电气自动化专业毕业设计英文翻译模板.docx

《电气自动化专业毕业设计英文翻译模板.docx》由会员分享，可在线阅读，更多相关《电气自动化专业毕业设计英文翻译模板.docx（7页珍藏版）》请在得力文库 - 分享文档赚钱的网站上搜索。

1、电气自动化专业毕业设计英文翻译模板 电气自动化专业毕业设计英文翻译 Computer control technology 1 Computer structure and function This section introduces the internal architecture of a computer and describes how instructions are stored and interpreted and explains how the instruction execution cycle is broken down into its various c

2、omponents. At the most basic level, a computer simply executes binary-coded results. For a general-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

3、A-1. Fig. 3-1A-1 Basic elements of a computer The memory stores instructions and data. The CPU reads and interprets the instructions, reads the data required by each instruction, executes the action required by the instruction, and stores the results back in memory. One of the actions that is requir

4、ed of the CPU is to read data from or write data to an external device. This is carried out using the input/output system. The external processor bus is a set of electric conductors that carries data, address and control information between the other computer elements. 1-1 The memory The memory of a

5、 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 called its address. The lowest address is 0. The manufacturer defines a word length for the processor that is an integral number of loca

6、tions long. In each word the bits can represent either data or instructions. For the Intel 8086/87 and Motorola MC6800 microprocessors, a word is 16 bits long, but each memory location has only 8 bits and thus two 8-bit locations must be accessed to obtain each data word. In order to use the content

7、s of memory, the processor must fetch the contents of the right location. 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 location t

8、o be read by the processor. The process of fetching the contents of a memory location does not alter the contents of that location. Instructions in memory Instructions stored in memory are fetched by the CPU and unless program branches occur, they are executed in the sequence they appear in memory.

9、An instruction written as a binary pattern is called a machine-language instruction. One way to achieve meaningful 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. 0001 0101 1000 XXXX 0100 0001 1000 XXXX

10、 0011 XXXX XXXX 0100 Fields Opcode Immediate code Operand data Branch address Set 5 in location 8 Subtract 1 f rom location 8 If zero, bran ch to location 4 16-bit instruction words . . XXXX : not u sed (or “don t care”) Fig. 3-1A-2 Arrangement of program and data in memory Each instruction in our s

11、imple 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), operand address, immediate operands, branch address. In a real instruction set there are many more instructions. There is also a much large

12、 number of memory locations in which to store instructions 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 range of the micropro

13、cessor without increasing the instruction length: variable instruction field, multiword instructions, multiple addressing modes, variable instruction length. We will not discuss them in detail. Data in memory data is information that is represented in memory as a code. For efficient use of the memor

14、y space and processing time, most computers provide the capability of manipulating data of different lengths and representations in memory. The various different representations recognized by the processor are called its data types. The data types normally used are: bit, binary-coded decimal digit (

15、4-bit nibble, BCD), byte (8 bits), word (2 bytes), double word (4 bytes). 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 datacharacter

16、 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 Standard Code for Information Interchange (ASCII). Type of memory In the applications of dig

17、ital control system, we also concerned with the characteristics of different memory techniques. For primary memory, 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 memor

18、y (RAM). In some case we do not want the information in memory to be lost. So we are willing to use special techniques to write into memory. If writing is accomplished only once by physically changing connections, the memory is called a read-only memory (ROM). If the interconnection pattern can be p

19、rogrammed to be set, the memory is called a programmable read-only memory (PROM). If rewriting can be accomplished when it is necessary, we have an erasable programmable read-only memory (EPROM). An electronically erasable PROM is abbreviated EEPROM. 1-2 The CPU The CPUs job is to fetch instructions 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 controller.