ADVANCES IN MATHEMATICAL ,PHYSICAL AND CHEMICAL SCIENCES

B.sc computers-2

1.    What is Number System? Explain various types of Number System?

Number system refers to a set of symbols and rules used to represent and manipulate numbers. In computers, numbers are represented using different number systems, such as binary, octal, and hexadecimal.

a.   Binary Number System:

●        The binary number system uses only two symbols, 0 and 1.

●        It is the most fundamental number system used in computers because it directly corresponds to the on and off states of electronic switches.

●        Each digit in a binary number is called a bit (short for binary digit), and a group of 8 bits is called a byte.

●        Binary numbers are often used in computer hardware, programming, and digital communication systems.

b.   Octal Number System:

●        The octal number system uses eight symbols, 0 to 7. Each digit in an octal number represents a power of 8.

●        Octal numbers are commonly used in computer programming, particularly when dealing with permissions or file systems.

●        Octal numbers are shorter than binary numbers and provide a convenient representation for grouping bits.

c.   Hexadecimal Number System:

●        The hexadecimal number system uses sixteen symbols, 0 to 9 and A to F, where A represents 10, B represents 11, and so on, up to F representing 15.

●        Each digit in a hexadecimal number represents a power of 16. Hexadecimal numbers are often used in computer programming, especially when dealing with memory addresses, colors, and binary data.

●        Hexadecimal numbers provide a more compact representation compared to binary or octal numbers.

Applications of Number Systems in Computers:

-   Binary numbers are used in computer hardware to represent digital signals and perform logical operations.

-   Octal numbers are used in file systems to represent permissions and file attributes.

-   Hexadecimal numbers are used in programming to represent memory addresses, machine code instructions, and data structures.

-   All number systems are used in data representation, data storage, and data manipulation in computer systems.

-   Converting between number systems is essential for understanding and troubleshooting computer systems.

-   Number systems are also used in cryptography, error detection and correction, and other areas of computer science.

 Decimal to Binary Conversion:

Sample Problem: Convert the decimal number 85 to binary.

Steps:

1.      Start with the decimal number.

2.      Divide the number by 2.

3.      Write down the remainder (0 or 1).

4.      Continue dividing the quotient from the previous step by 2 until the quotient becomes 0.

5.      Write down the remainders in reverse order to get the binary equivalent.

Solution:

- 85 divided by 2 is 42 with a remainder of 1.

-   42 divided by 2 is 21 with a remainder of 0.

-   21 divided by 2 is 10 with a remainder of 1.

-   10 divided by 2 is 5 with a remainder of 0.

-   5 divided by 2 is 2 with a remainder of 1.

-   2 divided by 2 is 1 with a remainder of 0.

-   1 divided by 2 is 0 with a remainder of 1.

Writing the remainders in reverse order: 1010101. So, the binary equivalent of decimal 85 is 1010101.

Decimal to Hexadecimal Conversion:

Sample Problem: Convert the decimal number 189 to hexadecimal.

Steps:

1.      Start with the decimal number.

2.      Divide the number by 16.

3.      Write down the remainder (0 to 15), replacing 10 with 'A', 11 with 'B', and so on.

4.      Continue dividing the quotient from the previous step by 16 until the quotient becomes 0.

5.      Write down the remainders in reverse order to get the hexadecimal equivalent.

Solution:

- 189 divided by 16 is 11 with a remainder of 13 (which is 'D' in hexadecimal).

- 11 divided by 16 is 0 with a remainder of 11 (which is 'B' in hexadecimal).

The remainders in reverse order are BD.

 

Binary to Decimal Conversion:

Sample Problem: Convert the binary number 110110 to decimal.

Steps:

1.      Start with the binary number.

2.      Write down the binary digits.

3.      Assign each binary digit a positional value: 2^0, 2^1, 2^2, and so on, from right to left.

4.      Multiply each binary digit by its corresponding positional value.

5.      Sum up the results to get the decimal equivalent.

Solution:

- Binary: 110110

- 0 * 2^0 = 0

- 1 * 2^1 = 2

- 1 * 2^2 = 4

- 0 * 2^3 = 0

- 1 * 2^4 = 16

- 1 * 2^5 = 32

Adding these values together: 0 + 2 + 4 + 0 + 16 + 32 = 54. So, the decimal equivalent of the binary number 110110 is 54. Hexadecimal to Binary Conversion:

Sample Problem: Convert the hexadecimal number 1A3 to binary.

Steps:

1.      Start with the hexadecimal number.

2.      Write down the hexadecimal digits.

3.      Convert each hexadecimal digit to its 4-bit binary equivalent.

4.      Concatenate the binary equivalents of the hexadecimal digits to get the binary representation.

Solution:

- Hexadecimal: 1A3

-   1 in hexadecimal is 0001 in binary.

-   A in hexadecimal is 1010 in binary.

-   3 in hexadecimal is 0011 in binary.

Concatenating these binary values: 000110100011.

So, the binary equivalent of the hexadecimal number 1A3 is 000110100011.

72.   Explain about Error detection and correction

Error detection and correction are techniques used in data communication and storage to ensure data integrity and reliability.

These methods help detect and, in some cases, correct errors that may occur during data transmission or storage, thereby improving the overall quality and accuracy of the data.

Error Detection:

Error detection is the process of identifying errors in transmitted or stored data. When data is transmitted over a communication channel or stored in a medium (such as a hard disk or memory), it is susceptible to errors due to noise, interference, or other factors. Error detection methods involve adding extra bits to the original data, known as redundancy, to enable the receiver to identify if any errors have occurred.

Common error detection techniques include:

1.    Parity Check: Parity check is a simple error detection technique used to ensure data integrity in digital systems. It involves adding an extra bit, called the parity bit, to a group of data bits. The parity bit is chosen in such a way that the total number of bits with a value of 1 (or 0, depending on the type of parity used) in the data, including the parity bit, is either even or odd.

●    Even Parity: The parity bit is set to make the total number of 1s (including the parity bit) even. If the data has an odd number of 1s, the parity bit is set to 1, making the total even.

●        Odd Parity: The parity bit is set to make the total number of 1s (including the parity bit) odd. If the data has an even number of 1s, the parity bit is set to 1, making the total odd.

During data transmission, the sender calculates the parity bit and includes it with the data. The receiver recalculates the parity bit based on the received data and checks if it matches the received parity bit. If they match, it indicates that no error has occurred during transmission. However, if they don't match, an error is detected.

Parity check can detect single-bit errors, where only one bit in the data has changed. However, it cannot correct errors or detect multiple errors.

 

2.    Cyclic Redundancy Check (CRC): CRC is a more sophisticated error detection technique commonly used in data communication and storage. It involves generating a checksum or code from the

data using polynomial division. The resulting code is appended to the data before transmission.

The receiver also performs the same polynomial division on the received data (including the code) and compares the calculated code with the received code. If they match, it indicates that no errors have occurred during transmission. However, if they don't match, an error is detected.

CRC provides a higher level of error detection capability compared to simple parity check. It can detect a wider range of errors, including burst errors where multiple consecutive bits are corrupted. While CRC can detect errors, it doesn't correct them. Instead, it relies on retransmission or higher-level error correction techniques to recover from errors.

CRC is widely used in network protocols, storage systems, and other applications where data integrity is critical.

Error Correction:

Error correction goes beyond error detection by not only identifying errors but also attempting to correct them automatically. This is especially useful in scenarios where data integrity is crucial, such as in critical communication systems or storage devices.

Common error correction techniques include:

-   Forward Error Correction (FEC): FEC adds redundant data to the original data, which allows the receiver to correct errors without the need for retransmission. It provides a level of resilience to errors and can recover from a certain number of errors, depending on the coding scheme used.

-   Automatic Repeat Request (ARQ): ARQ is a feedback-based error correction method. The receiver detects errors and requests the sender to retransmit the corrupted data. The process continues until the data is received correctly, or a predefined number of retransmissions is reached.

73.   What is a Networking Device? List out the Networking Devices .

A networking device is any hardware or software component used to facilitate communication and data exchange between devices in a computer network. These devices help manage, control, and direct data traffic, enabling efficient and reliable data transmission between connected devices.

1.   Repeater:

A repeater is a simple networking device used to amplify and regenerate signals in a network. It operates at the physical layer of the OSI model and is primarily used to extend the reach of a network by boosting the signal strength of data transmissions. When data travels over long distances, it may suffer from signal degradation, resulting in data loss or errors. Repeaters receive weak signals, amplify them, and retransmit them to extend the network's coverage.

2.   Hub:

A hub is a basic networking device that operates at the physical layer of the OSI model. It serves as a central connection point for multiple devices in a network. When a device sends data to a hub, the hub broadcasts the data to all connected devices. As a result, all devices connected to the hub receive the data, even if it is intended for a specific device. Hubs are considered legacy devices and are less common in modern networks due to their limitations in handling network congestion and inefficient use of bandwidth.

 

3.   Bridge:

A bridge is a networking device that operates at the data link layer of the OSI model (Layer 2). It connects two or more network segments and uses their MAC (Media Access Control) addresses to selectively forward data between them. Unlike hubs, bridges filter and forward data only to the segment where the intended destination device is located, reducing unnecessary data transmission and minimizing network collisions. Bridges are used to break up large collision domains and segment network traffic, which improves network performance and efficiency.

4.   Switch:

A switch is an advanced networking device that operates at the data link layer (Layer 2) or the network layer (Layer 3) of the OSI model. It is more intelligent than hubs and bridges and has the capability to learn the MAC addresses of connected devices. Switches use this information to create a MAC address table, enabling them to forward data directly to the appropriate destination device without broadcasting to all connected devices. This process is known as packet switching, which reduces unnecessary data transmission and collisions. Switches are the most common devices used in modern wired Ethernet networks.

5.   Router:

A router is a networking device that operates at the network layer (Layer 3) of the OSI model. It is used to connect multiple networks together and make decisions about how to route data packets between them based on IP addresses. Routers maintain routing tables to determine the best path for data to reach its destination across interconnected networks. They are essential in connecting different networks, such as the internet, and play a vital role in directing data traffic efficiently between networks.

6.   Gateway:

A gateway is a device or software component that connects networks with different communication protocols or architectures. It serves as an intermediary between different networks to facilitate data exchange.

Gateways can perform protocol translation, data format conversion, and other necessary tasks to ensure seamless communication between otherwise incompatible networks

4. What are signals in Computers?Explain in brief about

Analog and digital signals.

An electrical or electromagnetic quantity (current, voltage, radio wave, micro wave, etc.) that carries data or information from one system (or network) to another is called a signal.

Here are some key points about signals and their usage in computers:

1.   Communication: Signals are used for communication between different components of a computer system

2.   Data Processing: Signals are used to represent and process data in computers. In digital systems, data is represented using binary signals, where each bit (0 or 1) represents a specific state

3.   Control: Signals are used for controlling the operation of various hardware components in a computer system.

4.   Input and Output: Signals are used to interface with input and output devices in computers. For example, when you press a key on a keyboard, it generates an electrical signal that is sent to the computer, indicating the specific key pressed

There are two major types of signals used in a computer they are:

a)    Analog Signals

A signal which is a continuous function of time and used to carry the information is known as an analog signal. An analog

signal represents a quantity analogous to another quantity, for example, in case of an analog audio signal, the instantaneous value of signal voltage represents the pressure of the sound wave.

Analog signals utilize the properties of medium to convey the information. All the natural signals are the examples of analog signals. However, the analog signals are more susceptible to the electronic noise and distortion which can degrade the quality of the signal.

b)   Digital Signal

A signal that is discrete function of time, i.e. which is not a continuous signal, is known as a digital signal. The digital signals are represented in the binary form and consist of different values of voltage at discrete instants of time.

Basically, a digital signal represents the data and information as a sequence of separate values at any given time. The digital signal can only take on one of a finite number of values.

Difference between Analog and Digital Signal

Analog Signal	Digital Signal
A signal for conveying information which is a continuous function of time is known as analog signal.	A signal which is a discrete function of time, i.e. non-continuous signal, is known as digital signal.
An analog signal is typically represented by a sine wave function.	The typical representation of a signal is given by a square wave function.
Analog signals use a continuous range of values to represent the data and information.	Digital signals use discrete values (or discontinuous values), i.e. discrete 0 and 1, to represent the data and information.
The bandwidth of an analog signal is low.	The bandwidth of a digital signal is relatively high.
The analog signals are more suitable for transmission of audio, video and other information through the communication channels.	The digital signals are suitable for computing and digital electronic operations such as data storage, etc.
Analog signals get affected by the electronic noise easily.	The digital signals are more stable and less susceptible to noise than the analog signals.
Analog signals use more power for data transmission.	Digital signals use less power than analog signals for conveying the same amount of information.
The analog signals give observational errors.	The digital signals do not given observational errors.
The common examples of analog signals are temperature, current, voltage, voice, pressure, speed, etc.	The common example of digital signal is the data store in a computer memory.

Explain briefly about Transmission data.

• Transmission media is a communication channel that carries the information from the sender to the receiver. Data is transmitted through the electromagnetic signals.
• The main functionality of the transmission media is to carry the information in the form of bits through LAN(Local Area Network).
• It is a physical path between transmitter and receiver in data communication.
• In a copper-based network, the bits in the form of electrical signals.
• In a fibre based network, the bits in the form of light pulses.
• In OSI(Open System Interconnection) phase, transmission media supports the Layer 1. Therefore, it is considered to be as a Layer 1 component.
• The electrical signals can be sent through the copper wire, fibre optics, atmosphere, water, and vacuum.
• The characteristics and quality of data transmission are determined by the characteristics of medium and signal.
• Transmission media is of two types are wired media and wireless media. In wired media, medium characteristics are more important whereas, in wireless media, signal characteristics are more important.
• Different transmission media have different properties such as bandwidth, delay, cost and ease of installation and maintenance.
• The transmission media is available in the lowest layer of the OSI reference model, i.e., Physical layer.

Causes Of Transmission Impairment:

• Attenuation: Attenuation means the loss of energy, i.e., the strength of the signal decreases with increasing the distance which causes the loss of energy.
• Distortion: Distortion occurs when there is a change in the shape of the signal. This type of distortion is examined from different signals having different frequencies. Each frequency component has its own propagation speed, so they reach at a different time which leads to the delay distortion.
• Noise: When data is travelled over a transmission medium, some unwanted signal is added to it which creates the noise.

There are primarily two types of transmission media:

1.   Guided Transmission Media (Wired):

Guided transmission media use physical conductors to transmit signals and data. The signals are confined within the physical medium, which provides a defined path for data transmission. Some common types of guided transmission media include:

-   Twisted Pair Cable: Consists of two insulated copper wires twisted together, commonly used for Ethernet networks and telephone lines.

-   Coaxial Cable: Contains a central copper conductor surrounded by an insulating layer, shield, and outer jacket. Coaxial cables were widely used in traditional cable TV networks and Ethernet connections.

-   Optical Fiber: Uses thin strands of glass or plastic to transmit data as pulses of light. Optical fiber offers high data transfer rates, low signal loss, and immunity to electromagnetic interference.

2.   Unguided Transmission Media (Wireless):

Unguided transmission media utilize the air or free space as the medium for transmitting signals. In wireless communication, data is propagated through the atmosphere in the form of electromagnetic waves. Common types of unguided transmission media include:

-   Radio Waves: Used in wireless communication technologies such as Wi-Fi, Bluetooth, and radio broadcasting.

-   Microwaves: Higher-frequency radio waves employed in microwave communication for point-to-point connections and satellite communication.

-   Infrared Waves: Used in short-range wireless communication, such as infrared data transfer between devices like remote controls and IrDA (Infrared Data Association) connections.

 

Each type of transmission medium has its advantages and limitations. Wired media generally provide higher data rates and more reliable connections but are limited by physical constraints and require proper installation. Wireless media offer mobility and flexibility but can be affected by interference and have limitations in terms of range and data rates.