In order to exploit the parallelism of the instruction-level
among programs, a single kernel processor has to be able to
run more than one program in a real parallel way. However,
almost all the traditional processors use the hardware PCs
to control programs to execute, named ”hardware PC+”.
This driving method is obviously unable to run more than
one program in a single kernel processor in a real parallel
way and therefore is unable to exploit the parallelism of
instruction-level among programs.