O-LevelComputer ScienceData Representation2210/12 · Oct/Nov 2021 · Q19 Marks
Denary is a number system that is used by programmers. Tick (✔) one box to show whether denary is a base-2, base-10 or base-16 number system. Tick (✔) Base-2 Base-10 Base-16
- (a)Denary is a number system that is used by programmers. Tick (✔) one box to show whether denary is a base-2, base-10 or base-16 number system. Tick (✔) Base-2 Base-10 Base-16[1]
- (b)Hexadecimal values can be used to represent denary values. Convert these four hexadecimal values into denary values. 05 20 1A AB Working space[4]
- (c)(i)Hexadecimal values can also be converted to binary values. Tick (✔) one box to show the correct 8-bit binary value for each hexadecimal value. (i) Hexadecimal value 25 Tick (✔) 00011001 00100101 10100001[1]
- (c)(ii)(ii) Hexadecimal value 1B Tick (✔) 00011011 10110001 00011010[1]
- (d)(i)(d) (i) Give one way that hexadecimal is used in website development.[1]
- (d)(ii)(ii) Give one way that hexadecimal is used in low-level programming.[1]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2021). The mark or mark type is shown in brackets.
- 1(a) - Base-10
- 1(b) - 5
- 1(b) - 32
- 1(b) - 26
- 1(b) - 171
- 1(c)(i) - 00100101
- 1(c)(ii) - 00011011
- 1(d)(i) Any one from: - To represent HTML colour codes; - In error messages
- 1(d)(ii) Any one from: - Assembly code/language; - Memory address locations; - In error messages; - Memory dump
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