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 function and significance of Napier’s Bone in early computing?

John Napier developed Napier’s Bones, a manually operated calculating device. It used 9 separate strips (bones) marked with numerals to multiply and divide. It was also the first machine to calculate using the decimal point system.

ii. How did Charles Babbage’s Difference Engine differ from the Analytical Engine?

Difference Engine was a mechanical computer that could do basic computations. It was a steam-powered calculating machine used to solve numerical problems.

Analytical Engine was a mechanical computer that took input from punch cards. It was capable of solving any mathematical problem and storing data in memory.

iii. 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.

iv. Name the three types of memory mentioned on the motherboard in the Von Neumann architecture.

1. Random Access Memory (RAM)
2. Read Only Memory (ROM)
3. Cache memory

v. 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.

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

vii. 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.

viii. What is pipelining, and how does it improve the efficiency of a CPU?

In a pipeline, multiple instructions are in different stages of execution simultaneously. This allows for better utilization of the CPU’s resources and faster execution of instructions. CPUs use pipelining to increase efficiency.

ix. 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.

x. 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

xi. 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
• Some impact printers, like dot matrix printers, can create carbon copies.
• They are more robust and durable.

Disadvantages:

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

Non-Impact Printers:

Advantages:

• They have very high Print Quality.
• They operate quietly compared to impact printers
• Their printing speed is fast.

Disadvantages:

• Non-impact printers are generally more expensive.
• They often require more complex maintenance.
• They have more mechanical problems than impact printers.

xii. 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.

xiii. 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.

xiv. 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.

xv. 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.

xvi. 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.

xvii. Explain the concept of a peer-to-peer network and its limitations 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. A peer computer on your desktop can share files and printers with other computers and it can simultaneously access other shared resources on the network.

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.

xviii. Compare and contrast the star and ring network topologies.

Star Topology	Ring Topology
In a star network topology, each network node is connected to a central device called a hub.	Ring topology is shaped just like a ring. It is made up of an unbroken circle of network nodes.
Failure of cable does not stop the functioning of the entire network.	If the ring is broken at any point, the entire network stops functioning.
Expensive topology to implement.	Not costly to implement.

xix. Why is mesh topology considered the most reliable but also the most expensive to implement?

In mesh topology, each node is directly connected to all the nodes. Data can be routed around failed computers or busy ones. It can manage high traffic. Therefore it is considered the most reliable topology.

It is considered the most expensive to implement because more cabling is required in this topology.

xx. 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 fourth generation, highlighting the key technological developments and their impact on computing.

First Generation Computers (1940 – 1956)

The following are some characteristics of first-generation computers.

• Vacuum tubes were used in first-generation computers.
• The processing speed was slow.
• Memory capacity was limited.
• These computers were massive, occupying entire rooms.
• First-generation computers were both costly and unreliable.
• They consumed significant power and generated substantial heat.
• Input relied on punched cards.
• Output was obtained through printouts via electric typewriters.
• Machine language was the only programming paradigm.

Second Generation Computers (1956 – 1963)

The following are some characteristics of second-generation computers.

• Second-generation computers replaced vacuum tubes with transistors, leading to enhanced efficiency.
• The adoption of transistors resulted in a reduction in computer size, accompanied by improvements in speed and memory capacity.
• Second-generation computers demonstrated increased reliability and cost-effectiveness.
• Key input and output methods included punch card readers, magnetic tapes, magnetic disks, and printers.
• Assembly language was employed for programming purposes.
• This generation introduced high-level programming languages such as FORTRAN and COBOL.

Third Generation Computers (1963 – 1971)

The following are the characteristics of the third generation of computers.

• Third-generation computers use Integrated Circuit (IC) chips.
• The utilization of IC chips led to enhancements in computer speed and memory.
• These computers demonstrated improvements in energy efficiency, size reduction, cost-effectiveness, and reliability compared to second-generation computers.
• Interaction with third-generation computers involved the use of a keyboard and monitor.
• These computers could concurrently run multiple application programs.

Fourth Generation Computers (1971 – Present)

The following are the characteristics of the fourth generation of computers.

• The introduction of microprocessors marked a defining feature of fourth-generation computers, leading to the emergence of microcomputers.
• Fourth-generation computers are known for their exceptional speed, large storage capacity, and the incorporation of advanced input/output devices.
• Microcomputers in this generation are characterized by their small size, high reliability, low power consumption, and affordability.
• A wide variety of software became available for use in microcomputers during the fourth generation.
• Operating systems with Graphical User Interfaces (GUIs) were developed during this period, enhancing user interaction and experience.
• Fourth-generation computers support multimedia software, enabling the integration of text, image, sound, and video.
• These computers are compatible with modern programming languages such as Visual Basic, C++, Java, and Python, facilitating the development of powerful software applications.
• Fourth-generation computers support a diverse range of portable and wireless input/output devices.

Q2. Discuss the importance of categorizing and understanding different types of systems, both natural and artificial, and provide examples of each type.

Natural Systems

A natural system is an interconnected collection of elements or components that exist in nature. These systems are typically found in the environment and are characterized by their ability to self-regulate, adapt, and maintain a certain degree of stability.

The following are a few examples of natural systems.

Ecosystems: Ecosystems are perhaps the most common and diverse natural systems. They encompass various types, including:

• Forest Ecosystems: Such as a tropical rainforest with its myriad of plant and animal species.
  • Aquatic Ecosystems: Like freshwater lakes, rivers, and marine ecosystems such as coral reefs.
  • Grassland Ecosystems: Such as the African savanna, is home to grazing animals like zebras and wildebeests.

Weather Systems: Weather systems involve the interactions of the Earth’s atmosphere, including phenomena like rainfall, wind patterns, and temperature changes.

Geological Systems: These systems encompass geological processes and features like: –

• Plate Tectonics: The movement of Earth’s lithospheric plates, leading to phenomena like earthquakes and volcanic eruptions.
• Mountain Systems: Such as the Himalayas, formed by tectonic plate collision.

Hydrological Systems: These systems involve the movement, distribution, and quality of water on Earth, including rivers, lakes, and the water cycle.

Solar System: Our solar system itself is a natural system, with the Sun, planets, moons, asteroids, and comets all interacting under the influence of gravity.

Biological Systems: Biological systems encompass a wide range of living organisms and their interactions:

• Human Body: A complex biological system with organs, tissues, cells, and biochemical processes.
• Coral Reef: An ecosystem built by coral colonies and inhabited by various marine species.
• Rainforest Canopy: The upper layer of rainforest, home to a unique set of plants and animals.

Artificial Systems

Artificial systems, also known as man-made or human-made systems, are created and designed by humans to serve specific purposes, solve problems, or achieve particular goals. Unlike natural systems, which occur organically in the natural world, artificial systems are intentionally constructed by humans to address various needs and objectives. These systems can range from simple devices to highly complex structures, and they exist in numerous domains.

The following are some common examples of artificial systems.

Communication Systems:

• Telephone Networks: Created to facilitate voice communication over long distances.
• Internet and Computer Networks: Built to enable data sharing and digital communication globally.
• Satellite Communication Systems: Developed for long-distance, wireless communication.

Information Systems:

• Databases: Used for storing and retrieving data efficiently.
• Software Applications: Such as word processors, spreadsheets, and video editing software.

Transportation Systems:

• Automobiles: Designed for personal and mass transportation on roads.
• Aircraft: Engineered for air travel, including commercial aeroplanes, helicopters, and drones.
• Trains and Rail Systems: Developed for efficient land transportation on tracks.
• Subways and Mass Transit: Designed to move large numbers of people within urban areas.

Energy Systems:

• Power Plants: Designed to generate electricity using various energy sources like coal, natural gas, nuclear, or renewable resources.
• Renewable Energy Systems: Including solar panels, wind turbines, and hydroelectric plants.
• Electrical Grids: Infrastructure for the distribution of electrical power.

Manufacturing Systems:

• Factory Automation: Systems that automate manufacturing processes, such as robotics and conveyor systems.
• Assembly Lines: Organized systems for mass-produced goods.

Healthcare Systems:

• Hospital Information Systems (HIS): Designed to manage patient records, billing, and other healthcare data.
• Medical Devices: Including MRI machines, X-ray equipment, and artificial organs.

Q3. Explain the characteristics and potential challenges associated with fifth-generation computers that aim to understand natural languages and possess thinking capabilities. What are the implications of such advancements in computing on society?

The following are the characteristics of the fifth generation of 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.
• Fifth-generation computers support advanced parallel processing capabilities, allowing them to execute multiple tasks simultaneously and handle complex computations more efficiently.
• A key aspect of fifth-generation computing is the ability to understand and respond to human languages. This involves developing systems capable of NLP (Natural language processing) and communication.
• These computers are planned to incorporate advanced ES (Expert systems), which are software programs designed to replicate the decision-making abilities of human experts in specific fields, like medicine, mining and engineering.
• In this generation of computers, user interfaces have become more intuitive and user-friendly, incorporating features like Voice recognition and gesture-based controls.

The timeline for the fifth generation is not as precisely defined as the earlier generations, but it is generally associated with ongoing advancements in computing that were expected to emerge in the late 20th century and beyond. The main objective of the fifth generation of computers is to develop devices that can understand natural languages and have thinking power. This is a big challenge for computer developers and programmers to design such systems and software for them.

Q4. 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.

Q5. 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

Hub is a connectivity device used in LAN. It connects multiple LAN devices on one network and makes them act together as a single network. A hub is a non-intelligent device that sends output to all the devices on the network. A hub has multiple input/output (1/0) ports, in which an input in one port results in it being an output in all the other ports, except the port where it was input.

Switch

Switch is a networking device that performs the same job as the hub but is considered as intelligent as the hub. It gathers information about the data packet and forwards it to only the node (e.g. computer) it was intended for. A data packet is a basic unit of communication over a computer network. When data is transmitted, it is broken down into packets which are reassembled to the original form once they reach the destination.

Router

A router is a communication device which is used to connect two or more networks. Today, most of the networks are connected to the Internet. When the computer is sending data to another computer on the Internet, a router receives the data packets, looks for the remote computer address and forwards it to a computer that is closer to the remote computer.

Gateway

A gateway is a device that is used to connect a network to another network that uses different protocols. If we have to link different kinds of networks, such as a network of IBM mainframe computers and a network of PCs, we might have to use a gateway. Gateways change the format of the data packets but not the contents of the message, to make it conform to the application program of the remote computer.

Q6. Discuss the advantages and limitations of different network topologies, including bus, star, ring, and mesh. 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.

Mesh Topology

In mesh topology, each node is directly connected to all the nodes.

Advantages of Mesh Topology

• Most reliable network topology.
• Data can be routed around failed computers or busy ones.
• Can manage high traffic.

Limitations of Mesh Topology

• Most expensive topology to implement.
• Setup and maintenance are difficult.

07. 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.

Q8. Explain the evolution of the Internet from its origins to the modern-day global network. What major technological advancements contributed to its growth?

Evolution of the Internet

The Internet has evolved from its origins in the 1960s as ARPANET, a U.S. Department of Defense project for research institutions and military installations, to become a global network of interconnected computer networks. In the 1970s, the development of TCP/IP protocols established the foundation for the modem Internet, allowing different networks to communicate.

The 1990s saw the emergence of the World Wide Web and web browsers, revolutionizing how people access and share information over the Internet. The 2000s brought broadband Internet and social media platforms, while the 2010s saw the rise of mobile Internet and the Internet of Things (loT). In the 2020s, the Internet continues to evolve with cloud computing, artificial intelligence, and 5G technology, impacting nearly every aspect of modern life.

09. Discuss the advantages and disadvantages of the Internet, considering factors like global connectivity, information access, privacy concerns, and digital addiction.

Advantages of the Internet

• The main advantages of the Internet include:
• Global Connectivity: Enables communication and access to information worldwide.
• Vast Information: Provides vast information resources and knowledge.
• Communication: Facilitates real-time communication and collaboration.
• E-commerce: Allows online shopping and digital transactions.
• Education: Supports online learning and research.
• Business: Enhances productivity and global reach.
• Entertainment: Offers streaming, gaming, and social media.
• Innovation: Promotes technological advancements and research.

Disadvantages of the Internet

• The main disadvantages of the Internet include:
• Privacy Concerns: Threats to personal data and online privacy.
• Cybersecurity Risks: Vulnerability to hacking and cyberattacks.
• Information Overload: Overwhelming amount of data and misinformation.
• Digital Addiction: Excessive screen time and online dependency.
• Digital Divide: Unequal access to the Internet worldwide.
• Online Harassment: Cyberbullying and harassment issues.
• Health Concerns: Physical and mental health impacts.

Q10. Explore common applications of the Internet and their impact on various aspects of society, including communication, education, business, entertainment, and research.

The main applications of the Internet include:

• Communication: Email, messaging, and video calls.
• Information Retrieval: Web browsing, search engines, and online databases.
• E-commerce: Online shopping, banking, and digital payments.
• Social Media: Networking, content sharing, and social interaction.
• Entertainment: Streaming, online gaming, and multimedia content.
• Education: Online courses, research, and e-leaming platforms.
• Business and Work: Remote work, collaboration, and e-commerce.
• Research and Innovation: Access to research materials and innovation platforms.

Select the suitable answer for the following Multiple choice questions.

i. What computing machine was capable of taking input from punch cards and storing data in memory?

a) Abacus                                                            

b) Analytical Engine       

c) Tabulating Machine                                   

d) Differential Analyzer.

ii. What technology replaced vacuum tubes in second-generation computers?

a) Transistors                                                    

b) Integrated Circuits (ICs)

c) Microprocessors                                         

d) Magnetic tapes

iii. Which computer generation introduced the use of Integrated Circuits (ICs)?

a) First Generation                          

b) Second Generation

c) Third Generation

d) Fourth Generation

iv. Which of the following is an example of a natural system?

a) Telephone network

b) Human body

c) Database

d) Automobile

v. Which component of the microprocessor controls the working of input/output devices and storage devices?

a) Arithmetic Logic Unit (ALU)

b) Control Unit (CU)

c) Memory Address Register (MAR)

d) Data Register (DR)

vi. Which type of memory retains data even when the computer is turned off?

a) RAM

b) ROM

c) Cache

d) Register

vii. 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

Select the suitable answer for the following Multiple choice questions.

viii. What is the smallest unit of memory in a digital computer?

a) Kilobyte

b) Bit

c) Byte

d) Megabyte

ix. Which memory type uses laser beams to read and write data?

a) RAM

b) Optical memory

c) Cache memory

d) ROM

x. In Von Neumann’s architecture, where are instruction data and program data stored?

a) In separate memory units

b) In the same memory unit

c) In the processor’s registers

d) In the cache memory

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. 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

xiii. 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

xiv. Which data communication standard is used for transferring web pages and related data on the World Wide Web?

a) TCP/IP

b) HTTP

c) FTP

d) SMTP

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)