OCR A Level Computer Science H446/01 Computer Systems JUNE 2022

A Level Computer Science H446/01 Computer Systems JUNE 2022 Time allowed: 2 hours 30 minutes INSTRUCTIONS • Use black ink. You can use an HB pencil, ...

A Level Computer Science H446/01 Computer Systems JUNE 2022 Time allowed: 2 hours 30 minutes INSTRUCTIONS • Use black ink. You can use an HB pencil, but only for graphs and diagrams. • Write your answer to each question in the space provided. If you need extra space use the lined pages at the end of this booklet. The question numbers must be clearly shown. • Answer all the questions. INFORMATION • The total mark for this paper is 140. • The marks for each question are shown in brackets [ ]. • Quality of extended response will be assessed in questions marked with an asterisk (*). • This document has 32 pages. ADVICE • Read each question carefully before you start your answer. OCR is an exempt Charity Turn over 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] (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] (ii) Write LMC code that will reset the value of the memory location labelled total to zero and then stop the program.