Structure and function of the MCS-51series
Structure and function of the MCS-51series one-chip computer MCS-51is a name of a piece of one-chip computer series which Intel Company produces.This company introduced8top-grade one-chip computers of MCS-51series in1980after introducing8one-chip computers of MCS-48series in1976.It belong to a lot of kinds this line of one-chip computer the chips have,such as8051,8031,8751, 80C51BH,80C31BH,etc.,their basic composition,basic performance and instruction system are all the same.8051daily representatives-51serial one-chip computers.
An one-chip computer system is made up of several following parts:(1)One microprocessor of8(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 as8031, 8032,80C,etc..(4)Four8run side by side I/O interface P0four 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 as12megahertas 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 on8persons of arithmetic operation and unit ALU of logic operation while including one,the1 storing device temporarilies of8,storing device2temporarily,8's accumulation
device ACC,register B and procedure state register PSW,etc.Person who accumulate ACC count by2input ends entered of checking etc.temporarily as one operation often,come from person who store1operation 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 on8051inside.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 of8for two,amounts to16.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 in8051one-chip computers,only need outer quartz crystal and frequency to finely tune the electric capacity,its frequency range is its 12MHZ of1.2MHZ.This pulse signal,as8051basic beats of working,namely the minimum unit of time.8051is 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.
There are ROM(procedure memory,can only read)and RAM in8051slices (data memory,can is it can write)two to read,they have each independent memory address space,dispose way to be the same with general memory of computer. Procedure8051memory and8751slice procedure memory capacity4KB,address begin from0000H,used for preserving the procedure and form constant.Data8051-87518031of memory data memory128B,address false00FH,use for middle result to deposit operation,the data are stored temporarily and the data are buffered etc..In RAM of this128B,there is unit of32byteses that can be appointed as the job register, this and general microprocessor is different,8051slice RAM and job register rank one formation the same to arrange the location.It is not very the same that the memory of MCS-51series one-chip computer and general computer disposes the way in addition.General computer for first address space,ROM and RAM can arrange in different space within the range of this address at will,namely the addresses of ROM
