BSc CSIT (TU) Science Introduction to Information Technology (BSc CSIT, CSC109) Question Paper 2081 Nepal

Generations of Computers

The evolution of computers is divided into five generations, classified by the electronic component (switching technology) used.

Each generation made computers smaller, faster, cheaper, more reliable and more energy-efficient.

Classification of Computers Based on Size

1. Microcomputers – Smallest and cheapest; built around a microprocessor; used by individuals. e.g. desktops, laptops, tablets, smartphones.
2. Minicomputers – Medium-sized, multi-user systems used by small/medium organisations for departmental tasks.
3. Mainframe computers – Large, powerful machines supporting hundreds of users simultaneously; used by banks, airlines and large enterprises for bulk data processing.
4. Supercomputers – Fastest and most expensive; perform trillions of operations per second; used in weather forecasting, scientific simulation, nuclear research. e.g. Cray series.

Conclusion: Generations describe technological evolution over time, whereas size-based classification describes capacity and processing power at any given time.

Data Representation

Data representation is the way data (numbers, characters, images, etc.) is encoded and stored inside a computer. Since digital computers use two-state electronic devices, all data is ultimately represented using the binary system (0s and 1s, called bits). Number systems are characterised by their base/radix — the number of distinct digits used.

Number Systems

Conversions

Binary → Octal: group bits in 3s from the right.

Binary → Hexadecimal: group bits in 4s from the right.

Octal → Binary: write each octal digit as 3 bits.

Hexadecimal → Binary: write each hex digit as 4 bits.

To Decimal (positional weighting): multiply each digit by base raised to its position.

Decimal → other base: repeated division by the base, reading remainders bottom-to-top.

Thus octal and hexadecimal act as compact, human-readable shorthands for binary because $8 = 2^3$ and $16 = 2^4$.

The Internet

The Internet is a global, public network of interconnected computer networks that communicate using the standard TCP/IP protocol suite. It allows billions of devices worldwide to exchange information.

Internet Services

• World Wide Web (WWW): linked hypertext documents accessed via browsers using HTTP/HTTPS.
• Email: electronic messaging using SMTP, POP3, IMAP.
• File Transfer (FTP): uploading/downloading files between hosts.
• Remote login (Telnet/SSH): accessing remote machines.
• Search engines, social media, VoIP, e-commerce, cloud and streaming services.

Role of IP Address, DNS and Protocols

IP Address: A unique numeric identifier assigned to each device on the network (e.g. IPv4 192.168.1.1, or IPv6). It enables addressing and routing so data packets reach the correct destination.

DNS (Domain Name System): A distributed directory that translates human-readable domain names (e.g. tu.edu.np) into machine IP addresses. Without DNS users would have to memorise numeric addresses.

Protocols: Agreed rules that govern communication. Key ones:

• TCP/IP – core suite; IP handles addressing/routing, TCP ensures reliable, ordered delivery.
• HTTP/HTTPS – web page transfer (HTTPS adds encryption).
• SMTP/POP3/IMAP – email; FTP – file transfer; DNS protocol – name resolution.

Communication flow: A user types a domain → DNS resolves it to an IP address → TCP/IP breaks the message into packets, routes them across the network, and reassembles them reliably at the destination, where the relevant application protocol (e.g. HTTP) interprets the data.

Characteristics of a Computer

1. Speed: Performs millions/billions of operations per second (measured in MIPS/FLOPS).
2. Accuracy: Produces error-free results; mistakes usually arise from wrong input (GIGO – Garbage In, Garbage Out).
3. Automation: Once a program is loaded, it executes tasks automatically without human intervention.
4. Diligence: Works continuously without fatigue, boredom or loss of concentration, retaining the same accuracy.
5. Versatility: Can perform many different types of tasks (calculation, document editing, communication, multimedia).
6. Storage / Memory: Stores huge amounts of data and retrieves it instantly when needed.

(Limitations: it lacks intelligence and decision-making of its own — it only follows instructions.)

Primary Memory vs Secondary Memory

Summary: Primary memory is fast, temporary working storage close to the CPU; secondary memory is slower, permanent, high-capacity storage used for long-term retention.

System Software

System software is a set of programs that controls and manages the operation of computer hardware and provides a platform on which application software runs. It acts as an interface between the user/application software and the hardware.

Types and Examples

1. Operating System (OS): Manages hardware resources, memory, processes, files and provides the user interface. e.g. Windows, Linux, macOS, Android.
2. Language Translators: Convert source code into machine code — compiler (whole program at once), interpreter (line by line), assembler (assembly → machine code).
3. Device Drivers: Enable the OS to communicate with hardware devices (printer driver, graphics driver).
4. Utility Programs: Maintain and optimise the system — antivirus, disk defragmenter, backup, compression tools.

Key point: Unlike application software (which serves the end user's specific tasks), system software serves the computer system itself.

Four Input Devices

1. Keyboard: The most common input device; converts pressed keys (letters, numbers, symbols, control keys) into coded signals for the computer.
2. Mouse: A pointing device that controls the on-screen cursor; used to point, click, drag and select graphical objects.
3. Scanner: Optically captures printed text, images or documents and converts them into a digital form that can be stored or edited.
4. Microphone: Captures sound/voice and converts analog audio into digital signals for recording, voice commands or communication.

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

Convert $(172)_{10}$

To Binary (divide by 2)

Reading remainders bottom-to-top:

To Octal (group binary in 3s from right)

Check: $2{\cdot}64 + 5{\cdot}8 + 4 = 128+40+4 = 172.$ ✓

To Hexadecimal (group binary in 4s from right)

Check: $A{\cdot}16 + C = 10{\cdot}16 + 12 = 160+12 = 172.$ ✓

Result: $(172)_{10} = (10101100)_2 = (254)_8 = (AC)_{16}$.

Network Topology

Network topology is the physical or logical arrangement (layout) of nodes (computers/devices) and the connecting links in a computer network. It describes how devices are interconnected and how data flows. Common types: bus, star, ring, mesh, tree and hybrid.

Star Topology

In a star topology, all nodes are connected to a central device (hub or switch) by individual point-to-point links. All communication between nodes passes through this central device.

Diagram (described): A central hub/switch in the middle with separate cables radiating out to each computer, forming a star-like shape.

Advantages

• Easy to install, manage and add/remove nodes.
• Failure of one cable or node does not affect the rest of the network.
• Easy fault detection and centralised management.

Disadvantages

• Requires more cable than bus/ring.
• The central hub/switch is a single point of failure — if it fails, the whole network goes down.

DBMS

A Database Management System (DBMS) is system software that allows users to create, store, organise, retrieve, manipulate and manage data in a database in an efficient and controlled way. It acts as an interface between users/applications and the physical database. Examples: MySQL, Oracle, MS SQL Server, MS Access, PostgreSQL.

Advantages of DBMS

1. Controls data redundancy – minimises duplicate storage of the same data.
2. Data consistency and integrity – enforces rules so data stays accurate and valid.
3. Data sharing – multiple users/applications can access the same data concurrently.
4. Data security – access controls, authentication and authorisation protect data.
5. Backup and recovery – built-in mechanisms restore data after failures.
6. Data independence – applications are insulated from changes in data storage structure.
7. Efficient querying – fast retrieval and updates using query languages (SQL).

Components of Multimedia

Multimedia is the integration of multiple forms of media — text, graphics, audio, video and animation — to present information interactively. Its five basic components are:

1. Text: The fundamental element used to convey information, titles, labels and content. Various fonts, sizes and styles improve readability.
2. Graphics / Images: Still pictures, drawings, charts and photographs (e.g. JPEG, PNG, GIF) that illustrate and enhance content.
3. Audio / Sound: Music, narration, sound effects and speech (e.g. MP3, WAV) that add an auditory dimension.
4. Video: Moving visual images with sound (e.g. MP4, AVI) used for demonstrations and realistic presentation.
5. Animation: A sequence of images displayed rapidly to create the illusion of motion, used to visualise concepts and add appeal.

(These components are combined and controlled through multimedia authoring software and require suitable hardware such as sound cards, speakers and displays.)

Computer Security Threats

A computer security threat is any potential danger that can exploit a vulnerability to harm a computer system, steal/damage data, or disrupt operations. Major threats include:

1. Malware (Malicious Software):
   • Virus – attaches to files and spreads, corrupting data.
   • Worm – self-replicates across networks without a host file.
   • Trojan horse – disguised as legitimate software but performs harmful actions.
   • Spyware / Adware – secretly monitors activity or shows unwanted ads.
2. Ransomware: Encrypts a user's data and demands payment for the decryption key.
3. Hacking / Unauthorised access: Intruders gain access to systems to steal or alter data.
4. Phishing: Fraudulent emails/websites trick users into revealing passwords or financial details.
5. Denial of Service (DoS/DDoS): Floods a system with traffic to make services unavailable.
6. Data theft and identity theft: Stealing confidential or personal information.

Protection measures: antivirus software, firewalls, strong passwords, regular updates, data backups, encryption and user awareness.