The Fundamentals of Computer Software
Data Structure
A data structure is a data type,Its values are composed of component elements that are related by some structure.
Since a data structure is a data type,it has a set of operations on its values,In addition,there may be operations that act on its component elements,The operations of a structured data type might not only act on the values of the data type,they might also act on component elements of the data structure.
The data type’s arrays and records are native to many programming languages,By using the pointer data type and dynamic memory allocation,many programming languages also provide the facilities for constructing linked structures,The first two higher-level abstract data types are stacks and queues,They are extremely important to computing.
A stack is a data type,Its major attributes are the way the insertion and deletion of its elements,The only element that can be deleted or removed is the one that was inserted most recently,Such a structure is said to have a last-in/first-out (LIFO) behavior.
Queues are familiar to us,The line of people waiting for service at a bank is an example of queues,The main feature of queues is that they follow a first-come/first-served rule,In queues,the earliest element inserted is the first served,In social settings,the rule appeals to our sense of equality and fairness,There are many applications of the first-in/first-out (FIFO) protocol of queues in computing,For example,the line of I/O requests waiting for access to a disk drive might be a queue,The line of computing jobs waiting to be run on a computer system might also be a queue.
参考译文数据结构数据结构是一种数据类型,其值是由通过某种结构相互关联的组成元素所构成的。
由于数据结构是一种数据类型,因此它有一组针对这些值的操作;而且,可能有一些操作是作用于其组成元素的。结构化的数据类型的操作不仅可以作用于数据类型的值,并且也可以作用于数据结构的组成元素。
数据类型数组和记录对众多程序设计语言来说都是固有的数据类型。通过使用指针数据类型和动态存储分配,很多程序设计语言还提供了建立链接结构的功能。我们将要讨论的两种更高一级的抽象数据类型是堆栈和队列,它们对计算至关重要。
堆栈是一种数据类型,其主要性质是由支配其元素的插入与删除的规则来决定的。惟一能被删除或移去的元素只能是最后插入的元素,这就是所谓具有后进先出(LIFO)性质的结构。
队列对我们来说是非常熟悉的。在银行等待服务的一队人,就是队列的一个例子。队列的主要特征是遵循先来先服务的规则。在队列中,最先插入的元素将最先被服务。这种原则与社会生活中人们公平合理的观念是一致的。队列的先进先出(FIFO)协议在计算中有很多应用。例如,等待访问磁盘驱动器的多个输入/输出请求就可以是一个队列。在计算机中等待运行的计算作业也同样是一个队列。
Operating Systems
What is an Operating System
The most important program on any computer is the Operating System or OS,The OS is a large program made up of many smaller programs,It control how the CPU communicates with other hardware components,It also makes computers easier to operate by people who don't understand programming languages,In other words,operating systems make computer users friendly.
ROM and RAM are very important to the OS,Part of a computer's operating system is built into ROM,The ROM operating system is also known as the BIOS (Basic Input Output System),The BIOS is responsible for waking up the computer when you turn it on,It also reminds the computer of all the parts it has and what they do.
The operating system also contains other programs that are important,This part of the operating system is stored on a computer's hard drive,When the computer is turned on,it is booted to RAM,This part of the operating system is known as DOS.
Types of Operating Systems
There are different operating systems available for PCs,but the most common is Windows,Windows was developed by a company named Microsoft,It uses a mouse and a GUI (Graphical User Interface) to help the user operate the computer.
There are several versions of Windows (Windows 95/98/ME/NT/2000/XP),Operating systems are constantly being improved or upgraded as technology advances,Upgrading an operating system can have several advantages,such as simplifying tasks and navigation,However,there can be disadvantages,too,Many older programs would no longer run within the new operating system.
参考译文操作系统什么是操作系统计算机中最重要的程序就是操作系统。操作系统是一个由很多小程序组成的大的程序。它控制CPU与硬件间的通信,方便不懂得编程语言的用户操作计算机。换句话说,操作系统使用户更友好地操作计算机。
RAM和ROM对操作系统来说非常重要。计算机操作系统中的一部分就建立在ROM上,这种ROM中的操作系统也叫BIOS。当你开机的时候BIOS负责唤醒计算机并提醒它所有的部分,而且告诉它们将做的工作。
操作系统还包括其他非常重要的程序。这部分操作系统是存储在计算机的硬盘上的,当开机的时候,它被读到RAM中。这一部分的操作系统被称为DOS。
操作系统的种类现在有很多适合PC机的操作系统,但最常见的就是Windows。它是由微软公司开发的,使用鼠标和图形用户界面来帮助用户操作计算机。
目前有几种Windows版本(Windows 95/98/ME/NT/2000/XP)。随着技术的提高,操作系统经常被改进和升级。升级一个操作系统会有很多好处,如任务简单了,便于导航;但是也有缺点,以前的很多程序在新的操作系统下不能运行了。
Windows 2000 Overview
With each new release of Windows,Microsoft gives you new and inventive technologies to build more useful,manageable,and scalable networks,Windows 2000 is the most innovative release to date,There are four separate products that form the Windows 2000:
Windows 2000 Professional
Windows 2000 Server
Windows 2000 Advanced Server
Windows 2000 Datacenter Server
Each of these products includes key advancements that change how you plan,design,and deploy Microsoft networks,To employ such groundbreaking features as Active Directory,Dynamic DNS (DDNS),you will need to plan ahead,Now we offer an overview of the key Windows 2000 technologies and services.
Active Directory
Microsoft networks that are built with Active Directory can help you when you meet these challenges,Unlike down level directory services,Active Directory is hierarchical,Active Directory stores each of your company's resources logically,forming a tree structure that mirrors your enterprise,Every resource in even the largest networks is easy to find and manage.
Security
The cornerstone of Windows 2000 security is Active Directory,It supports the granular access control,inheritance,and delegation of administrative task,This gives you the flexibility to secure resources without compromising your network's purpose,Fine-granted access control is not offered in Windows NT 3.x or 4.0,This often forces you to assign permissions that give either too little or too much control,
Storage
The Encrypting File System (EFS) would not be possible without extensions to NTFS,New Technology File System (NTFS) 5.0 is the foundation for several enhancement in Windows 2000,Sharing and managing your company's data is top priority,You must gain complete control of storage to be a successful administrator.
Networking
The improvements to networking in Windows 2000 are groundbreaking,For example,you have the opportunity in Windows 2000 to remove all NetBIOS traffic from your network,The Dynamic Domain Name System (DDNS) can entirely eliminate your dependence on NetBIOS and WINS,Some of the topics covered in this section are new in Windows 2000,others represent improvement to existing technologies.
Enterprise Management
Along with its advances in directory management,security,public key cryptography,storage,and networking,Windows 2000 includes improvement in enterprise management,Total Cost of Ownership (TCO) is a leading concern shared by many companies,After you deploy a particular technology,a TCO study will consider the cost of maintaining (or owning),In corporate networks,most TCO efforts are aimed at reducing the expense of managing desktops.
参考译文
Windows 2000概述随着每一个新的Windows版本的发行,微软都会带来一些创新的技术,用来架构更为有用的、易于管理的、可伸缩的网络。Windows 2000是一个迄今为止最为创新的版本。Windows 2000操作系统共包括4个独立的产品:
Windows 2000专业版
Windows 2000服务器版
Windows 2000高级服务器版
Windows 2000数据中心服务器版上述这些产品都提供了一些关键技术,这些技术改变了你规划、设计、架构微软网络的方式。为了使用如活动目录、动态域名系统等创造性的特性,你应该使规划更具前瞻性。下面我们来对Windows 2000的关键技术和服务作一些概要性的介绍。
活动目录用活动目录架构的微软网络能帮助你处理很多问题。与以前低级的目录服务不同,活动目录是分层次的。活动目录逻辑上存储了你公司中的每一个资源,形成树状结构来镜像你的公司资源。甚至在最大的网络里的任何资源,都易于查找和管理。
安全性
Windows 2000安全性的基石是活动目录。它支持粒度访问控制、继承性、管理任务的授权,所有的这些都给你以足够的灵活性去保证资源安全而又不损害网络用途。Windows NT 3.x或者Windows NT 4.0并没有提供比较好的访问控制。这经常迫使你分配的权限不是太多就是太少。
存储没有NTFS的扩展是不可能实现加密文件系统的。NTFS 5.0是Windows 2000许多功能增强的基础。共享和管理公司的数据是最高的优先级。作为一个成功的系统管理员,你必须具有完整的存储控制权。
联网
Windows 2000联网方面的改进是有创造性的。例如,在Windows 2000中,你有机会消除网络里的所有NetBIOS通信,动态的DNS可以彻底消除对NetBIOS和WINS的依赖。这部分中的有些技术在Windows 2000里是全新的,而有些却是现有技术的改进。
企业管理随着目录管理、安全性、公共密钥加密、存储和联网技术的发展,Windows 2000也包括了对企业管理的改进。总拥有成本TCO是许多公司共同关心的首要课题。在你部署一个技术后,TCO研究要考虑的是维护(或拥有)成本。在公司网络中,大多数TCO努力的目标是减少台式电脑管理的费用。