BSc CSIT (TU) Science Introduction to Information Technology (BSc CSIT, CSC109) Question Paper 2074 Nepal

Definition of a Computer

A computer is an electronic device that accepts data (input), processes it according to a set of stored instructions (a program), produces meaningful information (output), and can store the results for future use. It works on the Input-Process-Output (IPO) model.

Characteristics of a Computer

• Speed: Performs millions/billions of operations per second (measured in MIPS / FLOPS).
• Accuracy: Produces error-free results; mistakes are usually due to wrong input or programs (GIGO – Garbage In, Garbage Out).
• Automation: Once a program is loaded, it executes instructions without human intervention.
• Diligence: Free from tiredness, boredom or loss of concentration; performs repetitive tasks with the same accuracy.
• Versatility: Can perform many different kinds of tasks (calculation, gaming, design, communication).
• Storage: Stores very large amounts of data and recalls it instantly.
• Reliability: Gives consistent, dependable results over long periods.

Generations of Computers

Each generation became smaller, faster, cheaper, more reliable and more energy-efficient than the previous one.

Computer Memory

Computer memory is the part of a computer that stores data, instructions and results, either temporarily or permanently, so that the CPU can access them during processing. It is measured in bytes (KB, MB, GB, TB).

Memory Hierarchy

Memory is organized as a pyramid based on speed, cost per bit, and capacity. As we move up the hierarchy speed and cost increase but capacity decreases.

            Registers        (fastest, smallest, costliest)
            Cache (L1/L2/L3)
            Primary / Main Memory (RAM, ROM)
            Secondary Storage (HDD, SSD, optical)
   ↓        Tertiary / Backup (magnetic tape)   (slowest, largest, cheapest)

• Registers: inside the CPU, fastest, hold operands of current operation.
• Cache: small fast memory between CPU and RAM, holds frequently used data.
• Primary memory: directly accessed by CPU (RAM, ROM).
• Secondary memory: permanent bulk storage (disks, tapes).

Primary vs Secondary Memory

Conclusion: Primary memory is fast, expensive and mostly temporary working memory, while secondary memory is slower, cheaper and provides permanent mass storage.

Computer Network

A computer network is a collection of two or more interconnected computers and devices that can communicate with each other to share resources (files, printers, internet) and exchange data, using transmission media and protocols.

Network Topologies

Topology is the physical or logical arrangement of devices (nodes) and links in a network.

1. Bus Topology

All devices connect to a single central cable (backbone).

• Advantages: Cheap, easy to install, uses less cable.
• Disadvantages: Backbone failure brings down whole network; difficult to troubleshoot; performance drops with more nodes.

2. Star Topology

All devices connect to a central hub/switch.

• Advantages: Easy to install and manage; failure of one node does not affect others; easy fault detection.
• Disadvantages: If central hub fails, whole network fails; needs more cable; cost of hub.

3. Ring Topology

Devices connected in a closed loop; data travels in one direction.

• Advantages: No collisions (token passing); equal access for all nodes; performs well under heavy load.
• Disadvantages: Failure of one node/link can break the ring; adding/removing nodes disrupts the network.

4. Mesh Topology

Every device is connected to every other device.

• Advantages: Highly reliable and fault-tolerant; provides multiple paths; secure.
• Disadvantages: Very expensive; complex wiring and maintenance; needs many ports/cables.

5. Tree (Hierarchical) Topology

Combination of bus and star arranged in a hierarchy.

• Advantages: Scalable; easy to manage in segments.
• Disadvantages: Dependent on root node; more cabling.

Conclusion: The choice of topology depends on cost, reliability, scalability and ease of maintenance required.

Analog vs Digital Computers

In short: An analog computer measures continuously varying physical quantities, whereas a digital computer counts and processes discrete data using binary digits, giving higher accuracy and storage.

Convert $(45)_{10}$ to Binary, Octal and Hexadecimal

Binary (divide by 2)

Reading remainders bottom to top: $(45)_{10} = (101101)_2$

Octal (divide by 8)

• $45 \div 8 = 5$ remainder $5$
• $5 \div 8 = 0$ remainder $5$

So $(45)_{10} = (55)_8$

(Check via binary grouping in 3s: $101\,101 = 5\,5 = (55)_8$.)

Hexadecimal (divide by 16)

• $45 \div 16 = 2$ remainder $13$ (= D)
• $2 \div 16 = 0$ remainder $2$

So $(45)_{10} = (2D)_{16}$

(Check via binary grouping in 4s: $0010\,1101 = 2\,D = (2D)_{16}$.)

Final Answers

System Software vs Application Software

System Software

System software is a set of programs that controls and manages the computer hardware and provides a platform for running application software. It operates the computer and acts as an interface between the user/applications and the hardware.

Examples:

• Operating systems: Windows, Linux, macOS, Android
• Device drivers: printer driver, graphics driver
• Utility programs: antivirus, disk defragmenter, file compression
• Language translators: compiler, interpreter, assembler

Application Software

Application software is a program designed to help the user perform specific tasks or solve particular problems. It runs on top of system software.

Examples:

• Word processors: MS Word
• Spreadsheets: MS Excel
• Presentation: MS PowerPoint
• Web browsers: Chrome, Firefox
• Media players, games, accounting software (e.g. Tally)

Key Difference

System software manages and runs the computer itself, while application software lets the user accomplish real-world tasks. Application software depends on system software to run.

Input Devices

An input device is a hardware device used to enter (feed) data, instructions and signals into the computer for processing. It converts human-readable data into machine-readable (binary) form.

Four Input Devices

1. Keyboard – The most common input device with a set of keys (alphabetic, numeric, function, control). Used to type text and commands into the computer.

2. Mouse – A pointing device that controls the cursor on screen. Movements and clicks are used to select, drag and open items in a graphical interface.

3. Scanner – An optical device that captures images, photos or printed text from paper and converts them into a digital form that can be stored and edited.

4. Microphone – An audio input device that captures sound/voice and converts it into digital signals, used for recording, voice commands and online communication.

(Other examples: joystick, light pen, touch screen, webcam, barcode reader, OMR/OCR/MICR readers.)

RAM vs ROM

In short: RAM is fast, volatile read/write memory that holds data and programs in current use, while ROM is non-volatile memory that permanently stores essential start-up instructions.

Operating System

An operating system (OS) is system software that manages all the hardware and software resources of a computer and acts as an interface between the user and the hardware. It controls the execution of programs and provides an environment in which application software can run. Examples: Windows, Linux, macOS, Android.

Main Functions of an Operating System

1. Process management – creates, schedules and terminates processes; allocates CPU time among them.
2. Memory management – allocates and deallocates main memory to processes and keeps track of usage.
3. File management – creates, stores, organizes, retrieves and deletes files and directories.
4. Device (I/O) management – controls input/output devices through device drivers.
5. Security and protection – controls access through passwords/authentication and protects data.
6. User interface – provides CLI or GUI for user interaction.
7. Resource and storage management – manages secondary storage and overall system resources.
8. Error detection and handling – detects and responds to hardware/software errors.

Components of a Data Communication System

Data communication is the exchange of data between two devices through a transmission medium. A data communication system has five basic components:

1. Message – The information (data) to be communicated, such as text, numbers, images, audio or video.

2. Sender – The device that generates and sends the message (e.g. computer, phone, workstation).

3. Receiver – The device that receives the message (e.g. computer, printer, mobile).

4. Transmission medium – The physical path through which data travels from sender to receiver. It may be guided (twisted pair, coaxial cable, optical fibre) or unguided (radio waves, microwave, infrared).

5. Protocol – A set of rules that governs data communication; both sender and receiver must follow the same protocol to communicate successfully (e.g. TCP/IP). Without a common protocol, devices cannot understand each other even if connected.

(A diagram would show: Sender → (Protocol) → Medium → Receiver, all carrying the Message.)

Multimedia

Multimedia is the integrated use of more than one form of media — text, graphics, audio, video and animation — in a single application, presented and controlled by the computer, usually in an interactive way. It combines these elements to communicate information more effectively.

Elements of Multimedia

Text, Graphics/Images, Audio (sound), Video, and Animation.

Applications of Multimedia

• Education and e-learning: interactive tutorials, computer-based training, simulations.
• Entertainment: video games, movies, music, animation films.
• Business: presentations, advertising, product demos, video conferencing.
• Medical: simulations, surgical training, diagnostic visualization.
• Web and social media: websites, streaming, online videos.
• Engineering and design: CAD, virtual reality, architectural walkthroughs.
• Public information: kiosks, digital signage, museums, GIS.

Multimedia makes information more engaging, interactive and easier to understand.

Computer Viruses

A computer virus is a malicious program (malware) that attaches itself to other files or programs and replicates by inserting copies of itself, often without the user's knowledge. When the infected program runs, the virus activates and spreads to other files, programs or computers, damaging data and degrading performance.

Characteristics

• Self-replicating and able to spread.
• Needs a host file/program and user action to execute.
• Often hidden, activates on a condition (date, event, file open).

Ways of Spreading

• Infected USB/external drives, email attachments, downloaded files, pirated software, and networks/internet.

Effects / Symptoms

• Slows down the computer, corrupts or deletes files, consumes memory, causes crashes, displays unwanted messages, and may steal or damage data.

Examples

• Melissa, ILOVEYOU, CIH (Chernobyl), Creeper.

Prevention

• Install and update antivirus software, scan external media, avoid suspicious downloads/attachments, keep regular backups, and update the operating system.