Structure and function of the MCS-51 series one-chip computer MCS-51 is a name of a piece of one-chip computer series which Intel Company produces. This company introduced 8 top-grade one-chip computers of MCS-51 series in 1980 after introducing 8 one-chip computers of MCS-48 series in 1976. It belong to a lot of kinds this line of one-chip computer the chips have,such as 8051, 8031, 8751, 80C51BH, 80C31BH,etc., their basic composition, basic performance and instruction system are all the same. 8051 daily representatives- 51 serial one-chip computers .
An one-chip computer system is made up of several following parts: ( 1) One microprocessor of 8 (CPU). ( 2) At slice data memory RAM (128B/256B),it use not depositting not can reading /data that write, such as result not middle of operation, final result and data wanted to show, etc. ( 3) Procedure memory ROM/EPROM (4KB/8KB ), is used to preserve the procedure , some initial data and form in slice. But does not take ROM/EPROM within some one-chip computers, such as 8031 , 8032, 80C ,etc.. ( 4) Four 8 run side by side I/O interface P0 four P3, each mouth can use as introduction , may use as exporting too. ( 5) Two timer / counter, each timer / counter may set up and count in the way, used to count to the external incident, can set up into a timing way too, and can according to count or result of timing realize the control of the computer. ( 6) Five cut off cutting off the control system of the source . ( 7) One all duplexing serial I/O mouth of UART (universal asynchronous receiver/transmitter (UART) ), is it realize one-chip computer or one-chip computer and serial communication of computer to use for. ( 8) Stretch oscillator and clock produce circuit, quartz crystal finely tune electric capacity need outer. Allow oscillation frequency as 12 megahertas now at most. Every the above-mentioned part was joined through the inside data bus .Among them, CPU is a core of the one-chip computer, it is the control of the computer and command centre, made up of such parts as arithmetic unit and controller , etc.. The arithmetic unit can carry on 8 persons of arithmetic operation and unit ALU of logic operation while including one, the 1 storing device temporarilies of 8, storing device 2 temporarily, 8's accumulation device ACC, register B and procedure state register PSW, etc. Person who accumulate ACC count by 2 input ends entered of checking etc. temporarily as one operation often, come from person who store 1 operation is it is it make operation to go on to count temporarily , operation result and loopback ACC with another one. In addition, ACC is often regarded as the transfer station of data transmission on 8051 inside . The same as general microprocessor, it is the busiest register. Help remembering that agreeing with A expresses in the order. The controller includes the procedure counter , the order is depositted, the order decipher, the oscillator and timing circuit, etc. The procedure counter is made up of counter of 8 for two, amounts to 16. It is a byte address counter of the procedure in fact, the content is the next IA that will carried out in PC. The content which changes it can change the direction that the procedure carries out . Shake the circuit in 8051 one-chip computers, only need outer quartz crystal and frequency to finely tune the electric capacity, its frequency range is its 12MHZ of 1.2MHZ. This pulse signal, as 8051 basic beats of working, namely the minimum unit of time. 8051 is the same as other computers, the work in harmony under the control of the basic beat, just like an orchestra according to the beat play that is commanded.
51系列單片機是具有一定結構和功能由英特爾公司生產(chǎn)的單片機產(chǎn)品。這家公司在1976年引入8位MCS - 48系列單片機后又在1980年推出了8位高檔的MCS - 51系列單片機。它包含很多種類型的單片機，例如8051，8031，8751，80C51BH，80C31BH等等，它們的基本組成，基本性能和指令系統(tǒng)都是一樣的。8051習慣性的用來代表51系列單片機。
一個單片機的系統(tǒng)由許多幾部分組成：（1）一個8位CPU微處理器。（2）靜態(tài)隨機存取存儲器，能夠儲存程序運行過程中產(chǎn)生的數(shù)據(jù)。（3）程序存儲器ROM / EPROM中（4KB/8KB），用來保存程序和一些原始數(shù)據(jù)。但是在一些單片機中不使用ROM / EPROM中，例如8031，8032，80c系列等。（4）4個8排的I / O并行接口P0 ~P3，每個口即可用作輸入也可用作輸出。（5）2個定時器/計數(shù)器，每個定時器/計數(shù)器可設置計數(shù)來計數(shù)外部事件，也可以設置成常用的定時方式，并可以根據(jù)計算或結果控制單片機的運行。（6）五個中斷源控制系統(tǒng)。（7）1個雙向串行I / O口的UART（通用異步接收器/發(fā)送器UART），用來實現(xiàn)單片機的串行通信。（8）振蕩器和時鐘產(chǎn)生電路，需要外部電源的石英晶體微調(diào)電路，允許接在最大12v的振蕩頻率上。以上每部分通過內(nèi)部數(shù)據(jù)總線連接。其中，CPU是單片機的核心，它是單片機的控制和指揮中心，ALU算數(shù)邏輯運算單元能夠進行算術運算和邏輯運算，其組成是1個 8暫時存儲器和2個 8位的累加器。Acc累加器是存放ALU運算結果的單元，一般數(shù)據(jù)通過它來傳送。此外，Acc常常被作為對8051內(nèi)的數(shù)據(jù)傳輸?shù)闹修D站。與通常的微處理器一樣，它是最繁忙的寄存器。有記憶功能并執(zhí)行命令。這個控制器包括程序計數(shù)器，可..