Assignment Code: CIT-001/ASSIGN/2023-24

Course Code: CIT-001

Assignment Name: Fundamentals of Computer Systems

Year: 2023-2024

Verification Status: Verified by Professor

There are four questions in this assignment, which carry 25 marks. Answer all the questions. You may use illustrations and diagrams to enhance the explanations. Please go through the guidelines regarding assignments given in the CIT Programme Guide. The examples, whenever asked to be given, should be different from those that are discussed in the corresponding course material.

Question 1:

(a) What is a computer system? Explain central processing unit (CPU) of computer system.

Ans) A computer system is a combination of hardware, software, and peripherals that work together to perform various computational tasks. It consists of several key components, including the central processing unit (CPU), memory, input/output devices, storage devices, and communication interfaces. The CPU, often referred to as the "brain" of the computer, is a vital component responsible for executing instructions, performing calculations, and coordinating the activities of other hardware components.

The Central Processing Unit (CPU)

The CPU is the primary component responsible for executing instructions and performing calculations in a computer system. It consists of several key elements:

a) Control Unit (CU): The control unit is responsible for fetching instructions from memory, decoding them, and executing them by coordinating the activities of other CPU components.

b) Arithmetic Logic Unit (ALU): The ALU performs arithmetic and logical operations, such as addition, subtraction, multiplication, division, and comparisons. It performs these operations based on instructions provided by the control unit.

c) Registers: Registers are small, high-speed memory locations within the CPU used to store data temporarily during processing. They include the instruction register (IR), program counter (PC), memory address register (MAR), memory data register (MDR), and general-purpose registers.

d) Cache Memory: Cache memory is a small, high-speed memory located inside or near the CPU. It stores frequently accessed data and instructions to speed up processing by reducing the time required to access information from slower main memory.

e) Clock: The CPU operates based on a clock signal that synchronizes the timing of various operations. The clock signal determines the speed at which the CPU executes instructions, commonly measured in gigahertz (GHz).

(b) What is storage devices? Briefly explain the various types of storage devices.

Ans) Storage devices are hardware components used to store and retrieve digital data in a computer system. They provide non-volatile storage, meaning they retain data even when the power is turned off. Storage devices vary in terms of capacity, speed, and access methods.

a) Primary Storage:

1) Random Access Memory (RAM): Volatile memory used by the CPU to temporarily store data and instructions during program execution.

2) Cache Memory: High-speed memory located near the CPU that stores frequently accessed data and instructions to speed up processing.

b) Secondary Storage:

1) Hard Disk Drives (HDDs): Non-volatile storage devices that use spinning disks coated with magnetic material to store data.

2) Solid State Drives (SSDs): Non-volatile storage devices that use flash memory chips to store data, providing faster access times and improved reliability compared to HDDs.

3) Optical Discs: Non-volatile storage media such as CDs, DVDs, and Blu-ray discs used for storing large amounts of data, multimedia, and software.

Question 2:

(a) What is Software? Explain job of operating system.

Ans) Software refers to a set of instructions or programs that control the operation of a computer system and enable it to perform specific tasks. It includes system software, such as operating systems and device drivers, as well as application software, such as word processors, web browsers, and games.

The operating system (OS) is a fundamental component of a computer system responsible for managing hardware resources, providing a user interface, and facilitating communication between software and hardware components. Its primary functions include:

a) Process Management: Allocating system resources to running processes and scheduling their execution.

b) Memory Management: Managing system memory to optimize usage and ensure efficient allocation of resources.

c) File System Management: Organizing and managing files and directories stored on storage devices.

d) Device Management: Controlling input/output devices, such as keyboards, mice, printers, and storage devices.

e) User Interface: Providing a user-friendly interface for interacting with the computer system, including graphical user interfaces (GUIs) and command-line interfaces (CLIs).

f) Security: Enforcing access controls, authentication, and data protection mechanisms to ensure system integrity and confidentiality.

(b) What is a Flowchart? How to draw Flowchart? Explain with the help of an example.

Ans) A flowchart is a graphical representation of a process or algorithm, depicting the sequence of steps or actions involved in achieving a specific outcome. It uses various symbols and connectors to illustrate the flow of control from one step to another, making complex processes easier to understand and analyse.

To draw a flowchart, follow these steps

a) Identify the process or algorithm you want to represent.

b) Determine the starting point and ending point of the process.

c) Break down the process into individual steps or actions.

d) Choose appropriate flowchart symbols to represent each step, decision point, or action.

e) Use arrows or connectors to indicate the flow of control between steps.

f) Arrange the symbols and connectors in a logical sequence to depict the flow of the process.

Example: Consider a simple flowchart representing the process of making a cup of tea

a) Start: Begin the process.

b) Boil Water: Heat water in a kettle.

c) Add Tea Leaves: Put tea leaves in a teapot.

d) Pour Hot Water: Pour hot water into the teapot.

e) Steep: Allow the tea too steep for a few minutes.

f) Serve: Pour the tea into a cup and serve.

g) End: Finish the process.

(c) Write a C program for finding whether a given number is even or odd.

Ans) This program prompts the user to enter an integer, then checks if the entered number is divisible by 2. If the remainder of the division is 0, the number is even; otherwise, it's odd. Finally, the program prints the result accordingly.

#include <stdio.h>

int main() {

int number;

// Input number from the user

printf("Enter an integer: ");

scanf("%d", &number);

// Check if the number is even or odd

if(number % 2 == 0) {

printf("%d is even.\n", number);

} else {

printf("%d is odd.\n", number);

}

return 0;

}

Question 3:

(a) What is computer network? Write classification of networks with illustration.

Ans) A computer network is a collection of interconnected devices that can share resources and communicate with each other. These devices can include computers, printers, servers, smartphones, and more. They connect through various communication channels, such as cables, Wi-Fi, or cellular networks.

Classifications of Networks

a) By Geographical Scope:

1) Personal Area Network (PAN): Covers a small area, typically connecting personal devices like phones and Bluetooth headsets (10 meters or less).

2) Local Area Network (LAN): Spans a limited area, such as a home, office, or school building (up to 1 kilometer).

3) Campus Area Network (CAN): Connects LANs within a single institution or campus (up to a few kilometers).

4) Metropolitan Area Network (MAN): Covers a city or metropolitan area (up to 50 kilometers).

5) Wide Area Network (WAN): Connects geographically dispersed LANs, spanning large distances (e.g., country, continent).

6) Global Area Network (GAN): The largest type, encompassing the entire internet.

b) By Purpose:

1) Private Network: Owned and managed by a single organization or individual, used internally.

2) Public Network: Accessible by anyone, like the internet.

3) Storage Area Network (SAN): Dedicated for high-speed storage access.

4) System Area Network (SAN): Connects high-performance computing systems within a cluster.

c) By Topology:

1) Bus: All devices connect to a single shared cable.

2) Star: Each device connects to a central hub or switch.

3) Ring: Devices form a closed loop, passing data from one to the next.

4) Mesh: Devices connect directly to multiple neighbours, creating a flexible network.

d) By Technology:

1) Wired: Uses physical cables (Ethernet, fibre optic) for data transmission.

2) Wireless: Uses radio waves or other wireless technologies (Wi-Fi, Bluetooth).

e) By Security:

1) Open Network: No access control or encryption.

2) Closed Network: Secured with authentication and encryption to restrict access.

(b) Explain following network devices:

i. Bridge

Ans) A bridge is a network device that connects two or more network segments, operating at the data link layer (Layer 2) of the OSI model. It does this by selectively forwarding traffic across segments depending on MAC addresses, essentially separating a vast network into smaller collision domains. This results in a reduction in network congestion and an improvement in performance. It is common practise in Ethernet networks to make use of bridges in order to increase the reach of a local area network (LAN) or to segment a network in order to improve its security and manageability.

ii. Repeater

Ans) A repeater is a vital network device that plays a crucial role in extending the reach of a network by amplifying signals and retransmitting them between different network segments. Operating at the physical layer (Layer 1) of the OSI model, repeaters regenerate incoming signals to compensate for signal degradation and attenuation that occur over long cable runs. By boosting the signal strength, repeaters enable data to travel farther distances without losing integrity, thereby ensuring reliable communication between network devices.

In Ethernet and other wired networks, repeaters are commonly deployed to overcome limitations in cable length and extend the coverage area of the network. They are particularly useful in environments where devices are spread out over considerable distances or where the existing infrastructure requires signal reinforcement to maintain data transmission quality. Without repeaters, network signals may become too weak or distorted to effectively reach their intended destinations, leading to communication failures and degraded network performance.

ii. Switch

Ans) A switch is a critical networking device that plays a fundamental role in connecting multiple devices within a Local Area Network (LAN) and facilitating efficient communication among them. By operating at the data link layer (Layer 2) of the OSI model, switches utilize MAC addresses to forward data packets directly to their intended destinations. Unlike hubs, which broadcast data to all devices on the network, switches create dedicated communication channels between devices, thereby reducing network congestion and improving bandwidth utilization.

Switches offer numerous advantages over hubs, including higher performance, enhanced security, and increased scalability. They can intelligently manage network traffic, prioritize data transmission, and segment the network into smaller collision domains, improving overall network efficiency. Additionally, switches support features such as VLANs (Virtual Local Area Networks) and port-based security measures, providing greater control and security over network resources. Due to their superior performance and functionality, switches have become indispensable components of modern Ethernet networks, supporting the seamless operation of various applications and services.

iv. Router

Ans) A router serves as a critical networking device that acts as a gateway between multiple networks, allowing them to communicate with each other efficiently. Operating at the network layer (Layer 3) of the OSI model, routers use IP addresses to route data packets between source and destination networks. They employ routing algorithms to determine the most optimal path for data transmission, considering factors such as network congestion, latency, and reliability. Additionally, routers maintain routing tables containing information about network topology, including available routes and associated metrics.

Routers perform essential functions such as packet forwarding, where they inspect incoming packets, determine their destination based on IP addresses, and forward them to the appropriate network interface. They also manage network traffic by prioritizing packets, implementing Quality of Service (QoS) policies, and enforcing access control lists (ACLs) for security purposes. Moreover, routers facilitate internet connectivity by performing Network Address Translation (NAT), allowing multiple devices within a network to share a single public IP address. Overall, routers play a crucial role in enabling communication between devices on different networks and facilitating internet connectivity for users worldwide.

c) What is network topology? Explain star and mesh topology with the help of suitable diagrams.

Ans) Network topology refers to the arrangement or layout of nodes and links in a computer network. The manner in which devices are connected to one another and the manner in which communication pathways are organised within the network are both defined by it.

a) Star Topology: In a star topology, each device is connected directly to a central hub or switch. All communication between devices passes through the central hub, which manages and controls the flow of data. This topology is easy to install, offers centralized management, and provides fault tolerance as a single link failure does not affect the entire network. However, it is dependent on the central hub, and if it fails, the entire network may be disrupted.

b) Mesh Topology: In a mesh topology, every device is connected to every other device in the network, creating multiple communication paths. This redundancy ensures reliability and fault tolerance, as data can be rerouted through alternative paths if one link fails. However, mesh topologies require a significant amount of cabling and are more complex to manage and configure compared to other topologies.

Question 4:

a) Explain use of Firewall and Packet Filtering.

Ans) Firewalls are essential network security devices designed to monitor and control incoming and outgoing network traffic based on predetermined security rules. They act as a barrier between an internal network and external networks, such as the internet, to prevent unauthorized access and protect against various cyber threats.

Packet filtering is a key function of firewalls, where individual data packets are inspected and either allowed or blocked based on predefined criteria. This criteria can include source and destination IP addresses, port numbers, protocols, and specific keywords or patterns within the packet content. By analyzing packet headers and content, firewalls can enforce security policies to block malicious traffic, unauthorized access attempts, and other potential threats, while allowing legitimate traffic to pass through.

Overall, firewalls and packet filtering play a crucial role in safeguarding network infrastructure, preventing unauthorized access, and maintaining network security and integrity.

(b) What is need of Network Security? Explain Integrity, Confidentiality and Availability in relation to Information Security.

Ans) Network security is essential to protect data and resources from unauthorized access, manipulation, and disruption. It ensures the confidentiality, integrity, and availability of information within a network, safeguarding against various threats such as unauthorized access, data breaches, malware attacks, and network outages.

a) Integrity: Integrity ensures that data remains unchanged and unaltered during storage, transmission, and processing. Network security measures such as encryption, digital signatures, and access controls help maintain data integrity by preventing unauthorized modifications or tampering.

b) Confidentiality: Confidentiality ensures that sensitive information is only accessible to authorized individuals or entities. Encryption, access controls, and secure communication protocols such as Virtual Private Networks (VPNs) are employed to protect data from unauthorized disclosure or interception.

c) Availability: Availability ensures that data and resources are accessible to authorized users when needed. Network security measures such as redundancy, load balancing, and Denial-of-Service (DoS) protection mechanisms help ensure uninterrupted access to network services, minimizing downtime and disruptions.