O-LevelComputer ScienceData Representation2210/12 · Oct/Nov 2023 · Q210 Marks

A register stores the binary number: 1 1 1 0 0 0 1 1

(a)Give the denary number for the binary number stored in the register.[1]
(b)Give the hexadecimal number for the binary number stored in the register.[2]
(c)A logical left shift of two places is performed on the binary number stored in the register. Complete the binary register to show its contents after this logical left shift.[1]
(d)The negative denary number –99 needs to be stored in the register. Complete the register to show the binary number that would be stored, using two’s complement. Show all your working.[2]
(e)The number 01001100 is added to 11100011 Add the two 8-bit binary numbers, using binary addition. Give your answer in binary. Show all your working.[4]

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2023). The mark or mark type is shown in brackets.

[1] 227
[2] One mark for each correct character in the correct order: // E3
[1] 1 0 0 0 1 1 0 0
[2] One mark for suitable working method e.g. flip and add 1 // One mark for correct answer // 10011101
[4] One mark for each correct nibble (max 2) // One mark for correct working e.g. correct carry // One mark for showing overflow bit // 1 // 1 1 1 0 0 0 1 1 // + 01001100 // 10010 1111

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.