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1、1第3章 Software Knowledge 3.1 Operating System3.2 Data Structures3.3 Programming Language3.4 专业英语应用模块23.1 Operating System What exactly does an operating system do?Basically,it performs a number of support functions.All modern operating systems are multitasking and can run several processes simultaneo
2、usly.In most computers there is only one CPU,so a multitasking operating system creates the illusion of several processes running simultaneously on the CPU.Operating systems can use virtual memory to run processes that require more main memory than is actually available.With this technique,space on
3、the hard drive is used to mimic the extra memory needed.3Main Contents of the Text Introduction Resource allocation and related functions Control of I/O Operations OS structure nResource allocation criteria depend on whether a resource is a system resource or a user-created resource.nTwo popular str
4、ategies for resource allocation are:Partitioning of resources;Allocation from a pool.45nTo 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.nThese standard instructions,referred to
5、as the Input/Output Control System(IOCS),are an integral part of most operating systems.nThey simplify the means by which all programs being processed may undertake I/O operations.6nOS design strongly depends on two factors:architectural features of the computer on which it operates,and features of
6、its application domain.nThe dependence on these two factors poses obvious difficulties in using an OS on computers with different architectures and different application domains.7nIn early operating systems,this approach faced several difficulties due to the monolithic structure of the OS.nThus,oper
7、ating systems did not provide clean interfaces between the architecture specific and architecture independent parts of their code.Hence the total porting effort was determined by the total size of OS code,rather than by the size of its architecture specific part.8Key Words allot 分配concurrently 同时发生地
8、considerable 相当的，重要的constraint 强制，约束criteria 标准critical 批评的，临界的domain 领域，范围embody 使具体化entrust 信托，委托illusion 幻影，幻想integral 整体的mechanism 机制，机理9Key Words mimic 模拟，模仿monolithic 整体的，完全统一的partition 分割perceive 感知，认知perceptible 可察觉的，感觉得到的primitive 原始的，基本的privilege 特权suspend 暂停，挂起undergo 经历utilization 利用10No
9、tes 1 The most common mechanism used to create this illusion is time slice multitasking,whereby each process is run individually for a fixed period of time.译文：产生这种错觉的最常用机制是时间分割多任务处理，以每个过程各自运行固定的一段时间的方式来实现的。过去分词短语used to create this illusion作定语，修饰mechanism；由 whereby引 导 的 是 非 限 制 性 定 语 从 句。whereby：by
10、means of which，以方式；凭借。11Notes 2 The processes appear to run simultaneously because the users sense of time is much slower than the processing speed of the computer.译文：由于用户的时间感觉比计算机的处理速度要慢得多，所以几个程序看起来是同时执行的。本句中由“because”引导原因状语从句，“much slower than”是比较结构。12Notes 3 Operating systems can use virtual memo
11、ry to run processes that require more main memory than is actually available.译文：实际可用空间不够时，为了运行那些需要更多主存储空间的程序，操作系统可以利用虚拟存储器。本句中，to run processes到句末为目的状语；由that引导的定语从句修饰和限定processes；than后面省略了主语that(that意指main memory)。13Notes 4 Both the partitioning and the pool-based allocation approaches can be used t
12、o manage the memory resource.译文：资源分区和基于资源池的分配方式都适用于存储器资源管理。本句的主语是由并列的两部分组成，即“Both the partitioning and the pool-based allocation approaches”，并且用被动态表示客观性。14Notes 5 Taking advantage of this facility,data read from one location may be distributed throughout computerized system.译文：利用这一功能，读自某一设备的数据可以分布贯穿
13、整个计算机处理系统。现在分词短语Taking做伴随状语；过去分词短语read from one location作定语，修饰主语data。15Reading Material Linux Operating System nLinux is an operating system that was initially created as a hobby by a young student,Linus Torvaids,at the University of Helsinki in Finland.nLinux is an implementation of the Unix design
14、 philosophy,which means that it is a multi-user system.nLinux is open.This means that all programmers and users can have access to the source code as well as the right to modify it.16Reading Material Linux Operating SystemnLinux is available in several formats.nIn order to get a better understanding
15、 of the way your Linux system works,or how to customize it to suit your needs,you should read the HOWTO documents.nLinux is one of the more stable operating systems available today.173.2 Data Structures Data structures organize data in ways that make algorithms more efficient.For example,consider so
16、me of the ways we can organize data for searching it.Data structures provide a more understandable way to look at data;thus,they offer a level of abstraction in solving problems.Data structures are reusable because they tend to be modular and context-free.They are modular because each has a prescrib
17、ed interface through which access to data stored in the data structure is restricted.18Main Contents of the Text An introduction to data structures Data structures and algorithms Data type 19nAny data structure is designed to organize data to suit a specific purpose so that it can be accessed and wo
18、rked with in appropriate ways.nIn computer programming,a data structure may be selected or designed to store data for the purpose of working on it with various algorithms.20nAlgorithms and data structures can be specified in any adequately precise language.nEnglish and other natural languages are sa
19、tisfactory if used with care to avoid ambiguity but more precise mathematical languages and programming languages are generally preferred.21nIf we provide a set of possible data values and a set of operations that act on the values,we can think of the combination as a data type.nLet us look at two c
20、lasses of data types.nWe will call any data type whose values we choose to consider atomic an atomic data type.Often we choose to consider integers to be atomic.22nWe will call any data type whose values are composed of component elements that are related by some structure a structured data type,or
21、data structure.nIn other words,the values of these data types are decomposable,and we must therefore be aware of their internal construction.23（1）Classes of data typesnAtomic data types(values are not decomposable).nData Structures(values are decomposable).（2）Data StructureA data type whose valuesnC
22、an be decomposed into a set of component data elements each of which is either atomic or another data structure.nInclude a set of associations or relationships(structure)involving the component elements.24Key Words Abstraction 抽象，摘要adequately 足够地，适当地arithmetic 算术，算法attribute 属性considerably非常地，很decom
23、pose分解equivalent相等的，同等的essential 重要的，本质的gracefully优美地heap 堆ingredient 组成，成分25Key Words irrelevant不恰当的，不相干的modular 有标准组件的property性质，属性recipe 食谱reusability可再使用地seemingly外观上地，表面上地simplistic过分简单化的superfluous多余的，过剩的terminate结束，终止26Notes 1 Data structures are context-free because they can be used with any
24、 type of data and in a variety of situations or contexts.译文：因为数据结构能用于任何类型的数据，并用于多种环境中，所以数据结构与使用环境无关。本句中的“because”引导原因状语从句。27Notes 2 General data structure types include the array,the file,the record,the table,the tree,and so on.译文：一般的数据结构类型包括数组、文件、记录、表、树等。本句中的“the array,the file,the record,the table
25、,the tree,and so on”是宾语，其中包含若干项并列部分。28Notes 3 One of the arts of computer programming is to suppress unnecessary detail of the problem and of the computer used.译文：计算机程序设计的艺术之一就是消除一个问题中和所用计算机不必要的细节。本句中的表语是不定式结构，“of the problem and of the computer used”是定语，修饰“detail”。29Notes 4 The essence of a data ty
26、pe is that it attempts to identify qualities common to a group of individuals or objects that distinguish it as an identifiable class or kind.译文：数据类型的本质是标识一组个体或目标所共有的特性，这些特性把该组个体作为可识别的种类。本句由两个复合句构成，均由“that”引导。第一个“that”引导表语从句；第二个“that”引导限定性定语从句，修饰“qualities”，“it”代表“a group of individuals or objects”。
27、30Notes 5 A data structure is a data type whose values are composed of component elements that are related by some structure.译文：数据结构是一种数据类型，其值是由与某些结构有关的组成元素所构成的。由“whose”引导的限定性定语从句修饰“a data type”，“that”引导的限定性定语从句修饰“component elements”。31Reading Material Stacks and Queues The end of a stack at which e
28、ntries are inserted and deleted is called the top of the stack.The other end is sometimes called the stacks base.To reflect the fact that access to a stack is restricted to the topmost entry,we use special terminology when referring to the insertion and deletion operations.The process of inserting a
29、n object on the stack is called a push operation,and the process of deleting an object is called a pop operation.Thus we speak of pushing an entry onto a stack and popping an entry off a stack.32Reading Material Stacks and Queues Queues occur frequently in everyday life and are therefore familiar to
30、 us.There are many applications of the first-in/first-out(FIFO)protocol of queues in computing.For example,the line of input/output(I/O)requests waiting for access to a disk drive in a multi-user time-sharing system might be a queue.The line of computing jobs waiting to be run on a computer system m
31、ight also be a queue.The jobs and I/O requests are serviced in order of their arrival,that is,the first in is the first out.333.3 Programming Language nA programming language represents a special vocabulary and a set of grammatical rules for instructing a computer to perform specific tasks.nBroadly
32、speaking,it consists of a set of statements or expressions understandable to both people and computers.34Main Contents of the TextnMachine Language nAssembly Language nHigh-Level Languages nC+and Object-Oriented Programming Encapsulation and Data hiding Inheritance and Reuse Polymorphism 35nAn execu
33、table program is a sequence of extremely simple instructions known as machine code.nMachine code instructions are binarythat is,sequences of bits(0s and 1s).36nLying between machine languages and high-level languages are assembly languages,which are directly related to a computers machine language.n
34、In other words,it takes one assembly command to generate each machine language command.Machine languages consist entirely of numbers and are almost impossible for humans to read and write.37nOnce an assembly-language program is written,it is converted to a machine-language program by another program
35、 called an assembler.nAssembly language is fast and powerful because of its correspondence with machine language.38nA 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 defined way.nThe high-level l
36、anguages are often oriented toward a particular class of processing problems.39 In a high-level language we would expect to find facilities to do the following:nstructure the program;ndefine data elements,give them a name,size and types;nprocess data elements(arithmetic/Boolean/transfer);ncontrol fl
37、ow of program(test,branch);nallow commonly used program to be used repeatedly(loops,subroutines,procedures);nallow input/output of data.40nC+is a highly portable language,and translators for it exist on many different machines and systems.nC+compilers are highly compatible with existing C programs b
38、ecause maintaining such compatibility was a design objective.nC+fully supports object-oriented programming,including the four pillars of object-oriented development:encapsulation,data hiding,inheritance,and polymorphism.41Key Words accelerator 加速器assembler 汇编程序，汇编器carburetor 化油器，汽化器encapsulation 封装e
39、xecutable 可执行的，可实行的facility 容易，便利，工具inheritance 继承injection 注满，充满42Key Words morph 变种，形态orthogonal 正交的，互相垂直的pillar 台柱，栋梁polymorphism 多态性，多形性roughly 粗略地scratch 凑合的，随意的subclass 子类subroutine 子程序terseness 简洁，简练turbocharger 涡轮增压器43Notes 1 Because these numbers are not understood easily by humans,computer
40、 instructions usually are not written in machine code.译文：由于这些数字令人难以理解，所以计算机指令通常不是用机器码来写的。本句中由“Because”引导原因状语从句，主句用被动语态。44Notes 2 It is a general-purpose and more comprehensive applications programming language developed by Ejarne Stroustrup at Bell Laboratory.译文：它是由贝尔实验室的Ejarne Stroustrup开发的一种通用的、更完
41、整的应用程序设计语言。本句中的“It”指C语言，表语是并列的两部分，“developed by”是过去分词短语作定语，修饰“language”。45Notes 3 Unlike other object-oriented languages,such as Smalltalk,C+is an extension of an existing language widely used on many machines.译文：不像其他的面向对象语言，如Smalltalk语言，C+是现有语言的一种扩展，它广泛地用于很多种机器。本 句 中 的“Unlike other object-oriented
42、languages”是状语，“such as Smalltalk”是同位语。46Notes 4 C+supports the properties of encapsulation and data hiding through the creation of user-defined types,called classes.译文：C+通过创建称为类的用户定义类型而支持封装和数据隐藏的属性。本句中的“through the creation of user-defined types”是状语，而“called classes”是同位语。47Notes 5 This new subclass
43、is said to derive from the existing type and is sometimes called a derived type.译文：这个新的子类从已存在类派生而来，可称为派生类。这是一个并列句，主语是“This new subclass”，本句使用被动语态。48Reading Material Software EngineeringnSoftware engineering is the application of tools,methods,and disciplines to produce and maintain an automated solu
44、tion to a real-world problem.nThe overall objective of software engineering is to give the reader a sense of the flow of events in an integrated system and software development effort,and appreciation for and understanding of the software engineers role in the system development process,and a compre
45、hensive preparation for assuming responsibilities of a software engineer.49Reading Material Software EngineeringnIn recent years,software engineering techniques have begun to reflect this underlying contradiction as illustrated by the emergence of the incremental model for software development.nThe
46、incremental model is evidence of the trend in software development toward prototyping in which incomplete versions of the proposed system,called prototypes,are built and evaluated.503.4 专业英语应用模块专业英语应用模块3.4.1 Computer Malfunction3.4.2 The Malfunctions of Main Board51引起计算机故障的原因：引起计算机故障的原因：（1）工作环境引起的故障
47、n静电常造成主板上的芯片被击穿，主板遇到电源损坏或电网电压瞬间产生的尖峰脉冲时，往往会损坏主板供电插头附近的芯片，主板上的灰尘也会造成信号短路。（2）人为原因引起的故障n带电插拔各种板卡，以及在装板卡及插头时用力不当造成对接口、芯片等的损害。52（3）接触不良引起的故障n各种芯片、插座、接口因锈蚀、氧化等原因而产生的故障。（4）器件质量问题引起的故障。（5）软硬件不兼容。n由于软硬件不兼容，造成系统不能启动或不能开机。（6）短路、断路引起的故障。53常见故障：常见故障：n启动计算机时屏幕显示“CMOS Battery Failed”。n故障现象：开机时屏幕显示“CMOS Battery Fai
48、led”。n故障原因：表明CMOS电池失效或电力不足。n解决方法：更换CMOS电池。54主板无法启动故障主板无法启动故障n故障现象：主板无法正常启动，同时发出“滴滴”警报声。n故障原因：出现这种现象的可能原因是，主板内存插槽质量低劣，内存条上的金手指与插槽簧片接触不良；也有可能是内存条上的金手指表面的镀金效果不好，在长时间工作中，镀金表面出现了很厚的氧化层；还有可能是，内存条生产工艺不够标准。n解决方法：将计算机机箱打开，断开电源，取出内存条，将出现在内存条上的灰尘或氧化层用橡皮擦干净，然后重新插入到内存插槽中即可。确保内存条不会左右晃动，这样也能有效避免金手指被氧化。要是上面的方法无法解决故障，可以更换新的内存条试试。55主板散热不良故障主板散热不良故障n故障现象：电脑频繁死机，在进行CMOS设置时也会出现死机现象。n故障原因：这种故障一般是主板散热不良或主板Cache（缓存）有问题引起的。n解决方法：如果因主板散热不够好而导致该故障，可以在死机后触摸CPU周围主板元件，会发现其温度非常高，在更换大功率风扇之后，死机故障即可解决。如果是Cache有问题造成的，则可以进入CMOS设置，将Cache禁止后即可。当然，Cache禁止后，机器速度肯定会受到影响。如果仍不能解决故障，只有更换主板或CPU了。