O-LevelComputer ScienceData Representation2210/12 · May/June 2015 · Q106 Marks
Letters from the alphabet are represented in a computer by the following denary (base 10) values: A = 97 G = 103 I = 105 L = 108 N = 110 The word "ALIGN" is stored as: 97 108 105 103 110
- (a)Convert each of the five values to binary. The first one has been done for you. Letter A (97): L (108): I (105): G (103): N (110): Denary value 01100001[2]
- (b)An encryption system works by shifting the binary value for a letter one place to the left. “A” then becomes: 11000010 This binary value is then converted to hexadecimal; the hexadecimal value for “A” will be: C2 For the two letters “L” and “G”, shift the binary values one place to the left and convert these values into hexadecimal: L: G: hexadecimal[4]
Mark scheme
Marking points from the official mark scheme (May/June 2015). The mark or mark type is shown in brackets.
- [2] (a) 1 mark for two correct lines, 2 marks for four correct lines L (108): 01101100 I (105): 01101001 G (103): 01100111 N (110): 01101110
- [4] (b) 1 mark for each correct binary value 1 mark for each correct hexadecimal value L: 11011000 D8 G: 11001110 CE
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