List and briefly define the possible states that define an instruction execution.

The possible states that define an instruction execution are as follows:

Instruction address calculation(iac):  Determine the address of the next instruction to be executed.

Instruction fetch (if): Read instruction from its memory location into the processor.

Instruction operation decoding: Analyze instruction to determine type of operation to be performed and operands to be used.

Operand address calculation (oac): If the operation involves reference to an operand in memory or available via I/O, then determine the address of the operand.

Operand fetch (of): Fetch the operand from memory or read it in from I/O.

Data operation: Perform the operation indicated in the instruction.

Operand store (os): Write the result into memory or out to I/O.