51 MCU oscillation cycle clock cycle machine cycle instruction cycle

      The oscillation cycle refers to the cycle of the oscillation source or the cycle of the external input clock that provides the timing signal for the single-chip microcomputer.
(2) Clock cycle The
      clock cycle is also called the state cycle or state time S. It is twice the oscillation cycle and is divided into P1 beat and P2 beat. Usually, arithmetic logic operations are completed in P1 beat, and data transfer operations between internal registers are completed in P2 beat. (Note the phase relationship between P1 and P2)
(3) Machine cycle
      A machine cycle consists of 6 states. If the execution process of an instruction is divided into several basic operations, the time required to complete a basic operation is called a machine cycle. The single-cycle instruction execution time of a single-chip microcomputer is a machine cycle.
(4) Instruction cycle
  The instruction cycle is the total time required to execute an instruction. The instruction cycle of the MCS-51 single-chip microcomputer usually consists of 1, 2, or 4 machine cycles.

For example: If the crystal frequency is Fosc=12MHz, and Tosc=1/12µS, what are the oscillation period, clock period, ALE, and machine period?
Oscillator
period:                    Tosc=1/Fosc=1/12µS
Clock (state, S) period: S     =2Tosc=1/6µS
ALE (address latch):      ALE =6Tosc=1/2µS
Machine period:                            =12Tosc=1µS