Computer English Unit 4 Software Development(计算机英语 第四单元 软件开发).doc

Unit 4 Software Development第四单元： 软件开发 Section A Computer Program课文A： 计算机程序 I. Introduction一、引言 A computer program is a set of instructions that directs a computer to perform some processing function or combination of functions.计算机程序是指挥计算机执行某种处理功能或功能组合的一套指令。 For the instructions to be carried out, a computer must execute a program, that is, the computer reads the program, and then follows the steps encoded in the program in a precise order until completion.要使指令得到执行，计算机必须执行程序，也就是说，计算机要读取程序，然后按准确的顺序实施程序中编码的步骤，直至程序结束。 A program can be executed many different times, with each execution yielding a potentially different result depending upon the options and data that the user gives the computer.一个程序可多次执行，而且，取决于用户提供给计算机的选项和数据，每次执行可能产生不同的结果。 Programs fall into major classes:程序分为两大类： application programs and operating systems.应用程序和操作系统。 An application program is one that carries out some function directly for a user, such as word processing or game playing.应用程序直接为用户执行某种功能，如处理文字或玩游戏。 An operating system is a program that manages the computer and the various resources and devices, monitors, keyboards, printers, and modems, so that they may be used by other programs.操作系统管理计算机以及与之相连的各种资源和设备，如随机存储器、硬盘驱动器、监视器、键盘、打印机和调制解调器，以便其他程序可以使用它们。 Examples of operating systems and DOS, Windows 95, OS/2, and UNIX.操作系统的例子包括： DOS、Windows 95、OS/2和UNIX。 II. Program Development二、程序开发 Software designers create new programs by using special applications programs, often called utility programs or development programs.软件设计者使用经常被称为实用程序或开发程序的专门应用程序来创建新程序。 A programmer uses another type of program called a text editor to write the new program in a special notation called a programming language.程序员使用称为文本编辑程序的另一种程序，来以称为编程语言的特殊符号编写新程序。 With the text editor, the programmer creates a text file, which is an ordered list of instruction, also called the program source file.程序员使用文本编辑程序创建一个文本文件，这个文本文件是一个有序指令表，也称为程序源文件。 The individual instructions that make up the program source file are c