Binary and Number Bases

Computer Science Data rep

Give four Reasons Hexadecimal is used.

• Easier to read and remember than a string of binary digits

• Quicker to write / type for humans

• Less chance of human error than Binary (as binary is just 1’s and 0’)

• Takes up less space on a page than binary

How many values can be stored in 8 bits?

128 (2^8)

What’s the largest number that can be stored in 8 bits?

127 (2^8 - 1)

How many bits in a byte?

8

How many bytes in one mebibyte (as a power of 2)?

2^20

What does ASCII stand for?

American Standard Code for Information Interchange

How many bits does ASCII use?

8

How many bits does Unicode use?

16

Name Four Types of Error Detection

• Parity Bits

• Checksums

• Majority Voting

• Check Digits

Describe how parity bits work

Parity bits are used in error detection by adding an extra bit to a binary string to ensure the total number of 1s is even (even parity) or odd (odd parity). This allows the detection of single-bit errors during data transmission.

What might cause an error to slip through parity bits?

If multiple Bits were to flip

Give four examples of what might cause a transmission error

• Electrical Interference

• Power Surges

• Synchronization Issues

• Worn Cables / Connectors

How does majority voting work?

Each bit is sent 3 times and whatever number (1 or 0) is more common, is assumed to be correct.

What is a drawback of majority voting?

It takes much longer to send the signal since each bit has to be sent 3 times.

How does a check digit work?

An extra digit is placed at the end of a datum to check for mistakes in a transmission. This digit can be calculated using an algorithm on the other bits in the datum

How does a checksum work?

The sum of the digits in the datum is sent to be compared with the datum.

What is a drawback of checksums?

Certain errors may cause the same sum to be generated