The processor and computer architecture — GCSE Computer Science practice questions

Question 1

A music app on a tablet mixes two tracks. To do this, the processor adds the volume values of the two tracks together.

Which part of the processor carries out the addition?

Accepted Answer

B: Arithmetic logic unit (ALU). The arithmetic logic unit (ALU) carries out arithmetic operations, such as addition, and logic operations, such as comparisons. The control unit decodes instructions and sends control signals but does not do the calculations itself. The MDR and PC are registers: they only hold values.

Question 2

A game was written to run on the processor of one handheld console. It cannot run on a different type of processor without being changed, because the two processors have different instruction sets.

What is an instruction set?

Accepted Answer

D: The list of all the machine code commands that the processor can process. An instruction set is the complete list of machine code commands that a particular processor can decode and execute. A program written for one instruction set uses those commands, so a processor with a different instruction set may not be able to run it unchanged.

Question 3

Two laptops are identical except that laptop Y's processor has a larger cache than laptop X's processor.

Which statement explains why laptop Y is likely to run a photo-editing app faster?

Accepted Answer

A: More of the frequently used instructions and data can be kept in fast memory in the processor, so it needs to fetch them from the slower RAM less often.. Cache is a small amount of very fast memory in, or very close to, the processor. It holds frequently used instructions and data, so they can be fetched faster than from RAM. A larger cache holds more of them, so the processor waits for RAM less often. Cache is volatile and does not change the clock speed.