计算机专业英语教程第5版中译英参考

Unit 1
A computer system consists of hardware system and software system. The hardware of the computer is usually divided into three major parts or three primary subsystems: the CPU, the memory subsystem, and the I/O subsystem.
The CPU performs many operations and controls computer. The memory subsystem is used to store program being executed by the CPU, along with the program’s data. The I/O subsystem allows the CPU to interact with input and output devices such as the keyboard and monitor of a personal computer. The components of the computer are connected to the buses.
The part of the computer that performs the bulk of data processing operations is called the central processing unit and is referred to as the CPU. In microcomputer, it is often called the microprocessor. The CPU is made up of three major parts: control unit, ALU, and register set.
Memory is also known as internal memory or main memory. It refers to the circuits in the computer that hold whatever programs and data are available for immediate use by the CPU.
I/O subsystem includes I/O devices and interface. There are a wide variety of I/O devices, such as mouse, printer, sensor, disk, and so on. Input-output interface provides a method for transferring information between internal storage and external I/O devices. Peripherals connected to a computer need special communication links for interfacing them with the CPU. The purpose of the communication link is to resolve the differences that exist between the central computer and each peripheral.
Unit 3
(a) A program is a list of instructions or statements for directing the computer to perform a required data processing task. Programming is a multistep process for creating that list of instructions.
(b) It is important to understand the difference between a class and an object of that class. A class is simply a specification for creating objects. Thus, a single class may create multiple objects.
(c) Java is an object-oriented, network-friendly high-lever programming language that allows programmers to build applications that can run on almost any operating system.
(e) Programming involves a great deal of creativity. The design is guide to the function or purpose of each component, but the programmer has great flexibility in implementing the design as code. No matter what language is used, each program component involves at least three major aspects: control structures, algorithms, and data structures.
Unit 4
The software system can be divided into two broad categories: application software and system software. Application software consists of the program for performing tasks particular to the machine’s utilization. In contrast to application software, system software comprises a large number of programs. These programs start up the computer and function as the principle coordinator of all hardware components and application software. Without system software loaded into RAM of your computer, your hardware and application software are useless.
System software can be grouped into three basic parts: operating system, utility software, and language translators. The majority of an installation’s utility software consists of programs for performing activities that are fundamental to computer installations yet not included in the operating system. In a sense, utility software consists of software units that extend the capabilities of the operating system.
A computer’s OS is the main collection of programs that manage its activities. The primary chores of an OS are management and control. The OS ensures that all actions requested by a user are valid and processed in an orderly fashion. It also manages the computer system’s resources to perform these operations with efficiency and consistency.
Application software is the software designed to help you solve problems specific to business or perform specific business tasks. Application software then is the layer of software closest to you. Basically, there are four categories of application software: productivity software, business and specialty software, entertainment software and education/reference software.
Unit 5
A computer network is often classified as being either a local area network (LAN), a metropolitan area network (WAN), or a wide area network (WAN). The connection of two or more networks is called an internetwork. The worldwide Internet is a well-known example of an internetwork.
LANs are privately owned networks within a single building or campus of up to a few kilometers in size. They are widely used to connect personal computers and workstations in company offices and factories to share resources and exchange information.
In general, a given LAN will use only one type of transmission medium. Various topologies are possible for LANs. The most common LAN topologies are bus, ring and star.
A MAN is basically a bigger version of a LAN and normally uses similar technology. MAN is designed to extend over an entire city. It may be a single network such as a cable television network, or it may be a means of connecting a number of LANs into a large network so that resources may be shared LAN-to-LAN as well as device-to-device. For example, a company can use a MAN to connect the LANs in all of its offices throughout a city.
A WAN spans a large geographical area that may comprise a country, a continent, or even the world. It provides long-distance transmission of data, voice, image, and video information over large geographical area.
In contrast to LANs, WANs may utilize public leased, or private communication devices, usually in combinations, and can therefore span an unlimited number of miles.
Unit 6
Transmission media are used to transfer messages over a network. For instance, the transmission media used in a network may be a privately owned set of cables, the public phone lines, or a satellite system. Transmission media can either be wired or wireless.
The three types of wired media most commonly used to carry messages are twisted-pair wire, coaxial cable, and fiber-optic cable. One of the most successful developments in transmission media in recent years has been fiber optics. Fiber-optic cable is commonly used for the high-speed backbone lines of a network, or for Internet infrastructure.
Wireless transmission media have become especially popular in recent years. They support communications in situations in which physical wiring is impractical or inconvenient, as well as facilitate mobility. Wireless media are commonly used to connect devices to a network, to share information between computers, to connect wireless mice to a computer, and for handheld PCs, wireless phones, and other mobile devices. Radio signals transferred through the air are the heart of most types of wireless media. In addition to conventional broadcast radio application, the microwave, cellular, and satellite transmission media also use radio signals to transmit data.
Radio transmissions require the use of a transmitter to send the radio signals through the air. A receiver (usually containing some type of antenna) accepts the date at the other end. When a device functions as both a receiver and transmitter, it is commonly called a transceiver or transmitter-receiver.
Unit 7
(a) Since many database systems users are not computer trained, developers hide the complexity from users through several levels of abstraction, to simplify user’s int eractions with the system: physical level, logical level, and view level.
(b) A database schema is specified by a set of definitions expressed by a special language called a data-definition language (DDL). The result of compilation of DDL statements is a set of tables that is stored in a special file called data dictionary, or data directory.
(c) The structured query language (SQL) is the most widely used and standard query language for relational database management systems. It is a kind of non-procedural language.
(d) An entity is a “thing” or “object” in the real world that is distinguishable from other objects. For example, each person is an entity, and bank accounts can be considered to be entities. Entities are described in a database by a set of attributes.
(e) Data warehouse is one of the newest and hottest buzzwords and concepts in the IT field and the business environment.
A data warehouse is a logical collection of information——gathered from many different operational databases——that supports business analysis activities and decision-making tasks.
Unit 9
(a) AI is currently being applied in business in the form of knowledge systems, which use human knowledge to solve problems. The most popular type of knowledge-based system is the expert system. An expert system is a computer program that attempts to represent the knowledge of human experts in the form of heuristics. The term heuristic is derived from the same Greek root as the word eureka, which means “to discover”.
(b) The user interface enables the manager to enter instructions and information into the expert system and to receive information from it. The instructions specify the parameters that guide the expert system through its reasoning processing. The information is in the form of values assigned to certain variables.
(c) The knowledge base contains both facts that describe the problem area and knowledge representation techniques that describe how the facts fit together in a logical manner. The term problem domain is used to describe the problem area.
(d) An expert system, also called a knowledge-based system, is an artificial intelligence system that applies reasoning capabilities to reach a conclusion. Expert systems are excellent for diagnostic and prescriptive problems.
(e) The DSS is not intended to replace the manager. The computer can be applied to the structured portion of the problem, but the manager is responsible for the unstructured portion——applying judgment or intuition and conducting analyses.
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