The Research And Design Of An8Bits MCU IP Core Compatible With Instructions Of MCS-51

MCU is a product of crossover study of microelectronics and computer technology,since the70’s twentieth century has been the hotspot in academic and industrial fields.MCU is widely used in national defence, electronic system, measurement system andconsumr electronic products.In this paper, the MCU is designed with top_down method. The MCU compatiblewith51instructions set. Harvard bus archetecture is chosen as the bus architecture ofMCU, of which the data bus and address bus are sepearted. The classical MCS-51MCUuses at least12clock periods to execute an instruction and the procedure is ratherlengthy. To overcome the problem, the execution of instructions is optimized, andoptimizes the design of decoder. So it uses only4clock periods to execute aninstruction. Compared to the classical MCS-51, the execution efficiency of MCU isimproved by at least6times. The modules of decoder, ALU are describled by VerilogHDL, which is structured language, so the MCU has good characteristics of clearstructure and strong expansion. The verification of the MCU indicated that the MCUcan be applied to embedded system.This paper first gives a brief introduction of MCU, then analysis the instructionsset detailly and design the MCU architecture according to the feature of instructions.Then the main modules are designed in this paper. Finallly, MCU is verified and theresult indicated that the function of MCU is correct and the MCU is completelycompatible with51instructions set.