Advanced level 2026 Holy Infant High School mock Computer science 2

I have extracted the data from your latest uploaded image, which focuses on Computer Architecture (specifically the Von Neumann model), floating-point binary representation, and System Analysis.

---

COMPUTER SCIENCE EXAMINATION SECTION

1) (i) Figure 1 shows some of the internal components of a processor and how the processor is connected to the main memory.

(Image description: A diagram of a Processor containing PC, MAR, CIR, MBR, and General Purpose Registers, connected via buses to a Main Memory table with addresses 0-7.)

• a) Describe how an instruction is fetched from main memory during the fetch stage of the fetch-execute cycle. Your description should cover the use of registers and buses, together with the role of main memory. (4 marks)

• b) During the decode and execute stages of the fetch-execute cycle the instruction that is being processed is stored in the CIR. Explain why the instruction could not be processed directly from the MBR. (3 marks)

• c) The computer system shown in Figure 1 uses the von Neumann architecture. The Harvard architecture is an alternative to this. Explain why the Harvard architecture is sometimes used in preference to the von Neumann architecture. (2 marks)

(ii) The following 16-bit binary pattern represents a floating-point number stored in two’s complement form. The twelve most significant bits are used for the mantissa and the four least significant bits are used for the exponent.

0	1	1	1	0	0	0	0	0	0	0	0	1	1	0	1

• a) Identify the binary value of the exponent. (1 mark)

• b) Identify the binary value of the mantissa. (1 mark)

• c) State whether the number stored is positive or negative. Justify your choice. (2 marks)

• d) Convert the binary floating-point number into denary. Show your working. (3 marks)

• e) The number of bits used for the exponent is increased to eight, and the number of bits used for the mantissa is decreased to eight. State the effects of this change. (2 marks)

---

2) (i) A local railway company is considering introducing a new system for its passengers using e-tickets on a smart phone. Before introducing this new system, analysis of the current system is required.

• a) Describe the steps that would be carried out in the analysis of the current system. (5 marks)

• The e-ticket will link to a database containing personal data.

• b) Give two examples of personal data that could be stored. (2 marks)

• c) Details of each of the passengers have been entered into the database. Give one reason why this data was verified on entry. (1 mark)

• d) Tick whether the following is a method of validation, verification or proof-reading. (4 marks)

---

Would you like the marking scheme for the fetch-execute cycle or help with the binary-to-denary conversion for the floating-point question?