I too need the clarification reguarding the querie
but as i know that in the advacement of the controller the cpu is designed to handel concurrent programming .
for example in initial stage of 8051 some instructions takes 7 to 8 machine cycyles to completely execute as the technology has advanced the present day cpu takes 1-2 machine cycle as the cpu can handle parallel processing.
its just up to my knowledge.if it is wrong please get the correct answer