電氣自動化畢業(yè)設(shè)計英文翻譯---計算機控制技術(shù)

1、<p>　　Computer control technology</p><p>　　1 Computer structure and function</p><p>　　This section introduces the internal architecture of a computer and describes how instructions are stor

2、ed and interpreted and explains how the instruction execution cycle is broken down into its various components.</p><p>　　At the most basic level, a computer simply executes binary-coded results. For a genera

3、l-purpose programmable computer, four necessary elements are the memory, central processing unit (CPU, or simply processor), an external processor bus, and an input/output system as indicated in Fig.3-1 A-1. </p>

4、<p>　　Fig. 3-1A-1 Basic elements of a computer</p><p>　　The memory stores instructions and data.</p><p>　　The CPU reads and interprets the instructions, reads the data required by each inst

5、ruction, executes the action required by the instruction, and stores the results back in memory. One of the actions that is required of the CPU is to read data from or write data to an external device. This is carried ou

6、t using the input/output system.</p><p>　　The external processor bus is a set of electric conductors that carries data, address and control information between the other computer elements.</p><p&g

7、t;　　1-1 The memory</p><p>　　The memory of a computer consists of a set of sequentially numbered locations. Each location is a register in which binary information can be stored. The “number” of a location is

8、 called its address. The lowest address is 0. The manufacturer defines a word length for the processor that is an integral number of locations long. In each word the bits can represent either data or instructions. For th

9、e Intel 8086/87 and Motorola MC6800 microprocessors, a word is 16 bits long, but each memory location</p><p>　　In order to use the contents of memory, the processor must fetch the contents of the right locat

10、ion. To carry out a fetch, the processor places (enables) the binary-coded address of the desired location onto the address lines of the external processor bus. The memory then allows the contents of the addressed memory

11、 location to be read by the processor. The process of fetching the contents of a memory location does not alter the contents of that location.</p><p>　　Instructions in memory Instructions stored in memory ar

12、e fetched by the CPU and unless program branches occur, they are executed in the sequence they appear in memory. An instruction written as a binary pattern is called a machine-language instruction. One way to achieve mea

13、ningful patterns is to divide up the bits into fields as indicated in Fig. 3-1A-2, with each field containing a code for a different type of information.</p><p>　　Fig. 3-1A-2 Arrangement of program and data

14、in memory</p><p>　　Each instruction in our simple computer can be divided up into four fields of 4 bits each. Each instruction can contain operation code (or opcode, each instruction has a unique opcode), op

15、erand address, immediate operands, branch address. </p><p>　　In a real instruction set there are many more instructions. There is also a much large number of memory locations in which to store instructions

16、and data. In order to increase the number of memory locations, the address fields and hence the instructions must be longer than 16 bits if we use the same approach. There are a number of ways to increase the addressing

17、range of the microprocessor without increasing the instruction length: variable instruction field, multiword instructions, multiple add</p><p>　　Data in memory data is information that is represented in memo

18、ry as a code. For efficient use of the memory space and processing time, most computers provide the capability of manipulating data of different lengths and representations in memory. The various different representation

19、s recognized by the processor are called its data types. The data types normally used are: bit, binary-coded decimal digit (4-bit nibble, BCD), byte (8 bits), word (2 bytes), double word (4 bytes).</p><p>　　

20、Some processors provide instructions that manipulate other data types such as single-precision floating-point data types (32bits) and double-precision floating-point data types (64 bits). There is another type of data—ch

21、aracter data. It is also usually represented in 8 bits. Each computer terminal key and key combination (such as shift and control functions) on a standard terminal keyboard has a 7-bits code defined by the American Stand

22、ard Code for Information Interchange (ASCII).</p><p>　　Type of memory In the applications of digital control system, we also concerned with the characteristics of different memory techniques. For primary mem

23、ory, we need it to be stored information temporarily and to be written and got information from successive or from widely different locations. This type memory is called random-access memory (RAM). In some case we do not

24、 want the information in memory to be lost. So we are willing to use special techniques to write into memory. If writing is acco</p><p>　　1-2 The CPU</p><p>　　The CPU’s job is to fetch instructi

25、ons from memory and execute these instructions. The structure of the CPU is shown in Fig. 3-1A-3. It has four main components: an arithmetic and logical unit (ALU), a set of registers, an internal processor bus and contr

26、oller.</p><p>　　Fig.3-1A-3 Central processing unit (CPU)</p><p>　　These and other components of the CPU and their participation in the instruction cycle are described in the following sections.&

27、lt;/p><p>　　Arithmetic and Logical Unit (ALU) The ALU provides a wide arithmetic operations, including add, subtract, multiply, and divide. It can also perform Boolean logic operations such as AND, OR, and COM

28、PLEMENT on binary data. Other operations, such as word compares, are also available. The majority of computer tasks involve the ALU, but a great amount of data movement is required in order to make use of the ALU instruc

29、tions.</p><p>　　Registers A set of registers inside the CPU in used to store information.</p><p>　　Instruction register When an instruction is fetched, it is copied into the instruction regist

30、er, where it is decoded. Decoding means that the operation code is examined and used to determine the steps of the execution sequence.</p><p>　　Programmer’s model of the CPU The collection of registers that

31、 can be examined or modified by a programmer is called the programmer’s model of the CPU. The only registers that can be manipulated by the instruction set, or are visibly affected by hardware inputs or the results of op

32、erations upon data, are the registers represented in the model.</p><p>　　Flag register The execution sequence is determined not only by the instruction but also by the results of the previous instructions. F

33、or example, if an addition is carried out in the ALU, data on the result of the addition (whether the result is positive, negative, or zero, for example) is stored in what is known as a flag register, status register, or

34、 condition register. If the next instruction is a conditional branch instruction, the flag word is tested in that instruction to determine if a br</p><p>　　Program counter (instruction pointer) The address o

35、f the next instruction is located in a register called the program counter. </p><p>　　Data registers When an instruction uses the registers to store data, the reference to the register in the instruction is

36、called register addressing. The reasons of making use of the internal registers to store data are that they can make the instructions shorter and make execution faster.</p><p>　　Address registers The interna

37、l registers can also be used for the storage of address of data in memory data. In such a case, the instruction word contains a register number (i.e. a register address). In the register is contained the address of memor

38、y data to be used in the instruction. This form of addressing is called register indirect addressing. The contents of the register are said to point to the data in memory.</p><p>　　Internal Processor Bus Th

39、e internal processor bus moves data between internal register. A bus is a set of closely grouped electric conductors that transfers data, address, and control information between functional blocks of the CPU. Data from a

40、 source register can be passed to a destination register when both are enabled onto (connected to) the bus.</p><p>　　Controller The controller provides the proper sequence of control signals for each instru

41、ction in a program cycle to be fetched from memory. A total program cycle comprises many instruction cycle, each instruction cycle can be divided up into its component machine cycles and each machine cycle comprises a nu

42、mber of clock cycle.</p><p>　　In order to fetch an instruction, for example illustrated in Fig.3-1A-4, the address in the program counter is placed on the address lines of the external bus (AB) at the onset

43、of clock cycle C1. Simultaneously, using a code on the control lines of the bus (CB), the CPU informs all devices attached to the bus that an “opcode” fetch machine cycle is being executed by the CPU. The memory allows t

44、he memory address to select the memory location containing the instruction. At C2 the controller places</p><p>　　Fig. 3-1A-4 A timing diagram for "operation-code fetch "</p><p>　　Exter

45、nal attention requests It is often necessary to stop the normal instruction processing sequence. One type of external attention request is the reset request. In the case of an unrecoverable error, a computer system may b

46、e required to reset itself .This would have the effect of initializing all important registers in the system and starting instruction execution from a standard memory location-usually location 0.</p><p>　　An

47、 input that is more commonly activated during the normal course of events is the interrupt request. An interrupt request signal from an external device can cause the CPU to immediately execute a service subroutine which

48、carries out the necessary actions. After completing the service subroutine, the processor will continue the task from which it was originally interrupted.</p><p>　　The third type of input is the bus request,

49、 or direct memory access(DMA) request. It is possible to have a terminal interface that stores up all the characters in a line of text until it receives a "carriage return." Then the interface requests the use

50、of the system bus, at which time the complete line of data is transferred to memory as fast as possible. In this way the processor simply becomes inactive until the transfer is completed.</p><p><b>　　1

51、-3 Buses</b></p><p>　　The bus is the most important communication system in a computer system. Under control of the CPU, a data source device and a data destination device are "enabled" onto(

52、equivalent to being connected to) the bus wires for a short transmission.</p><p>　　External processor bus The internal processor bus described in Sec. is connected to the external processor bus by a set of b

53、us buffers located on the microprocessor integrated circuit.</p><p>　　System bus The microcomputer board can communicate with other boards by connecting its bus to an external system bus through a connector.

54、</p><p>　　1-4 Computer Input and Output</p><p>　　A set of registers external to the CPU is associated with what is known as the input/output (I/O) system. The I/O system is connected to the exte

55、rnal processor bus using control, address, and data buses through an I/O registers in an interface. There are basically two ways that are used to address I/O register.</p><p>　　In the first method, called I/

56、O-mapped input/output, the operation code itself has special I/O instructions that address a numbered register in the interface called an I/O port.</p><p>　　The second method of addressing I/O registers give

57、s the I/O ports addresses that lie within the memory address range of the CPU. This is called memory-mapped I/O. Of course there must not be any memory locations at the same address as I/O locations.</p><p>

58、　　One of the benefits of the memory-mapped approach is that the full range of memory addressing modes is available to the addressing of I/O registers.</p><p>　　2 Fundamentals of Computer and Networks</p&g

59、t;<p>　　2-1 Organization of Computer System</p><p>　　A computer is a fast and accurate symbol manipulating system that is organized to accept, store, and process data and produce output results under

60、the direction of a stored program of instructions. This section explains why a computer is a system and how a computer system is organized. Key elements in a computer system include input, processing, and output devices.

61、 Let's examine each component of the system in more detail.</p><p>　　Input Devices Computer system use many devices for input purpose. Some INPUT DEVICES allow direct human/machine communication, while

62、some first require data to be recorded on an input medium such as a magnetizable material. Devices that read data magnetically recorded on specially coated plastic tapes or flexible or floppy plastic disks are popular. T

63、he keyboard of a workstation connected directly to (or ONLINE to) a computer is an example of a direct input device. Additional direct input devic</p><p>　　Central Processing Unit The heart of any computer

64、system is the central processing unit (CPU). There are three main sections found in the CPU of a typical personal computer system: the primary storage section, the arithmetic-logic section, and the control section. But t

65、hese three sections aren't unique to personal computers. They are found in CPUs of all sizes. </p><p>　　Output Device Like input units, output device are instruments of interpretation and communication

66、between humans and computer system of all size. These device take output results from the CPU in machine-coded form and convert them into a form that can be used (a) by people (e.g. a printed and /or displayed report) or

67、 (b) as machine input in another processing cycle.</p><p>　　In personal computer systems, display screen and desktop printers are popular output devices. Larger and faster printers, many on-line workstations

68、, and magnetic tape drives commonly found in large systems.</p><p>　　The input/output and secondary storage units are sometimes called peripheral devices (or just peripherals). This terminology refers to the

69、 fact that although these devices are not a part of the CPU, they are often located near it. Besides, a computer system also includes buses, ROM(read only memory), RAM(random access memory), parallel port and serial port

70、, hard disk, floppies and CD(compact disk)drive, and so on.</p><p>　　2-2 Operating System</p><p>　　Operating systems have developed over the past thirty years for two main purposes. First, they

71、provide a convenient environment for the development and execution of programs. Second, operating systems attempt to schedule computational activities to ensure good performance of the computing system.</p><p&

72、gt;　　The operating system must ensure correct operation of the computer system. To prevent user programs form interfering with the proper operation of the system, the hardware was modified to create two modes: user mode

73、and monitor mode. Various instructions (such as I/O instructions and halt instructions) are privileged and can only be executed in monitor mode. The memory in which the monitor resides must also be protected from modific

74、ation by the user. A timer prevents infinite loops. Once these ch</p><p>　　As we have stated, operating systems are normally unique to their manufacturers and the hardware in which they are run. Generally, w

75、hen a new computer system is installed, operational software suitable to that hardware is purchased. Users want reliable operational software that can effectively support their processing activities.</p><p>

76、　　Though operational software varies between manufacturers, it has similar characteristics. Modern hardware, because of its sophistication, requires that operating systems meet certain specific standards. For example, co

77、nsidering the present state of the field, an operating system must support some form of on-line processing. Functions normally associated with operational software are:</p><p>　　Job management;</p>&l

78、t;p>　　Resource management;</p><p>　　Control of I/O operations</p><p>　　Error recovery;</p><p>　　Memory management.</p><p>　　2-3 Networks</p><p>　　Commun

79、ication between distributed communities of computers is required for many reasons. At a national level, for example, computers located in different parts of the country use public communication services to exchange elect

80、ronic messages (mail) and to transfer files of information from one computer to another. Similarly, at a local level within, say, a single building, distributed communities of computer-based workstations use local commun

81、ication networks to access expensive shared resources—</p><p>　　Although the physical separation of the communicating computers may vary considerably from one type of application to another, or, at the heart

82、 of any computer communication network is the data communication facility which, may be a PSDN, a private LAN or perhaps a number of such networks interconnected together. However, irrespective of the type of data commun

83、ication facility, an amount of hardware and software is required within each attached computer to handle the appropriate network-dependen</p><p>　　3 Stepper motor</p><p>　　Stepper motor is the e

84、lectric pulse signals into angular displacement or linear displacement of the open-loop stepper motor control element pieces. In the case of non-overloaded, the motor speed, stop position depends only on the pulse freque

85、ncy and pulse number, regardless of load changes, when the driver receives a step pulse signal, it will drive a stepper motor to Set the direction of rotation of a fixed angle, called the "step angle", which th

86、e angle of rotation is fixed step by step operat</p><p><b>　　3-1 Work</b></p><p>　　Induction motor is a stepper motor, does it work is the use of electronic circuits, the DC power su

87、pply into a time-sharing, multi-phase timing control current, this current stepper motor power supply, the stepper motor to work properly , The drive is sharing power supply for the stepper motor, the polyphase timing co

88、ntroller.</p><p>　　Although the stepper motor has been widely used, but the stepper motor does not like a normal DC motor, AC motor in the conventional use. It must be double-ring pulse signal; power driver

89、circuit composed of the control system can be used. Therefore, it is not easy with a good stepping motor, which involves mechanical, electrical, electronics and computers, and much other specialized knowledge.</p>

90、<p>　　As the stepper motor actuators, electromechanical integration, one of the key products, widely used in a variety of automatic control systems. With the development of microelectronics and computer technology,

91、 increasing demand for stepper motor has applications in all areas of the national economy.</p><p>　　3-2 Categories</p><p>　　Now more commonly used include the reaction of step motor stepper mot

92、or (VR), permanent magnet stepper motor (PM), hybrid stepper motors (HB) and single-phase stepper motor.</p><p>　　3-3 Permanent magnet stepper motor</p><p>　　Permanent magnet stepper motor is ge

93、nerally two-phase, torque, and smaller, usually 7.5 degree step angle or 15 degrees;</p><p>　　Permanent magnet stepper motor output torque, dynamic performance, but a large step angle.</p><p>　　

94、3-4 Reaction Stepper Motor</p><p>　　Reaction is generally three-phase stepping motor can achieve high torque output, step angle of 1.5 degrees is generally, but the noise and vibration are large. Reaction by

95、 the stepper motor rotor magnetic circuit made of soft magnetic materials, a number of the stator phase excitation winding, the use of permeability changes in torque.</p><p>　　Step Motor simple structure, lo

96、w production costs, step angle is small; but the dynamic performance is poor.</p><p>　　3-5 Hybrid Stepping Motor</p><p>　　Hybrid Step Motor combines reactive, permanent magnet stepper motors of

97、both, it's a small step angle, contribute a large, dynamic performance, is currently the highest performance stepper motor. It is also sometimes referred to as Permanent Magnet Induction Stepping Motor. It consists o