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Fundamentals of Information Technology CBMCA3T02

RTMNU B.Com Semester 3 · Minor: Computer Applications · 4 units · notes for every unit

UniversityRTMNU – Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur
CourseB.Com (Four Year UG Programme, NEP 2020)
SemesterSemester III
Paper codeCBMCA3T02
Paper titleFundamentals of Information Technology
CategoryMinor – Computer Applications
Credits4 credits (60 hours theory)
MarksTheory exam: 80 marks + 20 marks internal (CIE) = 100; minimum 40 to pass
Syllabusas per official RTMNU NEP 2020 B.Com syllabus (Direction No. 21 of 2024), session 2025-26

Unit topics below follow the official RTMNU syllabus. RTMNU official website · All RTMNU B.Com papers

Units

  1. 1Unit I: Understanding the Computer; Memory and Storage SystemsNotes
  2. 2Unit II: Input Devices; Output DevicesNotes
  3. 3Unit III: Computer Software; Programming LanguagesNotes
  4. 4Unit IV: Data Communication and Networks; Operating SystemsNotes

RTMNU B.Com Sem 3 · CBMCA3T02 · Unit I

Unit I: Understanding the Computer; Memory and Storage Systems

Syllabus topics (RTMNU)

  • Understanding the Computer: Introduction
  • Evolution
  • Generation
  • Classification and Application of Computers
  • Memory and Storage Systems: Introduction
  • Memory representation
  • Random Access Memory
  • Read Only Memory
  • Storage systems
  • Magnetic storage systems
  • Optical storage systems
  • Magneto optical system
  • Solid-state storage devices

Understanding the Computer: Introduction

Definition: A computer is an electronic machine that accepts data (input), processes it according to a set of instructions (program), stores it and gives the result (output).

The word comes from "compute", which means to calculate. Today a computer does much more than calculation: billing in a shop, online banking, railway booking (IRCTC), GST return filing and so on.

Basic working (IPOS cycle): Input → Processing → Output, with Storage at every step.

Characteristics of a computer:

  1. Speed – it works in microseconds and nanoseconds.
  2. Accuracy – results are correct if data and program are correct (GIGO: Garbage In, Garbage Out).
  3. Diligence – it does not get tired or bored.
  4. Versatility – it can do many different kinds of work.
  5. Storage – it can store huge data and recall it at any time.
  6. Automation – once a program is given, it works without human help.
  7. No IQ / No feelings – it cannot think or decide on its own; it only follows instructions.

Evolution of Computers

  • Abacus (ancient China) – beads on rods for counting.
  • Napier's Bones (John Napier, 1617) – rods for multiplication.
  • Pascaline (Blaise Pascal, 1642) – first mechanical adding machine.
  • Leibniz Calculator (1670s) – could also multiply and divide.
  • Jacquard Loom (1801) – used punched cards to control weaving patterns.
  • Difference Engine and Analytical Engine (Charles Babbage, 1822 and 1830s) – the Analytical Engine had the idea of input, memory (store), processing (mill) and output. Babbage is called the "Father of the Computer". Ada Lovelace is called the first programmer.
  • Tabulating Machine (Herman Hollerith, 1890) – punched cards for the US census; his company later became part of IBM.
  • Mark I (1944) and ENIAC (1946) – early electro-mechanical and electronic computers.
  • Stored program concept (John von Neumann) – program and data both kept in memory. Modern computers follow this idea.

Generations of Computers

GenerationPeriod (approx.)Main technologyExamples / features
First1940–1956Vacuum tubesENIAC, UNIVAC; very large, much heat, machine language
Second1956–1963TransistorsIBM 1401; smaller, faster, assembly language, magnetic core memory
Third1964–1971Integrated Circuits (IC)IBM 360; high-level languages, operating systems, keyboard and monitor
Fourth1971–presentMicroprocessor (VLSI)Personal computers, laptops; GUI, networks, internet
FifthPresent and futureULSI, Artificial IntelligenceVoice assistants, robots, parallel processing
Exam tip: For the generations question, draw the table above. Periods differ slightly in books, so write "approximately".

Classification of Computers

(A) On the basis of working (type of data):

  1. Analog – works on continuous data such as temperature or speed (e.g. speedometer).
  2. Digital – works on discrete data in 0 and 1 (e.g. PC, laptop).
  3. Hybrid – mix of both (e.g. ICU patient-monitoring machine).

(B) On the basis of size and power:

  1. Supercomputer – fastest; used for weather forecasting and research (e.g. PARAM series by C-DAC, India).
  2. Mainframe – serves thousands of users at once; used by large banks, railways, insurance companies.
  3. Minicomputer – medium size, serves a department or small firm.
  4. Microcomputer – personal computer: desktop, laptop, tablet, smartphone.

(C) On the basis of purpose: General-purpose (do many jobs, e.g. PC) and Special-purpose (one job only, e.g. ATM, washing machine controller).

Applications of Computers

  • Business – accounting (Tally), payroll, inventory, billing, GST filing.
  • Banking – core banking, ATM, UPI, net banking.
  • Education – online classes, e-books, results (RTMNU online results).
  • Health – patient records, scanning machines, telemedicine.
  • Government – Aadhaar, DigiLocker, income-tax e-filing.
  • Transport – railway and air ticket booking.
  • Entertainment and communication – email, social media, films, games.

Memory and Storage Systems: Introduction and Memory Representation

Memory is the part of the computer that stores data and instructions. It is of two kinds: primary memory (main memory – RAM, ROM; directly used by the CPU) and secondary memory (storage – hard disk, CD, pen drive; permanent).

Memory representation: A computer stores everything in binary form (0 and 1).

UnitEqual to
1 Bit0 or 1 (Binary digit)
1 Nibble4 bits
1 Byte8 bits (one character)
1 Kilobyte (KB)1024 bytes
1 Megabyte (MB)1024 KB
1 Gigabyte (GB)1024 MB
1 Terabyte (TB)1024 GB

Each memory location has a unique address. Characters are stored using codes such as ASCII and Unicode.

Random Access Memory and Read Only Memory

RAM: Read-write main memory that holds programs and data being used now. It is volatile (data is lost when power goes off). Types: SRAM (static, faster, used in cache) and DRAM (dynamic, needs refreshing, used as main memory).

ROM: Memory whose contents are written at the factory and can only be read. It is non-volatile. It stores the BIOS (start-up program). Types: PROM (programmed once), EPROM (erased by ultraviolet light), EEPROM (erased electrically; flash memory is a form of it).

BasisRAMROM
Full formRandom Access MemoryRead Only Memory
NatureVolatileNon-volatile
OperationRead and writeRead only
UseRunning programs and dataStart-up (BIOS) instructions
SizeLarger (4 GB, 8 GB etc.)Small

Storage Systems

Secondary storage keeps data permanently, has large capacity and low cost per byte, but is slower than RAM.

1. Magnetic storage systems: Data is stored as magnetised spots on a coated surface.

  • Magnetic tape – sequential access, cheap, used for backup.
  • Floppy disk – old, small capacity (1.44 MB).
  • Hard disk – metal platters with read/write heads; direct access; large capacity (in GB/TB).

2. Optical storage systems: Data is read and written using a laser beam. Examples: CD (about 700 MB), DVD (4.7 GB single layer), Blu-ray (25 GB single layer). Types: ROM (read only), R (write once), RW (rewritable).

3. Magneto-optical system: Uses both a laser and a magnet. The laser heats a spot and the magnet changes its direction; reading is done by laser. It is long-lasting and rewritable, but now rarely used.

4. Solid-state storage devices: No moving parts; use flash memory chips. Examples: pen drive, memory card, SSD. They are fast, light, shock-proof and use less power, but cost more per GB than hard disks.

Remember: Primary memory = fast, small, costly (RAM is volatile). Secondary storage = slow, large, cheap, permanent.

Likely exam questions

  1. (Long, 8/16 marks) What is a computer? Explain the evolution and generations of computers.
  2. (Long, 8/16 marks) What is memory? Explain RAM and ROM with their types, and describe magnetic, optical and solid-state storage devices.
  3. (Short, 4 marks) State any four characteristics of a computer.
  4. (Short, 4 marks) Distinguish between RAM and ROM.
  5. (Short, 4 marks) Write a short note on classification of computers on the basis of size.

RTMNU B.Com Sem 3 · CBMCA3T02 · Unit II

Unit II: Input Devices; Output Devices

Syllabus topics (RTMNU)

  • Input Devices: Introduction
  • Keyboard
  • Pointing devices
  • Scanning devices
  • Optical recognition devices
  • Digital camera
  • Voice recognition system
  • Data acquisition sensors
  • Media input devices
  • Output Devices: Introduction
  • Display monitors
  • Printers
  • Impact printers
  • Non-impact printers
  • Plotters
  • Voice output systems
  • Projectors
  • Terminals

Input Devices: Introduction

Definition: An input device is a hardware device used to enter data and instructions into a computer. It changes data from human-readable form into a form the computer understands (binary).

Keyboard

The keyboard is the most common input device. It enters letters, numbers and commands. The standard layout is QWERTY (named after the first six letters of the top letter row).

  1. Alphanumeric keys – letters A–Z and digits 0–9.
  2. Function keys – F1 to F12, for special jobs (F1 usually opens Help).
  3. Numeric keypad – on the right side, for fast entry of figures (useful for accountants).
  4. Cursor/arrow keys – move the cursor.
  5. Special keys – Enter, Shift, Ctrl, Alt, Esc, Tab, Caps Lock, Delete.

Pointing Devices

Pointing devices move a pointer (cursor) on the screen and select items.

  • Mouse – moved on a flat surface; left click, right click, scroll wheel. Types: mechanical (ball), optical, wireless.
  • Trackball – an upside-down mouse; the ball is rolled with the thumb.
  • Joystick – a stick used in games and in controlling machines.
  • Light pen – a pen-shaped device to point or draw directly on the screen.
  • Touch pad – a flat pad on laptops, moved with a finger.
  • Touch screen – the screen itself takes input by touch (ATMs, smartphones, railway enquiry kiosks).

Scanning Devices and Optical Recognition Devices

Scanner: converts a paper document or photo into a digital image. Types: flatbed scanner (page placed on glass), handheld scanner, sheet-fed scanner.

Optical recognition devices read marks or characters using light:

  1. OCR (Optical Character Recognition) – reads printed text and converts it into editable text.
  2. OMR (Optical Mark Reader) – reads pencil/pen marks in boxes; used to check MCQ answer sheets in competitive exams.
  3. MICR (Magnetic Ink Character Recognition) – reads characters printed in magnetic ink at the bottom of bank cheques (the MICR code). Banks use it for fast cheque clearing. Strictly, it is magnetic reading, but books study it with this group.
  4. Bar code reader – reads the black-and-white bar code on products; used at billing counters in supermarkets like D-Mart.
  5. QR code scanner – a camera reads a square QR code; used in UPI payments.
Exam tip: OCR reads characters, OMR reads marks, MICR reads magnetic-ink characters on cheques. Write one use for each.

Digital Camera

A digital camera captures photos and videos and stores them as digital files on a memory card instead of film. The image can be transferred to a computer directly. Its quality is measured in megapixels. A webcam is a small digital camera used for video calls and online meetings.

Voice Recognition System

A voice recognition (speech recognition) system lets a user give input by speaking into a microphone. The software changes spoken words into text or commands. Examples: voice typing on a phone, voice search, smart assistants. It helps people who cannot type and people with disabilities. Limits: background noise and different accents can cause errors.

Data Acquisition Sensors

Sensors collect data directly from the physical world and send it to a computer automatically, without a human typing it. Examples: temperature sensors in a factory, motion sensors in security systems, biometric fingerprint scanners for attendance and Aadhaar authentication, GPS sensors in vehicles, and sensors in smart electricity meters.

Media Input Devices

Media input devices bring audio and video into the computer: microphone, webcam, video camera, audio/video capture card and TV tuner card. They are used for video conferencing, online teaching, YouTube recording and multimedia work.

Output Devices: Introduction

Definition: An output device is a hardware device that gives the result of processing to the user in a human-understandable form, such as text, picture, sound or printed paper.

Output is of two kinds: Soft copy (seen on screen or heard, not permanent) and Hard copy (printed on paper, permanent).

Display Monitors

The monitor (Visual Display Unit) shows soft-copy output. Picture quality depends on resolution (number of pixels, e.g. 1920×1080), screen size (measured diagonally in inches) and refresh rate.

  • CRT (Cathode Ray Tube) – old, bulky, heavy, high power use.
  • LCD (Liquid Crystal Display) – flat, light, low power.
  • LED – LCD screen lit by LEDs; brighter and more power-saving.
  • OLED / Plasma – used in high-quality TVs and phones.

Printers: Impact and Non-impact Printers

A printer gives hard-copy output on paper.

Impact printers strike the paper through an inked ribbon.

  1. Dot matrix printer – pins form characters as dots; cheap; can print carbon copies (used for bills and bank passbooks).
  2. Daisy wheel printer – letter-quality, slow, now outdated.
  3. Line printer – prints one full line at a time; used for big volumes.

Non-impact printers print without striking the paper.

  1. Inkjet printer – sprays tiny drops of ink; good for colour photos at home.
  2. Laser printer – uses laser and toner powder; fast, sharp, used in offices.
  3. Thermal printer – uses heat on special paper; used for shop receipts and ATM slips.
BasisImpact printerNon-impact printer
MethodHits paper through ribbonNo contact (ink, laser, heat)
NoiseNoisyQuiet
SpeedSlowerFaster
QualityLowerHigh
Carbon copiesPossibleNot possible
ExamplesDot matrix, daisy wheel, lineInkjet, laser, thermal

Printer speed is measured in CPS (characters per second), LPM (lines per minute) or PPM (pages per minute); print quality in DPI (dots per inch).

Plotters

A plotter prints large, accurate drawings such as building plans, maps, charts and engineering designs. Types: drum plotter (paper on a rotating drum) and flatbed plotter (paper on a flat table). Architects and engineers use them.

Voice Output Systems

These give output as sound: speakers, headphones and speech synthesizers (text-to-speech). Examples: railway station announcements, IVR phone banking ("Press 1 for balance"), screen readers for blind users.

Projectors

A projector shows the computer screen as a large image on a wall or screen. Used in classrooms, seminars and business presentations. Types: LCD projector and DLP projector.

Terminals

A terminal is a combination of an input device (keyboard) and an output device (monitor) connected to a central computer.

  • Dumb terminal – no processing power; only sends input and shows output.
  • Smart terminal – has some processing power and memory.
  • Intelligent terminal – a full computer that can work alone.

Examples: bank teller counters, railway reservation counters, POS (point-of-sale) billing terminals.

Remember: Monitor and speaker give soft copy; printer and plotter give hard copy.

Likely exam questions

  1. (Long, 8/16 marks) What is an input device? Explain the keyboard, pointing devices and optical recognition devices (OCR, OMR, MICR, bar code reader).
  2. (Long, 8/16 marks) What is an output device? Explain display monitors and different types of printers. Distinguish between impact and non-impact printers.
  3. (Short, 4 marks) Write a short note on MICR and its use in banks.
  4. (Short, 4 marks) Explain plotters and their types.
  5. (Short, 4 marks) What is a terminal? State its types.

RTMNU B.Com Sem 3 · CBMCA3T02 · Unit III

Unit III: Computer Software; Programming Languages

Syllabus topics (RTMNU)

  • Computer Software: Introduction
  • Types of computer software
  • System management programs
  • System development programs
  • Standard application programs
  • Programming Languages: Introduction
  • History of programming languages
  • Generations of programming languages
  • Characteristics of good programming languages

Computer Software: Introduction

Definition: Software is a set of programs (instructions), data and related documents that tells the computer hardware what to do and how to do it.

Hardware is the physical part we can touch (monitor, CPU); software is the logical part we cannot touch. Hardware without software is useless, like a body without a mind.

BasisHardwareSoftware
MeaningPhysical parts of a computerPrograms that run on the hardware
TouchCan be touchedCannot be touched
Wear and tearWears out with timeDoes not wear out, but may need updates
ExamplesKeyboard, printer, hard diskWindows, MS Word, Tally

Types of Computer Software

Software is mainly of two types:

  1. System software – controls and manages the computer itself and helps other programs run. It works close to the hardware. It covers system management programs and system development programs.
  2. Application software – helps the user do a particular job, such as typing a letter, preparing accounts or making a presentation.
BasisSystem softwareApplication software
PurposeRuns and manages the computerDoes a specific user task
DependenceCan run aloneNeeds system software to run
User contactMostly works in the backgroundUser works with it directly
ExamplesWindows, Linux, compiler, antivirusMS Excel, Tally Prime, Photoshop

By availability, software may also be proprietary (paid licence, e.g. MS Office), freeware (free to use), shareware (free trial) or open source (source code free to change, e.g. Linux, LibreOffice).

System Management Programs

These programs manage the computer's hardware and resources and keep the system running smoothly.

  1. Operating system – the main system program; manages CPU, memory, files and devices (e.g. Windows, Linux, Android).
  2. Utility programs – do maintenance jobs: antivirus, disk cleanup, disk defragmenter, backup, file compression (ZIP).
  3. Device drivers – small programs that let the OS talk to a device such as a printer or scanner.
  4. Communication software – manages data transfer over networks.

System Development Programs

These programs help programmers write, test and run new programs.

  1. Language translators – change a program written by a programmer (source code) into machine code (object code):
    • Assembler – translates assembly language into machine language.
    • Compiler – translates the whole high-level program at once and lists all errors (e.g. C compiler).
    • Interpreter – translates and runs one line at a time; stops at the first error (e.g. Python, BASIC).
  2. Editors – used to type and change program code.
  3. Linker – joins different object code files and library files into one executable program.
  4. Loader – loads the executable program into memory for running.
  5. Debugger – helps find and remove errors (bugs).
  6. Program libraries and IDEs – ready-made routines and integrated tools in one package (e.g. Visual Studio).
BasisCompilerInterpreter
TranslationWhole program at onceLine by line
Speed of executionFasterSlower
ErrorsShown together after compilingShown one at a time
Object codeCreated and savedNot saved
ExampleC, C++Python, BASIC

Standard Application Programs

These are ready-made, general-purpose programs used by most people and businesses:

  • Word processing – letters, reports (MS Word, Google Docs).
  • Spreadsheet – calculations, budgets, charts (MS Excel).
  • Presentation – slides (MS PowerPoint).
  • Database management – storing and searching records (MS Access, MySQL).
  • Accounting – books of accounts, GST (Tally Prime, Busy).
  • Graphics and multimedia – photo and video editing.
  • Communication – web browsers, email.

Besides these, firms may use customised (tailor-made) software made for their own needs, such as a bank's core banking system.

Programming Languages: Introduction

Definition: A programming language is a set of words, symbols and rules (syntax) used to write instructions (programs) for a computer.

Like Hindi or Marathi has grammar, every programming language has its own grammar called syntax.

History of Programming Languages

  • 1940s – programs written directly in machine language (0s and 1s).
  • Early 1950s – assembly languages using short codes like ADD, SUB.
  • 1957 – FORTRAN (for scientific work), developed at IBM.
  • 1959 – COBOL (for business data processing).
  • 1964 – BASIC (easy language for beginners).
  • 1972 – C language (Dennis Ritchie, Bell Labs).
  • 1980s – C++ (object-oriented).
  • 1990s – Java, Python, JavaScript, HTML for internet use.

Generations of Programming Languages

GenerationLanguageFeatures
1GLMachine languageOnly 0 and 1; fastest; very hard to write; machine dependent
2GLAssembly languageUses mnemonics (ADD, MOV); needs assembler; machine dependent
3GLHigh-level languagesEnglish-like words; needs compiler/interpreter; machine independent (C, COBOL, Java)
4GLVery high-level languagesSay "what" to do, not "how"; used for databases and reports (SQL)
5GLNatural / AI languagesBased on logic and rules; used in artificial intelligence (Prolog)
Remember: Low-level languages (1GL, 2GL) are close to the machine; high-level languages (3GL onwards) are close to the human.

Characteristics of Good Programming Languages

  1. Simplicity – easy to learn and understand.
  2. Readability – programs can be read and understood by others.
  3. Naturalness – suits the type of problem (e.g. COBOL for business).
  4. Portability – the same program runs on different computers.
  5. Efficiency – program runs fast and uses less memory.
  6. Structured approach – supports clear, step-by-step program design.
  7. Easy debugging – errors can be found and corrected easily.
  8. Abstraction – lets the programmer hide complex details.
  9. Compactness – a job can be written in fewer lines.
  10. Extensibility – new features and libraries can be added.
Exam tip: In an 8-mark question on characteristics, write at least 8 points, each with a one-line explanation.

Likely exam questions

  1. (Long, 8/16 marks) What is software? Explain the types of computer software with examples, including system management programs, system development programs and standard application programs.
  2. (Long, 8/16 marks) What is a programming language? Explain the generations of programming languages and state the characteristics of a good programming language.
  3. (Short, 4 marks) Distinguish between system software and application software.
  4. (Short, 4 marks) Distinguish between a compiler and an interpreter.
  5. (Short, 4 marks) Write a short note on utility programs.

RTMNU B.Com Sem 3 · CBMCA3T02 · Unit IV

Unit IV: Data Communication and Networks; Operating Systems

Syllabus topics (RTMNU)

  • Data Communication and Networks: Introduction
  • Data communication using modem
  • Computer network
  • Network topologies
  • Network protocol and software
  • Application of network
  • Operating Systems: Introduction
  • History of operating systems
  • Functions of operating systems
  • Process management
  • Memory management
  • File management
  • Device management
  • Security management
  • Types of operating systems
  • Providing user interface
  • Introduction to MS-DOS and Windows
  • Popular operating systems

Data Communication and Networks: Introduction

Definition: Data communication is the exchange of data between two devices through a transmission medium such as a cable or radio waves.

Five components: (1) Message – the data sent; (2) Sender; (3) Receiver; (4) Medium – wire, optical fibre, radio waves; (5) Protocol – the rules both sides follow.

Modes of transmission: Simplex (one way only, e.g. radio broadcast), Half-duplex (both ways but one at a time, e.g. walkie-talkie), Full-duplex (both ways at the same time, e.g. telephone call).

Data Communication Using Modem

A modem (MOdulator–DEModulator) connects a computer to the internet through a telephone or cable line. The computer gives digital signals, but the line carries analog signals.

  • Modulation – changing digital signals into analog signals at the sending end.
  • Demodulation – changing analog signals back into digital at the receiving end.

Types: internal and external modems, DSL/broadband modems, cable modems, and wireless (dongle) modems. Speed is measured in bps (bits per second).

Computer Network

Definition: A computer network is a group of two or more computers and devices connected together to share data, resources (printer, internet) and software.

TypeArea coveredExample
PAN (Personal Area Network)A few metresPhone connected to earphones by Bluetooth
LAN (Local Area Network)One room, building or campusComputer lab of a college
MAN (Metropolitan Area Network)A cityCable TV network in Nagpur
WAN (Wide Area Network)Country or whole worldInternet, a bank's all-India branch network

Network devices: hub, switch, router, NIC (network interface card) and modem.

Network Topologies

Topology is the physical or logical layout in which computers (nodes) are connected in a network.

  1. Bus – all nodes on one main cable (backbone). Cheap and easy; but if the main cable fails, the whole network stops.
  2. Star – every node connected to a central hub/switch. Easy to manage and a fault in one cable affects one node only; but if the hub fails, all stop.
  3. Ring – nodes form a closed circle; data moves in one direction. Orderly; but one break can stop the network.
  4. Mesh – every node connected to every other node. Very reliable; but costly and needs much cable.
  5. Tree – groups of star networks joined to a bus; good for large organisations.
  6. Hybrid – mix of two or more topologies.
Exam tip: Draw a small diagram for each topology and write one merit and one demerit.

Network Protocol and Software

A protocol is a set of rules for sending and receiving data on a network. Common protocols:

  • TCP/IP – the basic protocol suite of the internet.
  • HTTP/HTTPS – for web pages (HTTPS is secure).
  • FTP – for file transfer.
  • SMTP, POP3, IMAP – for sending and receiving email.

The OSI model explains network communication in 7 layers: Physical, Data Link, Network, Transport, Session, Presentation and Application. Network software includes network operating systems, drivers, browsers and email clients.

Application of Network

  • Sharing printers, files and one internet connection in an office.
  • Email, chat and video conferencing.
  • Online banking, UPI and ATM networks.
  • E-commerce (Flipkart, Amazon) and online ticket booking (IRCTC).
  • E-governance – GST portal, income-tax e-filing, DigiLocker.
  • Online education and cloud storage.

Operating Systems: Introduction and History

Definition: An operating system (OS) is system software that works as an interface between the user and the computer hardware and manages all the computer's resources.

History: The earliest computers (1940s) had no OS. In the 1950s simple batch systems ran jobs one after another. In the 1960s multiprogramming and time-sharing systems came, and UNIX was developed at Bell Labs (around 1969). In 1981 MS-DOS came for IBM PCs. In the 1980s–90s GUI systems like Apple Macintosh and Microsoft Windows became popular. Linux appeared in 1991. Today mobile OS like Android and iOS are most used.

Functions of Operating Systems

  1. Process management – a process is a program in running state. The OS creates, schedules and ends processes and decides which process gets the CPU and for how long (CPU scheduling).
  2. Memory management – keeps track of RAM, gives memory to programs and takes it back when they finish. It uses virtual memory when RAM is not enough.
  3. File management – creates, names, saves, copies, deletes and arranges files and folders, and controls who can open them.
  4. Device management – controls input/output devices through device drivers and handles their requests.
  5. Security management – protects data with passwords, user accounts, access rights and firewalls, and guards against viruses.
  6. Providing user interface – lets the user give commands:
    • CLI (Command Line Interface) – typed commands (MS-DOS).
    • GUI (Graphical User Interface) – icons, windows, menus and mouse (Windows).

Types of Operating Systems

  1. Batch OS – similar jobs grouped and run together without user interaction.
  2. Multiprogramming / Multitasking OS – many programs run at the same time.
  3. Time-sharing OS – CPU time divided among many users in turn.
  4. Real-time OS – gives response within a fixed time (air-traffic control, ATMs).
  5. Network OS – manages computers on a network (Windows Server).
  6. Distributed OS – many computers work as one system.
  7. Single-user and Multi-user OS – MS-DOS is single-user; UNIX is multi-user.
  8. Mobile OS – Android, iOS.

Introduction to MS-DOS and Windows

MS-DOS (Microsoft Disk Operating System) is a single-user, single-tasking, CLI operating system. Commands are typed at the prompt (C:\>).

  • Internal commands (built in): DIR, CLS, COPY, DEL, REN, MD, CD, RD, DATE, TIME, TYPE.
  • External commands (separate files): FORMAT, CHKDSK, XCOPY, DISKCOPY.

Windows is a GUI-based, multitasking OS by Microsoft. Main parts: desktop, icons, taskbar, Start menu, File Explorer, Control Panel/Settings and Recycle Bin. Versions include Windows 95, XP, 7, 10 and 11.

BasisMS-DOSWindows
InterfaceCLI (typed commands)GUI (icons, mouse)
TaskingSingle-taskingMultitasking
Ease of useDifficult for beginnersEasy and user-friendly
Multimedia and internetVery limitedFull support
  • Microsoft Windows – most used on desktops and laptops.
  • macOS – by Apple, for Mac computers.
  • UNIX – multi-user OS used in servers.
  • Linux – free and open-source; versions include Ubuntu and Red Hat; widely used in servers. BOSS Linux is an Indian version developed by C-DAC.
  • Android – by Google, open-source mobile OS; most smartphones in India use it.
  • iOS – by Apple, for iPhones.
Remember: OS functions = Process, Memory, File, Device, Security management + User interface.

Likely exam questions

  1. (Long, 8/16 marks) What is a computer network? Explain its types and the various network topologies with their merits and demerits.
  2. (Long, 8/16 marks) What is an operating system? Explain its functions (process, memory, file, device and security management) and types of operating systems.
  3. (Short, 4 marks) What is a modem? Explain modulation and demodulation.
  4. (Short, 4 marks) Write a short note on network protocols.
  5. (Short, 4 marks) Distinguish between MS-DOS and Windows.