Specimen Marking Scheme - Paper 1 Edexcel Computer Science IGCSE

Paper 1: Principles of Computer Science Question number Answer Additional guidance Mark 1(a) Any one from: • non-English characters can’t be represented • 7/8 bits can’t represent all characters • not enough bits to represent all characters. (1) Question number Answer Additional guidance Mark 1(b) (3) Question number Answer Additional guidance Mark 1(c) 4S 1B 2W Accept S4 B1 W2 (1) Question number Answer Additional guidance Mark 1(d) A 0 1 0 0 1 1 0 1 (1) Question number Answer Additional guidance Mark 1(e) Any one from: • data is permanently removed • original cannot be reconstructed. (1) Question number Answer Additional guidance Mark 2(a) 1 mark for extending the given pattern in the question. 1 mark for the correct number of patterns. 28 × 28 × 28 × 28 × 28 × 28 × 28 × 28 × 28 × 28 × 28 × 28 × 28 × 28 × 28 × 28 1 mark for 216. 1 mark for correct number of patterns. 216 × 216 × 216 × 216 × 216 × 216 × 216 × 216 1 mark for each correct exponent. (28)16 (216)8 2128 (2) Question number Answer Additional guidance Mark 2(b)(i) C 1 1 0 0 0 1 0 0 (1) Question number Answer Additional guidance Mark 2(b)(ii) D 0 1 1 0 1 1 0 0 (1) Question number Answer Additional guidance Mark 2(c) Any one from: • data packets only travel in a single direction from node to node (so there are no packet collisions) • only one machine at a time can use the network (because it uses a token-passing mechanism) (1) Question number Answer Additional guidance Mark 2(d)(i) 1 mark for the correct order (highest to the lowest). 1 Transport 2 Network 3 Data Link (1) Question number Answer Additional guidance Mark 2(d)(ii) Application (1)