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1

Which register pair works together during memory access — one holding the address and one holding the data?

Hard 3 Marks

One register holds where to look the other holds what is found there.

A PC and IR

B ACC and PC

C MAR and MDR

D IR and ACC

2

A program instruction says: add two numbers and store the result. Which sequence of CPU components is involved?

Hard 3 Marks

Trace the instruction through each CPU component in order.

A CU fetches then IR decodes then MAR executes

B PC provides address CU fetches and decodes ALU adds ACC stores result

C MDR fetches ALU decodes CU executes

D IR fetches MAR decodes MDR executes

3

Which of the following correctly identifies all three main CPU components and their roles?

Hard 3 Marks

Match each component to its specific role — control calculate or store.

A CU performs calculations ALU controls data flow Registers store programs permanently

B CU controls and coordinates ALU performs arithmetic and logic Registers provide fast temporary storage

C CU stores data ALU fetches instructions Registers decode operations

D CU manages secondary storage ALU manages primary memory Registers manage I/O devices

4

If the Program Counter currently holds address 100 and an instruction is fetched what value will the PC most likely hold next?

Hard 3 Marks

The PC must always point to the NEXT instruction — what address comes after 100?

A Still 100

B 99 (decremented by 1)

C 101 (address of the next instruction)

D 0 (reset after each fetch)

5

What is the difference between the CU and the ALU?

Hard 3 Marks

One manages and one calculates — which does which?

A CU performs calculations while ALU controls data flow

B CU controls and coordinates operations while ALU performs arithmetic and logical operations

C Both the CU and ALU perform the same tasks

D CU stores data while ALU stores instructions

Computer Studies