Chapter 1: Computer System

Introduction to Computer

Definition of Computer:

  • Computer – Common Operating Machine Particularly Used for Trade, Education and Research.
  • ‘Computer’ comes from the Latin word “computare” which means to calculate.
  • An electronic device that can perform a variety of tasks in accordance with a set of instructions called a program.
  • Accepts data from  an input device, processes it into useful information and displays the output.


Characteristics of Computer:

  • Speed: Computer can work very fast. It can process millions of pieces of information in seconds.
  • Storage: Computers can store a large amount of data (text, graphic, pictures, audio, video, etc.) temporarily or permanently, as required in various storage devices such as hard disk, pen drive etc.
  • Accuracy: Computers can process data without any errors. But if there are faults in data, instruction or program, it will result in wrong output. It is known as Garbage in Garbage out (GIGO).
  • Versatility: Computers can perform various tasks such as surfing the internet, playing games, playing songs, watching movies, working on documents, printing, sending email, mathematical calculation, programming etc.
  • Diligence: Computers do not have feelings or emotion, taste, knowledge and experience. Thus, it never feels tired or boring to do a task repeatedly for a long time.
  • Automation: Computers can be programmed to perform complex tasks automatically. For example: Email Scheduling, Automated reply on social media etc.
  • Non-intelligent: Computer is just a dumb machine and cannot take its own decisions. Human’s have to provide some instructions to perform so that computers can perform any task.
  • Word Length: It is the number of bits CPU can process in parallel at a time for example 8, 16, 32, 64, 128. Higher the word length, the better the performance of the computer. 


Advantages and Disadvantages of Computer


  1. Accurate and reliable machine.
  2. Much faster than humans.
  3. High storage capacity.
  4. Never feels tired and exhausted like a human being.
  5. Versatile device
  6. Error free result


  1. Expensive device
  2. Required skilled manpower to operate
  3. Discourage physical activities / affect human health
  4. Rise of computer crimes like hacking, virus, pornography etc.
  5. Need repair, update and maintenance frequently.
  6. Depend on electricity to work.


Application of Computers


  1. Online accounting facility like checking current balances, deposits etc. 
  2. ATM machines – interconnected computer system
  3. Internet banking for accessing accounts, transferring money, and paying bills.


  1. Work with CAM/CAD software packages like AutoCAD, CATIA, Etabs etc..
  2. Designing and developing machine drawings, building drawings, circuit drawings, 3D views etc.


  1. Diagnosing illness and monitoring patient’s status
  2. Look inside a person’s body and study in detail with the help of automated imaging techniques like UltraSound, CT scans, MRI scans etc.
  3. Storage of patients data in an efficient manner.


  1. Used as information resource, teaching aid, library system, result system, students record etc.
  2. Remote learning, audio-visual packages, interactive exercises etc.
  3. Online registration, mock exams, entrance exam and interviews
  4. Interactive learning and taking virtual field trips with the help of AR/VR 


  1. Book tickets for flight, bus, movies
  2. Online hotel reservations


  1. Information of defense system,  
  2. Secured database and record 
  3. Tracking, surveillance and controlling the flight, targeting ballistic missiles
  4. Control the access to atomic bombs


  1. Online buying and selling of goods and services
  2. Collaborating with business partners and suppliers, conducting electronic transactions
  3. File management, calculating the bills, office communication, administrative work, decision making etc.


  1. Working with graphics and images. Ex: Photoshop
  2. Audio or video composition, editing. Ex: Adobe Premiere Pro, Da Vinci Resolve
  3. Making special effects like VFX in science fiction movies.

Desktop publishing:

  1. Create page layouts for magazines, newspapers, books etc. Ex: Adobe Illustrator, InDesign etc.


  1. Real time communication(chatting, video call) over the internet. Ex. Zoom call
  2. Connects with people around the world with the help of emails, social media etc. For example Gmail, Facebook, Instagram, WhatsApp etc.


  1. Data processing and maintenance of database of citizens record
  2. Create paperless environment
  3. Aid in country’s defense organizations like missile development, satellite, rocket launches etc.

Planning and Scheduling:

  1. Store contact information, generate plans, schedule appointments and deadlines etc.
  2. For example: Project management with Jira, Gmail Scheduling etc.


History of Computer

  1. Mechanical Calculating Era:

            a)  Abacus

        1. Abacus: earliest calculating device, still in use today.
        2. Originated in China 3000 years ago.
        3. “ABACUS” derived from Roman words “ABAC” and “ABAX” (dust and sand).
        4. Wooden frame, beads on parallel bars for counting.
        5. Experienced users perform fast calculations, rivaling electronic calculators.

           b) Napier’s Bone

        1. 1617AD: John Napier invented rods for simple multiplication.
        2. ‘Bones’: rods with carved numbers for easy multiplication.
        3. Napier is better known for inventing logarithms.

         c) Slide Rule

        1. 1620 AD: William Oughtred invented the Slide Rule, combining logarithm and Napier’s bones.
        2. Slide Rule used logarithmic scales for rapid multiplication, division, and other calculations.
        3. Engineers and mathematicians extensively used slide rules until electronic calculators replaced them.

        d) Pascaline

        1. Around 1642 AD: Blaise Pascal invented a simple mechanical calculator.
        2. Pascal’s calculator used gears and wheels to register numbers.
        3. It could add and subtract easily but couldn’t multiply or divide.
        4. Recognized as the first mechanical calculating device.

        e) Stepped Reckoner

        1. Stepped Reckoner: Mechanical calculator invented by Gottfried Wilhelm Leibniz in 1671AD.
        2. Modified the Pascaline and made his own.
        3. Used until replaced by electronic calculators in the 1960’s.

        f) Babbage ‘s Engine (Difference Engine and Analytical Engine)

        1. 1822AD: Charles Babbage developed the Difference Engine for algebraic equations.
        2. 1833 AD: Designed Analytical Machine, inspired by Jacquard’s punched cards.
        3. Prototype of the modern computer with input, storage, output, and program control.
        4. Babbage’s ideas ahead of his time, technology limitations prevented completion.
        5. Babbage is known as the Father of Modern Computers.

      g) Lady Augusta Ada

        1. Ada Lovelace: Mathematician, Lord Byron’s daughter.
        2. Assisted Babbage, advocated a binary system.
        3. First computer programmer.
        4. “Ada” programming language named after her by U.S. Defense.
        5. Recognized for significant computer science contributions.

      h) George Boole

        1. 19th Century (1950s): English mathematician, symbolic logic.
        2. Discovered Boolean Algebra in mathematics.
        3. Pioneered modern electronic computers with 0 and 1 representation.
        4. Introduced “on” and “off” states for communication.

     i) Tabulating Machine

        1. 1886: Hollerith’s Tabulating Machine inspired by Jacquard.
        2. Used punch cards for faster census calculation.
        3. Founded Tabulating Machine Company (TMC).
        4. 1923: TMC merged, formed IBM.
        5. IBM: Top computer manufacturer today.


2) Electro-Mechanical Era:

     a) Mark I

        1. Also known as IBMASCC (IBM Automatic Sequence Control Calculator).
        2. 750,000 parts, 500 miles of wire, complex.
        3. Huge: 50ft long, 8ft high, 3ft wide.
        4. Dimension: 50 feet long, 8 feet high, 3 feet wide. 
        5. About  32 tons and had 18000 vacuum tubes
        6. Operations: Add, subtract, multiply, divide, table reference.
        7. Handled up to 23-digit numbers.
        8. Multiplication took 3-5 seconds.
        9. Mark II: Used high-speed electromagnetic relays, not electro-mechanical counters.

     b) ABC(Atanasoff Berry Computer)

        1. 1942: Atanasoff and Berry invented ABC.
        2. First electronic special-purpose computer.
        3. Designed for complex math problems like linear equation.
3) Electronic Computers Era:

     a) ENIAC

        1. ENIAC: First general-purpose electronic computer.
        2. Invented in 1946 by Mauchly and Eckert.
        3. Created for US armed forces.
        4. Capable of 5000 additions, 300 multiplications per microsecond.
        5. Used over 18000 vacuum tubes, high power consumption.


      b) J.V. Neumann

        1. 1945: J.V. Neumann discovered the stored program concept.
        2. Crucial for modern digital computer development.
        3. Improved speed, flexibility, efficiency.
        4. Known as “father of stored programs.”


     c) EDSAC

        1. 1949: EDSAC created by Maurice Wilkes.
        2. Used J.V. Neumann’s techniques.
        3. Introduced “Initial Orders” (first assemblers).
        4. Enabled symbolic programming instead of machine code.


      e) EDVAC

        1. 1952: Mauchly, Eckert, and von Neumann create EDVAC.
        2. First stored-program computer, storing instructions and data.
        3. Marked crucial step in modern computing evolution.


      f) UNIVAC

        1. UNIVAC was invented in 1951 by John Mauchly and J.P. Eckert.
        2. Used magnetic tape for input and output.
        3. Installed in 1954 at the office of General Electric Company.
        4. Marked the arrival of commercially available digital computers for business and scientific purposes.


Inventors J. Presper Eckert and John Mauchly Maurice Wilkes John von Neumann J. Presper Eckert and John Mauchly
Year of Invention 1946 1949 1952 1961
Memory No stored program concept Mercury delay lines Stored-program concept Mercury delay lines
Programming Wired plugboards Paper tape and later magnetic tape Binary-coded instructions stored in memory Binary-coded instructions stored in memory
Applications Ballistic trajectory calculations, cryptography, etc. Scientific calculations, computer science research Influenced subsequent computer architectures Business data processing, scientific calculations


Evolution of Computer Technology

First Generation of Computer (1940 – 1956)
  • First generation computers (1940-1956) used Vacuum Tubes.
  • These computers were large, occupying significant space, and had high failure rates, necessitating frequent maintenance.
  • First generation computers were primarily designed for scientific applications.

Feature of First Generation Computer:

  1. Vacuum Tubes: Key hardware, large size, short lifespan.
  2. Slow speed, challenging maintenance, limited programming.
  3. Machine-level language for coding.


Vacuum Tube

  • Early electronic devices in first-generation computers.
  • Developed by Lee De Forest in 1908 AD.
  • Controlled and amplified electronic signals.
  • Fragile, required high electricity, and large in size.


Second Generation of Computer (1956 – 1963)
  • Second generation of computers – solid-state devices. 
  • Transistors replaced Vacuum tubes, magnetic core storage utilized.
  • Reduced failure rate, smaller size, faster, and more reliable computers.
  •  Efficient programming methods evolved.

Feature of Second Generation Computer:

  1. Transistors: Key hardware advancement.
  2. Magnetic core memory: Reliable, smaller primary storage.
  3. Lower power consumption, no heat.
  4. High-level programming (FORTRAN, COBOL).
  5. Commercial and scientific use.

Examples: IBM 1401, Honeywell 400, CDC 1604, ICL 1901 etc.


  • Invented in 1947 by Bardeen, Shockley, and Brattain.
  • Replaced vacuum tubes in second-generation computers.
  • Reduced failure rates, smaller size, and faster computers.
  • Significant advancement in computer technology.


Third Generation of Computer(1964 – Early 1970s)
  • Introduced integrated circuits (ICs) for data processing.
  • ICs combined multiple transistors on a single chip, reducing size and power consumption.
  • Computers became smaller, faster, and more reliable.
  • High-level programming languages like COBOL and FORTRAN were developed.
  • Operating systems evolved, improving user interaction and multitasking capabilities.
  • Time-sharing systems allowed multiple users to access a single computer simultaneously.
  • The era of minicomputers began, catering to smaller organizations’ computing needs.

Feature of Third Generation Computer:

  1. They are built with IC chips with SSI (Single Scale Integration) and MSI (Middle Scale Integration) technologies.
  2. Larger magnetic core memory.
  3. Larger capacity magnetic disk and tapes.
  4. More flexible with input/output devices.
  5. Smaller in size and had better performance and reliability.
  6. Extensively used high level programming language.
  7. Mini computers emerged from this generation.
  8. Easier to upgrade than the previous generation system.
  9. Operating system program used to control input/output in this generation.

Examples: IBM 360/370, CDC 6600, PDP 11, ICT 1900, Honeywell 2200 series etc.

Integrated Circuits (ICS)

  • Invented in the late 1950s and early 1960s, ICs revolutionized electronic technology.
  • Replaced the bulky and unreliable individual components used in early computers.
  • ICs enabled the creation of smaller, faster, and more energy-efficient electronic devices.
  • Today, ICs are an essential component in almost all electronic devices, driving advancements in technology and computing power.


Fourth Generation of Computer (Early 1970s – Till Date)
  • Introduction of the microprocessor marked the fourth generation.
  • A microprocessor contains all essential circuits on a single chip.
  • Reduced size and cost of computers significantly.
  • Opened new horizons for computer applications.

Feature of Fourth Generation Computer:

  1. Used VLSI/Microprocessor as a key hardware technology.
  2. Semiconductor memories replaced magnetic core memories.
  3. Larger storage capacity and fast processing speed.
  4. Personal /desktop computers were introduced.
  5. Small, affordable, reliable and easy to use.
  6. GUI based operating system introduced. (Windows)
  7. High speed computer networking also developed.
  8. Introduced electronic mailing system.

Examples: IBM PC, APPLE II, Motorola M6800, DCM, Burroughs B7700 etc.


  • INTEL-4004, the first microprocessor, introduced in 1971.
  • Sparked the fourth generation of computers.
  • Led to the Personal Computer Revolution.
  • Reduced computer size and cost significantly.
  • Opened new horizons for computer applications.


Fifth Generation of Computer (Present and Beyond)
  • In the developmental stage.
  • Utilizing Ultra Large Scale Integration (ULSI) and superconductors with Gallium Arsenide (GA) or Biochips.
  • Combining hardware and software for Artificial Intelligence (AI) similar to human intelligence.
  • Expert systems are crucial software aspects of the fifth generation.

Feature of Fifth Generation computer:

  1. Utilization of Ultra Large Scale Integration (ULSI) technology.
  2. Incorporation of superconductors using materials like Gallium Arsenide (GA) or Biochips.
  3. Integration of hardware and software to achieve Artificial Intelligence (AI) comparable to human intelligence.
  4. Development of Expert systems as crucial software components.
  5. Expected to dominate other technologies in the future.

Examples: PARAM super computer, IBM notebooks, SUN, IBM SP/2 etc.

Artificial Intelligence(AI)

  • Simulates human intelligence and behavior in machines.
  • Involves algorithms for reasoning, learning, and problem-solving.
  • Applied in autonomous vehicles, virtual assistants, medical diagnosis, and more.
  • Rapidly advancing and transforming various industries.


Feature First Generation Second Generation Third Generation Fourth Generation Fifth Generation
Time Period 1940s – 1956s 1956s – 1963s 1964s – 1970s 1970s – Till Date Present and Beyond
Main Component Vacuum Tubes Transistors Integrated Circuits Microprocessors AI, Quantum Tech
Size Large Smaller Smaller Much Smaller Shrinking
Speed Slow Faster Faster Much Faster Varies
Programming Languages Machine Language Assembly Language High-Level Languages High-Level Languages AI Languages
Memory Magnetic Drum, Delay Lines Core Memory Semiconductor Memory RAM, Hard Drives RAM, SSDs, Cloud Storage
Applications Scientific, Military Business, Scientific Business, Real-time Personal Computers, AI, Big Data
Power Consumption Very High High Moderate Moderate to Low Varies
Examples ENIAC, UNIVAC I IBM 1401, CDC 1604 IBM System/360, PDP-8 Intel 8086, Macintosh IBM Watson, Google’s Quantum Supremacy, various AI systems


Measurement Unit of Processing Speed and Storage Unit 

Computer processing Speed

    • Complex calculation at very high speed.
    • Measure in terms of second
    • Measured in Hertz (Hz) or its multiples (kHz, MHz, GHz).
    • Represents the number of cycles per second that a processor can execute.
    • Determines how fast a computer can perform calculations and process data.
    • Advances in technology have led to significant improvements in processing speed over the years.


Computer Processing Speed

Units Equivalent
1000 th of a second 1 Milliseconds (MS)
1000 th of a milliseconds 1 Microseconds (μs)
1000 th of a microseconds 1 Nanosecond (ns)
1000 th of a nanoseconds 1 Picoseconds (ps)
1000 th of a picoseconds 1 Femtoseconds (fs)


Measurement Unit

    • Measure in Bytes
    • A byte represents one character, a letter, digital, or symbol.
    • Bytes measure in groups of Kilobytes, Megabytes, Gigabytes, Terabytes
    • Bytes measure the memory and storage capacity.
0,1 1 bit
4 Bit 1 Nibble
8 Bits or 2 Nibble 1 Byte, 1 Character
1024 Bytes 1 Kilobyte (KB)
1024 KB 1 Megabyte (MB)
1024 MB 1 Gigabyte (GB)
1024 GB 1 Terabyte (TB)
1024 TB 1 Petabyte (PB)
1024 PB 1 Exabyte (EB)


Super, Mainframe, Mini and Microcomputers

  • Fastest, most expensive, and largest computers worldwide.
  • Have extensive storage capacity and processing speed at least 10 times faster than other computers.
  • Used for weather forecasting, earthquake prediction, and scientific research, complex scientific simulations etc.

Characteristics or applications of supercomputers:

  1. Excellent results in animations.
  2. Virtual testing of nuclear weapons and critical medical tests.
  3. Studying and understanding climate patterns for weather forecasting.
  4. Designing flight simulators for pilot training.
  5. Diagnosing critical diseases, brain injuries, and strokes accurately.
  6. Scientific research analyzing data from exploring the solar system and Earth’s movements.
  7. Predicting fog and pollutants in the atmosphere for smog control.
  8. Enhancing security by decrypting passwords for protection.

Example: PARAM, CRAY -1, CDC Cyber 203, Cray XMP etc.

Uses: Weather Forecasting, Aircraft and Space Engineering, Scientific Researcher, etc.


Mainframe Computer
  • Medium or large, powerful, and expensive.
  • Perform tasks for thousands of users simultaneously.
  • Execute billions of instructions per second and process large data volumes simultaneously.
  • Operated by trained personnel in air-conditioned rooms.
  • Used by large companies in various industries like gas and electricity suppliers, airlines, and police for critical operations and data processing.

Characteristics of Mainframe Computers:

  1. Process huge amounts of data, e.g., millions of transactions in the banking sector.
  2. Long life span, running smoothly for up to 50 years after proper installation.
  3. Excellent performance with large-scale memory management.
  4. Can distribute workload among other processors and terminals.
  5. Fewer chances of errors or bugs, quickly fixable without performance impact.
  6. Ability to protect stored data and ongoing information exchange.

Examples: IBM 370, CYBER 170, UNIVAC 1100 series etc.

Uses: Industries, Banking, Insurance companies, Airlines, Air Traffic Control, etc.


  • Powerful, once exclusive to mainframes’ tasks.
  • Multiprocessing system supporting 4 to 200 users simultaneously.
  • Used by small to medium-sized businesses for data processing needs.
  • Typically a standalone device.

Characteristics of Minicomputer:

  1. Lightweight, portable, and easy to carry.
  2. Less expensive than mainframe computers.
  3. Fast processing capabilities relative to its size.
  4. Long-lasting battery life.
  5. Operates without the need for a controlled environment.

Example: IBM sys/3, PDP-II, Hewlett Packard 3000 etc.

Uses: University, Scientific Research, Industries, etc.


Micro Computer
  • Uses a microprocessor.
  • Smallest general-purpose computer.
  • Also known as Personal Computer (PC).
  • Used by a single person at a time.
  • Commonly used in offices, homes, classrooms, shops, and entertainment.

Characteristics of a microcomputer:

  1. Smallest in size among all computer types.
  2. Limited software compatibility.
  3. Designed for personal work with one user at a time.
  4. Less expensive and user-friendly.
  5. No special skills or training required.
  6. Often equipped with a single semiconductor chip.
  7. Capable of multitasking, such as printing, scanning, browsing, and video watching.

Example: IBM PCs, Apple/Macintosh, Dell, etc

Uses: Entertainment, Desktop, Business, School, College, Personal, etc.

Difference between mini and micro computers
Mini computer Micro computer
more powerful than micro computers. less powerful than mini computers.
comparatively more expensive. comparatively cheaper.
bigger in size so that nearly 50 terminals can work smaller in size & can work only single terminal.
not general purpose. general purpose computers.


Desktop Computer

  • Designed to fit on top of the desk, with the monitor placed on top of the computer.
  • Used for general-purpose tasks like data entry and desktop publishing.


  • High-performance computer designed for specialized tasks.
  • Typically used for professional applications like 3D modeling, CAD, video editing, scientific simulations, etc.
  • Offers powerful processing capabilities and advanced graphics capabilities.
  • Often used in engineering, design, multimedia, and scientific fields.
  • Provides a balance between performance and affordability compared to supercomputers.


  • Portable and used for computing on-the-go.
  • Powerful like moderate PCs but smaller and lightweight.
  • Designed to be used comfortably on one’s lap.
  • Contains a built-in keyboard, flat LCD display, touchpad, and CD/DVD drive.
  • More expensive than a regular PC due to its portability and compactness.


  • Small handheld computing device.
  • Fits in the palm of your hand.
  • Limited computing power for basic tasks.
  • Replaced by smartphones and more advanced devices.

Tablet PC

  • Flat, thin mobile devices with touchscreen displays and rechargeable batteries.
  • Popular for their features, specialized apps, and portability.
  • Vary in operating systems and processors.
  • Apple and Intel are major manufacturers of tablet processors.

Smart Phone

  • Greatest tech revolution since the Internet.
  • Combines cell phone and handheld computer functions.
  • Does everything a personal computer can do.
  • Portable and more handy than a PC.
  • Offers various features like email, web, music, camera, GPS, voice recognition, and more.
  • Acts as a personal assistant, delivering information and answering questions.
  • More personal due to 24/7 accessibility.


  • A type of lightweight and thin laptop computer.
  • Typically equipped with high-performance processors and solid-state drives (SSDs).
  • Designed for portability and long battery life.
  • Usually features a sleek and stylish design.
  • Introduced by Intel as a premium category of laptops.


Mobile Computing and its Application

  • Variety of devices for accessing data and information from anywhere.
  • Transports data, voice, and video over networks via mobile devices.
  • Can connect to LAN, WLAN, or mobile phone services.
  • Exciting future with advancements in AI, integrated circuitry, and processor speed.
  • Potential for compact, handheld organizers or smaller mobile computers.
  • Impactful for the common man, opening new horizons for business and governments.
  • Significant role in business and improving public sector facilities.


  • Portability: Easy movement within and between learning environments.
  • Social Interactivity: Data sharing and collaboration among users.
  • Context Sensitivity: Responding to real or simulated data unique to the current location, environment, or time.
  • Connectivity: Digital communication of data in any environment.
  • Individual: Providing scaffolding and customization for individual learners.
  • Small Size: Handheld, palmtop, or smartphone dimensions for easy carrying.
  • Wireless Communication: Capable of communication with similar devices, computers, networks, and portable phones.


  • Insufficient bandwidth
  • Security problems, Malware
  • Power consumption – must rely entirely on battery power.
  • Small screen of most device still limit types of file and data transfer (i.e streaming video)
  • Increase in global stress levels
  • Total waste of humanity playing idiotic social games

Application of Mobile Computing:


  • Business on mobile devices and wireless networks.
  • Access e-business apps from anywhere.
  • Strategic benefits and efficiency.
  • Mobile tickets reduce staff needs.
  • Managers present, access data remotely.
  • Direct mobile ads, micro-payments, shopping.
  • Transportation tracks shipments, guides drivers.
  • Manufacturing controls, tracks using mobile.
  • Speeds up business, enhances customer interaction.


  • Examination results displayed on mobile devices, such as NEB board examination results.
  • Mobile classrooms launched, allowing students to access educational material through mobile devices.
  • Search engines with features to find books, research papers, and other educational material using mobile devices.


  • Mobile apps for healthcare professionals to access patient records and medical information.
  • Remote patient monitoring through wearable devices and mobile apps.
  • Telemedicine services for virtual consultations and diagnoses.
  • Medical education and training apps for healthcare professionals.
  • mHealth apps for patients to track health and access information.
  • Real-time communication among medical teams in emergencies.
  • Mobile computing aids in medical research and data collection.


  • Offered over Internet, voice, and mobile phones via SMS.
  • Mobile devices receive transaction updates and notifications.
  • No need to visit banks, as transactions can be done remotely.
  • Plastic money (debit/credit cards) widely used for transactions.
  • ATMs wirelessly connected to handheld devices in remote areas.
  • Credit card authorization done on mobile POS terminals with wireless adapters.


  • Used for grading in simulator training environments.
  • Access reservation, flight schedule, and ticketing information for busy travelers.
  • Virtual check-in and automated baggage handling for regular customers.
  • Flight arrival and departure information provided to people on mobile devices.
  • Faster and easier baggage check-in with barcode scanning.
  • Airport security and monitoring is made easier with mobile devices.


  • Delivers high-performance, energy-efficient solutions.
  • Provides soldiers with access to information anytime, anywhere, improving situational awareness.
  • Small, ultra-mobile devices reduce size and weight for soldiers’ convenience.
  • Enables easy communication and flexibility in the field.
  • Fighter planes equipped with mobile devices for better tracking and communication.


  • Real-time traffic information through mobile apps and GPS navigation.
  • Route planning and avoidance of traffic congestion.
  • Live updates on road closures, accidents, and traffic conditions.
  • Mobile technology for traffic management and control.
  • Mobile-based payment solutions for tolls and parking.

Emergency Situation

  • Ambulance with high-quality wireless connection for carrying vital information about injured persons.
  • Enables doctors to be consulted for diagnosis in real-time.
  • Wireless networks essential in natural disasters like earthquakes, tsunami, flood, and fire.
  • Decentralized, wireless ad-hoc networks can handle emergencies in the worst conditions.
  • Mobile computing plays a vital role in medical emergencies, facilitating quick and efficient responses.


 Computer system and I/O devices

Concept of Computer Architecture and Computer Organization
  • Visible structure of a computer
  • Science of selecting and interconnecting hardware components
  • Aims to meet functional performance and cost goals
  • Defines the logical structure of the computer system
  • Backbone for building successful computer systems
  • Influences quality attributes like performance and reliability
  • Before performing any task, a computer needs detailed instructions (Input → Process → Output).
  • Hardware: Physical components; Software: Instructions enabling tasks.
  • Data flow between units (CU, ALU) and memory via registers.
 Components of Computer System

Integrated components working together for a desired result.

  • Input Unit: This unit accepts instructions and data.
  • Central Processing Unit (CPU): This unit performs processing of instructions and data inside the computer.
  • Output Unit: This unit communicates the results to the user.
  • Storage Unit: This unit stores temporary final results

Input Unit:

  • Input unit links the external environment to the computer system.
  • Accepts data and instructions from various input devices.
  • Converts data into computer-acceptable binary codes using input interfaces.
  • Supplies converted data to the computer system for processing.
  • Example: Keyboard, mouse, scanner, punched cards etc.

Processor/Central Processing Unit:

  • Brain of the computer system.
  • Processes input data and converts it into meaningful output.
  • Interprets data and instructions, coordinates operations.
  • Works with data in binary form (1s and 0s).
  • Translates results into characters, numbers, and symbols for the user.


  • Small, fast storage units within the CPU.
  • Hold data and instructions temporarily during processing.
  • Used for quick access and manipulation of data.
  • Play a crucial role in speeding up computer operations.

Control Unit

  • Part of the CPU responsible for coordinating and controlling computer operations.
  • Interprets program instructions and directs data flow within the CPU.
  • Manages the execution of instructions, fetching data from memory, and processing them.
  • Ensures proper synchronization and coordination between different CPU components

Arithmetic Logic Unit(ALU)

  • Part of the CPU responsible for performing arithmetic and logical operations.
  • Performs calculations like addition, subtraction, multiplication, and division on binary data.
  • Handles logical operations such as AND, OR, and NOT for decision-making.
  • Essential for executing mathematical and logical tasks within the computer system.

Memory/Storage Unit

  • Stores data and instructions for the computer system.
  • Includes both primary memory (RAM) and secondary storage (hard drives, SSDs).
  • Primary memory is used for active data during computation.
  • Secondary storage stores data for long-term use and data retention.

Auxiliary Memory or Storage

  • Secondary storage devices used for long-term data storage.
  • Examples include hard drives, solid-state drives (SSDs), external drives, and optical disks.
  • Slower access compared to primary memory (RAM) but larger capacity.
  • Used for storing files, programs, and data not actively used by the CPU.

Output Unit:

  • Supplies computation results to the external environment.
  • Results in binary form and need conversion to human-readable form.
  • Output interfaces convert coded results into readable format.
  • Transmits converted results to the outside world.
  • Example: monitor, printer, speaker, plotter etc.
  • Result of progress in VLSI technology.
  • Contains CPU in a single integrated silicon chip.
  • Performs arithmetic, logic, and control functions.
  • Found at the heart of personal computers and workstations.
  • Intel 4004 (1971) was the first microprocessor by Intel.
  • Major manufacturers: Intel, Motorola, IBM, AMD, and Cyrix.

Function of Microprocessor:

  • Performs various functions within a computer system.
  • Executes arithmetic operations (addition, subtraction, etc.).
  • Handles logical operations (AND, OR, NOT) for decision-making.
  • Controls the flow of instructions and data within the CPU.
  • Serves as the core processing unit in computers and digital devices.

Characteristics of Microprocessor

  • Integrated circuit: Microprocessors are contained in a single silicon chip.
  • CPU functions: Perform arithmetic, logic, and control operations.
  • Versatility: Can execute a wide range of instructions and tasks.
  • Central role: At the heart of most digital devices and computers.
  • Advancements: Evolve rapidly due to progress in VLSI technology.
  • Manufacturers: Produced by companies like Intel, Motorola, IBM, AMD, and Cyrix.

Components of Microprocessor

The components of a microprocessor (CPU) include:

  • Arithmetic Logic Unit (ALU): Performs arithmetic and logical operations on data.
  • Control Unit (CU): Manages and coordinates the execution of instructions.
  • Registers: Small, fast storage units for holding data during processing.
  • Instruction Decoder: Interprets and decodes program instructions.
  • Clock: Provides timing signals to synchronize CPU operations.
  • Bus Interface Unit: Handles communication with other parts of the computer system.
  • Cache Memory: Fast, on-chip memory for temporarily storing frequently accessed data.
  • Floating-Point Unit (FPU) (sometimes): Handles floating-point arithmetic operations.
  • Bus Interconnects: Connects the CPU to other system components like memory and I/O devices.
Bus System
  • Electrically conducting path for data transmission in digital devices.
  • Consists of parallel conductors (wires or tracks) on a PCB or silicon chip.
  • Each wire carries one bit, determining the device’s word size (e.g., 8-bit bus).
  • Latch at each end stores and synchronizes transmitted data.
  • Facilitates communication between different parts of a computer system.
  • Types of Bus:- Address Bus, Control Bus and Data Bus.


Types of Bus:

Address Bus:

      • Transfers memory or I/O device addresses
      • Unidirectional
      • Intel 8085 microprocessor’s Address bus: 16 bits
      • Allows addressing of 65,536 memory locations

Data Bus:

      • Transfers data within Microprocessor, Memory, and I/O devices
      • Bidirectional
      • Microprocessor word length depends on data bus
      • Intel 8085 microprocessor’s Data bus: 8 bits

Control Bus:

      • Used by CPU to communicate with internal devices
      • Transmits control signals through physical connections
      • Minimizes communication lines between components and CPU
Primary Memory
  • Also known as Main Memory, volatile.
  • Holds data and instructions currently being processed.
  • Stores operating system and computer runtime data.
  • Limited capacity, data lost when power is off.
  • Divided into two subcategories: RAM (Random Access Memory) and ROM (Read-Only Memory).

Random Access Memory(RAM):

    • Accessed in any random order, very fast.
    • Read and write capabilities, volatile (loses data when power is off).
    • Expensive compared to secondary memory (cost per gigabyte).
    • Computer systems use both RAM and cheaper secondary memory.
    • RAM stores data for imminent processing, freeing up space for the next data chunk.
    • Types: DRAM, SRAM

Read-only Memory (ROM):

    • Data can be read, not written.
    • Fast and non-volatile, retains data without power.
    • Often installed near the CPU on the motherboard.
    • Contains bootstrap code for computer startup and firmware in electronic devices.
    • Types: PROM, EPROM, EEPROM

Cache Memory:

    • High-speed semiconductor memory to speed up the CPU.
    • Acts as a buffer between CPU and main memory.
    • Stores frequently used data and programs to reduce access time.

L1 and  L2 Cache :

  • L1 Cache: The first level of cache memory, located closest to the CPU.
      • Very fast and small in size, holds frequently accessed data and instructions.
      • Reduces CPU access time and enhances performance.
  • L2 Cache: The second level of cache memory, located farther from the CPU compared to L1 cache.
      • Larger than L1 cache but slower, still faster than main memory (RAM).
      • Stores additional data and instructions for the CPU to access quickly.
      • Also helps improve overall system performance.


    • Temporary storage in computer memory (RAM) to hold data before use.
    • Used to prevent stalling or skipping in audio, video, and network data.
    • Improves performance in various areas like hard disks, video cards, and running programs.
    • Buffers make computers run more efficiently and reduce waiting times.


Secondary Memory

Storage Device:

    • Hardware used to store and retain data in a computer system.
    • Can be internal (e.g., hard drives, SSDs) or external (e.g., USB flash drives, external hard drives).
    • Stores data even when the power is off (non-volatile).
    • Provides long-term data storage and retrieval for the computer.

Magnetic Disk:

    • A type of storage device that uses magnetism to store data.
    • Examples include Hard Disk Drives (HDDs) and Magnetic Tape Drives.
    • Data is written and read using magnetic heads that move across the disk’s surface.
    • Offers high capacity and relatively fast access times for data retrieval.
    • Widely used for long-term storage in computers and data centers.

Hard Disk:

    • Consists of magnetic disks (platters) for recording and storing data.
    • Data remains intact even when the computer is turned off (non-volatile).
    • Housed inside the hard drive, which reads and writes data to the disk.
    • Hard drives transmit data between the CPU and disk.
    • Hard disk capacity is expressed in gigabytes (GB).
    • Larger capacity allows for more programs and data storage on the computer.

Floppy Disk:

    • Magnetic storage medium for computers.
    • Consists of a thin, flexible magnetic disk in a plastic carrier.
    • Requires a floppy disk drive (FDD) to read and write data.
    • Widely used for software distribution, file transfer, and data backup in early personal computing.
    • Sizes: Initially 8-inch, then 5.25-inch (1.2 MB), and 3.5-inch (1.44 MB) floppy disks.

Flash Memory:

    • Flash Memory: Non-volatile, electronically reprogrammable memory chip.
    • Used in USB flash drives, digital cameras, smartphones, tablets, and SSDs.
    • Retains data without power, making it ideal for portable devices.

Pen Drive:

    • A portable storage device also known as a USB flash drive.
    • Uses flash memory to store data.
    • Plugs into a computer’s USB port for data transfer and storage.
    • Compact and convenient for carrying files between devices.
    • Popular for backup, data transfer, and portable storage needs.

Memory Card:

    • A small, portable storage device used in digital devices.
    • Utilizes flash memory technology for data storage.
    • Commonly used in cameras, smartphones, tablets, and other portable devices.
    • Comes in various formats like SD, microSD, and CompactFlash.
    • Provides additional storage capacity and easy data transfer between devices.

Magnetic Tape:

    • A storage medium that uses a magnetic coating on a thin plastic tape.
    • Historically used for data storage and backup in mainframe computers.
    • Still used in some archival and backup systems for large data volumes.
    • Sequential access storage, slower than disk-based storage.
    • Offers high storage capacity but slower data retrieval compared to modern storage devices.

Optical Disk:

    • Secondary storage medium using optical disks.
    • Uses laser beam technology for reading and writing data.
    • Relatively new compared to magnetic storage.
    • High storage capacity compared to magnetic disks.
    • Random access device for quick access to various data.
    • No head crash issue as the read/write head does not touch the disk surface.
    • Common optical disks include CD-ROM, CD-RW, and DVD-ROM.
    • Drawback: Longer access time compared to magnetic disks.


    • Compact Disk Read Only Memory.
    • Write Once Read Many (WORM) type of disk.
    • Data can be written on CD-R only once.
    • Created using a CD recordable (CD-R) drive attached to a computer.
    • Spiral track on the disk with photosensitive dye.
    • Laser beam creates pits for 1’s and no pits for 0’s to record data.
    • A CD-ROM drive is used to read data from the disk.


    • CD-RW: Compact Disk Rewritable.
    • Similar to CD-ROM, but data can be erased and written multiple times.
    • Laser beam changes the chemical property during the writing process.
    • A CD-RW disk has a lifetime of 100 or more erase-write cycles.
    • Capacity of CD-RW is 700 MB.


    • Compact Disk Recordable.
    • A type of optical storage medium that can be written on once.
    • Data can be recorded (burned) onto the disk using a CD-R drive.
    • Once data is written, it cannot be erased or changed.
    • CD-Rs are widely used for data backup, music, and software distribution.


    • Digital Versatile Disk.
    • Larger storage capacity compared to CDs.
    • Uses a laser beam of shorter wavelength for higher data density.
    • Consists of a polycarbonate plastic base and a refreshing layer.
    • Smaller pits and closer tracks increase storage capacity.
    • DVD-ROM capacity ranges from 4.7 GB to 20 GB in single and double layers.
    • Primarily used for distributing multimedia applications.

Blu-ray Disc:

    • High-capacity optical disk medium for HD video.
    • Records, rewrites, and plays back high-definition content.
    • Supersedes DVDs with its larger storage capacity.
    • Uses blue lasers in drives, allowing for more data storage.
    • Blu-ray discs can hold up to 17 GB of data compared to CDs (700 MB) and DVDs (up to 4.7 GB).

Other External Storage Device:

    • Hard Disk, Used for backup and data transfer.
    • Not permanently attached to the computer.
    • Examples: External Hard disk, External DVD, Pen drives.

Memo Stick:

    • Sony’s proprietary flash memory for digital devices.
    • Used in cameras, camcorders, and Sony electronics.
    • Comes in two versions: Memory Stick PRO and Memory Stick PRO Duo.
    • High-speed versions support data transfer rates up to 80 Mbps.
    • Capacity ranges from 4 MB to 256 GB, with a theoretical max of 2 TB.
    • Used at storage of media for portable devices.


Difference Between Primary Memory and Secondary Memory
Primary Memory Secondary Memory
Main memory of the computer. Long-term storage.
Fast access speed. Slower access speed.
Volatile (data is lost when powered off). Non-volatile (data is retained when powered off).
Limited capacity. Larger capacity.
More expensive per unit of storage. More cost-effective for larger storage needs.


 Input Devices
    • Hardware enabling data entry and communication with the computer.
    • Electromechanical devices for data input and command input.
    • Captures information and translates it for processing and storage in the computer.
    • Examples: Keyboard, mouse, touchpad, joystick, scanner, microphone, etc.


  • Primary input device for data and instruction entry.
  • Contains keys for letters, digits, symbols, and functions.
  • Follows the QWERTY layout like a standard typewriter.
  • Includes numeric keypad, function keys, special keys, and cursor control keys.
  • Three types of keyboards: 
    • XT keyboard (83 keys)
    • AT Keyboards (101 keys)
    • Enhanced keyboard ( More than 101 keys)


  • Pointing input device connected to the computer.
  • Controls the movement of the mouse pointer on the screen.
  • Usually has two buttons (left and right).
  • Left button functions like the enter key on the keyboard.
  • Right button has special functions.
  • Mouse can be classified into three groups.
  • Types of Mouse:
    • Mechanical mouse
    • Optical mouse
    • Wireless mouse


  • Input device that converts paper documents into electronic format.
  • Scanned images can be edited, manipulated, and stored on the computer.
  • Also known as optical scanners, using a light beam to scan the data.


  • Pointing device to move the cursor on a monitor.
  • Stick with a spherical ball at both ends.
  • Moves in all four directions, similar to a mouse.
  • Mostly used in computer games to control cursor velocity.
  • Also used in flight simulators, training simulators, CAD/CAM systems, and industrial robots.

Magnetic Ink Character recognition (MICR):

  • Input device for reading human-readable characters printed with magnetic ink.
  • Recognizes characters on documents like cheques, eliminating manual data entry.
  • Ensures accuracy and saves time in data entry.

Optical Mark Recognition (OMR):

  • Input device recognizing marks made with pencil or pen on preprinted forms.
  • Special forms designed with annotated boxes for clear response marking.
  • Document reader transcribes marks into electrical pulses for the computer.
  • Used in checking objective question papers, surveys, and time sheets for factory employees.

Optical Character Recognition(OCR):

  • Optical input device to read printed characters and convert them into codes for storage in the computer.
  • Limited success due to high equipment cost and restricted character set.
  • Uses special fonts designed for OCR readers.

Barcode Reader:

  • Machine-readable code with parallel vertical lines of varying widths.
  • Used for labeling goods in supermarkets and numbering books in libraries.
  • Read by a barcode reader using reflective light.
  • Information from the barcode is fed into the computer for recognition based on bar thickness and spacing.

Digital Camera:

  • Stores images digitally, not on film.
  • Images can be transferred to a computer for manipulation and printing.
  • Inexpensive and fast compared to film cameras.
  • Records images in electronic form using bits and bytes.
  • Focuses light onto a semiconductor device to capture images electronically.

Touch Screen:

  • Display screen device allowing direct selection or activation by touching.
  • Registers input when the screen is touched by a finger or object.
  • Used for accessing information with minimal effort.
  • Not suitable for inputting large amounts of data.
  • Commonly used in information providing systems like hospitals, airlines, railway reservation counters, amusement parks, etc.


  • Stationary pointing device sensing finger movement across a sensitive surface.
  • Translates movement into pointer movement on the screen.
  • Commonly used in laptops and can be connected to PCs.
  • Also found in PDAs and media players like iPods.
  • Equipped with two or three buttons functioning as mouse buttons.
  • Some touchpads are strike-sensitive, allowing taps for various operations like selecting objects or maximizing/minimizing windows.


  • Input device for capturing sound in digital form.
  • Used for adding sound to multimedia presentations and music mixing.


Output Devices
    • Converts machine-readable information into human-readable form.
    • Opposite function of an input device.
    • Displays processed information in graphical, alphanumeric, or audio-visual format.


  • Soft output device displaying graphical and textual information.
  • Also known as VDT (video display terminal) and VDU (video display unit).
  • Contains electronic circuits, power supply, and buttons for signal manipulation.
  • Traditional monitors used CRT (cathode ray tubes), but modern ones use LCD, LED, Plasma, etc.
  • Various connectors like VGA, DVI, HDMI, DisplayPort, and Thunderbolt used to connect computers to monitors.

CRT Monitor

  • Stands for “Cathode Ray Tube,” used in computer monitors since 1950.
  • Utilizes electron beams to display pictures on the screen.
  • Beams of electrons illuminate the screen rapidly to create motion.
  • CRT monitors are not expensive, display black & white images, and are considered reliable.

Advantage of CRT Monitor:

  1. Good color reproduction and image quality.
  2. Suitable for graphic-intensive applications and gaming.
  3. Wide viewing angles with consistent colors.

Disadvantage of CRT Monitor:

  1. Bulkier and heavier than modern monitors.
  2. Higher power consumption.
  3. Limited resolution options compared to LCD and LED monitors.
  4. Susceptible to screen flickering and eye strain.
  5. Phased out due to advancements in LCD and LED technology.


Liquid Crystal Display (LCD) Monitor

  • LCD stands for “Liquid Crystal Display.”
  • It is a flat panel monitor that uses monochrome pixels illuminated by light to display images.
  • Originally designed for television, LCD technology is now used in various home appliances.
  • LCD is commonly found in calculator screens and digital watches.

Advantage of LCD:

  1. Slim and lightweight design, making them portable and easy to handle.
  2. Low power consumption, resulting in lower energy costs.
  3. Minimal heat production, contributing to a cooler working environment.
  4. Sharp and clear image quality with minimal flickering.
  5. Suitable for high-resolution displays, ideal for multimedia and gaming.

Disadvantage of LCD:

  1. Limited viewing angles can cause color and brightness distortion.
  2. Slower response times can lead to motion blur in fast-paced content.
  3. Potential for dead or stuck pixels, which can be distracting.
  4. Higher cost compared to CRT monitors, especially for larger sizes and high-end models.
  5. Limited color reproduction compared to other display technologies like OLED or QLED.


Light Emitting Diode (LED) Monitor

  • LED stands for Light-Emitting Diodes.
  • LED monitors have a flat-panel design.
  • They use light-emitting diodes for back lighting instead of cold cathode fluorescent (CCFL) used in LCD monitors.
  • LED monitors are more energy-efficient and environmentally friendly.
  • They consume less power compared to CRT and LCD monitors.

Advantage of LED Monitor

  1. Energy-efficient and eco-friendly.
  2. Slim and lightweight design.
  3. Long lifespan and durability.
  4. Brighter and more vibrant colors.
  5. No flickering and better contrast ratio.

Disadvantage of LED Monitor

  1. Higher cost.
  2. Limited viewing angles.
  3. Potential for backlight bleeding.
  4. Color accuracy issues.
  5. Potential manufacturing defects.



  • Printer is an output device that prints paper documents.
  • It produces hard copies of electronic documents.
  • Printers can print text, images, and color documents.
  • Modern printers have high DPI for fine resolution.
  • They can be connected via USB or wirelessly over Wi-Fi.
  • Multiple printers can be used on a single computer with the right drivers.

Impact Printers/Dot-matrix Printers

  • Impact printers use a printhead that strikes an inked ribbon to create characters with dots.
  • They are durable and can create carbon copies with multipart forms.
  • Print quality is lower compared to modern printers.
  • They are noisy due to the mechanical printing process.
  • Less common today as inkjet and laser printers offer higher print quality and quieter operation.


Non impact Printers / Inkjet Printers / Laser Printers

Non-impact Printers:

  • Do not use a striking mechanism like impact printers.
  • Common types include inkjet printers and laser printers.

Inkjet Printers:

  • Use small ink droplets to create images on paper.
  • Suitable for printing photos and graphics with high color accuracy.
  • Generally more affordable upfront but can be costly to maintain with ink replacement.

Laser Printers:

  • Use toner (powdered ink) and a laser beam to create images on paper.
  • Faster and more efficient for text documents.
  • Often preferred in office settings due to their high printing speed and lower cost per page.


Difference between Impact printer and Non impact printer
Impact Printer Non Impact Printer
1.Mechanical touch between printing head and paper. 1. No mechanical touch between printing head and paper.
2. Low efficiency compared to non-impact printers. 2. Higher efficiency compared to impact printers.
3. Slower printing speed. 3. Faster printing speed.
4. Produces sound during printing. 4. Silent operation during printing.
5. Capable of printing multiple copies (carbon copies) simultaneously. 5. Capable of printing single copies at a time.
6. Not suitable for printing graphics. 6. Suitable for printing graphics.
7. Low cost. 7. High cost.
8. Example: Dot matrix, daisy wheel, line printer 8. Example: Inkjet printer, Laser printer, Thermal printer.



  • Speakers are soft output devices for computer systems.
  • They receive audio input from the computer’s sound card.
  • Produce audio output in the form of sound waves.
  • Most computer speakers are active, with an internal amplifier.
  • Can increase the volume or amplitude of the sound.
  • Typically come in pairs for stereo sound from two separate audio channels.
 Hardware Interfaces
  • Hardware interface architecture is used to connect two devices together.
  • It includes the design of plugs and sockets, wires, and electrical signals.
  • Connectors and ports in a computer establish communication between the CPU and storage devices.

Serial Port:

  • Serial ports (COM ports) support sequential data transmission and are bi-directional.
  • Bi-directional communication allows devices to both receive and transmit data.
  • Serial ports serialize data, transmitting 8 bits one at a time.
  • Advantages include lower cable costs and smaller cables.
  • Disadvantages include slower data transmission compared to parallel ports.
  • Used to connect external modems, scanners, and older computer mice.
  • Comes in two versions: 9-pin and 25-pin. 9-pin is the current standard.
  • Data travels at 115 Kb per second.

Parallel Port:

  • Parallel ports (LPT ports) were developed to connect printers to PCs.
  • Data is sent 8 bits (1 byte) at a time and transmitted in parallel, all at once.
  • Standard parallel port can send 50 to 100 kilobytes of data per second.
  • Originally, parallel ports were unidirectional, sending data in one direction for each pin.
  • Bi-directional parallel ports (SPP) were introduced with the PS/2 in 1987.
  • Bi-directional communication allows devices to both receive and transmit data.

USB Port:

  • USB stands for “Universal Serial Bus.”
  • It is the most common type of computer port used in today’s computers.
  • USB can connect various peripherals, including keyboards, mice, printers, cameras, etc.
  • USB allows the connection of up to 127 peripherals using USB hubs.
  • USB is faster than older ports like serial and parallel, with USB 1.1 supporting up to 12Mb/sec and USB 2.0 supporting up to 480 Mbps.
  • It was introduced in 1997 but gained popularity with the introduction of the Apple iMac in late 1998.
  • USB is a widely-used cross-platform interface for both Macs and PCs.


  • HDMI stands for “High Definition Multimedia Interface.”
  • It is a digital interface used to connect High Definition and Ultra High Definition devices like HDTVs, monitors, gaming consoles, cameras, and Blu-Ray players.
  • HDMI carries audio signals (compressed/uncompressed) and video signals.
  • It has 19 pins, and HDMI 2.0 is the latest version, supporting digital video signals.


  • Expansion slots are found on the motherboard and hold expansion cards to enhance a computer’s functionality, like video, network, or sound cards.
  • The expansion cards are directly connected to the motherboard through the expansion slots, providing direct access to the hardware.
  • It’s essential to check the available expansion slots in a computer before buying an expansion card.
  • Older systems may require a riser board for additional expansion cards, but modern computers often have integrated features on the motherboard, reducing the need for extra expansion cards.