【正文】 ght Intel microprocessor 8008. Because 8008 USES is P in gully MOS microprocessor, and therefore still belong to the first generation of microprocessors. 1973 Intel pany develop 8 bits of the microprocessor 8080。s first microputer. 1976 the Intel pany develop MCS 48 series of 8 bits of single chip microcontroller, this also is published. Zilog pany in 1976 development Z80 microprocessor, widely used in microputer and industrial automatic control equipment. At that time, Zilog, Motorola and Intel microprocessor field in Japan. In the early 1980s, the Intel pany in MCS 48 series microcontroller, on the basis of launched MCS 51 series 8 bits of highgrade microcontroller. MCS 51 series microcontroller whether pieces (RAM capacity, I/O mouth function, system extension aspects had the very big enhancement. Singlechip the bus: we know that a circuit is always from the ponents through wires connected, and in analog circuits, the connection does not bee a problem, because the devices are generally serial interrelationship between the various devices connection is not much, but not the same as puter circuits, which is based on the microprocessor as the core, the device must be connected with the microprocessor, the device must be between the mutual coordination and so on need to connect on a lot of If still the same as analog circuits, in the microprocessor and a separate connection between the devices, the quantity line will be many alarmingly so in the microprocessor introduced the concept of bus, all devices share the connection All devices of all eight data lines from eight public online, which is equivalent to all devices in parallel, but only this is not enough, if there is two devices send data simultaneously, a 0, a 1, then , the receiving party received what is it? This situation is not allowed, so to pass the line of control to control the device time job, any time there can be only one device to send data (which may have multiple devices simultaneously receiving). Device39。0 39。139。s address has been provided for the chip designers, and can not be changed, the external unit can be singlechip developers to decide, but Yes there is some address must be the unit (see procedures for the implementation process). Data: This is the object of treatment by the microprocessor, in a variety of different applications in different circuits, in general, the data may be processed so have several situations: 1 ? address (such as MOV DPTR, 1000H), that address 1000h into the DPTR. 2 ? the way the words or control characters (such as MOV TMOD, 3), 3 which controls the characters. 3 ? constants (such as MOV TH0, 10H) 10H that is constant from time to time. 4 ? The actual output value (such as the mouth then P1 lantern light to light the whole, then the implementation of instruction: MOV P1, 0FFH, to light the whole dark, then the implementation of instruction: MOV P1, 00H) and 00H are here 0FFH actual output value. Another example is the font code for the LED, is the actual output value. Understanding of the address, the nature of instructions, running is not difficult to understand why the process of running fly, the data will be implemented as instructions. Three, P0 mouth, P2 and P3 the mouth of the second function Usage: often on P0 beginner I, P2 and P3 mouth I use the second function puzzled think the second function and the original features have a switch between the process, or that there have to be a directive, in fact, the port39。can not be used as generalpurpose I / O port use39。should not39。not39。0000 39。000039。s ROM must exist in the39。in this unit, and39。 in the storage unit must be a mand. Friday, the stack: the stack is a region, are used to store data, the region does not have any unique position, that is a part of internal RAM, special is its data storage and access methods, namely, the socalled 39。, and the stack has a special data transmission mand, ie39。and39。, there is a special unit specifically for its services, that is, the stack pointer SP, when they first PUSH instruction, the SP on (at the original value of the foundation on) automatically add one, whenever the implementation of a POP instruction, SP on (at the original value basis) minus one automatically. Because of the value of SP can be used to change directions, so as long as the stage at the beginning of the proceedings to change the value of the SP, you can put the stack set up the required memory units, such as at the beginning of the proceedings, with a MOV SP, 5FH instructions when put on the stack from the memory modules installed in the unit 60H start. The normal procedure at the beginning of the total that there is a stack pointer of the instruction set, because at startup, SP initial value of 07H, thus the stack from the beginning the next unit 08h, and 08h to 1Fh in the region 8031 is the second, Three, four working registers area, often used, this will lead to data chaos. The author has prepared a different program, not exactly the same instructions to initialize the stack, which is the author39。s study, development and application of puter application will create and intelligent control of scientists and engineers. SCM is widely applied in instrumentation, household appliance, medical equipment, aerospace, special equipment of intelligent management and process control and other fields, roughly can divide the following several categories: 1. In intelligent instruments on the application Singlechip microputer with small size, low power consumption, control function is strong, flexible, miniaturization and extended use convenience etc, which are widely used in instrumentation, bined with different kinds of sensors, which can realize such as voltage, power, frequency, humidity, temperature and flow rate, speed, thickness, Angle, length,