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Unit 4
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, whereas 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 language software, which provides programmers with the tools they need to write programs. In addition to these task-based 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 outlets;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, 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 ;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, 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.

Exercises

I. Choose the best answer for each of the following :

1. Computer programs in the text_____.

A. differ a great deal from software

B. control the working of a computer

C. handle invisible chores only such as managing the screen and maintaining disk files

D. can not perform word processing, database and the like

2. The two categories of software that are neither system or application software, but contain elements of both are_____.

A. system and language software

B. network and application software

C. system and application software

D. language and network software

3. The so-called canned programs are so described depending on_____.

A. the tasks they perform

B. the way they are obtained

C. the developer who creates them

D. the user who uses them

4. Which of the following is true?_____

A. Software never carries a fee for those who like the program.

B. Vaporware is made free by its developer.

C. Freeware and public domain software is a task-based software.

D. Packaged software may be available at the market from a retailer.

5. Which of the following about the language software is true?_____

A. It is free of charge.

B. It helps programmers write programs.

C. It is a kind of infamous software.

D. It reaches the market at the time it promised.

6. A disk drive_____.

A. belongs to the categories of software

B. works the same way as the computer

C. is one of the peripheral devices

D. translates data flows from similar sources.

7. Which software is a master control program of a computer stored in memory?

A. System

B. Application

C. Network

D. Software

8. Which of the following about application software is false?_____

A. It helps people work.

B. It is a utility.

C. It is different from language software.

D. It can’t run a computer.

9. From the last paragraph we know that_____.

A. once a computer has been programmed, it can do as much as one wishes

B. some instructions are embedded in some specialized automobile engines

C. programs can be built into hardware itself but can’t exist independently

D. a general purpose computer contains some built in programs;therefore, it doesn’t need external programs

10. From the text, we can infer that_____.

A. some computers don’t have system software

B. software such as Winword, Excel and Foxpro focus on a single task

C. for a computer to perform a useful task, both the system and application software are inevitable

D. language software helps people to learn a language

II. Say whether the following statements are true or false according to the information given in the text :

1. Software is sometimes referred to as a program.

2. Usually software is classified depending on the kinds of work done by a computer.

3. Shareware doesn’t reach the market at all.

4. A master control program interprets user commands.

5. An application software can manipulate text, numbers, graphics but not the combination of these elements.

6. Winword does not have as much computing power as Wordpad.

7. A general purpose computer doesn’t contain any built-in programs.

8. A programmed computer can do as much as the software controlling it enables it to do.

9. Wristwatches are too small for people to install a computer in.

10. Programs can’t be built into the hardware itself. SD7SE3UgXtWXy7AOeRy45d6ezvklsmPMA4AXU9iDdsYeBpSBzvwd+A/cxub8kr8g

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