O-LevelComputer ScienceData Representation2210/12 · Oct/Nov 2024 · Q313 Marks

A user enters data that is hexadecimal into a computer system. The data is converted to binary to be processed by the computer.

(a)(i)Give one similarity between hexadecimal and binary.[1]
(a)(ii)Give two differences between hexadecimal and binary. 1 2[2]
(b)Data that is denary can also be converted to binary. Give the binary number for each of the three denary numbers. 15 180 235 Working space[3]
(c)Denary numbers can also be converted to hexadecimal. Give the hexadecimal number for each of the three denary numbers. 14 100 250 Working space[3]
(d)(i)A binary integer that is stored in a register in the computer has a logical left shift performed on it. Describe the process of the logical left shift that is performed on the binary integer.[2]
(d)(ii)State what effect this will have on the binary integer.[1]
(e)A negative binary integer needs to be stored in a register in the computer. Give the name of the number system that can be used to represent negative binary integers.[1]

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2024). The mark or mark type is shown in brackets.

[1] 3(a)(i) They are both number systems
[2] 3(a)(ii) • Binary is base-2 whereas hexadecimal is base-16 • Binary only uses numbers whereas hexadecimal also uses letters // Binary only uses 0 and 1 whereas hexadecimal uses 0 to 9/A to F
[3] 3(b) • (0000)1111 • 10110100 • 11101011
[3] 3(c) • E • 64 • FA
[2] 3(d)(i) Any two from: • Each/All/Every value/digit/bit in the binary number is shifted/moved to the left • The left most/most significant bit is lost • A 0 is added as the right most/least significant bit
[1] 3(d)(ii) The binary integer is multiplied by 2
[1] 3(e) Two's complement

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