计算机英语课文内容翻译（15分）
CHAPTER 1
1.1
We build computer to solve problems. Early computer solved mathematical and engineering problems , and later computers emphasized information processing for business applications. Today , computers also control machines as diverse as automobile engines, robots, and microwave ovens. A computer system solves a problem from any of these domains by accepting input, processing it, and producing output. Figure 1-1 illustrates the function of a computer system.
Figure 1-2 shows these components in a block diagram. The lines between the blocks represent the flow of information flows from one component to another on the bus , which is simply a group of wires connecting the components. Processing occurs in the CPU and main memory . The organization in Figure 1-2, with the components connected to each other by the bus, is common. However, other configurations are possible as well.
The classification just described is based on physical size as opposed to storage size. A computer system user is generally more concerned with storage size, because that is a more direct indication of the amount of useful work that the hardware can perform.Speed of computation is another characteristic that is important to the user. Generally speaking, users want a fast CPU and large amounts of storage, but a physically small machine for the I/O devices and main memory.
1.2
A processor is a functional unit that interprets and carries out instructions. Every processor comes with a unique set of operations such as ADD, STORE, or LOAD that represent the processor’s instruction set. Computer designers are fond of calling their computers machines, so the instruction set is sometimes referred to as machine instructions and the binary language in which they are written is called machine language! [1] Y ou shouldn’t confuse the processor’s instruction set with the instructions found in high-level programming languages, such as BASIC or Pascal.
The control unit is the functional unit that is responsible for supervising the operation of the entire computer system. In some ways, it is analogous to a telephone switch-board with intelligence because it makes the connections between various functional units of the computer system and calls into operation each unit that is required by the program currently in operation
The arithmetic and logic unit (ALU) is the functional unit that provides the computer with logical and computational capabilities. Data are brought into the ALU by the control unit, and the ALU performs whatever arithmetic or logic operations are required to help carry out the instruction
1.3
Below the L1 cache is the Level 2,or L2 cache. In today’s Pentium-class processors ,the L2 cache is usually on the processor chip itself .In fact ,If you could lift the lid of a Pentium or Athlon processor and look at the silicon die itself under a microscope you might be surprised to find that the biggest percentage of chip area was taken up by the cache memories
Below the L1 cache is the Level 2,or L2 cache. In today’s Pentium-class processors ,the L2 cache is usually on the processor chip itself .In fact ,If you could lift the lid of a Pentium or Athlon processor and
look at the silicon die itself under a microscope you might be surprised to find that the biggest percentage of chip area was taken up by the cache memories.[
The virtual memory interface is shown in Fig.1-6. A real memory of 16M bytes and a virtual memory of 2G bytes are shown for illustration; many modern virtual memory systems are much larger than this. Virtual-memory space is divided into equal-sized groups called pages. A page in a modern computer is 1K, 2K, or 4K bytes. Real memory is also divided into the same equal-sized groups, called page frames. When information is moved between virtual-memory space and real-memory space, a complete page is moved.
Section 3 discussed how virtual memory extends the address space of a processor. However, the latency of real memory is too long to support high-performance processors. Even with the high-speed DRAMs used today for real memory, something must be done to overcome this latency problem.
CHAPTER 2
2.1
Multiprogramming, which was developed to improve performance, also allows time sharing. Time shared operating systems allow many users (from one to several hundred) to use a computer system inter-leavingly at the same time. Other operating systems types include real time systems and multiprocessor systems.
The management of resources in a computer system is another major concern of the operating system. Obviously, a program cannot use a device if that hardware is unavailable. As we have seen, the operational software oversees the execution of all programs. It also monitors the devices being used. To accomplish this, it establishes a table in which programs are matched against the devices they are using or will use .The operating system checks this table to approve or deny use of a specific device.
In effect , the program undergoing execution signals the operating system that an I/O operation is desired, using a specific I/O device. The controlling software calls on the IOCS software to actually complete the I/O operation. Considering the level of I/O activity in most programs, the IOCS instructions are extremely vital.
CHAPTER 3
3.1
Selecting a PC for home or business use must begin with the all-important question “What do I want the system to do? ” Once you ’ve determined what tasks the system will be used for, you must choose among the software and hardware alternatives available. If you’re not really sure what you want a system to do, you should think twice about buying one. Computer systems that are configured to match the requirements of certain applications (such as preparing a novel) often perform poorly at ot hers (playing power-hungry multimedia games, for example). You can easily make expensive mistakes if you’re uncertain about what you want a system to do.
When you take possession of a new computer system, you should find that most of the hardware and software you need are already in place. Y ou ’ll need to connect the components and start the system up;
then, you’ll be off and running. If your system does not include a piece of hardware or software that you want it to have, you can usually buy and install it yourself relatively easily.
A final, but optional, step in setting up your new system is customizing the settings. Most PCs include options for background images, color schemes, themes, screen savers, screen resolution, the order of items on the menus, and so forth. In Windows, the desktop options are accessible through the Control Panel, as shown in Fig.3-1, Y ou can also use the Control Panel to set up your network and Internet settings.
3.2
The Windows desktop appears on the screen after a computer using the Windows operating system has completed the boot process. The desktop is where documents, folders, programs, and other objects are displayed when they are being used, similar to the way documents and file folders are laid on a desk when they are being used. Thought the appearance of the Windows desktop can be customized, all desktops contain common elements, such as desktop icons, the taskbar, the Start button, windows, and task buttons (see Fig.3-2).
The principle component of the GUI is the window. As mentioned earlier, a window is a rectangular area of information that is displayed on the screen. These windows can contain programs and documents, as well as menus, dialog boxes,icons, and a variety of other types of data.
A menu is a set of options--usually text based —from which the user can choose to initiate a desiredaction in a program. At the top of many windows is a menu bar showing the main menu categories (see Fig.3-2). Pull-down menus (also called drop--down menus) display on the screen when the user selects an item on the menu bar. As shown on the right-most screen in Fig.3-2, in some Microsoft programs (such as Windows and some versions of Microsoft Office) a feature called personalized menus can be used.
CHAPTER 4
4.1
The OSI model is shown in Fig.4-1 (minus the physical medium). This model is based on a proposal developed by the International Standards Organization (ISO) as the first step toward international standardization of the protocols used in the various layers. The model is called the ISO OSI (Open System Interconnection) Reference Model because it deals with connecting open systems —that is, systems that are open for communication with other systems.
There are two end-to-end protocols in the transport layer, one of which is TCP (Transmission Control Protocol), another is UDP (User Datagram Protocol). TCP is a connection-oriented protocol that allows a byte stream originating on one machine to be delivered without error on any other machine in the internet.UDP is an unreliable, connectionless protocol for applications that do not want TCP’s sequencing of flow control and wish to provide their own.
The network layer defines an official packet format and protocol called IP (Internet Protocol). The job of the network layer is to deliver IP packets where they are supposed to go.
4.2
The most widespread topology for LANs designed to function as data communication for the interconnection of local computer-based equipment is the star topology , in which the major equipments used to connect a variety of computer-based devices are hubs or switches. Typical LAN product of using the star topology is the most famous Ethernet, which dominates the LAN world today.
The 100Base-T Ethernet which is known as Fast Ethernet has the same topology as 10Base-T showing in Fig.4-3. Using this topology, we can build a fast Ethernet and need NICs of 100Mb/s and hub of 100Mb/s and don’t need cabling any more .
Switches are basically multi-port bridges, but share some characteristics with routers. Like routers, switches work by dividing up the network into a number of segments, each of which can operate without interference from traffic local to any of the other segments. Switching is performed at layer 2 of the seven-layer model-the same as bridging. Since it is performed at layer 2, the MAC address is used, which is independent of protocol address. Like a bridge, a switch learns which address reside on each of its ports and then switches data appropriately. A switch can be designed using conventional microprocessors or dedicated ASIC (Application-Specific Integrated Circuit) technology.
CHAPTER 5
5.1
ARPAnet is abbreviated from “Advanced Research Projects Agency Network”. Landmark packet-switching network established in 1969. ARPAnet was developed in the 1970s by BBN and funded by ARPA.It eventually evolved into the Internet. The term ARPAnet was officially retired in 1990.
There are two kinds of E-mail protocol used in the Internet. One is Simple Mail Transfer Protocol (SMTP) which accepts incoming connections and copies messages from them into the appropriate mailboxes . Another is Post Office Protocol-3 (POP3) which fetches E-mail from the remote mailbox and stores it on the user’s local machine to be read later.
Telnet is used for remote terminal connection, enabling users to log in to remote systems and use resources as if they were connected to a local system.
5.2
Mobile Web use-or wireless Web, as it is frequently referred to-is one of the fastest growing Web applications today . Notebook and handheld devices frequently use attached or built-in modems to access the Internet; most mobile phones and pagers have Internet connectivity built in.
Another type of dial-up connection is ADSL which is the most common way to access the Internet today . Sometimes ADSL is called as broadband accessing, because it provides more wide bandwidth than that the regular modem provides.
Unlike satellite and fixed wireless connections, which use a cable to connect the modem to some type of fixed transceiver, mobile wireless connections allow the device to be moved from place to place. Consequently , most handheld PCs and other mobile devices (like Web-enable cell phones) use a mobile wireless connection and access the Internet through the same wireless network as cell phones and messaging devices.
CHAPTER 6
6.1
Until now there has always been a clear division between public and private networks. A public network, like the public telephone system and the Internet, is a large collection of unrelated peers that exchange information more or less freely with each other. The people with access to the public network may or may not have anything in common, and any given person on that network may only communicate with a small fraction of his potential users.
Using the Internet for remote access saves a lot of money . Y ou ’ll be able to dial in wherever your Internet service provider (ISP) has a point-of-presence (POP). If you choose an ISP with nationwide POPs, there ’s a good chance your LAN will be a local phone call away . Some ISPs have expanded internationally as well, or have alliances with ISPs overseas. Even many of the smaller ISPs have toll-free numbers for their roaming users. At the time of this writing, unlimited access dial-up PPP accounts, suitable for business use, are around $25 per month per user.At any rate, well-chosen ISP accounts should be cheaper than setting up a modem pool for remote users and paying the long-distance bill for roaming users.Even toll-free access from an ISP is typically cheaper than having your own toll-free number, because ISPs purchase hours in bulk from the long-distance companies.
Using our previous example of the customer database, it ’s easy to see how a VPN could expand the Intranet application’s functionality. Suppose most of your salespeople are on the road, or work from home. There ’s no reason why they shouldn’t be able to use the Internet to access the Web server that houses the customer database application. You don’t want just anyone to be able to access the information, however, and you ’re also worried about the information itself flowing unencrypted over the Internet. A VPN can provide a secure link between the salesperson’s laptop and the Intranet web server running the database, and encrypt the data going between them. VPNs give you flexibility, and allow practically any corporate network service to be used securely across the Internet.
6.2
For some time now, large business enterprises have used electronic commerce to conduct their business-to-business transactions. Electronic data interchange (EDI) on private networks began in the 1960s, and banks have been using dedicated networks for electronic funds transfer (EFT) almost as long. Recently, however, with the increased awareness and popularity of the Internet, electronic commerce has come to encompass individual consumers as well as businesses of all sizes.
To many, electronic commerce is defined as the buying and selling of products and services over the Internet, but there are many more aspects. From its inception, electronic commerce had included the handling of purchase transactions and funds transfers over computer networks. It’s grown now to include the buying and selling of new commodities such as electronic information. And the opportunities for companies seeking to take advantage of the capabilities of electronic commerce are greater than merely adopting our present view of commerce to performing those same transactions over electronic networks.
Electronic commerce is a system that includes not only those transactions that center on buying and selling goods and services to directly generate revenue, but also those transactions that support revenue generation, such as generating demand for those goods and services, offering sales support and customer service (see Fig.6-1), or facilitating communications between business partners.
计算机英语课文内容翻译（15分）
CHAPTER 1
1.1
We build computer to solve problems. Early computer solved mathematical and engineering problems , and later computers emphasized information processing for business applications. Today , computers also control machines as diverse as automobile engines, robots, and microwave ovens. A computer system solves a problem from any of these domains by accepting input, processing it, and producing output. Figure 1-1 illustrates the function of a computer system.
Figure 1-2 shows these components in a block diagram. The lines between the blocks represent the flow of information flows from one component to another on the bus , which is simply a group of wires connecting the components. Processing occurs in the CPU and main memory . The organization in Figure 1-2, with the components connected to each other by the bus, is common. However, other configurations are possible as well.
The classification just described is based on physical size as opposed to storage size. A computer system user is generally more concerned with storage size, because that is a more direct indication of the amount of useful work that the hardware can perform.Speed of computation is another characteristic that is important to the user. Generally speaking, users want a fast CPU and large amounts of storage, but a physically small machine for the I/O devices and main memory.
1.2
A processor is a functional unit that interprets and carries out instructions. Every processor comes with a unique set of operations such as ADD, STORE, or LOAD that represent the processor’s instruction set. Computer designers are fond of calling their computers machines, so the instruction set is sometimes referred to as machine instructions and the binary language in which they are written is called machine language! [1] Y ou shouldn’t confuse the processor’s instruction set with the instructions found in high-level programming languages, such as BASIC or Pascal.
The control unit is the functional unit that is responsible for supervising the operation of the entire computer system. In some ways, it is analogous to a telephone switch-board with intelligence because it makes the connections between various functional units of the computer system and calls into operation each unit that is required by the program currently in operation
The arithmetic and logic unit (ALU) is the functional unit that provides the computer with logical and computational capabilities. Data are brought into the ALU by the control unit, and the ALU performs whatever arithmetic or logic operations are required to help carry out the instruction
1.3
Below the L1 cache is the Level 2,or L2 cache. In today’s Pentium-class processors ,the L2 cache is usually on the processor chip itself .In fact ,If you could lift the lid of a Pentium or Athlon processor and look at the silicon die itself under a microscope you might be surprised to find that the biggest percentage of chip area was taken up by the cache memories
Below the L1 cache is the Level 2,or L2 cache. In today’s Pentium-class processors ,the L2 cache is usually on the processor chip itself .In fact ,If you could lift the lid of a Pentium or Athlon processor and
look at the silicon die itself under a microscope you might be surprised to find that the biggest percentage of chip area was taken up by the cache memories.[
The virtual memory interface is shown in Fig.1-6. A real memory of 16M bytes and a virtual memory of 2G bytes are shown for illustration; many modern virtual memory systems are much larger than this. Virtual-memory space is divided into equal-sized groups called pages. A page in a modern computer is 1K, 2K, or 4K bytes. Real memory is also divided into the same equal-sized groups, called page frames. When information is moved between virtual-memory space and real-memory space, a complete page is moved.
Section 3 discussed how virtual memory extends the address space of a processor. However, the latency of real memory is too long to support high-performance processors. Even with the high-speed DRAMs used today for real memory, something must be done to overcome this latency problem.
CHAPTER 2
2.1
Multiprogramming, which was developed to improve performance, also allows time sharing. Time shared operating systems allow many users (from one to several hundred) to use a computer system inter-leavingly at the same time. Other operating systems types include real time systems and multiprocessor systems.
The management of resources in a computer system is another major concern of the operating system. Obviously, a program cannot use a device if that hardware is unavailable. As we have seen, the operational software oversees the execution of all programs. It also monitors the devices being used. To accomplish this, it establishes a table in which programs are matched against the devices they are using or will use .The operating system checks this table to approve or deny use of a specific device.
In effect , the program undergoing execution signals the operating system that an I/O operation is desired, using a specific I/O device. The controlling software calls on the IOCS software to actually complete the I/O operation. Considering the level of I/O activity in most programs, the IOCS instructions are extremely vital.
CHAPTER 3
3.1
Selecting a PC for home or business use must begin with the all-important question “What do I want the system to do? ” Once you ’ve determined what tasks the system will be used for, you must choose among the software and hardware alternatives available. If you’re not really sure what you want a system to do, you should think twice about buying one. Computer systems that are configured to match the requirements of certain applications (such as preparing a novel) often perform poorly at ot hers (playing power-hungry multimedia games, for example). You can easily make expensive mistakes if you’re uncertain about what you want a system to do.
When you take possession of a new computer system, you should find that most of the hardware and software you need are already in place. Y ou ’ll need to connect the components and start the system up;
then, you’ll be off and running. If your system does not include a piece of hardware or software that you want it to have, you can usually buy and install it yourself relatively easily.
A final, but optional, step in setting up your new system is customizing the settings. Most PCs include options for background images, color schemes, themes, screen savers, screen resolution, the order of items on the menus, and so forth. In Windows, the desktop options are accessible through the Control Panel, as shown in Fig.3-1, Y ou can also use the Control Panel to set up your network and Internet settings.
3.2
The Windows desktop appears on the screen after a computer using the Windows operating system has completed the boot process. The desktop is where documents, folders, programs, and other objects are displayed when they are being used, similar to the way documents and file folders are laid on a desk when they are being used. Thought the appearance of the Windows desktop can be customized, all desktops contain common elements, such as desktop icons, the taskbar, the Start button, windows, and task buttons (see Fig.3-2).
The principle component of the GUI is the window. As mentioned earlier, a window is a rectangular area of information that is displayed on the screen. These windows can contain programs and documents, as well as menus, dialog boxes,icons, and a variety of other types of data.
A menu is a set of options--usually text based —from which the user can choose to initiate a desiredaction in a program. At the top of many windows is a menu bar showing the main menu categories (see Fig.3-2). Pull-down menus (also called drop--down menus) display on the screen when the user selects an item on the menu bar. As shown on the right-most screen in Fig.3-2, in some Microsoft programs (such as Windows and some versions of Microsoft Office) a feature called personalized menus can be used.
CHAPTER 4
4.1
The OSI model is shown in Fig.4-1 (minus the physical medium). This model is based on a proposal developed by the International Standards Organization (ISO) as the first step toward international standardization of the protocols used in the various layers. The model is called the ISO OSI (Open System Interconnection) Reference Model because it deals with connecting open systems —that is, systems that are open for communication with other systems.
There are two end-to-end protocols in the transport layer, one of which is TCP (Transmission Control Protocol), another is UDP (User Datagram Protocol). TCP is a connection-oriented protocol that allows a byte stream originating on one machine to be delivered without error on any other machine in the internet.UDP is an unreliable, connectionless protocol for applications that do not want TCP’s sequencing of flow control and wish to provide their own.
The network layer defines an official packet format and protocol called IP (Internet Protocol). The job of the network layer is to deliver IP packets where they are supposed to go.
4.2
The most widespread topology for LANs designed to function as data communication for the interconnection of local computer-based equipment is the star topology , in which the major equipments used to connect a variety of computer-based devices are hubs or switches. Typical LAN product of using the star topology is the most famous Ethernet, which dominates the LAN world today.
The 100Base-T Ethernet which is known as Fast Ethernet has the same topology as 10Base-T showing in Fig.4-3. Using this topology, we can build a fast Ethernet and need NICs of 100Mb/s and hub of 100Mb/s and don’t need cabling any more .
Switches are basically multi-port bridges, but share some characteristics with routers. Like routers, switches work by dividing up the network into a number of segments, each of which can operate without interference from traffic local to any of the other segments. Switching is performed at layer 2 of the seven-layer model-the same as bridging. Since it is performed at layer 2, the MAC address is used, which is independent of protocol address. Like a bridge, a switch learns which address reside on each of its ports and then switches data appropriately. A switch can be designed using conventional microprocessors or dedicated ASIC (Application-Specific Integrated Circuit) technology.
CHAPTER 5
5.1
ARPAnet is abbreviated from “Advanced Research Projects Agency Network”. Landmark packet-switching network established in 1969. ARPAnet was developed in the 1970s by BBN and funded by ARPA.It eventually evolved into the Internet. The term ARPAnet was officially retired in 1990.
There are two kinds of E-mail protocol used in the Internet. One is Simple Mail Transfer Protocol (SMTP) which accepts incoming connections and copies messages from them into the appropriate mailboxes . Another is Post Office Protocol-3 (POP3) which fetches E-mail from the remote mailbox and stores it on the user’s local machine to be read later.
Telnet is used for remote terminal connection, enabling users to log in to remote systems and use resources as if they were connected to a local system.
5.2
Mobile Web use-or wireless Web, as it is frequently referred to-is one of the fastest growing Web applications today . Notebook and handheld devices frequently use attached or built-in modems to access the Internet; most mobile phones and pagers have Internet connectivity built in.
Another type of dial-up connection is ADSL which is the most common way to access the Internet today . Sometimes ADSL is called as broadband accessing, because it provides more wide bandwidth than that the regular modem provides.
Unlike satellite and fixed wireless connections, which use a cable to connect the modem to some type of fixed transceiver, mobile wireless connections allow the device to be moved from place to place. Consequently , most handheld PCs and other mobile devices (like Web-enable cell phones) use a mobile wireless connection and access the Internet through the same wireless network as cell phones and messaging devices.
CHAPTER 6
6.1
Until now there has always been a clear division between public and private networks. A public network, like the public telephone system and the Internet, is a large collection of unrelated peers that exchange information more or less freely with each other. The people with access to the public network may or may not have anything in common, and any given person on that network may only communicate with a small fraction of his potential users.
Using the Internet for remote access saves a lot of money . Y ou ’ll be able to dial in wherever your Internet service provider (ISP) has a point-of-presence (POP). If you choose an ISP with nationwide POPs, there ’s a good chance your LAN will be a local phone call away . Some ISPs have expanded internationally as well, or have alliances with ISPs overseas. Even many of the smaller ISPs have toll-free numbers for their roaming users. At the time of this writing, unlimited access dial-up PPP accounts, suitable for business use, are around $25 per month per user.At any rate, well-chosen ISP accounts should be cheaper than setting up a modem pool for remote users and paying the long-distance bill for roaming users.Even toll-free access from an ISP is typically cheaper than having your own toll-free number, because ISPs purchase hours in bulk from the long-distance companies.
Using our previous example of the customer database, it ’s easy to see how a VPN could expand the Intranet application’s functionality. Suppose most of your salespeople are on the road, or work from home. There ’s no reason why they shouldn’t be able to use the Internet to access the Web server that houses the customer database application. You don’t want just anyone to be able to access the information, however, and you ’re also worried about the information itself flowing unencrypted over the Internet. A VPN can provide a secure link between the salesperson’s laptop and the Intranet web server running the database, and encrypt the data going between them. VPNs give you flexibility, and allow practically any corporate network service to be used securely across the Internet.
6.2
For some time now, large business enterprises have used electronic commerce to conduct their business-to-business transactions. Electronic data interchange (EDI) on private networks began in the 1960s, and banks have been using dedicated networks for electronic funds transfer (EFT) almost as long. Recently, however, with the increased awareness and popularity of the Internet, electronic commerce has come to encompass individual consumers as well as businesses of all sizes.
To many, electronic commerce is defined as the buying and selling of products and services over the Internet, but there are many more aspects. From its inception, electronic commerce had included the handling of purchase transactions and funds transfers over computer networks. It’s grown now to include the buying and selling of new commodities such as electronic information. And the opportunities for companies seeking to take advantage of the capabilities of electronic commerce are greater than merely adopting our present view of commerce to performing those same transactions over electronic networks.
Electronic commerce is a system that includes not only those transactions that center on buying and selling goods and services to directly generate revenue, but also those transactions that support revenue generation, such as generating demand for those goods and services, offering sales support and customer service (see Fig.6-1), or facilitating communications between business partners.