error checking and character sets

Question 1

what is a parity bit

Answer 1

an extra bit added to a string of binary code to ensure that the total number of 1-bits in the string is even or odd

Question 2

how to get an even parity

Answer 2

If the data already has an even number of 1-bits, the parity bit is set to 0; if odd, the parity bit is set to 1

Question 3

how to do an odd parity

Answer 3

Ensures the total number of 1-bits in the data is odd. If the data already has an odd number of 1-bits, the parity bit is set to 0; if even, the parity bit is set to 1

Question 4

what would happen if one of the bits get corrupted using parity bit

Answer 4

the computer will change one of the bits, however it doesn’t know exactly which but has been corrupted

Question 5

what is majority voting and wheres it used

Answer 5

an error detection and correction method where each bit of data is sent multiple times (usually three times). The receiver checks each set of bits and uses the value that appears most frequently.

• used in space communication, critical financial transactions

Question 6

What is a check digit and how is it used?

Answer 6

• an additional digit added to a number (such as a barcode or bank account number) that is calculated from the other digits in the number.
• It is used to detect errors in data entry or transmission.

Question 7

Where would check digit be used in?

Answer 7

In applications, where therewill be manual input, which has high likelihood of human error

Question 8

what are checksums

Answer 8

• a mathematical algorithm applied to a block of data

— the data from the block is used in order to create the original checksum which is then added and transmitted along with the original data

— if the checksums match, the data has been transmitted correctly

Question 9

how many combinations of 0s and 1s can a byte hold

Answer 9

256

Question 10

how many bits are in a byte

Answer 10

8

Question 11

what are character sets

Answer 11

a collection of characters used to represent text in a computer system

Question 12

how to fix there not being enough characters

Answer 12

create a character set that is larger than 1 byte/8 bits

Question 13

unicode character sets are at least how long

Answer 13

16 bits long, giving us an increase in combination of 0s and 1s

Question 14

what is the job of the parity bitin odd or even parity

Answer 14

• used to ensure that the total number of 1s in each byte, including the parity bit equals an odd or even number

Question 15

what is overflow

Answer 15

where a carry from the most significant bit requires an additional bit

Question 16

what is an unsigned representation

Answer 16

a binary representation that can only represent positive numbers

Question 17

what is signed representation

Answer 17

can represent both positive and negative numbers

Question 18

why was unicode introduced instead of ascii

Answer 18

• to enable the representation of a greater range of characters
• so that more languages can be represented
• improved portability of documents

Question 19

advantages of using majority voting over parity bit

Answer 19

• majority voting can identify and correct errors due to the majority bits being taken as the correct value
• more effective at detecting errors, as parity bit may miss errors if an even number of bits are corrupted
• can detect multiple errors as each triplet represents one bit of data and can identify tan error on that but

Question 20

explain how the even parity works using the roles of the sending and receiving device

Answer 20

• sender counts the number of 1s in the bit pattern and adds an extra bit to ensure even number of 1s
• receiver counts the number of 1s in the bit pattern received
• if there are an odd number of 1s, it identifies that an error has occurred

Question 21

A data transmission system uses even parity.
Explain how the receiver will perform error detection on a received byte

Answer 21

• If the number of 1s received/in the byte is even, the data is (assumed to have been)
  received correctly
• If the number of 1s received/in the byte is odd, the data has been corrupted / is
  incorrect;

Question 22

what is a byte

Answer 22

a group of 8 bits

Question 23

how many values can be represented with n bits

Answer 23

2^n

Question 24

quantities of bytes (10^n)

Answer 24

• kilo, k - 103
• mega, M - 106
• giga, G - 109
• tera, T - 1012

Question 25

quantities of bytes (2^n)

Answer 25

• kibi, Ki - 2^10
• mebi, Mi - 2^20
• gibi, Gi - 2^30
• tebi, Ti - 2^40

Question 26

What is a character code

Answer 26

a binary representation of a character used by computers to store and manipulate text.

Question 27

What are the advantages and disadvantages of majority voting?

Answer 27

Advantages:

• Can detect and correct errors, making it more reliable than simple error detection methods.
• Effective in environments with high noise like telecommunications
• Ensures high data integrity by using redundancy

DISADVANTAGES:
- Requires multiple transmissions of the same data, increasing bandwidth and storage requirements.

• Latency: Increases latency in data transmission due to the additional data being sent and processed

Question 28

What are the advantages and disadvantages of parity bits?

Answer 28

Advantages:

Simplicity: Easy to implement and understand, requiring minimal additional resources.

Speed: Quick error detection method with minimal processing overhead.

Low Overhead: Adds only a single bit to each data unit, minimally increasing data size.

Disadvantages:

Limited Detection: Can only detect single-bit errors and fails with multiple bit errors.

No Correction: Capable only of error detection, not correction.

False Positives: May not detect some types of errors, leading to potential data integrity issues

Question 29

What are the advantages and disadvantages of check digits?

Answer 29

Advantages:

• Easy to calculate and verify, requiring minimal computational resources.
• Commonly used in applications such as barcodes, ISBNs, and account numbers.

Disadvantages:

• Primarily used for numeric data, not effective for binary or alphanumeric data.
• Can only detect errors, not correct them.
• May not detect all types of errors, especially complex or multiple errors

Question 30

where is parity bit used

Answer 30

Internal computer memory, basic network communication