Following is the 9th class computer notes for unit 1 according to the Federal Board of Intermediate and Secondary Education (FBISE)

Unit 1 Computer System

Give short answers to the following short response questions (SRQs)

i. What is the primary goal of fifth-generation computers?

The primary focus of fifth-generation computers is to develop and utilize AI (Artificial Intelligence) technologies. This involves machines (called Robots) who can learn, think, innovate, reason, and solve problems automatically and independently.

ii. Differentiate between volatile and non-volatile memory.

Volatile	Non-volatile memory
RAM is a volatile memory.	ROM is a Non-volatile memory.
RAM is READ/WRITE memory.	ROM is read-only memory.
Information stored in it is lost when the computer is turned off.	The programs stored in it are not lost when the computer is turned off.

iii. Show memory hierarchy with the help of a diagram.

iv. Why is the word size of a processor important, and how does it affect the computer’s performance?

The number of bits in a word is called the word size. A computer with a bigger word size can transfer more bits into the microprocessor at a time for processing, improving the computer’s processing speed.

v. Imagine you are building a custom computer for a friend. Give three considerations you would take into account when choosing the type and size of memory for this computer.

a) The primary consideration would be the type of memory. Generally, DDR4 RAM is the current standard for most modern systems

b) The amount of memory needed depends on the intended usage of the computer. For gaming or content creation, I’d aim for at least 16GB of RAM to ensure smooth multitasking

c) The physical size of the memory modules must match the motherboard’s memory slots.

vi. You are a computer technician tasked with upgrading an older computer with a slow CPU. How might you improve its performance without replacing the entire CPU?

• Adding more RAM helps the CPU handle tasks better.
• Changing the hard drive to SSD makes the computer faster.
• Cleaning up the computer by removing unnecessary programs.
• Keeping the computer’s software and drivers up to date

vii. Your school is planning to purchase new printers for the computer lab. Give three advantages and disadvantages of impact and non-impact printers to help them make a decision.

Impact Printers:

Advantages:

• Their printing is very cheap
• They are more robust and durable.

Disadvantages:

• They produce a lot of noise while printing.
• Their print quality is poor.

Non-Impact Printers:

Advantages:

• They have very high Print Quality.
• Their printing speed is fast.

Disadvantages:

• Non-impact printers are generally more expensive.
• They often require more complex maintenance.

viii. What does OOP stand for, and which programming languages commonly use this paradigm?

OOP stands for Object-oriented programming, which is a programming method based on the concept of objects like a student, vehicle, or building.

The most widely used programming languages that utilize this paradigm are:

• C++
• Visual Basic
• Java

ix. Define “protocol” in the context of data communication.

A protocol is a set of rules that governs data communications. It represents an agreement between the communicating devices. Without a protocol, two devices are connected but may not be communicating with each other.

x. Define simplex, half-duplex, and full-duplex modes of communication with one example each.

In Simplex mode, the communication takes place in only one direction. Radio and television broadcastings are also examples of simplex transmission.

In half-duplex mode, communication takes place in both directions, but not at the same time. For example, communication between a computer and a credit card machine.

In full-duplex mode, the communication takes place in both directions at the same time. One common example of full-duplex communication is the telephone network. When two people are communicating by a telephone line, both can talk and listen at the same time.

xi. What are start and stop bits, and where are they used in data transmission?

The start bit tells the receiver that a character is coming and the stop bit indicates that the transmission of the character has ended. Start and Stop bits are used in asynchronous transmission.

xii. How does a switch differ from a hub in a network?

A switch is a networking device that performs the same job as the hub but is considered more intelligent than a hub. It gathers information about the data packet and forwards it to only the node (e.g. computer) it was intended for.

xiii. How does asynchronous transmission differ from synchronous transmission, and in what situations are they typically used?

In asynchronous transmission, the time interval between two characters is variable and not fixed. Start and Stop bits are used in asynchronous transmission. This type of transmission is ideal for slow-speed communication when gaps may occur during transmission. An example of asynchronous transmission is keyboard data transmission.

In synchronous transmission, the time interval between two characters is always the same. It does not require transmission of start and stop bits. Synchronous transmission is faster than asynchronous because fewer bits have to be transmitted. The best example of synchronous transmission is the data transmission between devices in network communications links.

xiv. Give three limitations of peer-to-peer network compared to a client/server network.

In Peer-to-Peer networks, every computer is capable of playing the role of client, server or both at the same time.

Peer-to-peer networks tend to be relatively small. Most of these networks fall to range between two and ten computers.

Large peer-to-peer networks become difficult to manage because so many network administrators control sharing and maintaining shared resources.

xv. What is the role of the Application Layer in the OSl model?

Application Layer provides services to end-users. It interacts with the operating system or application software whenever the user wants to send files, read messages or perform other network-related activities.

Give Long answers to the following extended response questions (ERQs) of the Computer System.

Q1. Describe the evolution of computer generations from the first generation to the fifth generation, highlighting the key technological developments and their impact on computing.

First Generation Computers (1940 – 1956)

• The first generation of computers relied on vacuum tubes as their core technology.
• These computers were slow and unreliable, consuming vast amounts of power.
• They were large in size, expensive to manufacture, and prone to overheating.
• Programming was done using machine language, which was challenging and limited.
• Input was provided through punched cards, and output was generated via printouts.

Second Generation Computers (1956 – 1963)

• The second generation marked the replacement of vacuum tubes with transistors, which revolutionized computing.
• These computers were smaller, faster, and more reliable compared to the first generation computers.
• They were more cost-effective, offering increased processing speed and memory capacity.
• Transistor Programming advanced to assembly languages and high-level languages such as FORTRAN (Formula Translation) and COBOL (Common Business Oriented Language).
• Input and output methods included punched cards, magnetic tapes, and disks.

Third Generation Computers (1963 – 1971)

• Integrated circuits (Ics), which combined multiple transistors.on a single chip, defined the third generation of computers.
• In this generation, computers became significantly smaller, faster, and efficient.
• They were highly reliable and introduced keyboards and monitors.
• These systems were capable of running multiple applications simultaneously, improving functionality.

Fourth Generation Computers (1971 – Present)

• The fourth generation saw the development of microprocessors, which integrated entire processing units onto a single chip.
• These computers offered exceptional speed, compact size, and vast storage capacities.
• Advanced graphical user interfaces (GUIs) and multimedia capabilities became standard.
• They supported modern programming languages such as C++, Java, and Python.
• Portable devices, including laptops and smartphones, became widespread and accessible.

Fifth Generation Computers

• The fifth generation focuses on artificial intelligence (Al)and natural language processing (NLP).
• Computers in this generation are capable of learning, reasoning, and solving problems autonomously.
• Advanced parallel processing allows these systems to handle complex tasks efficiently.
• Voice recognition and gesture controls have become common.

Expert systems and ROBOTS are used in specialized fields like medicine and engineering.

Q2. Discuss the importance of both natural and artificial systems by providing examples of each type.

Natural Systems

Natural systems occur organically in nature, characterized by self-regulation, adaptability, and stability. They consist of interconnected elements that work harmoniously without human intervention. These systems are highly complex and interdependent, performing roles that are vital to life and ecology.

Natural systems include ecosystems (forests, grasslands, aquatic), weather patterns, geological systems (mountains), the solar system, and biological systems (human body), showcasing interconnected processes and adaptations.

Artificial Systems

Artificial systems are human-designed and built to fulfill specific needs or solve problems. They are intentionally created and often require maintenance to remain functional. These systems allow humans to achieve specific purposes and are often modifiable or can be innovated rapidly

Artificial systems include communication networks (e.g., telephone, internet, satellites), information systems (e.g., databases, software), transportation systems (e.g., cars, planes, trains), energy systems (e.g., power plants), manufacturing systems (e.g., robotics), and healthcare systems (e.g., medical devices).

Q3. Explain the fundamental components of network communication, and how they work together to facilitate data transfer.

Network Communication Components

Data communication is the process of transferring information from one point to another in a networking environment. Communication Network Network communication consists of five basic components.

Sender

A sender, also called a transmitter is a computer/device that sends a message (data or information) from source to destination in a communication network. It may be a computer, workstation, cell phone or camera.

Message

Message is the data or information that is to be transmitted. Message can be in the form of text, audio, video, or any combination of these.

Medium

Medium is the path through which a message travels from source to destination. A medium can be wired, for example, telephone cable, coaxial cable and fibre optics. It can also be wireless for example Bluetooth, Wi-Fi, microwave, radio wave and satellite.

Receiver

The receiver is the device which receives the transmitted message. It can be a computer, workstation, telephone handset or television set.

Protocol

A protocol is a set of rules that governs data communications. It represents an agreement between the communicating devices. Without a protocol, two devices are connected but may not communicate with each other.

Q4. Describe the roles of common communication devices like hubs, switches, routers, and gateways in data communication. How do they contribute to the functionality of a network?

Hub

A hub is a basic device that connects multiple devices in a Local Area Network (LAN). It broadcasts data to all connected devices, meaning every device sees the same data. Hubs are simple but inefficient since they send data to every device, regardless of the intended recipient.

Switch

A switch is a more intelligent device compared to a hub. It inspects incoming data packets, determines which device the data is for, and sends it only to the correct device. This reduces network traffic and increases efficiency.

Router

A router connects multiple networks, often linking a local network to the:internet. It determines the best path for data packets to travel from one network to another and forwards them accordingly. Routers help direct internet traffic and are essential for network communication.

Gateway

A gateway connects different types of networks that use different protocols. It acts as a translator, converting data formats from one network to another to ensure compatibility. For instance, it may connect a network of PCs with an IBM mainframe network.

Q5. Discuss the advantages and limitations of different network topologies, including bus, star, and ring. When should each topology be used in a network design?

Bus Topology

Bus network topology connects each node to the network along a single piece of cable, called a bus.

Advantages of Bus Topology

• Suitable for a small network.
• Requires less cable to implement.
• Easy to connect a computer or a peripheral device to the network.
• A terminator is installed at each end of the cable to prevent signals from reflecting onto the bus and causing errors. A terminator is a device that is attached to the ground.

Limitations of Bus Topology

• If the single cable is damaged or broken at any point, the entire network can go down.
• Difficult to identify the problem if the entire network goes down.
• Not suitable for a large network.

Star Topology

In a star network topology, each network node is connected to a central device called a hub. Large networks can require many hubs and hubs can be connected to create a single large network.

Advantages of Star Topology

• It is suitable for both small and large networks.
• Easy to install and wire.
• Easy to detect and remove faults.
• Failure of cable does not stop the functioning of the entire network.

Limitations of Star Topology

• Failure of the hub causes the entire network to go down.
• Expensive topology to implement. Lengthy cable with a hub is required to install star topology

Ring Topology

Ring topology is shaped just like a ring. It is made up of an unbroken circle of network nodes.

Advantages of Ring Topology

• Each node is directly connected to the ring.
• Easy to install and wire.
• Data on the network flows in one direction.
• Not costly to implement.

Limitations of Ring Topology

• If the ring is broken at any point, the entire network stops functioning.
• Slower than other network topologies.

06. What is the OSl model, and how does it help in understanding the process of data communication? Explain each of the seven layers and their functions.

OSI Model

ISO created a standard model for data communication systems called the Open Systems Interconnection (OSI) model.

The seven layers of the OSI model are described below.

Layer 7 – Application Layer

Application Layer provides services to end-users. It interacts with the operating system or application software whenever the user wants to send files, read messages or perform other network-related activities.

Layer 6 – Presentation Layer

Presentation Layer takes the data provided by the Application Layer and converts it into a standard format that the other layers can understand.

Layer 5 – Session Layer

Session Layer performs functions that enable two applications or two pieces of the same application to communicate across the network. It performs security, name recognition, logging and other similar functions.

Layer 4 – Transport Layer

Transport Layer establishes connections between two computers on the network. It handles quality control by ensuring that the data received is in the correct format and order

Layer 3 – Network Layer

Network Layer decides which physical path-way the data should take to reach the destination. The communication device Router works in the network layer.

Layer 2 – Data Link Layer

Data Link Layer defines the format of data on the network. This layer converts the data into packets and checks them before putting them on the path-way. The communication device Switch works in this layer.

Layer 1 -Physical Layer

The physical layer defines cables and signalling. It provides hardware such as cables and connectors for sending and receiving data. Cables, hubs and repeaters work in this layer.

Q.7. Discuss any three common applications of the Internet and their impact on various aspects of society, including communication, education, business, entertainment, and research.

Three common applications of the Internet and their impacts on society include:

1. Communication

Common applications in this category include email, instant messaging, and video calls.

The Internet has revolutionized social interaction by enabling global connectivity. It facilitates real-time communication and collaboration, allowing individuals and organizations to interact instantly regardless of geographical barriers, which has transformed how people maintain relationships and conduct daily interactions.

2. Education

The Internet is widely used for online courses, e-learning platforms, and academic research.

It has significantly enhanced learning by providing access to vast information resources and knowledge. Educational software and e-learning platforms (such as Learning Management Systems) offer digital resources for teaching and assessment, making education more accessible and supporting continuous skill development.

3. Business and Work

Key applications include e-commerce (online shopping and banking), digital payments, and remote work.

The Internet has enhanced productivity and provided businesses with a global reach. E-commerce allows for convenient 24/7 digital transactions, while remote work and online collaboration tools have changed traditional office structures, allowing for greater flexibility and efficiency in the workforce.

Additionally, the Internet plays a vital role in research and innovation by providing access to global research materials, which promotes technological advancements and allows scientists to identify hidden patterns in complex data.

Select the suitable answer for the following Multiple choice questions.

i. Which technology replaced vacuum tubes in second-generation computers?
a) Transistors
b) Integrated Circuits (ICs)
c) Microprocessors
d) Magnetic tapes

ii. What is the primary goal of fifth-generation computers?
a) Fast speed
b) Thinking power
c) Enhanced memory
d) Faster microprocessors

iii. Which computer generation introduced the use of Integrated Circuits (ICs)?
a) First Generation
b) Second Generation
c) Third Generation
d) Fourth Generation

iv. In which generation of computers was the microprocessor developed?
a) First Generation
b) Second Generation
c) Third Generation
d) Fourth Generation

v. What is the function of the motherboard in a computer system?
a) To store and retrieve data permanently
b) To connect and integrate all hardware components
c) To perform mathematical calculations
d) To display output on a monitor

vi. Which component of the microprocessor controls the decision-making processes?
a) Arithmetic Logic Unit (ALU)
b) Control Unit (CU)
c) Memory unit
d) Registers

vii. Which type of memory retains data even when the computer is turned off?
a) RAM
b) ROM
c) Cache
d) Register

viii. What is the main purpose of Cache memory?
a) Store program instructions
b) Provide high-speed storage
c) Control input/output devices
d) Perform arithmetic operations

ix. What is the smallest unit of memory in a digital computer?
a) Kilobyte
b) Bit
c) Byte
d) Megabyte

x. Which memory type uses laser beams to read and write data?
a) RAM
b) Optical memory
c) Cache memory
d) ROM

xi. What is the primary function of the buses in a computer’s memory system?
a) Control memory operations
b) Display graphics
c) Transmit data between components
d) Perform arithmetic operations

xii. Which component of data communication converts the electrical signal into a suitable form for transmission?
a) Message
b) Medium
c) Protocol
d) Sender

xiii. What is the primary function of the Presentation Layer in the OSI model?
a) Establishing connections between computers
b) Converting data into a standard format
c) Deciding the physical path of data
d) Sending data in both directions simultaneously

xiv. In which network topology is data transmission unidirectional, like radio or television broadcasts?
a) Star Topology
b) Bus Topology
c) Mesh Topology
d) Ring Topology

xv. Which network architecture requires each computer to act as either a server or a client but not both simultaneously?
a) Client/Server Network
b) Peer-to-Peer Network
c) Metropolitan Area Network (MAN)
d) Wide Area Network (WAN)

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