Hybrid computers

ANALOG COMPUTER

• In Analog Computers, data is represented as continuously varying voltage and
  operate essentially by measuring rather counting.
• As the data is continuously variable, the results obtained are estimated and not
  exactly repeatable.
• It can able to perform multiple tasks simultaneously and also capable to work
  effectively with the irrational number. E.g. 1/8 = 0.125 and 1/6=0.1666.

DIGITAL COMPUTER

• The digit computer is a machine based on digital technology which represents
  information by numerical digit.
• In Digital Computers data is represented as discrete units of electrical pulses. Thedata is measured in quantities represented as either the ‘on’ or ‘off’ state.
• Therefore, the results obtained from a digital computer are accurate.
  
• Virtually all of today’s computers are based on digital computers.

HYBRID COMPUTER

• It combines the good features of both analog & digital computers.
• It has a speed of analog computer & accuracy of digital computer.
• Hybrid Computers accept data in analog form and present output also in
  digitally.
• The data however is processed digitally.
  
• Therefore, hybrid computers require analog-to-digital and digital-to-analog
  converters for output. 

• The computers are classified in four types on the based on data processing:
  

• Micro computer
• Mini computer
• Mainframe computer
  
• Super computer

 MICRO COMPUTER

• Micro computers are the computers with having a microprocessor chip as it
  central processing unit.
• Originated in late 1970s.
• First micro computer was built with 8 bit processor.
• Microcomputer is known as personal computer.
• Designed to use by individual whether in the form of pc’s, workstation or
  notebook computers.
• Small in size and affordable for general people.
  
• Ex: IBM PC, IBM PC/XT, IBM PC/AT

SUPER COMPUTER

• Most powerful & most expensive computer.
• Used for complex scientific application that requires huge processing power.
• Used multiprocessor technology to perform the calculation very speedy.
  
• They are special purpose computers that are designed to perform some
  specific task.

GENERATIONS OF THE COMPUTER

• In Computer language, “Generation” is a set of Technology. It provides a frameworkfor the growth of the computer technology. There are totally Five Computer Generations till today.

FIRST GENERATION

• Duration: 1942-1955
• Technology: vacuum tube
  o Used as a calculating device.
  o Performed calculations in milliseconds.
  o To bulky in size & complex design.
  o Required large room to place it.
  o Generates too much heat & burnt.
  o Required continuously hardware maintenance.

SECOND GENERATION

• Duration: 1955-1964
• Technology: transistor
  o 10 times Smaller in size than 1st generation system.
  o Less heat than 1st generation computers.
  o Consumed less power than 1st generation system.
  o Computers were done calculations in microseconds.
  o Air-conditioner is also required.

THIRD GENERATION

• Duration: 1965-1975
• Technology: IC chip
  o Smaller in size than 1st & 2nd generation computers.
  o Perform more fast calculations than 2nd generation systems.
  o Large & fast primary/secondary storage than 2nd generation computers.
  o Air –conditioner is required.
  o Widely used for commercial applications.
  o General purpose computers.

FOURTH GENERATION

• Duration: 1975-1989
• Technology: Microprocessor chip
  o Based on LSI & VLSI microprocessor chip.
  o Smaller in size.
  o Much faster than previous generations.
  o Minimum hardware maintenance is required.
  o Very reliable as computer to previous generation computers.
  o Totally general purpose computer.

FIFTH GENERATION

• Duration: 1989 to Present
• Technology: ULSI microprocessor chip
  o Much smaller & handy.
  o Based on the ULSI chip which contains 100 million electronic components.
  o The speed of the operations is increased.
  o Consumed less power.
  o Air-conditioner is not required.
  o More user friendly interface with multi-media features.
  o High level languages are allowed to write programs.

BLOCK DIAGRAM OF COMPUTER

• A simple computer system comprises the basic components like Input Devices, CPU(Central Processing Unit) and Output Devices.