The assembly language of ELAN MCU is very similar to MCS-51 MCU, but the two are completely non-stop architecture.

I concluded, first look at the stack structure. MCS-51 single chip microcomputer stack is opened in RAM space, and users are required to estimate the amount of stack usage according to the program call, and then define the top address of the stack pointer. When the user reads and writes the data in the stack area, the program will run away. The stacks of ELAN and pic microcontrollers have independent fixed depths. Users cannot directly read and write the stack area. Only when a program call occurs, will the address of the protection site be pushed onto the stack, so it will not run away, but the depth It is still limited, so it is not advisable to nest too many functions.

1. The internal structure of ELAN MCU is the same as PIC MCU. The bus structure of MCS-51 MCU is von Neumann type. The computer fetches instructions and data in the same storage space, and the two cannot be performed at the same time. The bus structure is a Harvard structure, and the instruction and data spaces are completely separated, one for instructions and one for data. Since the program and data can be accessed at the same time, the data throughput rate is improved. It is precisely because of the Harvard dual-bus structure that is used in the PIC microcontroller, the difference from common microcontrollers is that the program and data buses can use different widths. The data buses are all 8-bit, but the command bus bits are 12, 14, and 16 bits respectively.

2. The instruction fetching and execution of MCS-51 single-chip microcomputer adopts a single instruction pipeline structure, that is, one instruction is fetched, and the next instruction is fetched after execution; while the instruction fetching and execution of PIC adopts a dual instruction pipeline structure, when an instruction is executed , Allow the next instruction to be fetched at the same time, thus achieving a single-cycle instruction.

3. All registers of the PIC microcontroller, including I/O ports, timers and program counters, all adopt RAM structure, and they only need one instruction cycle to complete the access and operation; while the MCS-51 microcontroller needs two or two More than cycles can change the contents of the register.

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