compulsory · CSS study notes
V. Information Technology
CSS GSA — Paper 7, Part-I, Section V (Information Technology)
This is the index for Information Technology. Each sub-topic below has its own sub-page with full notes, MCQ traps, and self-test questions.
Past Paper Weightage
- ROM/RAM, AI fundamentals, OSI layers, fiber optics, and GPS are the most reliably repeated questions in this section.
Sub-topics
Past paper practice
- RAM/ROM, AI, fiber optics, GPS/Navstar, and OSI layers repeat almost every year — master these first
Past Paper Questions (FPSC GSA Paper 7, 2016–2025)
Each question gives a Full Answer (write this in the exam) and Quick Notes (bullets for fast revision).
2025 — Part-I MCQs
- BIOS is stored in: relates to ROM (firmware that starts the boot process, stored in non-volatile ROM, not RAM)
- Bandwidth refers to: the amount of data that can be transmitted over a network connection in a given time (data transfer capacity, usually in bits/sec)
- AI (as a field of study) is generally credited to: John McCarthy, who coined the term "Artificial Intelligence" in 1956
- A common AI programming language: LISP (and Python in modern AI work)
- Space waves (used in microwave/satellite communication) require: Line of Sight (LOS) propagation between transmitter and receiver
2025 — Q5(c) [5] AI vs Traditional Programming; Branches of AI
Full Answer: Traditional programming follows a fixed set of explicit, human-written rules and instructions to process input and produce a predetermined output — the program's behavior does not change unless a programmer rewrites the code. Artificial Intelligence, by contrast, uses algorithms (particularly machine learning) that learn patterns from data and improve their performance over time without being explicitly reprogrammed for every scenario, allowing them to handle new, unseen situations. Major branches of AI include Machine Learning (systems that learn from data), Natural Language Processing (understanding and generating human language), Computer Vision (interpreting images/video), Robotics (physical AI-driven machines), and Expert Systems (rule-based systems that mimic human expert decision-making).
Quick Notes:
- Traditional programming: fixed rules, same output for same input, no self-improvement
- AI: learns from data, improves over time, handles new/unseen situations
- Branches: Machine Learning, NLP, Computer Vision, Robotics, Expert Systems
2025 — Q5(d) [5] Advantages of Optical Fibers
Full Answer: Optical fibers offer several major advantages over traditional copper cables: they provide much higher bandwidth, allowing far greater data transmission capacity; they experience very low signal attenuation (loss), enabling data to travel much longer distances without needing repeaters; they are immune to electromagnetic interference since they carry light rather than electrical signals; they are more secure, as they are very difficult to tap without physical disruption; they are lighter and thinner than equivalent copper cables; and they are made from silica (sand-based), a more abundant and often cheaper raw material than copper.
Quick Notes:
- Higher bandwidth, low signal loss (long distance without repeaters)
- Immune to electromagnetic interference, more secure (hard to tap)
- Lighter/thinner than copper, made from abundant silica
2024 — Q2(b) [5] Mechanism of Fiber Optic Cable for Signal; Construction
Full Answer: A fiber optic cable transmits data as pulses of light rather than electrical signals. Its construction consists of a central core (thin strand of glass or plastic through which light travels), surrounded by cladding (a layer with a lower refractive index than the core), and an outer protective buffer/jacket coating. The mechanism relies on total internal reflection: because the core has a higher refractive index than the cladding, light entering the core at the correct angle reflects entirely off the boundary between core and cladding every time it hits it, rather than escaping, allowing the light signal to travel long distances down the fiber with minimal loss, even around gentle bends.
Quick Notes:
- Structure: core (glass/plastic, light travels here) → cladding (lower refractive index) → protective jacket
- Mechanism: total internal reflection — core's higher refractive index keeps light bouncing inside
2024 — Q5(b) [5] Software vs Hardware, with Examples
Full Answer: Hardware refers to the physical, tangible components of a computer system that can be seen and touched, such as the CPU, monitor, keyboard, mouse, hard disk, and RAM. Software refers to the intangible set of instructions, programs, and data that tell the hardware what to do and how to perform tasks, such as an operating system (Windows), a word processor (Microsoft Word), a web browser (Chrome), a spreadsheet program (Excel), and an antivirus program. Hardware provides the physical platform, while software provides the logic and instructions that make the hardware useful.
Quick Notes:
- Hardware (physical): CPU, monitor, keyboard, mouse, hard disk
- Software (instructions): Windows (OS), MS Word, Chrome, Excel, antivirus
- Hardware = the machine; Software = what tells it what to do
2023 — Q5(c) [5] How Does the Navstar GPS System Work?
Full Answer: Navstar GPS (Global Positioning System) is a satellite-based navigation system consisting of a constellation of at least 24 satellites orbiting the Earth, each continuously broadcasting its precise location and the exact time the signal was sent. A GPS receiver on the ground picks up signals from at least four of these satellites simultaneously and calculates the time each signal took to arrive; since radio waves travel at a known constant speed (the speed of light), the receiver converts this time delay into distance from each satellite. Using a process called trilateration, the receiver combines the distances from at least four satellites to calculate its own precise position (latitude, longitude, and altitude) anywhere on Earth. Applications include navigation (vehicles, aircraft, ships), mapping and surveying, timing synchronization, and location-based services on smartphones.
Quick Notes:
- Constellation of 24+ satellites broadcasting location + exact time
- Receiver measures signal delay from 4+ satellites → converts to distance
- Trilateration combines distances → calculates precise position
- Uses: navigation, mapping, timing, smartphone location services
2023 — Q5(d)(i) [2.5] Network vs Internet
Full Answer: A network is a group of two or more computers or devices connected together, within a limited or defined scope (such as a single office or building), to share resources, data, and communication — for example, a Local Area Network (LAN). The internet is a vast, global network of interconnected networks, linking millions of private, public, academic, and government networks worldwide using standardized communication protocols (TCP/IP), allowing devices anywhere in the world to communicate and share information.
Quick Notes:
- Network = limited-scope connection of devices (e.g. LAN in one office)
- Internet = global "network of networks" using TCP/IP protocol, worldwide scope
2023 — Q5(d)(ii) [2.5] Application vs Program vs Software
Full Answer: A program is a specific set of coded instructions written to perform a single, particular task, such as a script that sorts a list of numbers. Software is the broader term encompassing all programs, data, and instructions that operate a computer system, including both system software (like an operating system) and application software. An application (or "app") is a specific type of software designed for the end-user to perform particular productive tasks, such as a word processor, a web browser, or a mobile app — in short, all applications are software, but software also includes system-level programs that are not user-facing applications.
Quick Notes:
- Program = single set of coded instructions for one task
- Software = umbrella term (system software + application software)
- Application = user-facing software for specific tasks (Word, browser, apps)
2022 — Q5(a) [5] Remote Sensing — Principle and Applications
Full Answer: Remote sensing is the science of collecting information about an object or area from a distance, typically using sensors mounted on satellites or aircraft that detect electromagnetic radiation reflected or emitted from the Earth's surface, without any physical contact. Its basic principle relies on the fact that different materials (water, vegetation, soil, urban structures) reflect and absorb electromagnetic radiation differently at different wavelengths, creating a distinct "spectral signature" that sensors can detect and use for identification and analysis. Important applications include weather forecasting and monitoring, agricultural crop health assessment, disaster management (flood/wildfire monitoring), urban planning and land-use mapping, military surveillance, and environmental monitoring such as tracking deforestation and glacier melt.
Quick Notes:
- Data collection from distance via satellite/aircraft sensors, no physical contact
- Principle: different materials reflect/absorb EM radiation differently (spectral signature)
- Applications: weather forecasting, agriculture, disaster management, urban planning, environmental monitoring
2022 — Q5(b) [5] Optical Fiber; How Fiber Optic Communication Works
Full Answer: (See 2024 Q2(b) above for the fuller model answer on construction — core, cladding, protective jacket, total internal reflection.) In fiber optic communication, an electrical data signal is first converted into a light signal by a transmitter (typically a laser or LED); this light signal travels through the fiber's core via total internal reflection with minimal loss over long distances; at the receiving end, a photodetector converts the light signal back into an electrical signal for use by the receiving device. This makes fiber optic communication extremely fast, high-capacity, and largely immune to electromagnetic interference.
Quick Notes:
- Construction: core + cladding + jacket, works via total internal reflection
- Process: electrical signal → light (laser/LED) → travels through fiber → photodetector converts back to electrical signal
- Benefits: fast, high-capacity, immune to interference
2022 — Q5(c) [5] Working and Structure of a Cell Phone
Full Answer: A cell phone (mobile phone) is a wireless communication device that connects to a cellular network made up of many geographically distributed base stations (cell towers), each covering a limited area called a "cell." When a call or data is initiated, the phone transmits a radio-frequency signal to the nearest base station, which relays it through the mobile network's switching infrastructure to its destination, whether another phone, a data server, or the internet. As the user moves, the network automatically "hands off" the connection from one cell tower to the next, keeping the connection uninterrupted. Structurally, a cell phone consists of a microprocessor/CPU, memory (RAM/storage), a radio transceiver (for sending/receiving signals), an antenna, a battery, a display screen, a microphone and speaker, and a SIM card (which identifies the subscriber to the network).
Quick Notes:
- Works via cellular network of base stations (cells); phone sends RF signal to nearest tower
- "Handoff" between towers keeps calls connected while moving
- Structure: CPU, memory, radio transceiver, antenna, battery, display, mic/speaker, SIM card
2022 — Q5(d) [5] Artificial Intelligence and Robotics
Full Answer: Artificial Intelligence (AI) is the branch of computer science focused on building systems capable of performing tasks that normally require human intelligence, such as learning, reasoning, problem-solving, perception, and language understanding. Robotics is the branch of engineering and technology concerned with designing, building, and operating physical machines (robots) that can carry out tasks autonomously or semi-autonomously, often in the physical world rather than purely in software. The two fields overlap significantly: AI provides the "brain" or decision-making intelligence, while robotics provides the physical body and mechanical actuation, together enabling machines such as self-driving cars, industrial robotic arms, and autonomous drones to sense their environment, make decisions, and act on them.
Quick Notes:
- AI = software intelligence: learning, reasoning, perception, language
- Robotics = physical machines that act autonomously in the real world
- Combined: AI = "brain", Robotics = "body" (e.g. self-driving cars, robotic arms)
2021 — Q5(c) [5] Computer Memory — Units and Types
Full Answer: Computer memory is measured in units that scale by powers of two/ten: bit (smallest unit) → byte (8 bits) → kilobyte (KB) → megabyte (MB) → gigabyte (GB) → terabyte (TB), each roughly 1,000× (or 1,024×) larger than the previous. Computer memory types are broadly divided into primary memory and secondary memory. Primary memory includes RAM (Random Access Memory, volatile, temporarily holds actively used data/programs, lost when power is off) and ROM (Read-Only Memory, non-volatile, permanently stores essential startup instructions like the BIOS). Secondary memory includes non-volatile, permanent storage devices such as hard disks, solid-state drives (SSDs), USB flash drives, and optical discs (CDs/DVDs), used for long-term data storage even when the computer is off.
Quick Notes:
- Units: bit → byte (8 bits) → KB → MB → GB → TB
- Primary memory: RAM (volatile, active use), ROM (non-volatile, stores BIOS/startup instructions)
- Secondary memory: hard disk, SSD, USB, CD/DVD (permanent storage)
2020 — Q5(c) [5] Open System Interconnection (OSI) Model and Its Layers
Full Answer: The OSI (Open Systems Interconnection) model is a conceptual framework that standardizes how different computer systems communicate over a network, dividing the communication process into seven distinct layers. From bottom to top: the Physical layer (transmits raw bits over physical media like cables), the Data Link layer (handles node-to-node data transfer and error detection), the Network layer (handles routing and addressing of data packets, e.g. IP addressing), the Transport layer (ensures reliable end-to-end data delivery, e.g. TCP), the Session layer (manages and maintains connections/sessions between applications), the Presentation layer (translates/formats/encrypts data for the application layer), and the Application layer (the layer closest to the end user, providing network services to software applications, e.g. HTTP, FTP). Each layer performs a specific function and communicates with the layers directly above and below it, making network design modular, standardized, and easier to troubleshoot.
Quick Notes:
- 7 layers (bottom to top): Physical → Data Link → Network → Transport → Session → Presentation → Application
- Mnemonic: "Please Do Not Throw Sausage Pizza Away"
- Purpose: standardizes network communication, modular design, easier troubleshooting
2020 — Q5(d) [5] What is GPS? How Does It Work?
Full Answer: (See 2023 Q5(c) above for the fuller model answer — same core content: GPS is a satellite-based navigation system using a constellation of satellites broadcasting location and time; a receiver calculates its distance from at least four satellites via signal delay and uses trilateration to determine its precise position.)
Quick Notes:
- GPS = satellite navigation, 24+ satellite constellation
- Receiver measures delay from 4+ satellites → trilateration → precise position
2019 — Q5(b) [5] Types of Computer Networks
Full Answer: Computer networks are classified mainly by geographic scope. A Local Area Network (LAN) connects devices within a small, limited area such as a single building or office, offering high speed and low latency. A Metropolitan Area Network (MAN) spans a larger area, such as a city, connecting multiple LANs together. A Wide Area Network (WAN) spans a very large geographic area, potentially covering countries or continents, with the internet being the largest example of a WAN. Other types include a Personal Area Network (PAN), covering a very small range around an individual (e.g. Bluetooth connections), and a Wireless Local Area Network (WLAN), a LAN that uses wireless technology (Wi-Fi) instead of physical cables.
Quick Notes:
- LAN: small area (office/building), fast, low latency
- MAN: city-wide, connects multiple LANs
- WAN: very large area/countries (internet = biggest WAN)
- PAN: personal range (Bluetooth); WLAN: wireless LAN (Wi-Fi)
2018 — Q5(a) [5] How Hard Disk Stores Data
Full Answer: A hard disk drive (HDD) stores data magnetically on one or more spinning circular platters coated with a magnetic material. A read/write head, mounted on an actuator arm, moves across the surface of the spinning platter and either magnetizes tiny regions of the disk in specific patterns to write data, or detects the existing magnetic patterns to read data, representing binary 1s and 0s. Data is organized into concentric circular tracks, which are further divided into sectors, allowing the drive to locate and access any specific piece of data quickly. Because it uses magnetic storage rather than volatile electronic charge, an HDD retains data permanently even when the power is switched off (non-volatile storage).
Quick Notes:
- Data stored magnetically on spinning platters
- Read/write head (on actuator arm) writes/reads magnetic patterns = binary 1s/0s
- Data organized in tracks + sectors; non-volatile (retains data with power off)
2018 — Q5(b) [5] Optical Fiber — Construction
Full Answer: (See 2024 Q2(b) above for the fuller model answer — same core content: core, cladding with lower refractive index, and protective outer jacket, working via total internal reflection to guide light signals through the fiber.)
Quick Notes:
- Core (light travels) + Cladding (lower refractive index) + protective jacket
- Works via total internal reflection
2018 — Q5(d) [5] How Is AI Helpful for Humanity?
Full Answer: Artificial Intelligence benefits humanity in numerous ways: in healthcare, it assists in disease diagnosis, drug discovery, and personalized treatment planning; in industry, it improves efficiency and safety through automation and predictive maintenance; in daily life, it powers virtual assistants, navigation apps, and recommendation systems; in agriculture, it helps optimize crop management and predict yields; in disaster response, it helps analyze data quickly to guide relief efforts; and in scientific research, it accelerates data analysis and pattern discovery across virtually every field. By automating repetitive tasks and processing vast amounts of data far faster than humans can, AI frees people to focus on more creative and complex work, while improving accuracy, efficiency, and accessibility of services.
Quick Notes:
- Healthcare: diagnosis, drug discovery, personalized treatment
- Industry: automation, predictive maintenance
- Daily life: virtual assistants, navigation, recommendations
- Agriculture, disaster response, scientific research: faster data analysis
- Overall: automates repetitive work, frees humans for creative tasks, improves accuracy/efficiency
2017 — Q4(d) [5] AC vs DC Power
Full Answer: Alternating Current (AC) is electric current that periodically reverses direction and changes magnitude, oscillating in a sine-wave pattern (in most countries, 50 or 60 times per second); it is the form of electricity supplied to homes and businesses because it can be efficiently transmitted over long distances at high voltage and then "stepped down" using transformers. Direct Current (DC) is electric current that flows steadily in a single, constant direction; it is used in batteries, solar panels, and most electronic devices' internal circuitry (which often converts incoming AC to DC via an adapter). AC is preferred for long-distance power transmission due to easy voltage transformation, while DC is preferred for stable, consistent power delivery in electronic components.
Quick Notes:
- AC: direction reverses periodically (sine wave), used for grid/home power, easy to transform voltage for long-distance transmission
- DC: flows in one constant direction, used in batteries/solar panels/electronics
2017 — Q5(a) [5] RAM vs ROM
Full Answer: RAM (Random Access Memory) is volatile memory that temporarily stores data and instructions that the CPU is actively using or processing; it allows fast read and write access, but all its content is lost when the power is turned off. ROM (Read-Only Memory) is non-volatile memory that permanently stores essential startup instructions, such as the BIOS/firmware needed to boot the computer; its content is typically written once during manufacturing and cannot easily be changed, and it retains data even when the power is off.
Quick Notes:
- RAM: volatile, temporary, fast read/write, holds active data — lost on power-off
- ROM: non-volatile, permanent, stores BIOS/firmware — retains data with power off
2017 — Q5(b) [5] Computer Buses
Full Answer: A computer bus is a communication pathway that transfers data, addresses, and control signals between different components inside a computer, such as the CPU, memory, and peripheral devices. There are three main types: the Data Bus, which carries the actual data being transferred between components; the Address Bus, which carries the memory address specifying where data should be read from or written to; and the Control Bus, which carries control signals (such as read/write commands and timing signals) that coordinate and synchronize the activities of different components. Together, these buses enable the orderly, coordinated flow of information throughout the computer system.
Quick Notes:
- Bus = communication pathway inside computer
- Data Bus: carries actual data
- Address Bus: carries memory address (where to read/write)
- Control Bus: carries control/timing signals
2017 — Q5(c) [5] Computer Block Diagram
Full Answer: A basic computer system's block diagram consists of four main functional units connected by buses: the Input unit (devices like keyboard, mouse, scanner that feed data and instructions into the computer), the Central Processing Unit or CPU (the "brain," itself divided into the Control Unit, which directs and coordinates operations, and the Arithmetic Logic Unit (ALU), which performs calculations and logical comparisons), Memory (Primary memory — RAM/ROM — for immediate data/instruction access, and Secondary memory — hard disk/SSD — for permanent storage), and the Output unit (devices like a monitor or printer that present the processed results to the user). Data flows from input, through the CPU (using memory as needed), to output.
Quick Notes:
- 4 main units: Input → CPU (Control Unit + ALU) → Memory (Primary + Secondary) → Output
- Flow: Input feeds CPU → CPU processes (using memory) → Output shows result
2017 — Q5(d) [5] Types of Computers
Full Answer: Computers are classified by size, processing power, and purpose into several categories. Supercomputers are the most powerful and expensive, used for extremely complex calculations such as weather forecasting and scientific simulations. Mainframe computers are large, powerful systems used by big organizations (banks, government) to process massive volumes of data for many users simultaneously. Minicomputers (now largely replaced by servers) are mid-sized systems used by smaller organizations. Microcomputers (personal computers) are the everyday computers used by individuals, including desktops, laptops, tablets, and smartphones. Embedded computers are specialized, single-purpose computer systems built into other devices, such as those found in washing machines, cars, and medical equipment.
Quick Notes:
- Supercomputer: most powerful, complex simulations/forecasting
- Mainframe: large orgs, high-volume multi-user processing
- Minicomputer: mid-size (mostly replaced by servers now)
- Microcomputer/PC: everyday use (desktop, laptop, tablet, smartphone)
- Embedded computer: single-purpose, built into other devices
2016 — Q3(a) [5] Artificial Intelligence — Short Note
Full Answer: Artificial Intelligence (AI) is the branch of computer science concerned with creating systems and machines capable of performing tasks that would normally require human intelligence, such as learning from experience, reasoning, problem-solving, understanding language, and perceiving their environment. AI systems range from simple rule-based expert systems to advanced machine learning and deep learning models that improve their performance by learning patterns from large amounts of data, without being explicitly programmed for every possible scenario. AI is applied today across healthcare, finance, transportation (self-driving cars), virtual assistants, and countless other fields, making it one of the most transformative technologies of the modern era.
Quick Notes:
- AI = computer science field building machines that mimic human intelligence (learning, reasoning, problem-solving)
- Ranges from rule-based expert systems to machine learning/deep learning
- Applications: healthcare, finance, self-driving cars, virtual assistants
2016 — Q3(b) [5] Fibre Optics and GPS — Short Notes
Full Answer: Fibre optics is a technology that transmits data as pulses of light through thin strands of glass or plastic fiber, using total internal reflection to keep the light confined within the fiber's core, enabling extremely fast, high-bandwidth, low-loss data transmission over long distances, immune to electromagnetic interference. GPS (Global Positioning System) is a satellite-based navigation system that uses a constellation of at least 24 orbiting satellites; a ground receiver calculates its precise position by measuring the time delay of signals received from at least four satellites and using trilateration, enabling accurate global positioning for navigation, mapping, and countless location-based applications.
Quick Notes:
- Fibre optics: light through glass/plastic fiber, total internal reflection, fast/high-bandwidth/low-loss
- GPS: 24+ satellite constellation, receiver uses signal delay + trilateration for position