ISCET Digital Systems & Microprocessors 2

Question 1

In a microprocessor system, what is the function of the program counter (PC)?

Accepted Answer

Holds the memory address of the next instruction to be fetched

Answer

The program counter holds the address of the next instruction to be fetched from memory, automatically incrementing after each fetch.

Question 2

Which addressing mode uses the instruction itself to contain the data value rather than an address?

Accepted Answer

Immediate addressing

Answer

Immediate addressing embeds the actual data value directly within the instruction, eliminating the need for a separate memory access.

Question 3

What logic function does a half adder implement?

Accepted Answer

Adds two bits and produces a sum and carry-out

Answer

A half adder takes two single-bit inputs and outputs a sum (XOR) and carry-out (AND), but cannot handle a carry-in.

Question 4

In a microprocessor, what is a 'bus cycle'?

Accepted Answer

The time to complete one read or write transaction on the system bus

Answer

A bus cycle is the sequence of events required to complete a single data transfer (read or write) between the CPU and memory or I/O.

Question 5

Which flip-flop type changes output state only on the active clock edge when both J and K inputs are HIGH?

Accepted Answer

JK flip-flop

Answer

The JK flip-flop toggles its output when both J=1 and K=1 on the active clock edge, resolving the forbidden state of the SR flip-flop.

(ISCET) International Society of Certified Electronics Technicians Practice Test