COMPUTER NOTES

 

Introduction to Computers

A Computer is an electronic device that performs calculations and operations based on instructions provided by a software or hardware program. 

Characteristics of Computers

1.           Speed – A computer can process millions of calculations per second. The speed of computation is very high.

2.           Accuracy - As computers work on inbuilt software programs, there is no scope for human errors and highly accurate.

3.           Diligence – Computers are highly reliable. They can perform complex and long calculations with the same speed and accuracy.

4.           Versatility - Computers are versatile in Nature. They can perform various operations at the same time. 

5.           Storage - Computers can store a large amount of data or instructions in its memory which can be retrieved at any point of time.

History of Computers

A Computer was intended for making a person capable of performing numerical calculations with the help of a mechanical computing device.  

Abacus

Abacus was the first counting device which was developed in China. It consists of a rectangular wooden frame and beads. The wooden frame contains horizontal rods and the beads which are passed through the rods. The beads of counters represent digits. The device is used to perform simple addition and subtraction.

Napier’s Bones

It was a device which contained a set of rods made of bones. It was developed by a Scottish Mathematician, John Napier. To perform multiplication and division, the device was developed. Napier also invented logarithms.

Pascaline

Pascaline was the first calculating device with a capability to perform additions and subtractions on whole numbers. It was developed by Blaise Pascal, a French

Mathematician.   The device made up of interlocked cog wheels having numbers 0 to 9 on its circumference. When one wheel completes its rotation, the other wheel moves by one segment

Punched Card System

Punched Card System was invented by Herman Hollerith, an American Statistician. It was used for storing and retrieving data. In the form of punched holes, the system data could be stored.

 

Charles Babbage’s Calculating Engines (1792-1871)

Babbage invented the Difference Engine to solve algebraic expressions and mathematical tasks accurately. Later, he designed some improvements to his first computer. The modified machine is called the Analytical Engine. He intended to design a machine with a collection of the four basic arithmetic functions. The design principle of the Analytical Engine can be divided into Input, Output, Memory, Central Processing Unit. The parts and working principle of an Analytical engine are the same as today’s computer. Hence, Charles Babbage is known as the Father of Computer.

Hollerith Machine

A Hollerith machine was incorporated with the tabular and punched cards. The machine could census the punched holes, recognise the number and make the required calculation and store the data of census. The machine was invented by Herman Hollerith.

Mark I Computer

The first electro-mechanical computing device was developed by Howard Hathaway Aiken. He used Hollerith’s punch card and Babbage’s statements to develop Mark I computer with IBM. In Mark III computer, he used some electronic components and Magnetic drum memory. In Mark IV computer, he used all electronic components and Magnetic drum memory & Magnetic core memory.

First Un-programmable Electronic Digital Computer (ABC)

The Atanasoff-Berry Computer (ABC) was the first electronic computer. It was designed by John Vincent Atanasoff and Clifford E. Berry. It was designed to solve systems of linear algebraic equations. It was also the first to use capacitors for storage.

Electronic Numerical Integrator and Calculator – ENIAC

ENIAC was the first electronic computer used for general purposes, such as solving numerical problems. It was invented by J. Presper Eckert and John Mauchly.

Electronic Discrete Variable Automatic Computer – EDVAC

EDVAC was the successor of ENIAC. In this computer, Binary numbers were used for arithmetic operations and the internal storage of instructions were also written in digital forms. 

Electronic Delay Storage Automatic Calculator – EDSAC

EDSAC was the first practical general-purpose stored-program electronic computer. It was built according to the von Neumann machine principles.

Universal Automatic Computer - UNIVAC

UNIVAC was the first commercially available computer. It was made by the EckertMauchly Computer Company. It represents the birth of the modern computers.

 

Third Generation Computers – (1965-1971)

The third-generation computers replaced transistors with integrated circuits (ICs). They performed computation in Nanoseconds. It used high-level languages like FORTRAN, COBOL, PASCAL, ALGO-68, BASIC was used. In this generation, remote processing, time-sharing, multi-programming operating system were used.

Examples - IBM-360 series, Honeywell-6000 series, PDP, IBM-370/168.

Fourth Generation Computers – (1971-1980)

The fourth-generation computers are used Very Large Scale Integrated (VLSI) circuits. Semi-conductor devices are used as primary memory. Magnetic disks are used as secondary storage. Problem-oriented fourth generation languages (4GL) are used. Multi-processing and multiprogramming operating systems are used.

Example – Apple series – I & II, IBM 4341, DEC 10, STAR 1000, PUP 11.

Fifth Generation Computers – (1980 - Present)

The fifth-generation computers use ultra large scale integrated (ULSI) chips that contain millions of components on a single chip. They are in the developmental stage which is based on the artificial intelligence. These computers can also respond to natural language input. Biochips will be used as memory devices and KIPS (Knowledge-based Information Processing System) architecture will be used.

Examples – Robots, Supercomputers.

Types of Computers

 

Based on Operation 

➢    Analog Computer - An Analog computer stores data continuously in the form of physical quantities and perform calculations with the help of measures. It produces output in the form of a graph. They are used in the calculation of physical variables such as voltage, pressure, temperature, speed, etc.

 

➢    gDigital Computer - A Digital computer is the most commonly used type of computer and is working with data represented in digital form, usually binary 0s and 1s. It can perform faster and give more accurate results. They are extensively used for solving complex problems in the field of engineering & technology, design, research and data processing.

 

➢    Hybrid Computer – A Hybrid computer is a combined feature of Analog and Digital computers. In large industries and businesses, a hybrid computer can be used for logical operations as well as efficient processing of differential equations.. 

Based on Configuration 

➢    Micro Computer – Microcomputers are small, inexpensive computer for personal use. They are popularly used at homes for playing games and surfing the Internet.

 

➢    Mini Computer - Minicomputers possess most of the features and capabilities of a large computer but are smaller in physical size. They are used as small or midrange operating business and scientific applications. 

 

➢    Mainframe Computer – Mainframe computers are expensive and large size computers and they are capable of supporting hundreds of users simultaneously. They are used for specific large-scale applications.

 

➢    Super Computer - Supercomputers are powerful, expensive and the fastest computers. They have architectural and operational principles from parallel and grid processing for performing billions and trillions of calculations per second. They are used for applications that require large amounts of mathematical computations like weather forecasting, fluid dynamics, graphic design etc. India launched ‘Mihir’ supercomputer recently to improve India’s weather forecasting.

 

Particulars	Name of the Computer
First Super Computer in the world	Cray CDC 6600
Fastest Super Computer in the world	Summit by the USA
First Super Computer of India	PARAM 8000
Fastest Super Computer in India	Pratyush

 

Based on Utility

 

➢    General Purpose Computer - A general purpose computer can perform an extensive variety of operations. It can store and execute different programs in its internal storage. All mainframes, servers, laptop and desktop computers, smartphones and tablets are general-purpose devices.

➢    Special Purpose Computer - Special purpose computers are designed to solve specific problems. The instructions are pre-programmed permanently in the computer. It completely controlled by automated manufacturing processes. Example – Aircraft control system, Electronic voting machines etc.

Based on Mode of Use

➢    Palmtop Computer – Palmtop computers are small which can fit in the palm of a hand. The electronic pen is used to give an input. They have small disk storage and can be connected to a wireless network.

 

➢    Laptop Computer – Laptop computers are portable with less weight. It can be transported easily and used in temporary space such as Airplane, Meetings etc. They are designed for low power consumption and have an attached keyboard and a touchpad.

 

➢    Personal Computer (PC) - A personal computer is a cost-effective computer that is designed for a single end-user. PC is dependent on microprocessor technology, which allows PC makers to set the entire central processing unit (CPU) on a single chip.

 

➢    Workstation - Workstation (WS) is faster than Personal Computer. It is designed for a user or group of users with better multitasking capability, additional Random-Access Memory, Higher-speed graphics adapters and drive capacity. 

 

➢    Client and Server – The server is a device that manages the sharing of network resources to the users. An Application server, File server, Virtual server, Mail server are some types of server. A client is the receiving end of the service which made by the server. It requests the server and gains access with the server.

Fundamentals of Computer

A computer system has four basic components.

 

Parts of a computer system

➢    Hardware - It represents the physical and tangible components of the computer (keyboard, mouse, monitor etc.)

 

➢    Software – It is a set of electronic instructions called programs that make the computer perform tasks.

 

➢    Data – It is a set of facts, which the computer stores and reads in the form of numbers.

 

➢    Users - Users are the people who make use of a computer to obtain certain results/ outcomes. 

Mother Board – It is the main printed circuit board of a computer that carries the central processing unit (CPU) chip, Read Only Memory (ROM), Random Access Memory (RAM) and the basic input output system (BIOS) chip.

The Basic Diagram of the Computer consists of Input Unit, Output Unit and Central

Input Unit

The input unit is used for giving instructios  and data by using input devices. It converts these instructions and data to the computer acceptable format and it suppliest he converted instructions and data to the computer system for further processing.

Central Processing Unit

The central processing unit (CPU) performs most of the processing inside a computer.

CPUs have been constructed on a single integrated circuit called a microprocessor. It 

consists of the control unit, the Arithmetic Logic Unit (ALU), and the memory unit.

Control Unit

The control unit manages the computer's various components. It reads and

interprets (decodes) the program instructions, transforming them into control 

signals that signals that other parts of the computer.

Arithmetic Logic Unit

The ALU can perform arithmetic and logical operations. The set of arithmetic

operations that an ALU supports to addition, subtraction and more complex 

mathematical operations. Logic operations involve Boolean logic like AND, OR,

XOR, and NOT. These can be useful for creating complicated conditional

Basic Computer Organization and Data processing Cycle

(3)        Memory Unit

(3)        Memory Unit

(3) memory units 

Computer main memory consists of primary and secondary memory.

Primary Memory  

Primary memory holds only those data and instructions on which computer is currently working. It has limited capacity and data is lost when power is switched off. It is generally made up of the semiconductor device. It is a volatile memory. The two types of primary memory are Random Access Memory (RAM) & Read Only Memory (ROM).

 

RAM (Random Access Memory) - RAM is the internal memory of the CPU for storing data, program and result of the program. It is read/write memory which stores data till the machine is working.  Some types of RAMs are Dynamic RAM (DRAM), Static RAM (SRAM) and Synchronous Dynamic RAM (SDRAM), etc.

 

Dynamic Random-Access Memory (DRAM) – Dynamic memory must be constantly refreshed, or it loses its contents. This type of memory is more economical.

 

Static Random-Access Memory – SRAM is faster and less volatile than DRAM but requires more power and is more expensive. It does not need to be refreshed like a DRAM.

 

Synchronous Dynamic Random-Access Memory - A type of DRAM that can run at much higher clock speeds.

 

ROM (Read Only Memory) - ROM stores data permanently on personal computers (PCs) and other electronic devices. It performs major input/output tasks and holds programs or software instructions. It is non-volatile.

 

MROM (Masked ROM) - The very first ROMs were hard-wired devices that contained a pre-programmed set of data or instructions. These kinds of ROMs are known as masked ROMs which are inexpensive.

 

PROM (Programmable Read Only Memory) - PROM can be modified only once by a user.  The user can buy a blank PROM and enter the desired contents using a PROM program.

 

EPROM (Erasable and Programmable Read Only Memory) - The EPROM can be erased by exposing it to ultra-violet light. EPROMs have a Quartz window in the package to expose the chip to UV light. They were widely used as the BIOS (Basic Input Output System) chips in computer motherboards.

 

EEPROM (Electrically Erasable and Programmable Read Only Memory) - The EEPROM is programmed and erased electrically. It can be erased and reprogrammed about ten thousand times. Both erasing and programming take about 4 to 10 milliseconds. They were also used as BIOS chips. 

Secondary Memory

Secondary memory stores data on a long-term basis. It cannot be processed directly by the CPU. It must first be copied into primary storage. Secondary memory devices include magnetic disks like hard drives and floppy disks, optical disks such as CDs and CDROMs, and magnetic tapes, USB Flash drives.

 

Hard drive – It is a non-removable storage device containing magnetic disks or platters rotating at high speeds. The hard drives store data in segments of concentric circles. It may spin at 5,400 to 15,000 RPM.

 

Floppy Disk - Floppy disk is composed of a thin, flexible magnetic disk sealed in a square plastic carrier. Floppy disks were widely used to distribute software, transfer files, and create backup copies of data. To read and write data from a floppy disk, a computer system must have a floppy disk drive (FDD).

 

Compact Disc (CD) - A compact disc is a portable storage medium that can be used to record, store data in digital form. They are fragile and prone to scratches.

 

Compact disc read-only memory (CD-ROM) - It is a storage device that can be read but can’t change or delete it.

 

Digital Video Disc (DVD) - A device currently used to store data in large amounts and accepts high definition material. A two-layered DVD can hold approximately 17 gigabytes of video, sound, or other data.

 

Blue-ray Disc – The upgraded version of CD and DVD discs and drives are the Blu-ray discs. It is commonly known as BD-ROM. The Maximum capacity of BD disc is 25GB if single layer and 50 GB if dual layer.

 

Holographic Versatile Disc (HVD) – It is a holographic storage format and has a maximum capacity of 3.9 terabytes.

 

Flash Drives – Flash drives are small, ultra-portable storage device. They connect to computers and other devices via a built-in USB plug. They are often referred to as pen drives, thumb drives, or jump drives. Mostly they have a storage capacity from 8 GB to 64 GB. 

Zip Disks – An advanced version of the floppy disk is known as Zip Disks. It was developed by Iomega. Zip disks are available in 100 and 250-MB and 750 MB capacities and they are used to store, share and back up large amounts of data.

 

Cache Memory - It is a very high-speed semiconductor memory which can speed up the CPU. It acts as a buffer between the CPU and main memory. Example:  Registers

Virtual Memory - Virtual memory permits software to use additional memory by utilizing the hard disk drive (HDD) as temporary storage.

Quick Revision

Types	Examples
Semiconductor Memory	RAM, ROM
Optical Memory	CD-ROM, CD-R, DVD, HVD, Blu-ray Disc
Magnetic Memory	Hard Disk Drive (HDD), Floppy Disk Drive (FDD)
Flash Memory	Pen drive, Memory card etc (EEPROM Technology devices)

Output Unit

The output unit provides the information from the computer to an external device. It presents a soft/ hard copy of the information which can be readable by the users.

 

Computer Peripheral

A peripheral device links to a computer system to enhance the functionality of the computer. It is not part of the core computer architecture. Input devices, output devices, and storage devices are the types of peripheral devices.

Input Devices

Input devices serve as a link between a user and the computer. It allows users to feed instructions and data to computers for processing, display, storage and/or transmission. Some input devices are:

1.        Keyboard – It is used to enter data into the computer in both alpha and numeric forms.

         Some important keys in a keyboard are:

(i)       Toggle Keys - It is used to change the input mode of a group of keys on a keyboard. Caps Lock, Num Lock, Scroll Lock are toggle keys.

        

➢    Caps Lock – Capitalizes all letters.

➢    Num Lock – Makes sure numbers are inputs from the keypad.

➢    Scroll Lock - Allows the arrow keys to scroll through the contents of a window.

(ii)      Modifier Keys - It is a special key (key combination) that temporarily modifies the normal action of another key when pressed together. Shift, Alt, Ctrl, Fn are modifier keys.

➢    Shift - used for capitalizing letters and entering different types of symbols.

                

➢    Function (Fn) - Other functions such as brightness and volume control.

➢    Control (Ctrl) - used for entering keyboard shortcuts, such as Ctrl+S, Ctrl+P etc.

➢    Alt - used in combination with the numeric keys and the Control key for entering keyboard shortcuts.

(iii)       Function Keys - A key on a computer keyboard, distinct from the main alphanumeric keys, to which software can assign a function. F1 - F12 keys are known as function keys and each key performs a different function. It may be used as single key commands (e.g., F5) or combined with one or more modifier keys (e.g., Alt+F4). 

 

(iv)       Escape Key – It is located in the upper left corner of a computer keyboard. It is often used to quit, cancel, or abort a process which is running on a computer.

 

2.           Mouse - It is a pointing and cursor-control device. A round ball at its base senses the movement of a mouse and sends corresponding signals to CPU when the mouse buttons are pressed. A mouse has two or three buttons called Left, Right, and Middle button.

 

3.           Joy Stick – It is used to move the cursor position on a monitor screen. It is mainly used in Computer Aided Design (CAD) and playing games on the computer. It can also be helpful as an input device for people with movement disabilities.

 

4.           Track Ball – It is mostly used in notebooks or laptops. It is a ball which is half inserted and by moving fingers on the ball, the pointer can be moved. 

 

5.           Scanner – It captures images from printed material and converts it into a digital format that can be stored within the PC. Flatbed Scanners, Hand Scanners, Sheetfed Scanner are some types of scanner.

 

6.           Barcode Reader – It is an electronic device for reading printed barcodes. A light sensor in the barcode reader can read the barcode and translates optical impulses into electrical impulses to store the data into the computer. It is an important tool for warehouse management and operations.

 

7.           Magnetic Ink Character Recognition (MICR) – It is a character recognition system that uses special ink and characters. It is used to verify the legitimacy or originality of paper documents, especially cheques. Information can be encoded in the magnetic characters. It provides a secure, high-speed method of scanning and processing information

 

8.           Optical Character Recognition (OCR) - It is a technology that recognizes text within a digital image. It converts the document to an editable text file.

 

9.           Optical Mark Recognition (OMR) – It is an electronic method that scans the document and reads the data from the marked fields and results can be transmitted into the computer. 

2.           Digitizer – It allows users to draw and manipulate graphics on the screen. It is also known as a graphics tablet. These kinds of tablets typically designed for CAD/CAM professionals.

 

 

3.           Touch Screen - It is a computer display screen that serves as an input device. A touchscreen can be touched by a finger or stylus. Touchscreen records the event and sends it to a controller for processing.

 

4.           Microphone – Microphone translates sound vibrations in the air into electronic signals. It enables many types of audio recording devices for purposes including communications, music and speech recording.

 

5.           Web Camera – It captures and stores images in digital form. The stored images can be can be archived on a photographic compact disc or external hard disk.

 

6.           Light Pen - It is a light-sensitive input device, used to select text, draw pictures and interact with user interface elements on a computer screen or monitor. 

Output Devices 

The Output devices are used to send data from a computer to another device. Examples are monitors, projectors, speakers, plotters, and printers etc.

1.        Monitors – Monitors are the main output device of a computer.  It forms images from tiny dots that are arranged in a rectangular form. The sharpness of the image depends on the number of pixels. There are two kinds of viewing screens used for monitors.

 

(i)          Cathode-Ray Tube (CRT) - The CRT display is made up of small picture elements called pixels. CRT tube creates an image on the screen using a beam of electrons.

 

(ii)         Flat- Panel Display - The flat-panel display refers to a class of video devices that have reduced volume, weight and power requirement in comparison to the CRT.

 

(iii)       Liquid Crystal Display (LCD) Monitor - LCD monitors use compact fluorescent tubes to illuminate and brighten the image on the screen and produce good image quality, resolution and contrast levels. 

 

(iv)       Light Emitting Diode (LED) Monitor - LED monitors use new backlighting technology to improve picture quality. The LED monitor is more lifelike and accurate due to the improved contrast ratios and colour saturation over LCD.  

 

Organic Light Emitting Diode (OLED) Monitor – This type of monitor made up of some organic material (containing carbon, like wood, plastic or polymers) that is used to convert the electric current into light. They are directly used to produce

(i)          the correct colour and there is no need for backlight which saves power and space. 

 

 

 

 

 

2.        Printers – Printers are output devices that prints information in the form of text/images on a paper. Impact Printers and Non-impact printers are the two types of printers.

 

(i)          Impact Printers - The impact printers print the characters by striking them on the ribbon which is then pressed on the paper. Examples: Dot-Matrix Printers, Line Printers, Daisy wheel printer, Drum printer, Chain printer, Band printer.

 

Dot-Matrix Printers – It prints characters as a combination of dots. They have a matrix of pins on the print head of the printer which form the character. They generally have 9-24 pins. Their speed is measured in cps (Character per second).

 

Line Printers - A line printer is an impact printer which can print one line of text at a time. It is also known as a bar printer.

 

(ii)         Non-Impact Printers - Non-impact printers print the characters on the paper without using ribbon. These printers print a complete page at a time, so they are also called as page printers. Examples - Laser Printers, Inkjet Printers etc.

 

Laser Printers - A laser printer is a popular type of personal computer printer that uses a non-impact photocopier technology. The type of ink used in a laser printer is dry. It gives high-quality output. The resolution of laser printers is measured in dpi (dots-perinch).

 

Inkjet Printers - Inkjet printers work by spraying ink on a sheet of paper. The type of ink used in an inkjet printer is wet.

 

(iii) Other Types

 

Solid Ink Printer - It is a type of colour printer. It works by melting the solid ink that applies the images to the paper. It is non-toxic and convenient to handle.

 

LED Printer - This type of printer uses a light emitting diode instead of a laser. It starts by creating a line-by-line image of the page.

 

3.        Plotters - A plotter is an output device used to produce hard copies of large graphs and designs on paper, such as construction drawings, architectural plans, and business charts. Drum plotters and Flatbed plotters are the types of plotters.

(i)          Drum plotter – It is a pen plotter that wraps the paper around a drum with a pin feed attachment. The drum then rotates the paper as pens move across it and draw the image. It is used to produce continuous output, such as plotting of earthquake activity. It is also known as Roller Plotter. 

 

(ii)         Flatbed plotter - It plots on paper that is spread and fixed over a rectangular flatbed table. It is used in the design of cars, ships, aircrafts, buildings, highways etc. It is also known as Table Plotter.

 

 Speaker - Speakers are one of the output devices used with computers. They

 

Functions of Operating systems

The operating system is the manager of all system resources. The functions of operating systems are:

➢    Memory Management

➢    Process Management

➢    Device Management

➢    File Management

➢    Storage Management

➢    Security

➢    Job Accounting

➢    Controls system performance

➢    Error detecting aids

➢    Coordination between other software and users

 

Memory Management - Memory management is the process of controlling and coordinating computer memory, conveying memory blocks to various running programs to enhance overall system performance. 

 

Process Management – Process Management allocates the processor (CPU) to a process and de-allocates the processor when a process is no longer essential. It can save the tracks of the processor and the status of the process.

 

Device Management – Device Management keeps track of all devices. This is called the Input/output controller and it decides which process gets the device, when, and for how long.

 

File Management – File Management allocates and de-allocates the resources. It keeps track of information, location, uses, status etc. The collective facilities are known as a file system.

 

Storage Management – Storage Management provides secondary storage to backup main memory. It can store all data and program permanently. Disk scheduling,

Storage allocation, Free space management are the activities in Storage Management. 

 

Security – Security controls the unauthorized access of programs, processes and data resources by means of passwords etc. It can be used to ensure that the files, memory segment, and other resources can be operated only by authorized users.

 

Job Accounting – It keeps track of time and resources used by various users and processes.

 

Control System Performance – Control System records delays between the request for a service and from the system. 

 Error Detecting Aids – Error detecting Aids ensure the consistent delivery of data across the network.  Production of dumps, traces, error messages and other debugging etc are techniques that enable reliable delivery of digital data over unreliable communication channels.

 

Coordination between other software and users - Operating System Coordinates and assigns compilers, interpreters, assemblers and other software to the various users of the computer systems.

Types of Operating Systems 

➢    Batch Operating System

➢    Multi-Programming Operating System

➢    Timesharing/Multitasking Operating System

➢    Distributed Operating System

➢    Real-Time Operating System

➢    Single-user operating System

 

Batch Operating System - The users of the batch operating system do not interact with the computer directly. Each user prepares his job on an off-line device like punch cards and submits it to the computer operator.

Disadvantages 

✓     Lack of interaction between the user and the job

✓     The speed of the process is slow. Hence Output is time taking  ✓           The CPU is in idle condition

 

Multiprogramming Operating System – The users of multiprogramming operating system can execute several programs simultaneously. The CPU keeps on processing. The processes which are running exist in main memory at a time.  

Disadvantages 

✓     The waiting time for the job is high

✓     Complicated schedule handling

 

Timesharing / Multitasking Operating System - Time-sharing or multitasking is a logical extension of multiprogramming. It is a technique which enables many people, located at various terminals, to use a computer system at the same time. The CPU executes multiple programs by switching among the programs. Unix is an example of timesharing OS.

Disadvantages 

✓     Less Reliability 

✓     Problem of Data Communication

 

Distributed Operating System – Distributed Operating System allows multiple users on different computers or terminals to access a single system with one Operating System on it. The processors communicate with one another through various communication lines. These are referred to as loosely coupled systems. Advantages 

✓     Potential Operation

✓     Better service to the customers. 

✓     The load on the host computer is reduced

✓     Delays in data processing are reduced

 

 

 

Single User Operating System – This type of operating system supports a single user at any given time. Single keyboard and Single monitor are used for interaction. Several programs can also run by a single user in this operating system.

 

Example – Windows 95, Windows XP etc

 

Real-Time Operating System – It is a data processing system in which the time interval required to process and respond to inputs is small. It is always online whereas online system need not be real time. They are used in scientific experiments, medical imaging systems, industrial control systems, weapon systems, robots, air traffic control systems, etc.

Examples – VRTX, RT Linux, Lynx etc

 

There are two types of real-time operating systems.

 

✓     Hard real-time systems - In this system, the critical tasks complete on time. Secondary storage is limited, and the data is stored in ROM. Virtual memory is almost never found.

Examples – Industrial control applications, Robots, etc

✓     Soft real-time systems - In this system, the time constraint is less strict. A critical real-time task gets priority and retains the priority until it completes. It has limited utility. 

Examples – Multimedia, Virtual reality, Advanced Scientific Projects like undersea exploration and planetary rovers, etc.

Advantages 

✓     It can be used in an embedded system

✓     Error-free 

✓     Better memory allocation

Disadvantages

✓            Algorithm is complex

 

Android - Android is the name of the operating system used on many smartphones and tablets. It is owned and maintained by Google. The recent version of Android is Android 9 Pie.

Other Terms related to Operating System

Booting - When the computer starts, the operating system is first loaded (as it is essential for running all other programs), this process is known as booting.

 

Cold Boot – Turn ON the computer from an OFF position is called Cold Booting. 

Warm Boot - A computer system starts up/reset from a complete powerless state is called Warm Booting.

Firmware - Firmware is a software program that is written to a hardware device. It allows the hardware to be updated. The contents are saved when a hardware device is turned off or loses its external power source.

Middleware - Middleware is a software layer situated between applications and operating systems. It enables communication and data management for distributed applications.

Software

The software is a group of instructions that instructing a computer to do specific tasks. It enables the user to interact with a computer. System Software and Application Software are two types of software.

System Software

It serves as an interface between a computer user, computer hardware and application software. It is also known as background software. Four types of system software are the following.

✓     Operating System

✓     Utility Programs ✓           Device drivers

✓     Language translators.

Operating System - Operating system (OS) is the program that acts as an interface between the user and computer hardware and application software. After the boot program, OS manages all the other programs in a computer. Examples - Linux, Unix, Microsoft Windows XP etc.

Utility Programs - Utility Programs help to manage, maintain and control computer resources. They are also known as service programs. Examples of utility programs are antivirus software, backup software, disk defragment, backup, disk clean etc.

Device Drivers - A device driver is designed to enable interaction with hardware devices. It controls a device that is attached to your computer. Printers, Displays, CDROM readers, Disk drives etc are the examples of the device driver.

Language Translator – Language Translator translates the high-level language program (input) into an equivalent machine language program (output). It also detects and reports the error during translation. Assembler, Compiler, Interpreter are types of a Language Translator.

Assembler – It converts assembly language program into machine language.

Compiler – It converts the program in a high-level language into low-level language and reports all the errors of the program along with the line numbers. C, C++ use compilers.

Interpreter – It converts the programs in a high-level language to low-level language. It translates line by line and reports the error once after completing the translation 

process. It gives better error diagnostics than a compiler. Python, BASIC, and Ruby use interpreters.

 

 

 

 

 

Application Software

Application software is a program or group of programs designed for end users. It enables the user to complete tasks, such as creating documents, spreadsheets, databases, and publications, doing online research, sending email, designing graphics etc. There are two types of application software.

✓     Basic application software

✓     Specialized application software

Basic application software - Basic application software is also known as general purpose applications and productivity applications. These programs are widely used in every discipline and occupation. Word processors, spreadsheets, database management systems, and presentation graphics are the common types of basic application software. Example - Microsoft office 2016.

Specialized application software - Specialized application software is designed for a specific task rather for a wide application area. Graphics programs, audio and video editors, multimedia creation programs, web authoring, and virtual reality programs are common types of specialized software.

Computer Languages

The different kinds of languages have been developed to perform various types of work on the computer. The two major types of programming languages are Low-Level Languages and High-Level Languages.

Low-Level languages

It is a programming language that deals with a computer's hardware and its configuration. It is very close to the computer’s native language. It is further divided into Machine and Assembly languages.

Machine Language – It consists of binary digits or bits. It can directly understand by the computer and does not need a translator program. It is also called the machine code. It is efficient but difficult to learn.

Advantages 

➢    Programs run fast.

➢    No translation program is required. 

Disadvantages 

➢    Difficult to program

➢    Debugging is also an issue

 

 

 

 

 

Assembly Language – A combination of letters and numbers forms the Assembly Language and a translator program is required to translate to the machine language. The operation codes and operands are given in the form of alphanumeric symbols which are known as mnemonic codes and can combine in a maximum of five-letter combinations e.g. ADD for addition, SUB for subtraction etc. This is also known as Symbolic Programming Language.

Advantages 

➢    Easier to understand and minimizes effort.

➢    Finding and correcting the errors are easy.       

Disadvantages 

➢    It is machine dependent (program written for one computer might not run in other computers with different hardware configuration) ➢ Writing of code is time-consuming.

High-Level languages 

A high-level language (HLL) is a programming language that enables a programmer to write programs independently. Such languages are closer to human languages. Higher level languages are simple languages that use English and mathematical symbols like +, -, %, / for its program construction.

Example – BASIC, C, C++, COBOL, FORTRAN, ALGOL, PASCAL, PROLOG.

BASIC - Beginner's All-purpose Symbolic Instruction Code (BASIC) was developed for students to write simple computer programs. It was designed by John Kemeney and Thomas Kurtz in 1963.

ALGOL - ALGOL is a short form of ALGOrithmic Language. It is a family of portable programming languages for scientific computations.

PROLOG - Prolog is used widely for artificial intelligence applications, particularly expert systems.

PASCAL - It is used to teach programming techniques. It was developed by Niklaus Wirth. 

FORTRAN - It is a programming language designed for numeric computation and scientific computing. FORmula TRANslation is an acronym of FORTRAN.

COBOL - Common Business Oriented Language is the full form of COBOL. It is used for business and administrative purposes. It can be read like regular English.

C – It is a general-purpose language which is used in many scientific programming situations. 

 

 

 

 

C++ - C++ is an object-oriented programming language and incorporates all the features offered by C.

Advantages  

➢    Independent of machines and can run on any computer

➢    Problem-oriented rather than machine oriented ➢      User-friendly

Disadvantages 

➢    Need time for translating.

Object-Oriented Programming

Object-oriented programming (OOP) is a software programming model built around objects. This model classifies data into objects and describes object contents and performance through the declaration of classes.

Simula is the first object-oriented programming language. The examples of objectoriented programming languages are Java, Python, JavaScript, C++, C#, PHP, Perl, .NET, Ruby Curl, Visual Basic, Smalltalk, Delphi, and Eiffel.

Java - Java is used for developing Mobile, Desktop, web, server-side and dynamic web applications.

JavaScript – JavaScript is designed for styling HTML Pages, interactivity to HTML Pages, Server-Side Scripting Operation, executing query related to DB on Serve.

Python - Python is a general-purpose programming language. It is used for developing complex scientific, numeric applications, data analysis, and visualization.

C# - C# is a general-purpose language was designed by Microsoft to be used for developing apps on the Microsoft platform.

PHP - PHP stands for Hypertext Pre-processor. It is a scripting language used for the development of web applications.

.Net-.Net is a programming framework developed by Microsoft, which can be used to build different types of applications such as Windows, Web application and Mobile based applications etc. 

Visual Basic - Visual Basic is an approachable language with a simple syntax for building type-safe, object-oriented apps. 

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