Computer Fundamental

 Computer System

Computer: - The word computer is generated from Latin word ‘compute’ which means to calculate. Computer is an electronic machine that accepts data and provide meaningful information.

Data- Data is the raw fact and figures that has no meaning. Ex. 45, Ajeet, Mohan, 14th April etc.

Information- Processed data is called information. 

Ex. Ajeet got 45 marks in computer.

Characteristics of Computer

    

Speed: - Computer has a very fast speed. It can perform many calculations in few seconds only. The unit of computer speed is ‘Hertz’ or Hz.

1000 Hertz = 1 Kilohertz (KHz)

1000 KHz = 1 Megahertz (MHz)

1000 MHz = 1 Gigahertz (GHz)

1000 GHz = 1 Terahertz (THz) 

Accuracy: - Computer never makes any mistake. All mistakes occur due to human being or wrong program logic.

Memory: - Computer can store a large amount of data. The unit of computer memory is ‘Byte’.

1 Byte = 8 bits = 2 nibble = 1 character

1024 Byte = 1 Kilo Byte (KB)

1024 KB = 1 Mega Byte (MB)

1024 MB = 1 Giga Byte (GB)

1024 GB = 1 Tera Byte (TB)

Reliability: -It is more reliable than a human being. It never gets tired, bored and confused.

Reduction in Man power and paper work.

Limitations of Computer

        No intelligence- Computer is a senseless device. It can not take any action without human interaction.

        Dependence on Power- Computer is an electronic machine.

Applications of Computer: - Computer is used in almost every field of our life.

Military- Missile control, communication, Planning and operation.

 Banks- All transactions are done using computer. ATM’s are making easy banking. 

Science and Research- 

ISRO (Indian Space Research Organization) 

DRDO (Defense Research and Development Organization)    

C-DAC (Center for Developing Advanced Computing)

These are the organizations that are using computers in research and development. 

4. Communication- E-Mails, Chatting, Video conferencing. 

5. Education- Computer based learning and online virtual classrooms made education easy. 

6. Healthcare- To identify cause of illness, Surgery, ECG, Ultrasound, MRI (Magnetic Resonance Imaging) etc. 

7. Business- Sales Analysis, making Budget, Payroll Management, Online transactions for paying bills.

Types of Computer

There are four types of computers based on size and speed.

• Micro Computer: - It is also known as Personal Computer (PC). It is used in homes, offices, banks and hospitals etc. Laptop, Tablet, PDA (Personal Digital Assistant), embedded system are examples of PC.

• Mini Computer: - Mini Computers are larger than Micro Computers. It is used in business, education and many other government departments. It can handle up to 200 terminals.

• Mainframe Computer: - Mainframe computers are larger than Mini Computers. These computers are high speed computers and can handle up to 50,000 users simultaneously.

• Super Computer: - Super Computers are the most powerful, expensive and fastest type of computers used for weather forecasting, space exploration, nuclear research etc. At present Summit supercomputer is the world’s most powerful in 2018 and Pratyush is India’s fastest super computer. 

There are three types of computers based on working

1. Analog Computers: - Analog computers are used to measure voltage, pressure, temperature etc. Speedometer, Thermometer are example of analog computers 

2. Digital Computers: - Digital Computers are worked on digits (0, 1). They can perform complex calculations and give fast result. Example- Micro Computer, Mini Computer, Mainframe and Super Computer.

3. Hybrid Computers: - These computers are the combination of analog and digital computer. Hybrid computers are used in oil refineries and atomic energy plants. Computer used in hospitals to measure the heartbeat of the patient and machines used in petrol pump.

Parts of Computer:- 

There are two parts of Computer

1. Software (S/w)

2. Hardware(H/w)

• Software (S/W): - A set of instructions is called program and collection of programs is called software. 

There are two types of software

1.  System Software

2. Application Software

System S/W: - System software controls the internal working of computer system. There are following types of System s/w.

• Operating System: - Operating System (o/s) controls the overall working and hardware parts of computer system. Windows, MS DOS, MAC, Linux are example of o/s.

Functions of o/s-  

Processor Management

Memory Management

Device Management

File Management

Job scheduling

• Translator – It is also called Language Processor. It translate High Level Language programs into machine understandable code (binary code). There are three language processors.

Compiler- Compiler converts whole program at once.

Interpreter- Interpreter converts line by line.

Assembler- Assembler converts only assembly language program into machine language.

• Device Drivers- Device drivers are special programs which controls the execution of particular hardware device.

• Utility s/w- Utilities are the programs that support the smooth functioning of a computer. Backup, System Restore, Disk defragmentator, Disk cleanup, Virus scanner etc. 

Application S/W- Application Software is developed by programmer to perform some specific task. There are following types of Application s/w.

• General Purpose-  MS Word, Excel, Power point, Access, DTP(Desktop Publishing)
• Specific Purpose-Tally, Reservation System, Attendance System, Payroll System etc.
• Customized- It is specially designed for a particular organization according to their requirement like mobile app or website.

Programming Languages- 

Programming languages are used to write a program. There are two types of Programming Languages.

• Low Level Languages- Machine Language or Binary Language
• High Level Languages- C, C++, Visual Basic, Java, BASIC, COBOL, FORTRAN etc.

* BASIC- Beginner’s All Purpose Symbolic Instruction Code

* COBOL- Common Business Oriented Language

* FORTRAN- Formula Translation

Generations of Programming Languages- 

• First Generation Language- Machine Language (0,1)
• Second Generation Language- Assembly Language(mnemonics)
• Third Generation Language- BASIC, FORTRAN, COBOL, C, C++ etc.
• Fourth Generation Language- Java, Visual Basic, Python, Oracle, SQL.
• Fifth Generation Language (Artificial Intelligence) - Prolog, ALGOL, Smalltalk, LISP etc.

Hardware (H/W) - The physical parts of a computer is called Hardware. There are four types of hardware parts.

• Input Devices
• Output Devices
• Processing Device
• Storage Devices

        Input Devices-

        

        Input devices are used to instruct the computer. Keyboard, Mouse, Scanner, OCR, BCR, OMR, MICR, Digital Camera, Web Camera Microphone, Touchscreen, Track ball are some popular input devices.

• Keyboard- Keyboard is a standard input device having many keys on its surface. The generic keyboard layout is known as QWERTY.  

1. Function Keys (F1-F12)

2. Typing Keys ( A-Z & 0-9)

3. Numeric keypad (17 Keys)

4. Control keys (Home, End, Insert, Delete, Page Up, Page Down, Ctrl, Alt, Esc) 

5. Navigation keys (4 Arrow Keys)

6. Special Purpose Keys(Enter, Shift, Caps Lock, Num Lock, Space Bar, Tab and Print Screen)

• Mouse- Mouse is a pointing device used to control the movement of the pointer on the screen developed by Douglas EngelBart in 1963. It has two buttons called left and right button and a wheel is present between the buttons to scrolling up and down.

There are following types of mouse.

        Mechanical Mouse

Optomechanical Mouse 

Laser Mouse

Optical Mouse

Blue Track Mouse 

• Scanner- Scanner is an input device that works like a photocopy machine. It used to convert hard copy data in to soft copy and display on computer screen. There are following types of scanner.

Drum scanner

Flatbed scanner

Handheld Scanner

There are some popular scanners also-

• OCR (Optical Character Recognition or Reader) - OCR is used to read a printed text from the book or magazine and convert it into a file and this file can be edited using a word processor. OCR cannot scan handwritten text but it can work well with handwritten capital letters.

• BCR (Bar Code Recognition or Reader) - BCR is a hand held scanner used to scan the bar code of a product for billing purpose in shopping stores.

 

• MICR (Magnetic Ink Character Recognition) – MICR is a scanner that recognizes character using a special ink. It is mainly used by banks in cheques processing. 

• OMR (Optical Mark Recognition) - OMR is also a scanner that is used to scan OMR sheets of multiple choice questions type examination in which student fill bubbles.

• Joystick- Joystick is a pointing device used to move cursor position on screen. It is a game controlling device. It can be moved in all four directions. It is mainly used in CAD (Computer Aided Designing) and playing games. It has two buttons called triggers.

• Light Pen- Light Pen is a light sensitive pointing device used to select and modify data on screen. It is also used in CAD (Computer Aided Designing).

Output Devices-

Output devices are used to display result. Monitor, Printer, Projector, Plotter and speaker are example of output devices.

• Monitor or VDU (Visual Display Unit) - Monitor is a standard soft copy output device looks like a television. There are following types of monitor.

1. CRT(Cathode Rays Tube) Monitor
2. LCD(Liquid Crystal Display) Monitor or TFT(Thin Film Transistor) Monitor
3. LED(Light Emitting Diode) Monitor
4. Touch Screen Monitor

• Printer- Printer is a hard copy output device used to print on paper. There are two types of printers.

1. Impact Printer- Impact printer allows physical contact between printer head and paper. DMP (Dot Matrix Printer), Daisy Wheel Printer.
2. Non-Impact Printer- Non-Impact Printers do not allow physical contact between the print head and paper. Thermal Printer, Ink-jet Printer and Laser Printer are example of Non-Impact Printer.

• Speaker- Speaker is an output device which is used to play sound.

• Plotter- Plotter is also an output device which is used to print graphics on paper or polyester films. Flatbed Plotter and Drum Plotter are two types of plotter.

Processing Device-

CPU (Central Processing Unit) is the brain of computer. It controls all the internal and external devices. It is also called Microprocessor. A CPU has three parts.

1. ALU (Arithmetic Logic Unit) - ALU performs arithmetic and logical calculations.
2. CU (Control Unit) - CU controls overall working of CPU.
3. MU (Memory Unit) – It stores data and instructions. 

Storage devices-

Storage devices are used to store data. There are two types of storage devices.

• Internal Memory (Primary Memory or Main Memory)
• External Memory (Secondary Memory or Auxiliary Memory)

• Internal Memory- It is temporary memory. It is very fast and expensive memory. There are two types of Internal Memory.

RAM (Random Access Memory) - RAM is a volatile memory. Data is washout from RAM whenever power goes off. It is read/write memory.  There are following types of RAM.

1. DRAM( Dynamic  Random Access Memory)
2. SRAM(Static Random Access Memory)
3. SDRAM(Synchronous Dynamic Random Access Memory)
4. DDR (Double Data Rate Memory)

    ROM (Read Only Memory) - ROM is non-volatile memory means data from ROM does not washout after power goes off. There are following types of ROM.

1. PROM( Programmable Read Only Memory)
2. EPROM(Erasable Programmable Read Only Memory)
3. EEPROM(Electrically Erasable Programmable Read Only Memory)

 Cache Memory- Cache Memory is a special high speed memory. It is more expensive than RAM. It is situated between CPU and RAM.

•  External Memory- It is permanent memory. There are following types of memory.

1. Hard disk- It is also called HD or HDD (Hard Disk Drive) or Winchester Disk. Hard disk is made up of disks known as platters. Each platter is logically divided into track and sector. A track that cuts across all platters is called a cylinder. A collection of sectors is called cluster. It can store data up to 5 Terabytes.   
2. CD-ROM- CD stands for Compact Disk. CD is an optical storage device which can store up to 650 MB to 900 MB data. It is read only memory. It is used to store games, songs, movies and software etc.   
3. DVD (Digital Versatile Disk or Digital Video Disk) - It is also an optical storage device can store 4.7 GB to 17 GB data. It is used to store software, high quality videos and games etc.  
4. Blu-Ray Disk- Blu-ray Disk is also an optical storage device. It can store up to 50 GB data. It stores High Definition (HD) videos as well as large amount of data. 
5. Flash Drive-It is also called Pen Drive or Thumb Drive. It is small and portable solid state storage device used to transfer data files from one computer to another computer.
6. Memory Stick- It is also called Memory Card generally used in mobile phones, digital camera. It can store up to 64 GB data and more. It is also a solid state storage device.