O-LevelComputer ScienceData Transmission2210/12 · Oct/Nov 2020 · Q29 Marks
Four 7-bit binary values are transmitted from one computer to another. A parity bit was added to each binary value creating 8-bit binary values. All the binary values have been transmitted correctly.
- (a)Tick (✔) to show whether an Even or an Odd parity check has been used for each binary value. 8-bit binary value Even (√) Odd (√) 11111111 01100110 01111011 10000000[4]
- (b)The data will also be checked using a checksum. Describe how a checksum can be used to check that the data has been transmitted correctly.[5]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2020). The mark or mark type is shown in brackets.
- [1] One mark for each correct row:
- [1] 11111111 -> Odd (✔)
- [1] 01100110 -> Even (✔)
- [1] 01111011 -> Odd (✔)
- [1] 10000000 -> Even (✔)
- [5] Any five from: A value is calculated from the data; The value is calculated using an algorithm // by example; The value is appended to the data to be transmitted; Value is recalculated after transmission; Values are compared; If the values match the data is correct // if the values do not match the data is incorrect
Write your answer and get it marked
On Oracle Prep you can write or photograph your own answer and have it marked by AI against this mark scheme, with feedback on what you missed.
Sign up free →