chapter two ： computer hardware

CHAPTER TWOCHAPTER TWO ：：Computer HardwareComputer HardwareCHAPTER TWOCHAPTER TWO ：：Computer HardwareComputer Hardware

第第 22 章：计算机硬件章：计算机硬件

of 166

Table Of Contents

Data Representation and Digital Electronics 2.1

Microprocessors and Memory 2.2

Storage Devices 2.3

2.4 Input and Output Devices

of 166

Data Representation and Digital Electronics

• How is it that a computer can work with documents, photos, videos, and sound recordings?

The answer to that question is what data representation and digital electronics are all about. Data representation makes it possible to convert letters, sounds, and images into electrical signals. Digital electronics makes it possible for a computer to manipulate simple "on" and "off" signals to perform complex tasks.

of 166


2.1.1 Digital Data Representation

2.1.2 Quantifying Bits and Bytes

2.1.3 Digital Electronics

of 166


2.1.1 Digital Data Representation

• Why are computers digital?

Most computers are digital, as opposed to analog, devices. A digital device works with discrete—distinct or separate—data or digits, such as 1 and 0. An analog device works with continuous data.

- 大多数的计算机都是数字设备，这是相对于模拟设备来说的。数字设备使用的是离散的（个别的、分离的）数据或数字，如 1 和 0 。

模拟设备使用的是连续型数据。

of 166


Most computers use the simplest type of digital technology—their circuits have only two possible states ("on" and "off"). When discussing these states, we usually indicate the "on" state with 1 and the "off" state with 0. These 1s and 0s are referred to as binary digits.

- 大多数的计算机都采用数字技术这种最简单的形式——它们的电路只有两种可能的状态(“ 开”和“关” ) 。在讨论这两种状态时，我们通常用 1 表示“开”状态，用 0 表示“关”状态。这些

1 和 0 就是二进制数字。

of 166

• How can a computer represent numbers using bits?

Computers represent numeric data using the binary number system, also called "base 2". The binary number system has only two digits: 0 and 1.

- 计算机使用二进制数字系统（亦称“基2” ）来表示数字型数据。二进制数字系统只有两种数字： 0 和 1 。


of 166


The binary number system allows computers to represent virtually any number simply by using 0s and 1s, which conveniently translate into electrical "on" and "off" signals.

- 二进制数字系统能够让计算机仅用若干的 0 和 1 就能表示几乎任何的数字，而且它们可以被很方便的转变成电信号的“开”和“关”状态。

进位制基本符号基数规则十进制

(Decimal)0,1,2,3,4,5,6,7,8,

9r=10

逢十进一

二进制 (Binary)

0,1 r=2 逢二进一

八进制 (Octal)

0,1,2,3,4,5,6,7 r=8 逢八进一

十六进制(Hexadecima

l)

0,1,2,3,4,5,6,7,8,9

A,B,C,D,E,F

r=16

逢十六进一

计算机技术领域中常用的几种进制

在计算机内部使用的是二进制，因为二进制：可靠性、可行性、简易性、逻辑性


of 166


• How can you convert a number from base r (r=2,8,16) to base 10?

- 方法： r 进制数的数符乘以相对应的位权，然后把各个乘积加（十进制加法）起来。

- 举例： 10101(B)=1*24+0*23+1*22+0*21+1*20=21 101.11(B)=1*22+0*21+1*20+1*2-1+1*2-2=5.75 101(O)=1*82+0*81+1*80=65 71.4(O)=7*81+1*80+4*8-1=57.5 1A2F(H)=1*163+10*162+2*161+15*160=6703

of 166


• How can you convert a number from base 10 to base r (r=2,8,16)?

- 方法：整数部分除以 r 取余数，直到商为 0 ，余数从右到左排列；小数部分乘以 r 取整数，整数从左到右排列。

- 举例： 100.345(D)=1100100.01011(B)

100(D)=144(O)=64(H)

低位

高位

100.345(D) = 1100100.01011(B)

2 100

5025

1263

1

…

2

2

2

2

22

0

10

0

1

10

…

…

…

…

…

…0

低位

高位 0.690╳ 2

1.520╳ 2

0.345╳ 2

╳ 2

1.380

0.760╳ 2

1.04


of 166

• How can you convert a number from base 8 or base 16 to base 2?

- 方法：八进制数的每一位对应二进制的三位，十六进制数的每一位对应二进制的四位。

- 举例： 7123(O) = 111 001 010 011 (B) 7 1 2 3

144.65(O) = 001 100 100.110 101 (B) 1 4 4 6 5

2C1D(H) = 0010 1100 0001 1101 (B) 2 C 1 D


of 166

• How can you convert a number from base 2 to base 8 or base 16?

- 方法：二进制数的整数部分从右向左进行分组，小数部分从左向右进行分组。转换成八进制 3 位一组，转换成十六进制 4 位一组，不足补零。

- 举例： 1 101 101 110.110 101 (B) = 1556.65(O) 1 5 5 6 6 5

11 0110 1110.1101 01 (B) = 36E.D4(H)

3 6 E D 4


of 166

• How can a computer represent words and letters using bits?

Character data is composed of letters, symbols, and numerals. Computers employ several types of codes to represent character data, including ASCII, EBCDIC, and Unicode.

- 字符型数据是由字母、符号和数字组成。计算机使用多种代码来表示字符型数据，包括ASCII 码、 EBCDIC 码和 Unicode 码。


of 166

ASCII 码美国标准信息交换码 - 用 7 个二进制位表示一个字符，可以为 128

个字符提供编码扩展型 ASCII 码 - 用 8 个二进制位表示一个字符，可以为 256

个字符提供编码EBCDIC 码扩展型二进制表示的十进制交换码 - 使用 8 个二进制位，为 256 个字符提供编码Unicode 码 - 使用 16 个二进制位，为 65000 个字符提供

编码


of 166


• Why does ASCII provide codes for 0,1,2,3,4,5,6,7,8,and 9?

Computers sometimes distinguish between numeric data and numerals. A computer uses the ASCII code numerals for numerical symbols, whereas it uses a binary number to code numeric data.

- 有时计算机要把数字型数据和数码区分开来。计算机使用 ASCII 编码的数码来表示数字符号，使用二进制数字对数字型数据进行编码。

of 166


• How does a computer convert sounds and pictures into codes?

To work with sounds and pictures, a computer must somehow digitize them into 1s and 0s. Computers convert colors and sounds into numbers, which can be represented by bits.

- 计算机要使用声音和图片的话，就必须先把它们数字化为 1 和 0 的序列，即要把颜色和声音转变成能够用位序列表示的数字。

of 166


• When a computer works with a series of 1s and 0s, how does it know which code to use?

To avoid confusion, most computer files contain a file header with information on the code that was used to represent the file data.

- 为了防止混淆，大多数的计算机文件都带有一个文件头，其中包含着关于文件中数据所采用的编码的信息。

of 166


2.1.2 Quantifying Bits and Bytes

• How can I tell the difference between bits and bytes?

The word "bit“ (abbreviation for "binary digit“) can be further abbreviated as a lowercase "b". A byte, on the other hand, is composed of eight bits and is usually abbreviated as an uppercase "B".

- “ 位” (“ 二进制数字”的缩写 ) 可被进一步缩写为一个小写的“ b” ；另一方面，一个字节由8 个

位构成，通常被缩写成一个大写的“ B” 。

of 166


Transmission speeds are usually expressed in bits, whereas storage space is usually expressed in bytes.

- 传输速度通常用位来表示，而存储容量通常用字节表示。

- For ExampleModem’s speed: 56 Kbps —56 kilobits per secondThe capacity of a hard disk drive: 8 GB —8 gigabytes

of 166


• What do the prefixes kilo-, mega- and giga- mean?

In the context of bits and bytes, "Kilo" is a prefix that means 210 (1024). The prefix "mega" refers to 220 (1048576). The prefix “giga" refers to 230.

- 对位和字节来说，“ kilo” 作为前缀代表210 ，前缀“ mega” 指的是 220 ，前缀“ giga” 指的是 230 。

of 166


A kilobit (abbreviated Kb or Kbit) is 1024 bits and a kilobyte (abbreviated KB or Kbyte) is 1024 bytes.

- 1Kb=1024b; 1KB=1024B

A megabit (abbreviated Mb or Mbit) is 1024 Kilobits (220 bits) and a megabyte (abbreviated MB or Mbyte) is 1024 kilobytes (220 bytes).

- 1Mb=1024Kb=220b; 1MB=1024KB=220B

of 166


2.1.3 Digital Electronics

• How does a computer store and transport all of those bits?

Because most computers are electronic devices, bits take the form of electrical pulses that can travel over circuits.

- 由于大多数的计算机都是电子设备，所以位序列都是以电子脉冲的形式在电路之中传输的。

of 166


• Does a typical computer owner need to mess around inside the system unit?

- 由于采用了 digital electronic technology使元件的小型化成为可能，现在的计算机才只包括很少的组成部分。

- 桌面计算机只需在系统单元内部添加或替换一些元件就能获得所需的功能。

- 笔记本电脑则在机箱外部提供了扩展和替换功能。

of 166


• What's a computer chip?

The terms "computer chip", "microchip", and "chip" originated as technical jargon for "integrated circuit."

- “ 计算机芯片”、“微芯片”和“芯片”这些词原来是集成电路技术使用的专业术语。

of 166


An integrated circuit (IC) is a super thin slice of semiconducting material (or "semiconductors") packed with microscopic circuit elements such as wires, transistors, capacitors, logic gates, and resistors.

- 集成电路是一种超薄的半导电性物质（或称“半导体”），它的表面上堆列着许多微小的电路元件，如电线、晶体管、电容、逻辑门和电阻。

of 166


The assortment of chips inside of a computer includes the microprocessor, memory modules, and support circuitry.

- 计算机内部芯片的种类包括微处理器、内存单元及支撑电路。

- 芯片封装的形状、大小各不相同，常见的有：双列直插式封装 DIP (Dual In-line Package)双列内置存储模型 DIMM (Dual In-line

Memory Module)针网阵列 PGA (Pin-Grid Array)

单列直插盒 SEC cartridge (Single Edge Contact

cartridge)

of 166

• How do chips fit together to make a computer?

The computer's main circuit board, called a motherboard or "main board", houses all essential chips and provides connecting circuitry between them.

- 计算机的主要电路板称为母板或“主板”，上面安放着所有的重要芯片并提供了芯片之间的连接电路。


of 166

Microprocessors and Memory

2.2.1 Microprocessor Basics

2.2.2 Microprocessor Performance Factors

2.2.3 Today’s Microprocessors

2.2.4 Random Access Memory

2.2.5 Read-only Memory

2.2.6 CMOS Memory

of 166


2.2.1 Microprocessor Basics

• Exactly what is a microprocessor? A microprocessor (sometimes

simply referred to as a “processor”, usually described as "a CPU on a chip") is an integrated circuit designed to process instructions.

- 微处理器（有时简称“处理器”，通常被描述为“基于一块芯片上的 CPU” ）是一种用于执行指令的集成电路。

of 166


• What does a microprocessor look like?

Depending on the brand and model, a microprocessor might be housed in an SEC cartridge or in a square PGA.

- 牌子和型号不同，微处理器的外观也不同，它可能被封装在单列直插盒 (SEC) 中，也可能被装在正方形的针网阵列 (PGA) 中。

of 166


Inside the chip carrier, a microprocessor is a very complex integrated circuit, containing as many as 300 million miniaturized electronic components. Some of these components are only 30 nanometers thick. A nanometer is one billionth of a meter.

- 封装内部的微处理器芯片是一种非常复杂的集成电路，包括 3 亿个微小的电子元件。其中的一些元件只有 30nm那么厚。 1nm指的是一米的十亿分之一。

of 166


微处理器内部的微型化电路分别构成了一些重要的功能区域，包括：

算术逻辑单元 ALU (Arithmetic Logic Unit) - 也称“运算器”，主要完成算术和逻辑运算，实现对数据的加工和处理。在运算过程中， ALU 用寄存器 (register)保存要处理的数据。

控制单元 Control Unit - 也称“控制器”，用于控制整个计算机的各个

部分自动协调地工作，它的基本功能就是从内存取指令并执行指令。

of 166


• Where does the microprocessor get its instructions?

A microprocessor executes instructions that are provided by a computer program. The list of instructions that a microprocessor can perform is called its instruction set. These instructions are hard-wired into the processor‘s circuitry.

- 微处理器执行的指令是由计算机程序提供。微处理器能够执行的指令列表称为指令集合。这些指令被固化在处理器的电路中。

of 166


• What happens when a computer executes an instruction?

The term instruction cycle refers to the process in which a computer executes a single instruction.

- 指令周期指的是计算机执行一条单指令的过程。

- 一个指令周期包括四个活动：取指令、解释指令、执行指令和形成下一条指令地址。

of 166


2.2.2 Microprocessor Performance Factors

• What makes one microprocessor perform better than another?

The performance of a microprocessor is affected by several factors, including clock speed, word size, cache size, instruction set, and processing techniques.

- 微处理器的性能受到若干因素的影响，包括时钟频率、字长、高速缓冲容量、指令集合

和处理技术。

of 166


• What do MHz and GHz have to do with computer performance?

The speed specifications that you see in a computer ad indicate the speed of the microprocessor clock — a timing device that sets the pace for executing instructions.

- 计算机广告中所说的速度指的是微处理器时钟的速度。微处理器的时钟是一种计时设备，用来设置指令执行的速度。

of 166


Most computer ads specify the speed of a microprocessor in megahertz (MHz) or gigahertz (GHz). Megahertz means a million cycles per second. Gigahertz means a billion cycles per second.

- 大多数的计算机广告中用兆赫兹和吉赫兹来具体说明微处理器的速度。兆赫兹意味着计算机每秒能够执行一百万 (106) 个时钟周期。吉赫兹意味着计算机每秒能够执行十亿 (109) 个时钟周期。

of 166


时钟周期 (clock cycle) 指的是微处理器执行一条加法指令所需要的时间，由 CPU 的时钟频率（主频）确定。它是微处理器领域内最小的时间单位。

- 假设某 CPU 的主频为 1GHz (Hz: 每秒次数，表示事件发生的频率 ) ，它的意思是指微处理器的时钟每秒能运行 10亿个周期，则它的时钟周期为： 1s/109 = 10-9s = 1ns

注意：时钟的速度和每秒微处理器能够执行的指令数并不相一致。

of 166


• Which is faster, an 8-bit processor or a 64-bit processor?

Word size refers to the number of bits that a microprocessor can manipulate at one time. Processors with a larger word size can process more data during each processor cycle, a factor that leads to increased computer performance.

- 字长指的是微处理器能够同时处理的位的个数。有更大的字长的处理器能够在每个处理器周期内处理更多的数据，因此字长

越长计算机性能越好。

of 166


• How does the cache size affect performance?

Cache is sometimes called "RAM cache" or "cache memory“. It is special high-speed memory that allows a microprocessor to access data more rapidly than from memory located elsewhere on the motherboard.

- 缓存有时也称为“ RAM缓存”或“缓冲存储器”，它是一种特殊的高速内存，与安装在主板上其他位置的内存相比，它能够使微处理器更

快的获得数据。

of 166


A Level 1 cache (L1) is built into the processor chip, whereas a Level 2 cache (L2) is located on a separate chip and takes a little more time to get data to the processor.

- 一级缓存被安装在处理器芯片内部，而二级缓存则存在于另一个芯片中，需要处理器花长一点时间才能获得数据。

- 理论上讲，缓存容量越大处理速度越快。但缓存容量是处理器的固有属性，不能由用户

来配置。

of 166


• What's the difference between CISC and RISC?

CISC (complex instruction set computer) 复杂指令集的计算机

- 所用的微处理器芯片带有复杂指令集，其中的每条指令执行时都需要几个时钟周期。

RISC (reduced instruction set computer) 精简指令集的计算机

- 所用的微处理器芯片带有有限的简单指令集。

of 166


关于两种技术的速度： - 理论上讲， RISC处理器要比 CISC处理器

速度快。 - 实际上， CISC处理器在完成某些处理任务时要优于 RISC ，而 RISC 在另一些处理任务上又优于 CISC 。

关于两种技术的应用： - Mac 的大多数处理器都采用 RISC 技术 - 大多数的 PC 机都采用 CISC 技术

of 166


• Can a microprocessor execute more than one instruction at a time?

Some processors execute instructions "serially"—that is, one instruction at a time. With serial processing, the processor must complete all of the steps in the instruction cycle before it begins to execute the next instruction.

- 一些处理器串行的执行指令，即一次只能执行一条指令。对于这种串行处理，处理器必须在指令周期内完成所有的步骤，才能开始

执行下一条指令。

of 166


However, using a technology called pipelining, a processor can begin executing an instruction before it completes the previous instruction. Many of today's microprocessors also perform parallel processing, in which multiple instructions are executed at the same time.

- 然而，采用一种叫做流水线的技术，处理器能够在完成前一条指令之前就开始执行下一条指令。现在的许多处理器还能够进行并行

处理，即同时执行多条指令。

of 166


• With so many factors to consider, how can I compare various Microprocessors?

Various testing laboratories run a series of tests to gauge the overall speed of a microprocessor. The results of these tests are called benchmarks.

- 很多不同类型的实验室做了一系列的测试以全面的评价微处理器的速度，这些测试的结果称为基准。

of 166


2.2.3 Today’s Microprocessors

• Which companies produce most of today's popular microprocessors?

Intel公司 —世界上最大的芯片制造商

- 1971年，第一个微处理器 Intel 4004诞生AMD公司 - Intel 的主要竞争对手Motorola公司 - 苹果机芯片的主要供应商

of 166


• Which microprocessor is best for your PC?

The microprocessor that's "best" for you depends on your budget and the type of work and play that you plan to do.

- 什么样的微处理器最适合你，这要取决于你的预算和你想要用它来做的工作类型。

of 166


• Can I replace my computer's microprocessor with a faster one?

It is technically possible to upgrade your computer's microprocessor, but computer owners rarely do so. One reason is the cost. The second reason is technical factors.

- 从技术上讲，把计算机的微处理器升级是可能的，但是人们很少这么做。原因之一是价钱；第二个原因就是技术因素。

of 166


2.2.4 Random Access Memory

• What is RAM?

RAM (Random Access Memory) is a temporary holding area for data, application program instructions, and the operating system.

- 随机存储器是一块能够暂时存储数据、应用程序指令和操作系统的固定区域。

of 166


• Why is RAM so important?

RAM holds raw data that is waiting to be processed, as well as the program instructions for processing that data. In addition, RAM holds the results of processing until they can be stored more permanently on disk or tape.

- RAM 用来保存等待处理的原始数据和用于处理该数据的程序指令。此外，在处理结果被长久的存储在磁盘或磁带上之前， RAM

还用于暂存这些结果。

of 166


In addition to data and application software instructions, RAM also holds operating system instructions that control the basic functions of a computer system.

- 除了数据和应用软件指令以外， RAM还要存储一些用于控制计算机系统基本功能的操作系统指令。

of 166


• How does RAM differ from hard-disk storage?

RAM holds data in circuitry, whereas hard-disk storage places data on magnetic media. RAM is temporary storage, whereas hard-disk storage is more permanent.

- RAM 把数据保存在电路中，而硬盘存储器把数据保存到磁性介质上； RAM 是暂时性存储器，而硬盘保存数据更长久。

of 166


• How does RAM work? In RAM, microscopic electronic parts

called capacitors hold the bits that represent data. Each bank of capacitors holds eight bits (one byte) of data. A RAM address on each bank helps the computer locate data, as needed, for processing 。

- 在 RAM 中有一些微小的电子元件叫做电容，用于保存代表数据的位。每一个电容存储体都保存着 8 个位（一个字节）的数据。 RAM 给每一个存储体标上地址，以帮助计算机按

照处理的需求来查找数据。

of 166


The contents of RAM can be changed just by changing the charge of the capacitors. Unlike disk storage, most RAM is volatile, which means that it requires electrical power to hold data.

- 通过改变电容的充放电，就能改变 RAM 中保存的内容。和磁盘存储器不同的是，大多数的 RAM 都是易丢失的，这就意味着它必须要有电源才能保存数据。

of 166


• How much RAM does your computer need?

Today's personal computers typically feature between 128 MB and 2 GB of RAM. The amount of RAM needed by your computer depends on the software that you use.

- 目前的个人计算机通常都带有 128MB 至2GB 的 RAM 。你的计算机所需 RAM 的容量取决于你所用的软件。

of 166


If a program exceeds the allocated space, the operating system uses an area of the hard disk, called virtual memory, to store parts of a program or data file until they are needed.

- 如果一个程序的所需超出了被分配的 RAM 空间，操作系统会使用一块称为虚拟内存的硬盘区域，把这个程序的一部分和数据文件保存起来，直到它们被需要为止。

of 166


• Do all computers use the same type of RAM?

No. RAM components vary in speed, technology, and configuration.

- 不是。不同的 RAM 在速度、生产技术和构造上都有很大差异。

- RAM 的速度常常以纳秒(nanosecond,ns) 来表示 (1ns = 10-9s) ，数字越小时表示 RAM 的速度越快。 RAM 的速度也可以用 MHz( 每秒百万个周期 ) 来表示，越高等级的 MHz意味

着速度越快。

of 166


目前大多数的个人计算机都采用 SDRAM 或 RDRAM ：

SDRAM (Synchronous Dynamic RAM) 同步动态随机存储器

- 速度很快、价格相对便宜RDRAM (Rambus Dynamic RAM)

Rambus 公司的动态随机存储器 - 比 SDRAM价格高、整体系统性能更好

of 166


2.2.5 Read-Only Memory

• How is ROM different from RAM?

ROM (read-only memory) is a type of memory circuitry that holds the computer's startup routine. ROM is housed in a single integrated circuit which is plugged into the motherboard.

- 只读存储器是一种用于存储计算机的开机例行程序的内存电路。它被安装在一块插在主板上的独立的集成电路（通常有 DIP

封装）中。

of 166


Whereas RAM is temporary and volatile, ROM is permanent and non-volatile. ROM circuitry holds "hard-wired" instructions that are a permanent part of the circuitry and remain in place even when the computer power is turned off.

- RAM 存储的数据是暂时的、易丢失的，而ROM 存储的数据是长久的、不易丢失的。 ROM 电路存储着“被固化了的”指令，这些指令是电路的永久的组成部分，即使在计算机断电

时，它们也保存在原位而不会丢失。

of 166


• If a computer has RAM, why does it need ROM too?

ROM contains a small set of instructions called the ROM BIOS (basic input/output system). These instructions tell the computer how to access the hard disk, find the operating system, and load it into RAM.

- ROM 中存储着一套称为基本输入 / 输出系统的指令集合。这些指令告诉计算机如何读写

硬盘、如何在硬盘上找到操作系统并把它装载到 RAM 中。

of 166


2.2.6 CMOS Memory

• Where does a computer store its basic hardware settings?

To store some basic system information, your computer needs a type of memory that's more permanent than RAM, but less permanent than ROM. CMOS is just the ticket.

- 为了存储一些基本的系统信息，你的计算机需要一种内存，它的数据保存时间比 RAM 要

长久，但又不如 ROM ，这就是 CMOS 。

of 166


CMOS (complementary metal oxide semiconductor) memory is a type of chip that requires very little power to hold data. It can be powered by a small battery that's integrated into the motherboard and automatically recharges while your computer power is on.

- 互补金属氧化物半导体存储器是一种只需要很少的电量就能够保存数据的芯片。把一块小电池集成到主板上就能给它供电，而且在

计算机开机后会电池会自动再充电。

of 166


• What's the most important information about memory provided by computer ads?

Even though ROM and CMOS have important roles in the operation of a computer, it is really RAM capacity that makes a difference you can notice.

- 尽管 ROM 和 CMOS 在计算机的正常运转上起着重要的作用，但只有 RAM 的容量大小不同时你才能够真正觉察到计算机性能的

- 差别。

of 166

Storage Devices

2.3.1 Storage Basics

2.3.2 Floppy Disk Technology

2.3.3 Hard Disk Technology

2.3.4 Tape Storage

2.3.5 CD Technology

2.3.6 DVD Technology

of 166

Storage Devices

2.3.1 Storage Basics

• What are the basic components of a data storage system?

A data storage system has two main components: a storage medium and a storage device. The term "storage technology" refers to a storage device and the media it uses.

- 一个数据存储系统包括两个元件：存储介质和存储设备。“存储技术”包括存储设备及其

使用的存储介质。

of 166

Storage Devices

A storage medium is the disk, tape, CD, DVD, paper, or other substance that contains data.

A storage device is the mechanical apparatus that records and retrieves data from a storage medium.

- 存储介质指的是磁盘、磁带、 CD 、 DVD 、纸或其它存储数据的物质。存储设备指的是向存储介质中记录和从存储介质中检索数据的机械设备。

of 166

Storage Devices

• How does a storage system interact with other computer components?

Data gets copied from a storage device into RAM, where it waits to be processed. After data is processed, it is held temporarily in RAM, but it is usually copied to a storage medium for more permanent safekeeping.

- 数据从存储设备被复制到 RAM 中，在那里等待被处理。数据被处理完后，仍然暂时存储在 RAM 中，但为了能更长久保管这些数据，

通常要把它们复制到存储介质中。

of 166

Storage Devices

The process of storing data is often referred to as “writing data” or “saving a file”.

The process of retrieving data is often referred to as "reading data", "loading data", or "opening a file".

- 存储数据的过程常被称为“写数据”或“保存文件”。检索数据的过程常被称为“读数据”、“装载数据”或“打开文件”。

of 166

Storage Devices

The data represented by 1s and 0s must be transformed into changes in the surface of a storage medium.

- 用 1 和 0 表示的数据必须对应的转换成存储介质表面上不同的变化形式。

Two types of storage technologies are commonly used for personal computers: magnetic and optical.

- 个人计算机常用的两种存储技术是：磁存储技术和光存储技术。

of 166

Storage Devices

• What's the difference between magnetic and optical storage technologies?

Hard disk, floppy disk, and tape storage technologies can be classified as magnetic storage, which stores data by magnetizing microscopic particles on the disk or tape surface.

- 硬盘、软盘和磁带存储器可以归属为磁性存储器，它们通过把盘或带表面上的微小

颗粒进行磁化来存储数据。

of 166

Storage Devices

A read-write head mechanism in the disk drive reads and writes the magnetized particles that represent data. Data stored magnetically can be easily changed or deleted simply by changing the magnetic orientation of the appropriate particles on the disk surface.

- 磁盘驱动器中的读写磁头用来读取或写入磁性微粒代表的数据。通过改变盘表面上的相应微粒的磁性性质，这种靠磁性存储

的数据就可以很容易被改变或删除。

Storage Devices

of 166

Storage Devices

CD and DVD storage technologies can be classified as optical storage, which stores data as microscopic light and dark spots on the disk surface. The dark spots are called pits. The lighter, non-pitted surface areas of the disk are called lands.

- CD 和 DVD 可以归属为光存储器，这种存储器用盘表面上的小亮点和小暗点来存储数据。小暗点叫做坑，小亮点（磁盘表面上

非凹陷的区域）叫做陆。

Storage Devices

of 166

Storage Devices

Optical storage gets its name because data is read using a laser light, and it is possible to see the data using a high-powered microscope. The transition between pits and lands is interpreted as the 1s and 0s that represent data.

- 光存储器因使用激光来读取数据而得名，用高倍显微镜就可以看到光盘表面上的数据。“坑”和“陆”之间的过渡转换可以解释成代表数据的 1 和 0 。

of 166

Storage Devices

• Can I add storage devices to my computer?

The system unit case for a desktop computer contains several storage device "parking spaces" called drive bays. If you have an empty bay of the right type and size, you can add a storage device. Bays come in two widths—51/4" and 31/2".

- 桌面计算机系统单元的机箱上有几个存储设备的“停车场”，叫做驱动器架。如果有型号和尺寸都适合的空驱动器架，你就可以添加

存储设备。驱动器架有两种宽度： 5.25 英寸和 3.5英寸。

Storage Devices

of 166

Storage Devices

• Which storage technology is best?

Each storage technology has its advantages and disadvantages. To compare storage devices, it is useful to apply four criteria: versatility, durability, speed, and capacity.

- 每种存储技术都既有优点又有缺点。要对存储设备进行比较，应遵循以下四个标准：通用型、耐久性、速度和容量。

of 166

Storage Devices

Versatility 通用性 - 一些存储设备 (such as floppy disk

drive) 只能从一种介质上存取数据，另一些通用性强的存储设备 (such as DVD drive) 可以从几种不同的介质上存取数据。

Durability 耐久性 - 大多数的存储技术都容易受到误操作或其他环境因素的影响，如受热和受潮。一般来说，光存储技术比磁存储技术不易因受破坏而导致数据丢失。

of 166

Storage Devices

Speed 速度Access time is the average time it

takes a computer to locate data on the storage medium and read it.

- 存取时间指的是一台计算机用于在存储介质上查找数据和读取数据所花费的时间。

- 个人计算机中存储设备的存取时间是以ms （毫秒 , 1/1000秒）来衡量，数字越小说明存取时间越短、存取速度越快。

- 存取时间最短的是随机存取设备。

of 166

Storage Devices

Random access (also called “direct access”) is the ability of a device to “jump” directly to the requested data.

- 随机存取（也叫“直接存取”）指的是一个设备直接“跳”到所需数据所在位置的能力。

- 随机存取设备有： floppy disk, hard disk, CD, and DVD drives

A tape drive must use slower sequential access by reading through the data from the beginning of the tape.

- 磁带驱动器必须采用从磁带的开头顺序的获得数据的慢速的顺序存取方式。

of 166

Storage Devices

Data transfer rate is the amount of data that a storage device can move from the storage medium to the computer per second.

- 数据传输速率指的是每秒钟存储设备能够从存储介质上获得的数据总量。

Capacity 容量Storage capacity is the maximum

amount of data that can be stored on a storage medium.

- 存储容量指的是能够存储到介质上的数据的最大量。

of 166

Storage Devices

2.3.2 Floppy Disk Technology

• Why is it called a "floppy disk"?

A floppy disk is a round piece of flexible mylar plastic covered with a thin layer of magnetic oxide and sealed inside a protective casing.

- 软盘是一种易弯曲的聚脂薄膜塑料物质，由一薄层的磁性氧化物包裹着，并封装在一个保护套中。

of 166

Storage Devices

• What's the capacity of a floppy disk?

- 软盘有各种大小和容量：最常见的： 1.44MB 容量的 3.5英寸软盘Zip盘 (Zip disk) ：有 100MB 、 250MB 和 750MB 三种容量超级软盘 (Superdisk) ：有 120MB 和 240MB 两种容量 - 虽然 Zip盘和超级软盘增加了存储容量，但标准的软驱却不能读取它们上面的数据。

of 166

Storage Devices

• How can Zip disks and Superdisks store so much more data than a standard floppy on the same size disk?

The amount of data that a disk stores depends on its density. Disk density refers to the closeness and size of the magnetic particles on the disk surface.

- 磁盘存储数据的数量取决于它的密度。盘密度是指盘表面上磁性微粒的紧密度和大小。

- Zip盘和超级软盘存储数据的密度比标准 3.5 英寸软盘要高，存储的数据也更多。

of 166

Storage Devices

• What are the disadvantages and advantages of floppy disk technology?

The major advantage of floppy disks is their portability.

The disadvantages of floppy disks are their limited storage capacity and a very slow access speed.

- 软盘的最大优点是携带方便。软盘的缺点是有限的存储容量和很慢的存取速度。

of 166

Storage Devices

• What does "HD DS" mean?

When you see “HD DS” on a box of floppy disks, it means “high-density double-sided” ( 高密度双面盘 ).

• Can I protect the data on a floppy disk?

A floppy disk features a write-protect window ( 写保护窗口 ). When you open the window, the disk is "write-protected", which means that a computer cannot

write data on the disk.

of 166

Storage Devices

2.3.3 Hard Disk Technology

• Why are hard disk drives so popular?

Hard disk technology is the preferred type of main storage for most computer systems for three reasons.

First, it provides lots of storage capacity.Second, it provides faster access to files

than provided by floppy disk drives. Third, a hard disk is economical.

of 166

Storage Devices

• How does a hard disk work?

A hard disk is one or more platters and their associated read-write heads. A hard disk platter is a flat, rigid disk made of aluminum or glass and coated with magnetic iron oxide particles.

- 硬盘包括一片或多片盘片及和这些盘片相关联的读写磁头。硬盘的盘片是一种铝制或玻璃制的扁平、坚硬的磁盘，其表面上覆盖着磁性金属氧化物微粒。

Storage Devices

of 166

Storage Devices

• What's all this business about Ultra ATA, EIDE, SCSI, and DMA?

A hard drive mechanism includes a circuit board called a controller that positions the disk and read-write heads to locate data. Disk drives are classified according to the type of controller.

- 硬盘驱动器结构中包括一个叫做控制器的电路板，用来给磁盘定位和帮助读写磁头查找数据。磁盘驱动器的类型是依据控制

器的类型来划分的。

of 166

Storage Devices

Popular drive controllers include Ultra ATA, EIDE, and SCSI.

Ultra ATA (Ultra AT Attachment) 超高级技术附件

EIDE (Enhanced Integrated Drive Electronics) 增强型集成驱动电路

SCSI (Small Computer System Interface) 小型计算机系统接口

- Ultra ATA 和 EIDE 本质上使用的是同一种基本的驱动技术， Ultra ATA驱动器的速度相当于 EIDE 的两倍。 SCSI驱动器的性能要

比 EIDE驱动器的性能强一些。

of 166

Storage Devices

The storage technology used on many PCs transfers data from a disk, through the controller, to the processor, and finally to RAM before it is actually processed.

- 许多 PC 机都采用这样的存储技术：首先通过控制器把磁盘上的数据传输到处理器中，然后再送到 RAM 中，这时数据才真正开始被处理。

of 166

Storage Devices

DMA (Direct Memory Access) technology allows a computer to transfer data directly from a drive into RAM, without intervention from the processor. UDMA (Ultra DMA) is a faster version of DMA technology. DMA and Ultra ATA are companion technologies.

- 直接存储访问技术允许计算机把数据直接从驱动器传到 RAM 中，而不用经过处理器。超级 DMA 是一种快速的 DMA 技术。 DMA 和

超级 ATA 是相伴而生的技术。

of 166

Storage Devices

• What's the downside of hard disk storage?

Hard disks are not as durable as many other storage technologies. If a read-write head runs into a dust particle or some other contaminant on the disk, it might cause what is called a head crash.

- 硬盘不如其他某些存储设备一样耐久。如果读写磁头碰到一个灰尘颗粒或是磁盘上其他一些脏东西，就可能会导致磁头划道。

of 166

Storage Devices

• Can I use a second hard disk drive as a backup?

Yes. One strategy is to use a second hard disk, which can be installed internally or connected externally. A more typical strategy is to use a removable hard disk, tape drive, or CD-writer.

- 可以。方法之一是使用另一块安装在内部或者连接在外部的磁盘。更常用的方法是使用一块移动硬盘、磁带驱动器或是 CD刻录机。

of 166

Storage Devices

Other supplementary storage devices, such as RAID, are used in situations where data is critical.

A RAID (redundant array of independent disks) storage device contains many disk platters, provides redundancy, and achieves faster data access than conventional hard disks.

- 冗余独立磁盘阵列存储设备包括很多的磁盘盘片，提供了冗余度，能比传统硬盘获得更

快的数据存取速度。

of 166

Storage Devices

2.3.4 Tape Storage

• What's the purpose of a tape drive? Many experts consider that a tape drive

is the best device for backing up data. A tape backup is a copy of the data on a hard disk, which is stored on magnetic tape and used to restore lost data.

- 许多专家把磁带驱动器看成是用于备份数据的最好的设备。磁带备份是硬盘上数据的一个副本，它被存储在磁带上，用于恢复丢失

的数据。

of 166

Storage Devices

• How does a tape drive work?

A tape is a sequential, rather than a random-access, storage medium. To locate a file, the tape drive must start at one end of the tape and read through all of the data until it finds the right header label.

- 磁带是一种顺序存取而不是随机存取的存储介质。要查找一个文件，磁带驱动器必须从磁带的一端开始，一直读取所有的数据，直

到找到正确的头标签为止。

of 166

Storage Devices

• Is it easy to install a tape drive?

Yes. Tape drives are available in either internal or external models. An internal tape drive fits into a standard drive bay. An external model is a standalone device that you can tether to your computer with a cable.

- 是的。磁带驱动器既有内置型又有外置型。内置的磁带驱动器适合使用标准驱动器架。外置的磁带驱动器是一种独立设备，可通过

电缆连接到计算机上。

of 166

Storage Devices

2.3.5 CD Technology

• Why would I want a CD-ROM drive in addition to a hard disk drive?

Unless you plan to download all of your new software from the Internet, your computer should have a CD drive so that you can install new software.

Furthermore, some software requires you to place the CD in the drive and leave it there while you use it.

of 166

Storage Devices

• What's the capacity and speed of a CD?

A single CD-ROM disk holds up to 680MB. Your computer can read data from a CD, but cannot record or store data on it.

The original CD-ROM drives were able to access 150 KB of data per second. A 48X CD-ROM drive, for example, would transfer data at a rate of 48X150 KB, or 7200 KB per second.

of 166

Storage Devices

• What's the difference between CD-ROM and ROM BIOS?

ROM BIOS refers to a chip on the motherboard that contains permanent instructions for the computer's boot sequence. A CD-ROM drive is an optical storage device that's usually installed in one of the system unit's drive bays.

- ROM BIOS 指的是主板上的一块保存着执行计算机引导程序的永久性指令的芯片。 CD-ROM驱动器指的是一种光存储设备，通常被

安装在系统单元的一个驱动器架中。

of 166

Storage Devices

• Can I create my own CDs?

Two CD-writer technologies called CD-R and CD-RW allow you to create your own CDs.

CD-R (Compact Disc Recordable) 可写型高密度盘：把数据记录在一种特殊的 CD-R盘上，但数据被写到CD-R上之后就再不能被擦除或修改。

CD-RW (Compact Disc Rewritable) 高密度可复写盘：允许你在 CD上写数据，

还允许你以后对数据进行修改。

of 166

Storage Devices

• Is CD-RW a viable replacement for a hard disk?

The process of accessing, saving, and modifying data on a CD-RW disk is relatively slow compared to the speed of hard disk access, so CD-RW is not a good replacement for a hard disk drive.

- 对 CD-RW盘上的数据进行访问、保存和修改的过程与硬盘的访问速度相比要慢一些，

因此 CD-RW并不是硬盘的合适的替代品。

of 166

Storage Devices

2.3.6 DVD Technology

• How is DVD different from CD technology?

DVD (“Digital Video Disc” 数字视盘 or “Digital Versatile Disk” 数字多用盘 ) is a variation of CD technology.

A computer's DVD drive can read disks that contain computer data (often called DVD-ROM disks), as well as disks that contain DVD movies (sometimes called

DVD-Video disks).

of 166

Storage Devices

A DVD holds much more data than a CD — about 4.7 GB (4700 MB) on a DVD compared with 680 MB on a CD-ROM.

- DVD 能比 CD保存更多的数据：一张DVD盘大约能保存 4.7GB 的数据，而一张 CD-ROM只能保存 680MB 的数据。

Like a CD-ROM disk, a DVD-ROM disk is stamped with data at the time of manufacture.

- 和 CD-ROM盘一样， DVD-ROM盘是在生产时就被记录上数据的。

of 166

The speed of a DVD drive is measured on a different scale than a CD drive. A 1X DVD drive is about the same speed as a 9X CD drive.

- DVD驱动器与 CD驱动器有着不同的速度度量单位。一个 1X DVD驱动器的速度大约相当于一个 9X CD驱动器的速度。

Storage Devices

of 166

• Is my computer DVD drive the same as the one that's connected to my television set?

Not exactly. The DVD player that you connect to your television includes MPEG decoding circuitry, which is not included on your computer's DVD drive.

- 不太一样。连接到电视机上的 DVD播放机包括 MPEG解码电路，而你的计算机的DVD驱动器中却没有。

Storage Devices

of 166

Storage Devices

• Are CDs and DVDs interchangeable?

You cannot play DVDs on your CD-ROM drive, but you can play CD-ROM, most CD-R, and most CD-RW disks on your DVD drive.

- 你不能在 CD-ROM驱动器上播放DVD ，但是可以在 DVD驱动器上使用 CD-ROM盘、大多数的 CD-R盘和大多数的 CD-RW盘。

of 166

Storage Devices

• Is there a DVD equivalent to CD-RW?

Today there are several competing technologies that make it possible to write data on DVD disks. All of these technologies can read DVD-ROM and DVD-Video discs, but each uses a different type of disk for recording.

- 现今已经出现了几种有竞争力的技术，使得在 DVD盘上写数据成为可能。这些技术能读取 DVD-ROM 和 DVD视频盘，但每种技术

都要在相应种类的盘上才能刻录数据。

of 166

Storage Devices

使用一种非常类似于 CD-R 技术的盘介质，DVD-R也可以写入一次数据，并且这些数据可以被大多数的 DVD驱动器和 DVD播放机读取。

DVD-RAM 、 DVD-RW 和 DVD+RW 都属于可读写的技术，它们可以被重复写入成百上千次。用这些设备刻录的盘都能够被刻录它们的同种设备读取，但是用其他设备读取这些盘时就可能会出问题。

of 166

Input and Output Devices

2.4.1

Expansion Slot, Card and Port

2.4.2

Installing Peripheral Devices

2.4.3 Display Devices

2.4.4 Printers

of 166


2.4.1 Expansion Slot, Card and Port

• How does a computer get data from RAM to a peripheral device?

Within a computer, data travels from one component to another over circuits called a data bus.

- 在计算机内部，数据是通过一种叫做数据总线的电路，从一个元件传输到另一个元件的。

of 166


One part of the data bus runs between RAM and the microprocessor. Another part of the data bus runs between RAM and various storage devices. The segment of the data bus that extends between RAM and peripheral devices is called the expansion bus.

- 这种数据总线的一部分用来连接 RAM 和微处理器，另一部分用来连接 RAM 和各种不同的存储设备。连接 RAM 和外部设备的这段数据

总线称为扩展总线。

of 166


• What's an expansion slot?

An expansion slot is a long, narrow socket on the mother-board into which you can plug an expansion card.

An expansion card is a small circuit board that provides a computer with the ability to control a storage device, an input device, or an output device.

- 扩展槽是主板上的一种又长又窄的插座，可以用来插扩展卡。扩展卡是一块小电路板，

它能让计算机对存储设备、输入和输出设备加以控制。

of 166


• What are the major types of expansion slots?

ISA (industry standard architecture) 工业标准结构

PCI (peripheral component interconnect) 外部元件互连

AGP (accelerated graphics port) 加速图形接口

- ISA属于较老的技术，用于一些速度较慢的设备； PCI具有较高的数据传输速率和 32位或 64 位的数据总线； AGP 提供了一条高速的

数据传输路径，主要用于安插图形卡。

of 166


• Do notebook computers also contain expansion slots?

Most notebook computers are equipped with a special type of external slot called a PCMCIA slot (personal computer memory card international association). This slot can hold more than one PC card.

- 大多数的笔记本计算机都配有一种特殊的外部扩展槽，叫做个人计算机内存卡国际联盟扩展槽。这种扩展槽可与多种 PC 卡相匹配。

of 166

笔记本计算机通常使用 PC卡作扩展卡。 PCMCIA 扩展槽可以按照 PC卡的厚度分为三种类型：

Type l slot - 只能接受最薄的 PC卡，如内存扩展卡。 Type ll slot - 可接受大多数常用的 PC卡，如声卡、网卡。Type lll slot - 可接受最厚的 PC卡，如硬盘驱动器；还可

以容纳 two Type l cards 、 two Type ll cards

或者 a Type l and Type ll card 。


of 166


• What is an expansion port?

An expansion port is any connector that passes data in and out of a computer or peripheral device.

- 扩展接口指的是用来向计算机或外设输入数据或者从计算机或外设向外输出数据的任何连接器。

An expansion port is often housed on an expansion card. A port might also be built into the system unit case of a desktop or

notebook computer.

of 166


• What are the major types of expansion cables?

Most connectors have a shape and pin designation such as DB-9 or C-50. Most types of connectors have male and female versions. The male version has pins that stick out, whereas the female version has holes.

- 大多数连接器上都标有关于形状和针脚数目的提示信息，如 DB-9 或 C-50 。多数连接器有雄性和雌性两种式样：雄性连接器的针脚

是凸出的，而雌性连接器有凹陷的洞。

of 166


• What's the best port to use for connecting peripheral devices?

USB ports are probably the most popular ports for connecting peripheral devices. Many kinds of peripheral devices —including mice, scanners, and joysticks —are available with USB connections.

- USB接口也许是用于连接外设的最受欢迎的接口。许多外设都可以与 USB接口进行连接，包括鼠标、扫描仪和游戏控制杆等。

of 166


2.4.2 Installing Peripheral Devices

• Is it difficult to install a new peripheral device?

The basic qualifications for installing peripheral devices are an ability to use a screwdriver and read directions.

- 安装外设的基本能力要求是会用螺丝刀和能读懂提示信息。

of 166


• Why do some peripheral devices include a disk or CD?

Some devices require software, called a device driver, to set up communication between your computer and the device. Typically, you'll use the device driver disk or CD one time to set up everything.

- 一些外设需要靠软件来建立与计算机之间的联系，这种软件称为设备驱动程序。通常，你要使用一次驱动程序盘或 CD盘来设置好

一切内容。

of 166


2.4.3 Display Devices

• What are the components of a typical computer display system?

The two key components of a computer display system include a graphics card and a display device, such as a CRT monitor or LCD screen.

- 计算机显示系统中的两个关键部件是图形卡和显示设备，显示设备有 CRT监视器、

LCD显示屏等。

of 166


A graphics card (also called a "video card" or a "graphics board") contains circuitry that generates the signals for displaying an image on the screen. It also contains special video memory, which stores screen images as they are processed, before they are displayed.

- 图形卡（也称为视频卡或图形板）的作用是用来产生在屏幕上显示图像的信号。图形卡中包含有特殊的视频存储器，用来存储那些

在显示前被处理的图像。

of 166


• What's the difference between a CRT and an LCD?

CRT (cathode ray tube) technology uses gun-like mechanisms to direct beams of electrons toward the screen and activate individual dots of color that form an image. CRTs offer an inexpensive and dependable computer display.

- 阴极射线管技术使用一个喷枪状的装置直接向屏幕上喷射电子流，激活形成图像的个别

的色点。 CRT监视器是一种廉价的、可靠的计算机显示器。

of 166


As an alternative to a CRT monitor, an LCD (liquid crystal display) produces an image by manipulating light within a layer of liquid crystal cells. Modern LCD technology is compact in size, lightweight, and provides an easy-to-read display.

- 作为 CRT监视器的可选替代品，液晶显示器是通过控制一层液晶单元内的光来产生图像的。现代的 LCD属于体积小、重量轻，具有易读特性的显示器。

of 166


• Which display device produces the best image?

Image quality is a factor of screen size, dot pitch, resolution, and color depth.

- 图像质量是屏幕尺寸、点间距、图形分辨率和色度共同决定的结果。

of 166


Screen size is the measurement in inches from one corner of the screen diagonally across to the opposite corner.

- 屏幕尺寸指的是从屏幕的一角沿对角线一直到对角的长度的英寸数。

- 在大多数的显示器上，实际显示的图像尺寸比标明的尺寸要小。现在的许多计算机广告中标有可视图像尺寸 (viewable image size, vis) 的测量值。 15英寸的显示器有大约 13.9英寸的 vis 。

of 166


Dot pitch (dp) is a measure of image clarity. A smaller dot pitch means a crisper image. Technically, dot pitch is the distance in millimeters between like-colored pixels — the small dots of light that form an image.

- 点间距是图像清晰度的量度。点间距越小就意味着图像看起来越鲜活。从技术上讲，点间距指的是彩色像素之间的距离，它用 mm作单位，而像素指的是形成图像的小亮点。

of 166


Your computer's graphics card sends an image to the monitor at a specific resolution, defined as the maximum number of horizontal and vertical pixels that are displayed on the screen.

- 计算机的图形卡是以特定的分辨率把图像送到显示器上的，分辨率指的是屏幕上能够显示的水平和垂直的像素的最大个数。

of 166


目前，显示器能提供的分辨率有：VGA (video Graphics Array) 视频图

形阵列 ——能够提供 640 x 480 的分辨率SVGA (Super VGA) 超级 VGA —— 能

够提供 800 x 600 的分辨率XGA (extended Graphics Array)

扩展图形阵列 ——能提供 1024 x 768 的分辨率

SXGA (Super XGA) 超级 XGA —— 能够提供 1280 x 1024 的分辨率

UXGA (Ultra XGA) 超高级 XGA ——能提供 1600 x 1200 的分辨率

of 166


The number of colors that a monitor and graphics card can display is referred to as color depth or "bit depth."

Windows allows you to select resolution and color depth. Most desktop owners choose 24-bit color at 1024 x 768 resolution.

- 显示器和图形卡能够显示的颜色的最大种类数称为色度或“位深度”。 Windows允许你对计算机的分辨率和色度进行设置。大多数的

桌面计算机使用者都选择 24 位的颜色和 1024 x 768 的分辨率。

of 166

• What about notebook computer display systems?

Many older notebooks had passive matrix screens, sometimes referred to as “dual-scan”. Newer notebooks feature an active matrix screen, sometimes referred to as “TFT” (thin film transistor).

- 许多老式的笔记本都使用无源矩阵显示屏，有时称为“双扫描”。新型的笔记本采用的是有源矩阵显示屏，有时称为“薄膜晶体管”。


of 166


2.4.4 Printers

• What features should I look for in a printer?

Today‘s printer technologies include ink jet, solid ink, thermal transfer, dye sublimation, laser, and dot matrix. These printers differ in resolution and speed.

- 目前打印机的种类包括喷墨、固体喷墨、热敏转移、均染升华、激光和点阵打印机几种。这些打印机在分辨率和打印速度上

都不太相同。

of 166


Resolution. The quality or sharpness of printed images and text depends on the printer's resolution—the density of the gridwork of dots that create an image. Printer resolution is measured by the number of dots it can print per linear inch, abbreviated as dpi.

- 分辨率。打印出的图像或文字的质量和清晰度取决于打印机的分辨率，这里的分辨率指的是用来构成图像的点格的密度，它的大小以每英寸长度上能够打印的点数来衡量，被

缩写为 dpi 。

of 166


Print speed. Printer speeds are measured either by pages per minute (ppm) or characters per second (cps).

Ten pages per minute is a typical speed for a personal computer printer.

- 打印速度。打印机速度的快慢或者以每分钟打印的页数 (ppm) ，或者以每秒钟打印的字符数 (cps) 来衡量。个人计算机打印机的一般打印速度为每分钟 10页纸。

of 166


• What's the most popular type of printer?

Today's most popular printer technology is ink jet printers because they print in color and they are inexpensive. An ink jet printer has a nozzle-like print head that sprays ink onto paper to form characters and graphics.

- 目前最受欢迎的打印机是喷墨打印机，因为能够以低廉的价格打印出彩色的效果。喷墨打印机有一个喷嘴状的打印头，用来向纸上

喷墨从而形成文字和图形。

of 166


• What's the difference between an ink jet printer and a solid ink printer?

A solid ink printer melts sticks of crayon-like ink and then sprays the liquefied ink through the print head’s tiny nozzles. A solid ink printer produces vibrant colors on most types of paper.

- 固体喷墨打印机先把蜡笔状的墨棒溶化了，再把溶化的墨通过打印头上的小喷嘴喷出。固体喷墨打印机能在大多数纸上产生出鲜艳

的颜色。

of 166


• What about thermal transfer and dye sublimation printers?

thermal transfer printer 热敏转移打印机

- 使用一个纸张大小的色带，色带上覆盖着多种颜色的蜡；打印头由成千上万个小加热元件组成，用来将蜡溶化到特殊涂层的纸上或透明的胶片上。

dye sublimation printer 均染升华打印机 - 与热敏转移打印机采用的技术很相似。不同之处是纸状色带上涂的是颜料而不是彩色的

蜡；打印头上加热元件的作用是把颜料溶化到特殊涂层的纸的表面上。

of 166

• Is a laser better than an ink jet?

- 激光打印机 (laser printer) 采用与复印机相同技术，都是把光照到一个光敏磁鼓上，通过磁鼓带有静电的墨就会被打印到纸上。

- 使用激光打印机要比喷墨打印机省钱。 - 激光打印机接受计算机发出的打印命令，但

是在打印之前会使用打印机控制语言 (PCL, Printer Control Language) 来构造打印页。

- 打印机语言需要占用内存，因此大多数的打印机都有 2MB~8MB 的内存容量。


of 166


• Why would anyone want a dot matrix printer?

A dot matrix printer produces characters and graphics by using a grid of fine wires.

- 点阵打印机通过使用一个细线构成的网格来产生字符和图形。

- 现在的点阵打印机主要用于做那些只需要低运转费用和低可靠性的非公事务，而不适用于高质打印。

of 166


• Is it easy to install a printer?

Most consumers typically use a parallel or USB port to connect a printer to a computer. Many printers come packaged with device driver software, which must be installed on your computer.

- 大多数用户都使用并行接口或 USB接口把打印机连接到计算机上。许多打印机都配有打印机驱动程序，这一程序必须安装到你的计算机上。

of 166

• Lab3: 配置多媒体计算机（实验要求：在英文版

WindowsXP环境下完成实验内容）

Labs

of 166

Chapter 2 专业词汇表

KEY TERMS

of 166

Homework

1. 完成教材 P61 中的实验任务 2 、 3 ，将转换过程和结果写在作业本上。

2. 完成教材 P100~103 SUMMARY 和P103~104 SITUATION QUESTIONS 中的填空。

3. 将 Lab3 的实验结果以附件的形式发送到电子邮箱 [email protected] 。

4. 将 SUMMARY 和 SITUATION QUESTION的内容翻译成中文，并写在作业本上。

5. 在作业本上写出 Chap2专业词汇表中的KEY TERMS及相应的中文含义。

6. 课后阅读：阅读教材 7.1 P316~325

chapter two ： computer hardware

Documents