OCR GCE A LEVEL 2022 COMPUTER SCIENCE QUESTION PAPER H446-1 PAPER 1-H446/01 Computer Systems

Answer all questions. 1 A charity uses a desktop computer to record financial donations that it receives. The computer contains a single core, 2.4GHz processor with 2MB cache. (a) The processor uses the Von Neumann architecture. (i) Describe what is meant by the term ‘Von Neumann architecture’. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [2] (ii) Give one way that the Harvard architecture differs from the Von Neumann architecture. ........................................................................................................................................... ...................................................................................................................................... [1] (b) The charity is concerned that the performance of the computer is not sufficient and wishes to replace the processor. Give two features of a replacement processor that would increase the typical performance of the computer. 1 ................................................................................................................................................ ................................................................................................................................................... 2 ................................................................................................................................................ ................................................................................................................................................... [2] 4 © OCR 2022 (c) Fig. 1 shows assembly code written using the Little Man Computer (LMC). The program calculates and outputs the total amount that is donated to the charity in any particular day. Depending on the amount, an additional bonus may be added to each amount donated. start INP STA donation SUB hundred BRP bonus nobonus LDA total ADD donation STA total OUT BRA start bonus LDA total ADD donation ADD twenty STA total OUT BRA start hundred DAT 100 twenty DAT 20 donation DAT 0 total DAT 0 Fig. 1 (i) The program shown in Fig. 1 is run once using three different inputs. Therefore, while the program is running once, it will output the updated total three times. Give the total values that are output when the values 10, 50 and 120 are input into this program. Output for 10 ..................................................................................................................... Output for 50 ..................................................................................................................... Output for 120 ................................................................................................................... [3] 5 © OCR 2022 Turn over (ii) Write LMC code that will reset the value of the memory location labelled total to zero and then stop the program. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [4] (iii) This program is run on a processor that allows pipelining. Define the term ‘pipelining’. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [3] (iv) Explain one benefit to the charity of using a processor that allows pipelining. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [2] 6 © OCR 2022 (d) The processor contains registers including the accumulator and the program counter. The contents of these registers are modified during the Fetch-Decode-Execute cycle. (i) Describe how the accumulator is used during the Fetch-Decode-Execute cycle. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [2] (ii) Describe how the program counter is used during the Fetch-Decode-Execute cycle. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... ...................................................................................................................................... [2] (iii) State the name of three other registers that are used during the Fetch-Decode-Execute cycle. 1 ........................................................................................................................................ ........................................................................................................................................... 2 ........................................................................................................................................ ........................................................................................................................................... 3 ........................................................................................................................................ ........................................................................................................................................... [3] 7 © OCR 2022 Turn over (e)* The charity has several desktop computers in their office that use a CISC processor. They are considering buying mobile devices for their staff to use when they are not in the office. Discuss whether these mobile devices should use the same CISC processors that are used in their desktop computers or if they should use a RISC processor instead. You should include the following in your answer: • the difference between each processor type • the suitability of each processor type for mobile devices. [12] ..............................................................................