The invention discloses a singlechip that supports MCS-51
instruction set, which comprises a ROM, an instruction fetching module, a RAM, an
arithmetic logic unit, a
special function register and a decoding module, and the like, adopts the way of an instruction with equal length, and adds a 3 lever pipeline function. The ROM is used for storing the application program of a user; the instruction fetching module provides the value of a
program counter PC to the ROM and reads the application program from the ROM, thereby finishing the instruction fetching of the pipeline operation in a first phase, and then decomposes the application program into the operation code and
operand which are transmitted to the decoding module; after the interruption module receives the interruption
signal, the interruption response
signal is returned. The decoding module fetches the operation code and
operand to be implemented from the instruction fetching module, determines the
control signal to other modules according to the operation code, and then finish a second phase and a
third phase of the pipeline operation. On the condition that the instruction
system of the MCS-51 series single-
chip remains unchanged, the speed for the operation of the instruction can be improved effectively.