Question 1: Describe the main steps involved in the fetch-execute cycle of a computer.

Answer: The fetch-execute cycle involves the CPU fetching an instruction from memory, decoding the instruction, executing the instruction, and then repeating the cycle for the next instruction.

Question 2: Explain the purpose of the program counter (PC) in the fetch-execute cycle.

Answer: The program counter (PC) keeps track of the memory address of the next instruction to be fetched from memory.

Question 3: In the context of the fetch-execute cycle, what is the role of the control unit?

Answer: The control unit directs the operation of the processor by interpreting instructions and coordinating the activities of other components.

Question 4: Identify three components involved in the fetch-execute cycle and briefly describe their function.

Answer: 1. Memory: Stores instructions and data. 2. Program Counter: Holds the address of the next instruction. 3. Arithmetic Logic Unit (ALU): Performs calculations and logical operations.

Question 5: Complete the following truth table for a NAND gate:

Answer: Inputs A and B | Output 0 0 | 1 0 1 | 1 1 0 | 1 1 1 | 0

Question 6: Draw a logic circuit that uses two AND gates and one OR gate to produce an output that is true only when both inputs A and B are true or when input C is true.

Answer: A correct sketch would show two AND gates: one with inputs A and B, producing an output. The second AND gate with input C. Both outputs are fed into an OR gate, which produces the final output.

Question 7: Sketch a diagram of a simple circuit that includes a battery, a switch, and a light bulb in series. Label each component clearly.

Answer: A correct sketch would show a battery connected in series with a switch, which is connected to a light bulb. The circuit completes when the switch is closed, allowing current to flow and the bulb to light.

Question 8: Explain how a NOT gate changes its input to produce an output.

Answer: A NOT gate inverts its input: if the input is 0 (false), the output becomes 1 (true); if the input is 1, the output becomes 0.

Question 9: What does it mean for a logic gate to be 'combinational'? Give an example.

Answer: A combinational logic gate produces an output based solely on the current inputs, without memory. An example is an AND gate.

Question 10: Describe the difference between the fetch phase and the execute phase in the fetch-execute cycle.

Answer: The fetch phase involves retrieving the instruction from memory, while the execute phase involves carrying out the instruction, such as performing a calculation or transferring data.

Question 11: Draw a truth table for an OR gate with two inputs, A and B, and an output labeled 'Output'.

Answer: Inputs A and B | Output 0 0 | 0 0 1 | 1 1 0 | 1 1 1 | 1