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1、计算机专业英语教案第3章博主目录 2009-06-18 22:58 阅读32评论0 字号： 大大 中中 小小 第3章 Software Knowledge 3.1 Data Structures 3.2 Operating System 3.3 Programming Languages 3.4 Software Engineering 3.5 Software Testing and Maintenance 3.2 Operating System? The purpose of an operating system is to provide an environment in whic
2、h a user may execute programs.? Operating systems exist because they are a reasonable way to solve the problem of creating a usable computing system.? The primary goal of an operating system is convenience for the user.? A secondary goal is efficient operation of the computer system.Resource Managem
3、ent ? The operating system provides the means for the proper use of these resources in the operation of the computer system.? We can view an operating system as a resource allocates.? The operating system sets up the order in which programs are processed, and defines the sequence in which particular
4、 jobs are executed? I/O Management ? To facilitate execution of I/O operations, most operating systems have a standard set of control instructions to handle the processing of all input and output instructions. ? These standard instructions, referred to as the input/output control system (IOCS), are
5、an integral part of most operating systems.? The controlling software calls on the IOCS software to actually complete the I/O operation.Classification of Operating Systems ? A single-user operating system expects to deal with one set of input devicesthose that can be controlled by one user at a time
6、.? A multi-user operating system is designed to deal with input, output, and processing requests from many users-all at the same time.? A network operating system provides communications and routing services that allow computers to share data, programs and peripheral devices.? A multitasking operati
7、ng system provides process and memory management services that allow two or more programs to run simultaneously.? All modern operating systems are multitasking and can run several processes simultaneously.? A desktop operating system is one that is designed for a personal computereither a desktop or
8、 notebook computer.? 3.3 Programming Languages? A programming language or computer language is a standardized communication technique for expressing instructions to a computer.? A language enables a programmer to precisely specify what data a computer will act upon, how these data will be stored/tra
9、nsmitted, and what actions to take under various circumstances of cases.? Programming languages are important tools for helping software engineers write better programs faster.Procedural programming and Object-oriented programming ? Procedural programming involves using your knowledge of a programmi
10、ng language to create computer memory locations that can hold values and writing a series of steps or operations that manipulate those values.? A single procedural program often contains hundreds of variable and thousands of procedure calls.? Object-oriented programming is an extension of procedural
11、 programming in which you take a slightly different approach to writing computer programs.? Writing object-oriented programs involves both creating objects and creating applications that use those objects.Machine Language ? An executable program is a sequence of extremely simple instructions known a
12、s machine code.? Machine code instructions are binarythat is, sequences of bits (0s and 1s). ? Because these numbers are not understood easily by humans, computer instructions usually are not written in machine code.Assembly Language ? Assembly language uses commands that are easier for programmers
13、to understand than are machine-language commands. ? Each machine language instruction has an equivalent command in assembly language.? Assembly language is sometimes inserted into a high-level language program to carry out specific hardware tasks or to speed up a high-level program.High-Level Langua
14、ges ? If the computer could translate convenient symbols into basic operations, why couldnt it also perform other clerical coding functions? A high-level programming language is a means of writing down, in formal terms, the steps that must be performed to process a given set of data in a uniquely de
15、fined way.? The high-level languages are often oriented toward a particular class of processing problems.Compiler and Interpreter ? A complier is a program that translates source code into object code.? Every high-level programming language comes with a compiler. ? Because compilers translate source code into object code, which is unique for each type of computer
