Question

Explain the following:

Machine Cycle

Answer 1

A machine cycle is the time required by the CPU to complete one basic operation.

• A machine cycle consists of one or more T–states (clock cycles).
• It represents a single step in executing an instruction.
• Different operations like fetching, reading, or writing are performed in separate machine cycles.

Sequence:

T–states → Machine Cycle → Instruction Cycle

An instruction like ADD may consist of:

• M1 (Opcode Fetch) → 4 T–states
• M2 (Memory Read) → 3 T–states
• M3 (Execution) → 2 T–states