机电工程专业英语 教学课件 作者 朱晓玲 Lesson 6.pptVIP

Lesson 6 The introduction of Single Chip Microcomputer Section I Words and Phrases Section II Text and Translation Section III Exercises and Answers Section I Words and Phrases Section I Words and Phrases Section II Text With the tremendous advances made in automatic control and automated equipment, the knowledge of Single Chip Microcomputer is very important. We’ll introduce some key hardware as follows: Central Processing Unit: The CPU is the brain of the microcontrollers reading user’s programs and executing the expected task as per instructions stored there in. Its primary elements are an 8 bit Arithmetic Logic Unit (ALU), Accumulator (Acc), few more 8 bit registers, B register, Stack Pointer (SP), Program Status Word (PSW) and 16 bit registers, Program Counter (PC) and Data Pointer Register (DPTR). Section II Text The ALU (Acc) performs arithmetic and logic functions on 8 bit input variables. Arithmetic operations include basic addition, subtraction, multiplication and division. Logical operations are AND, OR, Exclusive OR as well as rotate, clear, complement and etc1. Apart from all the above, ALU is responsible in conditional . branching decisions, and provides a temporary place in data transfer operations within the device. B register is mainly used in multiply and divide operations. During execution, B register either keeps one of the two inputs and then retains a portion of the result. For other instructions, it can be used as another general purpose register. Program Status Word keeps the current status of the ALU in different bits. Section II Text Stack Pointer (SP) is an 8 bit register. This pointer keeps track of memory space where the important register information is stored when the program flow gets into executing a subroutine2. Normally SP is initialized to 07H after a device reset and grows up from the location 08H. The Stack Pointer is automatically incremented or decremented for all PUSH or POP inst