2.2 · Lesson 1 of 5
Errors and parity checks
Syllabus 2.2.1Syllabus 2.2.2
What this lesson covers
- Explain how errors occur during transmission
- Describe parity checks (odd and even, byte and block)
Key vocabulary
- Data collision
- When two devices send at the same time and the data is corrupted.
- Transmission error
- When data doesn't arrive exactly as it was sent: bits are flipped, lost or gained.
- Interference
- Other electrical signals that disturb data as it travels and can cause errors.
- Flipped bit
- A bit that has changed during transmission, from 1 to 0 or from 0 to 1.
- Parity bit
- An extra bit added to a byte so the number of 1s is odd or even, as agreed.
- Odd parity
- Each byte, including its parity bit, must contain an odd number of 1s.
- Even parity
- Each byte, including its parity bit, must contain an even number of 1s.
- Parity check
- The receiver counts the 1s in each byte to check they match the agreed parity.
- Parity block
- A table of bytes with a parity bit for each row and each column, so the flipped bit can be found.
Check your learning
- Quick check: 4 questions
- Key vocabulary test: 9 terms
- Activity 1: Parity bits · 8 questions
- Activity 2: Find the error · 4 parity blocks
- Activity 3: Errors and parity quiz · 8 questions