计算机专业英语 本课程知识结构 计算机专业英语 第1篇 第4篇 第2篇 第1篇 基础篇 Chapter 1 Architecture of Computer Systems Text Any discussion of computer architectures,of how computers and computer systems are organized,designed,and implemented,will inevitably make reference to the “von Neumann architecture” as a basis for comparison,because virtually every electronic computer ever built has been rooted in this architecture. [1] 返 回 第1篇 基础篇 We have strong intuitive feelings about the “von Neumann architecture”, because this is what we have always used.This is “the way computers work”.To comprehend how computer designers conceive,or to appreciate what new choices must be found,it is necessary to have a definitive understanding of what the von Neumann architecture is and is not and what its implications are. The von Neumann architecture based on three ideas:four subsystems,stored program concept and sequential execution of instructions.[2] 第1篇 基础篇 Four Subsystems According to Von Neumann’s preliminary discussion, the general purpose computing machine contains four main “organs”.These are identified as relating to arithmetic,memory,control,and connection with the human operator.In other words,they are the arithmetic logic unit,the control unit, the memory,and the input output devices that we see in the classical model of what a computer “looks like”. The control unit(CU), arithmetic logic unit(ALU) and register constitute the central processing unit(CPU) 第1篇 基础篇 Four Subsystems According to Von Neumann’s preliminary discussion, the general purpose computing machine contains four main “organs”.These are identified as relating to arithmetic,memory,control,and connection with the human operator.In other words,they are the arithmetic logic unit,the control unit, the memory,and the input output devices that we see in the classical model of what a computer “looks like”. The control unit(CU), arithmetic logic unit(ALU) and register constitute the central processing unit(CPU) 第1篇 基础篇 Stored Program Concept To Von Neumann,the key to building a general purpose device lies in its ability to store not only its data and the intermediate results of computation,but also to store the instructions,or orders, which bring about the computation. [3]In a general purpose one, the instructions must be as changeable as the numbers they acted upon. Therefore, why not encode the instructions into numeric form and store instructions and data in the same memory? Von Neumann proposes that programs and data should be stored in the same binary number format in the memory device.[4] 第1篇 基础篇 Usually,this is viewed as the principal contribution provided by Von Neumann’s insight into the nature of what a computer should be,which brings the significant breakthrough in the development of the general purpose electronic computer used today. That is what we all know— the concept of a stored program. 第1篇 基础篇 Sequential Execution of Instructions Based on the stored program concept, computers store programs and data in a slow to access storage medium(such as a hard disk) and work on them in a fast access, volatile storage medium (RAM).[5]However, this concept has a perceived bottle neck:it is designed to process instructions one after another instead of using faster parallel processing. [6]When the program executes,the message seems to appear all at once,but the speed of the computer has deceived you. In fact, one instruction executes in sequence,that is at a time: fetching one instruction from memory,interpreting (decoding) it and executing it. The computer does not go on to the next instruction until the one it is working on is completed. 第1篇 基础篇 Key Words & Terms according to 依照…… architecture breakthrough constitute decode encode fetch implication instruction intuitive in sequence parallel processing preliminary stored program concept sequential subsystem 第1篇 基础篇 Chapter 2 Data Structure Text 返 回 In computer science,the way information is organized in the memory of a computer is called a data structure. [1] It’s a data type whose values are composed of component elements that are related by some structure. Much of programming involves the storage and retrieval of data. Many of the most efficient algorithms for important problems are based on the use of specific data structures;the efficiency of the algorithm depends on the efficiency of the underlying data structure.[2]Software design often involves the choice of appropriate data structures. 第1篇 基础篇 For example, imagine that you are asked to create a database of names with ABC company’s management and employees. To start your work,you make a list of everyone in the company along with their position, as shown in Table 2-1. Name Position Name Position Aaron Manager Martha Employee Charles VP Patricia Employee George Employee Rick Secretary Jack Employee Sarah VP Janet VP Susan Manager John president Thomas Employee Kim Manager Zack Employee Larry Manager 第1篇 基础篇 Although this list contains both name and position,it does not tell you which managers are responsible for which workers and so on. If you want your database to represent the relationships between management and employees at ABC,a tree diagram depicted Figure 2-1 is a much better structure for showing the work relationship at ABC. 第1篇 基础篇 These two diagrams are examples of different data structures. If you want to locate the employee’s record very quickly,you can use the list that keeps the names of the employees in alphabetical order;If you want to see relationships between employees, the tree structure is much better. There are many different data structures that programmers use to organize data in computers. Each data structure has certain operations that naturally fit with data structure. Often these operations are bundled with the data structure and together they are called a data type. An example of several common data structures are array,linked list,stack,queue, binary tree,and hash table. 第1篇 基础篇 List A collection of items accessible one after another beginning at the head and ending at the tail. Stack A collection of items in which only the most recently added item may be removed. The latest added item is at the top. Basic operations are push and pop. Also known as “last in, first out” or LIFO. Queue A collection of items in which only the earliest added item may be accessed. Basic operations are add (to the tail) or enqueue and delete (from the head) or dequeue. Delete returns the item removed. Also known as “first in, first out” or FIFO. 第1篇 基础篇 List A collection of items accessible one after another beginning at the head and ending at the tail. Stack A collection of items in which only the most recently added item may be removed. The latest added item is at the top. Basic operations are push and pop. Also known as “last in, first out” or LIFO. Queue A collection of items in which only the earliest added item may be accessed. Basic operations are add (to the tail) or enqueue and delete (from the head) or dequeue. Delete returns the item removed. Also known as “first in, first out” or FIFO. 第1篇 基础篇 Tree A data structure accessed beginning at the root node. Each node is either a leaf or an internal node. An internal node has one or more child nodes and is called the parent of its child nodes.[3]All children of the same node are siblings. Contrary to a physical tree,the root is usually depicted at the top of the structure, and the leaves are depicted at the bottom. 第1篇 基础篇 Key Words & Terms algorithm alphabetical appropriate array depict dequeue diagram enqueue hash table queue retrieval sibling stack 第1篇 基础篇 Abbreviations FIFO(First In First Out) FIFO(Last In First Out) 后进先出 第1篇 基础篇 Chapter 3 File Format Text In general terms,a file format in the what type of information is contained in a These are usually designated by the one to three) characters(the extensions) after filename.[1] 返 回 PC world signifies particular file. four (usually the period in a TXT A file ending in “.TXT” usually designates that the file is a plain text file. This can contain virtually any type of text — a recipe,documentation for software,a book report draft,or whatever. When a file ending in “.TXT” is double clicked,a text editor,such as notepad,should appear, allowing you to view and/or edit the contents of the file. 第1篇 基础篇 PDF If a file has the extension .pdf,then it most likely is in the Portable Document Format (PDF),developed by Adobe Systems, Inc. PDF maintains the original document formatting for both printing and viewing on a multiple computing platforms, including Windows,UNIX and Mac. Although they contain the complete formatting of the original document,including fonts and images, PDF files are highly compressed, allowing complex information to be downloaded efficiently.[2] To view PDF files, you must download the Adobe Acrobat Reader,which is free software for viewing and printing Adobe Portable Document Format (PDF) files on major hardware and operating system platforms. 第1篇 基础篇 For storing digital images,there is a large number of formats too. Most formats were developed for particular programs,some have become the standards,and a few formats were developed specifically for interchanging files between different programs and computers. [3] Following are some of the formats most commonly used. 第1篇 基础篇 BMP BMP is the native bitmap file format of the Microsoft Windows environment. It efficiently stores mapped or unmapped RGB graphics data with pixels 1 bits,4 bits, 8 bits,or 24 bits in size. BMP is an excellent choice for a simple bitmap format which supports a wide range of RGB image data. Bitmap images can be produced from existing drawings or photographs by “scanners” and edited with “image editing” programs such as Adobe Photoshop.[4] GIF A mapped bitmap format developed for file interchange, commonly used for icons and other graphics on the Web.The GIF (Graphic Interchange Format) is limited to 256 colors.A single GIF file can combine several frames together for basic animated motion.A good compression method is built into the format. 第1篇 基础篇 JPEG Named after the Joint Photographic Experts Group,JPEG is a lossy codec for storing and transferring full color digital images that’s often used to post photography and artwork on the Web.[5]JPEG compression takes advantage of the human eye’s inability to see minute color changes,removing portions of data from the original picture file.When creating a JPEG file, varying amounts of compression can be selected,depending on the desired file size and image quality. TIFF TIFF(Tag Image File Format) is a flexible container format for digital still images.It can incorporate various forms of compression (like JPEG),or can be uncompressed.Some digital cameras offer a special TIFF mode for capturing uncompressed photos;however,these files require many times more storage space than JPEGs,and can quickly fill up your camera’s available memory. 第1篇 基础篇 Key Words & Terms bitmap camera codec compress designate draft extension incorporate interchange lossy motion notepad pixel platform 平台 第1篇 基础篇 Abbreviations GIF(Graphic Interchange Format) JPEG(Joint Photographic Experts Group) PDF(Portable Document Format) TIFF(Tag Image File Format) 标签图像文件格式 第1篇 基础篇 Chapter 4 Database Management System Text A database management system (DBMS),sometimes just called a database manager,is a program that lets one or more computer users create, access,update and manage the data.[1] Technically speaking,it is a software system that uses a standard method of cataloging,retrieving,and running queries on data. Databases are usually designed to manage large bodies of information. This involves definition of structures for information storage (data modeling),provision of mechanisms for the manipulation of information (file and systems structure, query processing), concurrency control if the system is shared by users, and providing for the safety of information in the database (crash recovery and security). 第1篇 基础篇 The DBMS manages user requests (and requests from other programs) so that users and other programs are free from having to understand where the data is physically located on storage media and,in a multi user system,who else may also be accessing the data.[2]In handling user requests,the DBMS ensures the integrity of the data (that is,making sure it continues to be accessible and is consistently organized as intended) and security (making sure only those with access privileges can access the data). 第1篇 基础篇 The goal of a DBMS is to provide an environment that is both convenient and efficient to use in retrieving information from the database and storing information into the database. [3]The most typical DBMS is a Relational Database Management System (RDBMS).The standard user and program interface for RDBMS is the Structured Query Language (SQL).A newer kind of DBMS is the object oriented database management system (ODBMS). A DBMS can be thought of as a file manager that manages data in databases rather than files in file systems.In IBM’s mainframe operating systems,the nonrelational data managers were (and are,because these legacy application systems are still used) known as access methods. 第1篇 基础篇 A DBMS is usually an inherent part of a database product.On PCs,Microsoft Access is a popular example of a single or small group user DBMS. Microsoft’s SQL Server is an example of a DBMS that serves database requests from multiple (client) users. Other popular DBMSs are IBM’s DB2,Oracle’s line of database management products, and Sybase’s products. 第1篇 基础篇 Key Words & Terms catalog consistently crash database definition inherent integrity involving manipulation persistent privilege Provision retrieve storage technically 包括,使…… 技术上 第1篇 基础篇 Abbreviations DBMS(database management system) RDBMS(Relational Data (base) Management System) SQL(Structured Query Language) 结构化查询语言 第1篇 基础篇 Chapter 5 IP Address Text Every computer that communicates over the Internet is assigned an IP address that uniquely identifies the device and distinguishes it from other computers on the Internet. [1]To make it easier for us to remember,a typical IP address is normally expressed in decimal format as a “dotted decimal number” like 192.168.10.126. But computers communicate in binary form. Look at the same IP address in binary 11000000.10101000.00001010.01111110 The four numbers in an IP address are called octets, because they each have eight positions when viewed in binary form. 第1篇 基础篇 Every IP address consists of 32 bits,often shown as 4 octets of numbers from 0 to 255 represented in decimal form instead of binary form.[2]It consists of two parts,the first part of an Internet address identifies the network on which the host resides,while the second part identifies the particular host on the given network. This creates the two level addressing hierarchy that is illustrated in Figure 5-1. NetworkNumber Host Number 第1篇 基础篇 In recent years, the network number field has been referred to as the network prefix because the leading portion of each IP address identifies the network number. All hosts on a given network share the same network prefix but must have a unique host number. [3]Similarly,any two hosts on different networks must have different network prefixes but may have the same host number. There are 5 different address classes plus certain special addresses. You can determine which class an IP address is in by examining the first 4 bits of the IP address. [4] 第1篇 基础篇 Default Network:The IP address of 0.0.0.0 is used for the default network. Class A Network:Binary address start with 0, therefore the decimal number can be anyone from 1 to 126. The first 8 bits (the first octet) identify the network and the remaining 24 bits indicate the host within the network. An example of a Class A IP address is 102.168.212.226, where “102” identifies the network and “168.212.226” identifies the host on this network. 第1篇 基础篇 Class B Network:binary addresses start with 10, therefore the decimal number can be anyone from 128 to 191. (The number 127 is reserved for loopback and is used for internal testing on the local machine. [5]) The first 16 bits (the first two octets) identify the network and the remaining 16 bits indicate the host within the network. An example of a Class B IP address is 168.212.226.204 where “168.212” identifies the network and “226.204” identifies the host on this network. 第1篇 基础篇 Loop back:The IP address 127.0.0.1 is used as the loop back address. This means that it is used by the host computer to send a message back to itself. It is commonly used for troubleshooting and network testing. Class C Network:binary addresses start with 110,therefore the decimal number can be anyone from 192 to 223. The first 24 bits (the first three octets) identify the network and the remaining 8 bits indicate the host within the network. An example of a Class C IP address is 200.168.212.226 where “200.168.212” identifies the network and “226” identifies the host on this network.[6] 第1篇 基础篇 Class D Network:binary addresses start with 1110, therefore the decimal number can be anyone from 224 to 239. Class D networks are used to support multicasting. Class E Network:binary addresses start with 1111, therefore the decimal number can be anyone from 240 to 255. Class E networks are used for experimentation. They have never been documented or utilized in a standard way. Broadcast:Messages that are intended for all computers on a network are sent as broadcasts. [7]These messages always use the IP address 255.255.255.255. 第1篇 基础篇 Key Words & Terms binary broadcast decimal distinguish hierarchy loop back multicasting prefix troubleshooting uniquely 第1篇 基础篇 Abbreviations IP(Internet Protocol) 网际协议,网间协议 第2篇 硬件篇 Chapter 6 CPU Text 返 回 CPU is the abbreviation of central processing unit,and pronounced as separate letters. Sometimes it is referred to simply as the processor or central processor. The CPU is the brains of the computer. It is responsible for handling all instructions and calculations it receives from other hardware components in the computer and software programs running on the computer.[1] For example,the CPU runs the operating system, the software programs installed on your computer,and device peripherals such as printers and flatbed scanners.In terms of computing power,the CPU is the most important element of a computer system. 第2篇 硬件篇 All the CPU does is run programs by fetching instructions from RAM,evaluating them, and executing them in sequence. The instructions are numbers of the binary system, in a special format that is unique for each machine. The CPU breaks an instruction into parts to see if it has to do something. For instance,a “1” in a certain position in an instruction could mean that the CPU would have to load data in from RAM, or that it would have to add two numbers.[2] After the CPU determines what an instruction is supposed to do,it tells its component parts what to do to complete the instruction. 第2篇 硬件篇 A CPU has three typical components,that is Arithmetic and Logic Unit(ALU),Control Unit(CU)and Registers. The ALU is made up of devices called gates that receive one or more inputs and,based upon what function they are designed to perform, output a result.[3]It performs simple arithmetic and logical operations, such as NOT, Left Shift, Right Shift,Add, Subtract,AND,and OR. CU extracts instructions from memory, decodes and executes them, calling on the ALU when necessary. Registers are temporary memory units that store words. The registers are located in the processor, instead of in RAM,so data can be accessed and stored faster. 第2篇 硬件篇 On large machines,CPUs require one or more printed circuit blocks. On personal computers(PC)and small workstations,the CPU is housed in a single chip called a microprocessor. [4] 第2篇 硬件篇 Key Words & Terms Access arithmetic and logic unit base on 基于…… Binary Chip control unit Execute Extract Load Microprocessor Peripheral Register Word Workstation 算术逻辑单元 第2篇 硬件篇 Abbreviations ALU(arithmetic and logic unit) BIOS(Basic Input/Output System) 基本输入/ CPU(central processing unit) PC(Personal Computer) PCB(Printed Circuit Block) 印刷电路板 第2篇 硬件篇 Chapter 7 Computer Memory Text Memory is something that stores, preserves and recalls data when needed.Your brain has this capability and memory inside computer is an electronic incarnation of this concept. [1] Computer memory is used to store data that needs to be accessed by the central processing unit (CPU).It is the CPU that performs the laborious tasks,the memory acts as storage for uncompleted tasks and other relevant information needed to accomplish those tasks. 第2篇 硬件篇 All the information in memory is encoded in fixed size cells called bytes.[2]A byte can hold a small amount of information, such as a single character or a numeric value between 0 and 255.The CPU will perform its operations on groups of one,two, four,or eight bytes,depending on the interpretation being placed on the data, and the operations required. 第2篇 硬件篇 Forms of Memory Although the term “computer memory” is commonly used to refer to RAM,there are various other forms of memory inside a computer—such as the hard disk drive. The illustration depicted in Figure 7-1 below outlines the common memory architecture adopted within most modern computers. 第2篇 硬件篇 Any of the four major categories of memory in the diagram above can feed information directly to the CPU. Each form of memory feeds the CPU at different speeds and efficiency due to their different technological make up. [3] Registers and cache will transfer data to the CPU at greater speeds than RAM and hard disk drives. As the forms of memory in the top of the pyramid are costly to make,their size are limited to make computers affordable.The size of memory forms towards the bottom of the pyramid is made larger to hold all the other data that other forms cannot handle. [4] 第2篇 硬件篇 It should also be noted here that physical RAM and cache are volatile in nature—meaning that they store,preserve and recall data so long as there is electrical power flowing through the system. Once a computer system is shut off,the physical RAM and cache are cleared. Disc storage by way of floppy disk,hard disk,CD ROM and DVD information those are required to be non There is a trade ROM drives holds volatile in nature. off between speed and cost,resulting in the development of such a pyramid like architecture.Information is prioritized in terms of importance and stability to determine which form of memory would hold the data.[5] 第2篇 硬件篇 Registers The bottle neck in a memory and CPU architecture is the slow transfer speeds between the two. The fastest, and sadly the most expensive, form of memory resolves this problem by having the memory within the CPU itself. Data within registers are instantly fed to the Arithmetic and Logic Unit(ALU) portion of the CPU making the relevant data instantly available. Registers are typically small in size and are controlled by the CPU’s compiler. 第2篇 硬件篇 Registers The bottle neck in a memory and CPU architecture is the slow transfer speeds between the two. The fastest, and sadly the most expensive, form of memory resolves this problem by having the memory within the CPU itself. Data within registers are instantly fed to the Arithmetic and Logic Unit (ALU) portion of the CPU making the relevant data instantly available. Registers are typically small in size and are controlled by the CPU’s compiler. 第2篇 硬件篇 Cache This form of memory can be considered as an intermediary between the main physical RAM and the CPU.The cache makes any data frequently used by CPU instantly available. If the required information is not located in the cache,a fetch is made from the main memory. There are two levels of cache:level 1 cache (primary cache) and level 2 cache (secondary cache). 第2篇 硬件篇 Level 1 cache is built directly on the CPU,just like the registers. It is small in size,ranging anywhere between 2 kilobytes(KB) and 128 KB. As this cache is closer to the CPU than level 2 cache,its transfer speeds are faster as a result. Level 2 cache is usually situated in close proximity to,but off,the CPU chip.[6]However, there are certain systems where the cache is built on the CPU like the level 1 cache. The size of level 2 cache ranges from 256 KB to 2 megabytes (MB). Both levels of cache use Static Random Access Memory (SRAM) to hold the data. 第2篇 硬件篇 Main Memory This is where most of the information that a CPU requires resides.“Main Memory” commonly refers to Physical Memory,although a computer uses an operating system imposed Virtual Memory in addition to physical memory. The amount of main memory on a computer is crucial because it determines how many programs can be executed at one time and how much data can be readily available to a program. 第2篇 硬件篇 Physical memory uses Dynamic Random Access Memory (DRAM) to store the data, and is considerably slower than the SRAM used by the cache. Information is exchanged between the main memory and the cache to ensure that the more commonly accessed information is placed in the cache to allow faster access speed. Operating system’s memory management will automatically remove data held in both the physical and virtual memory. The physical memory acts as an Input/Output(I/O) channel for data exchanged between the computer memory and other forms of electronic storages. 第2篇 硬件篇 Virtual Memory Most operating systems have a form of memory management that caters for memory needs beyond a computer system’s physical memory through the use of a swap file. [7]There is a need for such memory management as operating systems themselves occupy a significant portion of physical memory. A swap file is a file located on a computer’s hard disk drive(HDD) that acts as an extension to physical memory. However,the HDD has much slower access times than any of the forms of memory discussed above. Hence, information is swapped between the main memory and the swap file to ensure that the more frequently used information is located in the main memory for faster access speeds. 第2篇 硬件篇 Key Words & Terms anywhere between Architecture bottle neck Cache Compiler Considerably disc storage Encode feed to Hierarchy Incarnation Intermediary Laborious 在…… 供应给…… 第2篇 硬件篇 Key Words & Terms level 1 cache level 2 cache Numeric physical memory Prioritize Proximity swap file trade off transfer speed virtual memory Volatile 把…… 易失性的 第2篇 硬件篇 Abbreviations DRAM(Dynamic Random Access Memory) HDD(Hard Disk Drive) I/O(Input/Output) 输入/ SRAM(Static Random Access Memory) 静态随机存储器 第2篇 硬件篇 Chapter 8 Other Hardware Text 返 回 PC(Personal Computer) is a system, consisting of many components. All the elements fall into one of two categories, hardware or software. The stuff you can actually see and touch, and will break if you throw it out of a fifth story window, is hardware.[1 Programs running upon hardware like Windows XP, are software. This article only talks about hardware. All the items listed below that make up a PC can be purchased individually at computer or web supply stores. Complete PCs can be purchased for about ¥3000 today, and the price keeps falling! A basic set of hardware found in most PCs includes: 第2篇 硬件篇 PC Case The PC Case is a thin sheet metal enclosure that houses the motherboard, power supply and various drives. The motherboard and power supply are mounted to the floor at the rear of the case. The drives(hard disk drive and CD/DVD) are mounted in enclosures called drive bays at the front of the case.[2] Motherboard The motherboard is the main circuit board in a PC. It contains all the circuits and components that run the PC. Major components found on the motherboard are CPU, BIOS, RTC and chip set. Primary connectors, like power, keyboard, mouse, display, IDE, serial connectors, parallel connectors and expansion card connectors, can be found on the motherboard too. 第2篇 硬件篇 Power Supply Power supply is installed in the back corner of the PC case, next to the motherboard. It converts 120v ac(standard house power) into DC voltages that are used by other components in the PC. Hard Disk Drive(HDD) The HDD installs in one of the 3 1/2 inch internal drive bays in the PC. It is powered by a 4 conductor cable coming from the power supply. [3 All of the information that’s “in your computer” is stored in your computer’s hard disk. 第2篇 硬件篇 Digital Video Disk drive(DVD The DVD is installed in drive bays in the PC. It is designed to optically access data stored in a DVD. Data between the DVD drive and the motherboard is carried on a 40 pin IDE cable. A standard DVD can store up to 4.7 GB on one side of the disk. A laser moves back and forth on the disk surface to access data at a very fast rate. Monitor The monitor is an output device. Two types of monitor technologies available to consumers are CRT monitors and LCD monitors. Cathode ray tube,CRT monitors are relatively heavy and big, and available in screen sizes from 14" to 21". A 17" display means that it is 17" measured diagonally from one corner of the tube to the other. [4 Liquid crystal display,LCD for short,consists primarily of two glass plates and some liquid crystal material between them.It is smaller and consumes much less power than CRT. 第2篇 硬件篇 Audio Device Primary audio output devices include speakers and headphones. Some speakers are builted into the side of the monitors. Other speakers are free standing. Active speakers amplify the sound signal from the sound card using battery or rectified AC house power.[6]Passive speakers are plugged into and are powered directly from the output signal provided by the “speaker out” port on the sound card. Cables and Wires Cables and wires connect all the components in PC together and provide power to them. 第2篇 硬件篇 Key Words & Terms cathode chip set circular component diagonally drive bay enclosure expansion card individually infrared transmitter motherboard 第2篇 硬件篇 Key Words & Terms parallel connector PC Case pin plug into power supply rectify serial connector sound card stuff voltage 第2篇 硬件篇 Abbreviations AC(Alternating Current) BIOS(Basic Input/Output System) 基本输入/输出系统 CRT(Cathode Ray Tube) DC(Direct Current IDE(Integrated Device Electronics) LCD(Liquid Crystal Display) 液晶显示;液晶显示器 第2篇 硬件篇 Chapter 9 Networking Hardware Text Networking hardware includes all computers,peripherals, interface cards and other equipments needed to perform data processing and communications within the network. Chapter 9 Networking Hardware File Server A file server stands at the heart of most networks.It is a very fast computer with a large amount of RAM and storage space, along with a fast network interface card.The network operating system software resides on this computer,along with software applications and data files that need to be shared. [1] 第2篇 硬件篇 Workstation All user computers connected to a network are called workstations.A typical workstation is a computer that is configured with a network interface card,networking software, and the appropriate cables.[2] Workstations do not necessarily need floppy disk drives because files can be saved on the file server. Almost any computer can serve as a network workstation. 第2篇 硬件篇 Network Interface Card The Network Interface Card(NIC),also called network adapter,provides the physical connection between the network and the computer workstation.Most of them are internal,with the card fitting into an expansion slot inside the computer. [3] Some computers,such as Mac Classics,use external boxes which are attached to a serial port or a SCSI port.Laptop computers can now be purchased with a network interface card built in. The network interface card is a major factor in determining the speed and performance of a network.It is a good idea to use the fastest network card available for the type of workstation you are using.They are usually purchased separately from a computer,although many computers (such as the Macintosh) now include an option for a pre installed network interface card. 第2篇 硬件篇 Switch Switch,also called hub,is a device that provides a central connection point for cables from workstations, servers,and peripherals.In a star topology,twisted pair wire is run from each workstation to a central switch/hub. Most switches are active,that is they electrically amplify the signal as it moves from one device to another. [4] Switches no longer broadcast network packets as hubs did in the past, they memorize addresses of computers and send the information to the correct location directly. Switches are sold with specialized software for port management. 第2篇 硬件篇 Repeater Since a signal loses strength as it passes along a cable, it is often necessary to boost the signal with a device called a repeater.[5]The repeater electrically amplifies the signal it receives and rebroadcasts it.Repeaters can be separate devices or incorporated into a concentrator.They are used when the total length of your network cable exceeds the standards set for the type of cable being used. [6] A good example of the use of repeaters would be in a local area network using a star topology with unshielded twisted pair cabling.The length limit for unshielded twisted pair cable is 100 meters. The most common configuration is for each workstation to be connected by twisted pair cable to a multi port active concentrator.The concentrator amplifies all the signals that pass through it allowing for the total length of cable on the network to exceed the 100 meters limit. [7] 第2篇 硬件篇 Bridge A bridge is a device that allows you to segment a large network into two smaller, more efficient networks. If you are adding to an older wiring scheme and want the new network to be up to date,a bridge can connect the two. A bridge monitors the information traffic on both sides of the network so that it can pass packets of information to the correct location. Most bridges can “listen” to the network and automatically figure out the address of each computer on both sides of the bridge. The bridge can inspect each message and,if necessary, broadcast it on the other side of the network. 第2篇 硬件篇 The bridge manages the traffic to maintain optimum performance on both sides of the network. You might say that the bridge is like a traffic cop at a busy intersection during rush hour.It keeps information flowing on both sides of the network,but it does not allow unnecessary traffic through. [8]Bridges can be used to connect different types of cabling, or physical topologies.They must,however, be used between networks with the same protocol. 第2篇 硬件篇 The bridge manages the traffic to maintain optimum performance on both sides of the network. You might say that the bridge is like a traffic cop at a busy intersection during rush hour.It keeps information flowing on both sides of the network,but it does not allow unnecessary traffic through. [8]Bridges can be used to connect different types of cabling,or physical topologies.They must,however, be used between networks with the same protocol. 第2篇 硬件篇 Router Router,also called gateway in earlier days,translates information from one network to another;it is similar to a super intelligent bridge. Routers select the best path to route a message,based on the destination address and origin. The router can direct traffic to prevent head on collisions,and is smart enough to know when to direct traffic along back roads and shortcuts.[9] While bridges know the addresses of all computers on each side of the network, routers know the addresses of computers, bridges,and other routers on the network. Routers can even “listen” to the entire network to determine which sections are busiest—they can then redirect data around those sections until they clear up. 第2篇 硬件篇 If you have a school LAN that you want to connect to the Internet, you will need to purchase a router.In this case, the router serves as the translator between the information on your LAN and the Internet.It also determines the best route to send the data over the Internet.Routers can direct signal traffic efficiently,route messages between any two protocols across fiber optic,coaxial,and twisted pair cabling. 第2篇 硬件篇 Key Words & Terms adapter bridge Concentrator configuration interface intersection laptop computer optimum performance peripheral port repeater router server switch topology workstation 工作站 第2篇 硬件篇 Abbreviations NIC(Network Interface Card) 网络接口卡 SCSI(Small Computer System Interface) 小型(计算)机系统接口 UTP(Unshielded Twisted Pair) 非屏蔽双绞线 第3篇 软件篇 Chapter 10 Operating System Text 返 回 An Operating System,or OS,is a software program that enables the computer hardware to communicate and operate with the computer software.Without a computer operating system,a computer would be useless.The operating system is the first thing loaded onto the computer by a boot program,[1]and it provides a software platform on top of which application programs can run. 第3篇 软件篇 The basic concepts of operating systems are processes,memory management,I/O management,the file systems,and security.[2] We can view operating systems from two points of views:resource manager and extended machines. From resource manager point of view, operating systems manage the different parts of the system efficiently;from extended machines point of view,operating systems provide a virtual machine to users that is more convenient to use. The main resource of a computer is hardware in the form of processors,storage, input/output devices,communication devices, and data. OS performs basic tasks,such as recognizing input from the keyboard,sending output to the display screen, keeping track of files and directories on the disk,and controlling peripheral devices such as disk drives and printers. [3] 第3篇 软件篇 Users can interact directly with the operating system through a user interface such as a command language or a Graphical User Interface(GUI).The application programs make use of the operating system by making requests for services through a defined Application Program Interface (API). OS makes sure that different programs and users running at the same time do not interfere with each other. [4] 第3篇 软件篇 Operating systems can be classified into different types, such as GUI,Multi user,Multiprocessing,Multitasking and Multithreading.Many computer operating systems will fall into more than one of them.A GUI operating system contains graphics and icons and is commonly navigated by using a computer mouse. A multi user OS allows multiple users to use the same computer at the same time or different times. A multiprocessing OS is capable of supporting and utilizing more than one computer processor. A multitasking OS is capable of allowing multiple software processes to run at the same time. A multithreading OS allows different parts of a software program to run concurrently.[5] 第3篇 软件篇 More recently,operating systems can be found on many of the devices we use every day,from cell phones to wireless access points. Today,for desktop or laptop,the most popular operating systems are Windows 2000,Windows XP and Windows Vista. Macintosh computers come pre loaded with OS/2,many corporate servers use the Linux or UNIX operating systems. [6] 第2篇 硬件篇 Key Words & Terms Boot Concept Concurrently Directory Efficiently Execute Interact Interfere Laptop Load Multitasking Multithreading Multiprocessing Navigate Platform Recognize 识别 第2篇 硬件篇 Abbreviations API(Application Programming Interface) 应用程序设计接口 GUI(Graphical User Interface) 图形用户接口(软件) WAP(wireless access point) 无线接入点 第3篇 软件篇 Chapter 11 Object oriented Programming Text There are two programming models: procedural programming and object oriented programming.[1] Historically,a program has been viewed as a logical procedure that takes input data,processes it,and produces output data. The programming challenge was seen as how to write the logic,not how to define the data. This is called procedural programming.In a procedural programming language like C,functions and data structures are the basic elements of design. Object-Oriented Programming(OOP)is another way of programming,which is organized around “objects” rather than “actions”,data rather than logic.[2]In an object oriented programming language,such as Java,objects and object interactions are the basic elements of design. 第3篇 软件篇 The first step in OOP is to identify all the objects you want to manipulate and how they relate to each other, which is known as data modeling.[3]Once you’ve identified an object, you generalize it as a class of objects and define the kind of data it contains and any logic sequences that can manipulate it.Each distinct logic sequence is known as a method.A real instance of a class is called (no surprise here) an “object” or,in some environments,an “instance of a class”. The object or class instance is what you run in the computer.Its methods provide computer instructions and the class object characteristics provide relevant data. You communicate with objects,and they communicate with each other with well defined interfaces called messages. [4] 第3篇 软件篇 What is an Object An object is a software bundle of variables and related methods. It is abstraction of real key to understanding object world object.Objects are oriented technology. Real world objects share two characteristics:They all have state and behavior. Person has state (name,birthday, age) and behavior(say,run,sleep).Identifying the state and behavior for real world objects is a great way to begin thinking in terms of object oriented programming.As mentioned above, software objects are abstraction of real world objects,so do the software objects share two characteristic too. 第3篇 软件篇 What is an Interface As you’ve already learned,objects define their interaction with the outside world through the methods that they expose.Methods form the object’s interface with the outside world.The buttons on the front of your television set, for example, are the interface between you and the electrical wiring on the other side of its plastic casing.You press the “power” button to turn the television on and off.In its most common form,an interface is a group of related methods with empty bodies. 第3篇 软件篇 What is a Class A class is a blueprint or prototype from which objects are created.Here we define a class models the state and behavior of a real world object.In the real world, you’ll often find many individual objects of the same kind.In object oriented terms,we say that John is an instance of the class of objects known as person. What is Inheritance The concept of a data class makes it possible to define subclasses of data objects that share some or all of the main class characteristics.[5]Object oriented programming allows classes to inherit commonly used state and behavior from other classes,just like students inherit all characteristics and behaviors from person. 第3篇 软件篇 Key Words & Terms Behavior Class Identify Inheritance Instance Instruction Interface Logic Object object oriented Procedural Prototype State 第3篇 软件篇 Abbreviations OOP(Object Oriented Programming) 面向对象程序设计 第3篇 软件篇 Chapter 12 Multimedia Text Multimedia,as the name implies,is the integration of 返 回 multiple forms of media. This includes text,graphics,audio, video,etc.For example, a presentation involving audio and video clips would be considered a “multimedia presentation”. A software that involves animations,sound,and text is called “multimedia software”.CDs and DVDs are often considered to be “multimedia formats”,since they can store a lot of data and most forms of multimedia require a lot of disk space. [1] 第3篇 软件篇 Multimedia is all about communicating in several ways.For example,the computer you are using is capable of flashing text and beeping when there is a problem.It is already a multimedia computer—anything else is a matter of degree. In other words, the more capable your computer is at handling sound, video and graphics, the better your multimedia packages will look. [2] The basic elements of multimedia program in a computer are Text:This is the base to most applications—the on screen display of words.The use of different styles,fonts and colors can be used to emphasize specific points. Images:Seeing a picture of an object has more impact than merely reading about it.Examples include conventional artwork, computer generated artwork, photographs or captured video frames. 第3篇 软件篇 Movies:You can present information which is normally outside the scope of the ordinary classroom,such as medical operations or archaeological excavations. Animation:Animations can render a procedure more accurately than that of a movie.For instance,objects which appear blurred within a movie can be represented more clearly. Sound:Sound can be used in strategic parts of the program or during a movie to emphasize certain points.This may include speech,audio effects(e.g. applause),ambient sound(e.g. the background sound of the sea etc.) and music. User Control:There has to be some degree of user control so as to provide students with the option to leave certain parts of the application and thus prevent boredom. [3]On screen options should exist for them to visit other areas of the program. 第3篇 软件篇 There are a number of terrific software packages that allow you to create multimedia presentations on your computer.Perhaps the best and most widely known is Microsoft’s PowerPoint. With PowerPoint a user can mix text with pictures,sound and movies to produce a multimedia slideshow that’s great for boardroom presentations or a computer kiosk but difficult to distribute. Due to the advancements in computer speeds and storage space,multimedia is commonplace today.A typical multimedia application is characterized by the following features: 第3篇 软件篇 • the different media it possesses and makes use of; • the use of digital technology; • the interaction it demands of the user; and the integration of sound,images,text and data into seamless applications. A multimedia application is often designed to support the learning process.Multimedia offers the experience of listening, looking and doing in a computer mediated setting.[4] It can be interesting,motivating,exciting and help students achieve understanding in new ways. 第3篇 软件篇 Key Words & Terms Ambient Animation Applause Archaeological Blur Boredom Capture Commonplace Excavation Font Frame Motivating Multimedia Render 第3篇 软件篇 Abbreviations CD(Compact Disc)只读光盘,光盘 DVD(Digital Video Disc)数字视频光盘 第3篇 软件篇 Chapter 13 Software Text Software is the general term for information that’s recorded onto some kinds of medium. [1]For example,when you go to the video store and rent or buy a tape or DVD,what you’re really getting is the software that’s stored on that tape or disk.Your VCR or DVD player are hardware devices that are capable of reading the software from a tape or disk and projecting it onto your TV screen,in the form of a movie. 第3篇 软件篇 Your computer is a hardware device that reads software too.Most of the software on your computer comes in the form of programs. A program consists of “instructions” that tell the computer what to do,how to behave.Just as there are thousands of albums you can buy on CD for your stereo,and thousands of movies you can buy to play on your VCR or DVD player,there are thousands of programs that you can buy to run on your computer.[2] When you buy a computer,you don’t automatically get every program produced by every software company in the world. You usually get some programs. For example, when you buy a computer it will probably have an operating system(like Windows XP) already installed on it. 第3篇 软件篇 Your computer is a hardware device that reads software too.Most of the software on your computer comes in the form of programs. A program consists of “instructions” that tell the computer what to do,how to behave.Just as there are thousands of albums you can buy on CD for your stereo,and thousands of movies you can buy to play on your VCR or DVD player,there are thousands of programs that you can buy to run on your computer.[2] When you buy a computer,you don’t automatically get every program produced by every software company in the world. You usually get some programs. For example, when you buy a computer it will probably have an operating system(like Windows XP) already installed on it. 第3篇 软件篇 If you do purchase a specific program,it would be to perform some specific task. For example,you might use a graphics program to handle photos, or you might use a word processing program to write text.Just as there are different brands of toothpaste,there are different brands of word processing programs, graphics programs,and Web browsers. For example,all graphics programs are designed to help you work with pictures.But there are many brands of graphics programs out there, such as Adobe Photoshop,CorelDRAW,and so on. As to Web browsers, popular brands include Microsoft Internet Explorer,Netscape Navigator,Google Firefox,and a few others. 第3篇 软件篇 Software is often divided into application software (programs that do work users are directly interested in) and system software(which includes operating systems and any program that supports application software).The term middleware is sometimes used to describe programming that mediates between application and system software or between two different kinds of application software(for example, sending a remote work request from an application in a computer that has one kind of operating system to an application in a computer with a different operating system). 第3篇 软件篇 Some general kinds of application software include • Productivity software,which includes word processors, spreadsheets, and tools for use by most computer users. • Presentation software,such as Microsoft PowerPoint. • Graphics software for graphic designers. • CAD/CAM software. • Specialized scientific applications. • vertical market or industry specific software(for example, for banking, insurance,retail,and manufacturing environments). 第3篇 软件篇 There are thousands of programs available for your PC,and no two people have exactly the same programs on their computers.The programs that are installed on your computer can all be found,and started from the All Programs menu(or some program group that’s accessible from All Programs menu). [3 When you click on the icon for a program,the program opens. This means the program appears on the screen,so you can use it. Each program will appear in its own program window on the Windows desktop. 第3篇 软件篇 Key Words & Terms Mediate Medium Middleware Project Spreadsheet Tape Retail Vertical 作为…… 第3篇 软件篇 Abbreviations CAD(Computer Aided Design) 计算机辅助设计 CAM(Computer Aided Manufacturing) 计算机辅助制造,计算机辅助制造技术 VCR(Video Cassette Recorder) 盒式录像机 第4篇 网络篇 Chapter 14 The Internet Text 返 回 Computers can be connected together on networks.A computer on a network can communicate with other computers on the same network by exchanging data and files or by sending and receiving messages. The Internet is a massive network of networks,a networking infrastructure.[1]Information that travels over the Internet communicates with each other via a variety of languages known as protocols. 第4篇 网络篇 There are elaborate protocols for communication over the Internet. A protocol is simply a detailed specification of how communication is to proceed.[2]For two computers to communicate at all,they must both be using the same protoco. The most basic protocols on the Internet are the Internet Protocol(IP) and the Transmission Control Protocol(TCP). These two protocols,which are referred to collectively as TCP/IP, provide a foundation for communication. [3]Other protocols use TCP/IP to send specific types of information.The Internet provides a number of services to the computers connected to it. These services use TCP/IP to send various types of data over the net.Among the most popular services are file sharing,e mail, and the World Wide Web. 第4篇 网络篇 WWW WWW,also known as “Web” or “3W”,stands for World Wide Web. The World Wide Web refers to all the resources and users on the Internet that are using the Hypertext Transfer Protocol (HTTP).It is a way of sharing resources with many people over the medium of the Internet.The Web is just a portion of the Internet, and is the key technology that popularized the Internet around the world. [4] 第4篇 网络篇 FTP FTP stands for File Transfer Protocol.It is a method to transfer files(documents, images…) over the Internet from one computer to another.It provides you an easy way to upload and download files between computers that are connected to the Internet.As with the Hypertext Transfer Protocol(HTTP),which transfers displayable Web pages and related files,FTP uses the Internet’s TCP/IP protocols. FTP is commonly used to transfer Web page files from their creator to the computer that acts as their server for everyone on the Internet. 第4篇 网络篇 You can use a web browser to connect to FTP addresses exactly as you would connect to HTTP addresses,or you can use a commercial program that offers a graphical user interface to connect to FTP addresses. Using a Web browser makes it easy for you to browse large directories and read and retrieve files. [7]While this method is convenient,web browsers are often slower and less reliable and have fewer features than dedicated FTP clients. Using graphical FTP clients simplifies file transfers by allowing you to drag and drop file icons between windows.When you open the program,enter the name of the FTP host and your username and password. If you are logging into an anonymous FTP server, you may not have to enter anything. 第4篇 网络篇 E-mail E-mail is one of the most widely used forms of communication today.It has many advantages over other forms of communication: it is easy to use,free of charge, fast,and delivers information in a digital format.E mail can be used to send any kind of computer file,including pictures,sounds,programs and movies. 第4篇 网络篇 Each Internet domain has a corresponding e mail server that manages all e mail addresses at that domain. E mail servers exchange e mail over the Internet using the Simple Mail Transfer Protocol(SMTP).Client applications log into the servers to send and receive e mail using one of several protocols, such as POP3 or IMAP. When you send an e mail,your client application first sends it to your e mail server, which then contacts the addressee’s e mail server and carries out a conversation over the Internet according to the rules defined by SMTP. Your e mail server asks the other e mail server if the user name is valid,and,if it is,transfers the e mail, where the receiving e mail server stores it until the addressee logs on and downloads it. Each Internet domain has an associated e mail server that manages all e mail addresses at that domain. 第4篇 网络篇 Key Words & Terms anonymous collectively conversation corresponding directory download foundation hypermedia hypertext infrastructure interface massive 宽大的,大而重的 第4篇 网络篇 Key Words & Terms medium proceed protocol specification request response retrieve upload 上传 第4篇 网络篇 Abbreviations FTP(File Transfer Protocol) HTTP(Hyper Text Transfer Protocol) IMAP(Internet Message Access Protocol) POP3(Post Office Protocol 3) 邮局协议第3 SMTP(Simple Mail Transfer Protocol) WWW(World Wide Web) 万维网(环球信息网 第4篇 网络篇 Chapter 15 Search Engine Text Search Engine is a program that searches documents for specified keywords and returns a list of the documents where the keywords are found.[1] However,the term search engine is often used to specifically describe systems like Baidu and Google that enable users to search for documents on the World Wide Web. Search engines are the key to finding specific information on the vast expanse of the World Wide Web. [2]Without sophisticated search engines,it would be virtually impossible to locate anything on the Web without knowing a specific URL. 第4篇 软件篇 Typically,a search engine works by sending out a spider to fetch as many documents as possible. Another program, called an indexer,then reads these documents and creates an index based on the words contained in each document. Each search engine uses a proprietary algorithm to create its index so that only meaningful results are returned for each query. The algorithm is what the search engines use to determine the relevance of the information in the index to what the user is searching for.[3] 第4篇 软件篇 When you query a search engine to locate information, you’re actually searching through the index that the search engine has created—you are not actually searching the Web. These indices are giant databases of information that is collected and stored and subsequently searched.Different search engines produce different results because not all indices are going to be exactly the same. And the search results are based on the index,so if the index hasn’t been updated since a Web page became invalid,the search engine will return dead links.[4] 第4篇 网络篇 Key Words & Terms Algorithm Engine indices(.pl) Invalid Proprietary Sophisticated Subsequent Typically 典型地,独特地 第4篇 网络篇 Chapter 16 Electronic Commerce 返 回 Text Electronic commerce or e commerce is a term for any type of business or commercial transaction that involves the transfer of information across the Internet.[1]It covers a range of different types of businesses,from consumer based retail sites,through auction or music sites,to business exchanges trading goods and services between corporations. It is currently one of the most important aspects of the Internet to emerge. 第4篇 网络篇 E-commerce allows consumers to electronically exchange goods and services with no barriers of time or distance. Electronic commerce has expanded rapidly over the past five years and is predicted to continue at this rate, or even accelerate. In the near future,the boundaries between “conventional” and “electronic” commerce will become increasingly blurred as more and more businesses move sections of their operations onto the Internet.[2] Business to Business or B2B refers to electronic commerce between businesses rather than between a business and a consumer.B2B businesses often deal with hundreds or even thousands of other businesses,either as customers or suppliers. Carrying out these transactions electronically provides vast competitive advantages over traditional methods. When implemented properly,e commerce is often faster, cheaper and more convenient than the traditional methods of bartering goods and services. 第4篇 网络篇 Electronic transactions have been around for quite some time in the form of Electronic Data Interchange or EDI. [3]EDI requires each supplier and customer to set up a dedicated data link (between them),where e commerce provides a cost effective method for companies to set up multiple,ad hoc links. Electronic commerce has also led to the development of electronic marketplaces where suppliers and potential customers are brought together to conduct mutually beneficial trade. The road to creating a successful online store can be difficult if unaware of e commerce principles.[4] Researching and understanding the guidelines required to properly implement an e business plan is a crucial part to becoming successful with online store building. 第4篇 网络篇 Shopping cart software is an operating system used to allow consumers to purchase goods and or services, track customers, and tie together all aspects of e commerce into one cohesive whole. While there are many types of software that you can use, customizable,turnkey solutions are proven to be a cost effective method to build, edit and maintain an online store. [5] How do online shopping carts differ from those found in a grocery store? The image is one of an invisible shopping cart.You enter an online store, see a product that fulfills your demand and you place it into your virtual shopping basket.When you are through browsing,you click checkout and complete the transaction by providing payment information. 第4篇 网络篇 To start an online business it is best to find a niche product that consumers have difficulty finding in malls or department stores.Also take shipping into consideration.Pets.com found out the hard way:dog food is expensive to ship FedEx! Then you need an e commerce enabled website. This can either be a new site developed from scratch,or an existing site to which you can add e commerce shopping cart capabilities. The next step, you need a means of accepting online payments. This usually entails obtaining a merchant account and accepting credit cards through an online payment gateway (some smaller sites stick with simpler methods of accepting payments such as PayPal). 第4篇 网络篇 Lastly,you need a marketing strategy for driving targeted traffic to your site and a means of enticing repeat customers.If you are new to e commerce,keep things simple— know your limitations. E-commerce can be a very rewarding venture,but you cannot make money overnight. It is important to do a lot of research, ask questions,work hard and make business decisions basing on facts learned from researching e “gut” feelings. commerce. Don’t rely on 第4篇 网络篇 Key Words & Terms Accelerate ad hoc Auction Barter Blur credit card cost effective e commerce Enticing Merchant Retail shopping cart Trade Transaction 交易 第4篇 网络篇 Abbreviations B2B(Business to Business) 商业机构对商业机构的电子商务模式 EDI(Electronic Data Interchange) 电子数据交换