Programs and Programming 程序与编程 Computer programs, which are also called software, are instruc

Programs and Programming

程序与编程

Computer programs, which are also called software, are instructions that cause the hardware-the machines-to do work. Software as a whole can be divided into a number of categories based on the types of work done by programs. The two primary software categories are operating systems (system software), which controls the working of the computer, and application software, which addresses the multitude of tasks for which people use computers. System software, thus, handles such essential, but often invisible, chores as maintaining disk files and managing the screen. whereasc^[1]application software performs word processing, database management, and the like. Two additional categories that are neither system nor application software, although they contain elements of both, are network software, which enables groups of computers to communicate, and Ianguage software, which provides programmers with the tools they need to write programs. In addition to these task_based^[2]categories, several types of software are described based on their method of distribution. These include the so-called canned programs or packaged software, developed and sold primarily through retail ourlets; freeware and public domain software, which is made available without cost by its developer; shareware, which is similar to freeware but usually carries a small fee for those who like the program; and the infamous vaporware, which is software that either does not reach the market or appears much later than promised.

Operating Systems

Different types of peripheral devices, disk drives, printers, communications networks, and so on handle and store data differently from the way the computer handles and stores it. Internal operating systems, usually stored in ROM memory,^[3]were developed primarily to coordinate and translate data flows from dissimilar sources, such as disk drives or coprocessors (processing chips that perform simultaneous but different operations from the central unit). An operating system is a master control program, permanently stored in memory, that interprets user commands requesting various kinds of services, such as display, print, or copy a data file, list all files in a directory, or execute a particular program.

Application

Application is a computer program designed to help people perform a certain type of work. An application, thus. differs from an operating system (which runs a computer), a utility (which performs maintenance or general purpose chores), and a language (with which computer programs are created). Depending on the work for which it was designed, an application can manipulate text, numbers, graphics, or a combination of these elements. Some application packages offer considerable computing power by focusing on a single task, such as Wordpad[4]; others, called integrated software, offer somewhat less power but include several applications, such as Winword, Excel and Foxpro.

Programming

A program is a sequence of instructions that tells the hardware of a computer what operations to perform on data. Programs can be built into the hardware itself, or they may exist independently in a form known as software. In some specialized, or-dedicated- computers the operating instructions are embedded in their circuitry; common examples are the microcomputers found in calculators, wristwatches, automobile engines, and microwave ovens. A general purpose computer, on the other hand, contains some built-in programs (in ROM) or instructions (in the processor chip), but it depends on external programs to perform useful tasks. Once a computer has been programmed, it can do only as much or as little as the software controlling it at any given moment enables it to do. Software in widespread use includes a wide range of applications programs-instructions to the computer on how to perform various tasks.

1. Application Program Interface

Application Program Interface is a set of routines that an application program uses to request and carry out lower level services performed by a computer's operating system. An application program carries out two types of tasks: those related to work being performed, such as accepting text or numbers input to a document or spreadsheet, and those related to maintenance chores, such as managing files and displaying information on the screen. These maintenance chores are performed by the computer's operating system, and an application program interface (API) provides the program with a means of communicating with the system, telling it which system level task to perform and when. On computers running a graphical user interface such as that on the Apple Macintosh, an API also helps application programs manage Window menus, icons, and so on. On local area networks, an API, such as IBMs NetBIOS, provides applications with a uniform means of requesting services from the lower levels of the network.

2. Word Processor

Word Processor is an application program for manipulating text-based documents; the electronic equivalent of paper, pen, typewriter, eraser, and most likely, dictionary and thesaurus. Word processors run the gamut from simple through complex,^[5]but all ease the tasks associated with editing documents (deleting, inserting, rewording, and so on). Depending on the program and the equipment in use, word processors can display documents either in text mode, using highlighting, underlining, or color to represent italics, boldfacing, and other such formatting, or in graphics mode, wherein formatting and, sometimes, a variety of fonts appear on the screen as they will on the printed page. All word processors offer at least limited facilities for document formatting, such as font changes, page layout, paragraph indention, and the like. Some word processors can also check spelling, find synonyms, incorporate graphics created with another program, correctly align mathematical formulas, create and print form letters, perform calculations, display documents in multiple on screen windows, and enable users to record macros that simplify difficult or repetitive operations.

Notes

[1]whereas: 连接词，表示对比，翻译成“而”。如：We are working, whereas they are playing我们在干活，而他们却在玩。

[2]task-based: 以任务为依据的，基于任务的。

[3]ROM memory: ROM是read-only memory的简写形式，只读存储器。

[4]Wordpad, Winword, Excel, and Foxpro：一些应用软件的名字，分别用于文字处理、电子表格和数据库。

[5]Word processors run the gamut from simple through complex. 文字处理软件负责从简单到复杂的所有工作。