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Computer hardware has four parts: the central processing unit (CPU) and memory, storage hardware, input hardware, and output hardware.
CPU The part of the computer that runs the program is known as the processor or central processing unit (CPU). In a microcomputer, the CPU is on a single electronic component, the microprocessor chip, within the system unit or system cabinet. The CPU itself has two parts: the control unit and the arithmetic-logic unit. In a microcomputer, these are both on the microcomputer chip.
The Control Unit The control unit tells the rest of the computer system how to carry out a program's instructions. It directs the movement of electronic signals between memory and the arithmetic-logic unit. It also directs these control signals among the CPU, input and output devices.
The Arithmetic-Logic Unit The arithmetic-logic unit, usually called the ALU, performs two types of operations—arithmetic and logical. Arithmetic operations are, as you might expect, the fundamental math operations: addition, subtraction, multiplication, and division. Logical operations consist of comparisons. That is, two pieces of data are compared to see whether one is equal to, less than, or greater than the other.
Memory Memory is also known as primary storage, internal storage, and it temporarily holds data, program instructions, and information. One of the most important facts to know about memory is that part of its content is held only temporarily. In other words, it is stored only as long as the computer is turned on. When you turn the machine off, the content will immediately vanish. The stored content in memory is volatile and can vanish very quickly.
Storage Hardware [1] The purpose of storage hardware is to provide a means of storing computer instructions and data in a form that is relatively permanent, that is, the data will not be lost when the power is turned off—and easy to retrieve when needed for processing. There are four kinds of storage hardware: floppy disks, hard disks, optical disk, and magnetic tape.
Floppy Disks Floppy disks are also called diskettes, flexible disks, floppies, or simply disks. The plastic disk inside the diskette cover is flexible, not rigid. They are flat, circular pieces of mylar plastic that rotate within a jacket. Data and programs are stored as electromagnetic charges on a metal oxide film coating the mylar plastic.
Hard Disks Hard disks consist of metallic rather than plastic platters. They are tightly sealed to prevent any foreign matter from getting inside. Hard disks are extremely sensitive instruments. The read-write head rides on a cushion of air about 0.000 001 inch thick. It is so thin that a smoke particle, fingerprint, dust, or human hair could cause what is known as a head crash. A head crash happens when the surface of the read-write head or particles on its surface contact the magnetic disk surface. A head crash is a disaster for a hard disk. It means that some or all of the data on the disk is destroyed. Hard disks are assembled under sterile conditions and sealed from impurities within their permanent containers.
Optical Disks Optical disks are used for storing great quantities of data. An optical disk can hold 650 megabytes of data—the equivalent of hundreds of floppy disks. Moreover, an optical disk makes an immense amount of information available on a microcomputer. In optical-disk technology, a laser beam alters the surface of a plastic or metallic disk to represent data. To read the data, a laser scans these areas and sends the data to a computer chip for conversion.
Magnetic Tape Magnetic tape is an effective way of making a backup, or duplicate, copy of your programs and data. We mentioned the alarming consequences that can happen if a hard disk suffers a head crash. You will lose some or all of your data or programs. Of course, you can always make copies of your hard-disk files on floppy disks. However, this can be time-consuming and may require many floppy disks. Magnetic tape is sequential access storage and can solve the problem mentioned above.
Input Hardware Input devices take data and programs, and people can read or understand and convert them to a form the computer can process. This is the machine-readable electronic signals of Os and 1s. Input hardware is of two kinds: keyboard entry and direct entry.
Keyboard Entry Data is input to the computer through a keyboard that looks like a typewriter keyboard but has additional keys. In this way, the user typically reads from an original document called the source document. The user enters that document by typing on the keyboard.
Direct Entry Data is made into machine-readable form as it is entered into the computer, no keyboard is used. Direct entry devices may be categorized into three areas: pointing devices (for example, mouse, touch screen, light pen, digitizer), scanning devices (for example, image scanner, fax machine, bar-code reader), and voice-input devices.
Output Hardware Output devices convert machine-readable information into people-readable form. Common output devices are monitors, printers, plotters, and voice output.
Monitors Monitors are also called display screen or video display terminals. Most monitors that sit on desks are built in the same way as television sets, and these monitors are called cathode-ray tubes. Another type of monitor is flat-panel display, including liquid-crystal display (LCD), electroluminescent (EL) display and gas-plasma display. An LCD does not emit light of its own. Rather, it consists of crystal molecules. [2] An electric field causes the molecules to line up in a way that alters their optical properties. Unfortunately, many LCDs are difficult to read in sunlight or other strong light. A gas-plasma display is the best type of flat screen. Like a neon light bulb, the plasma display uses a gas that emits light in the presence of an electric current.
Printers There are four popular kinds of printers: dot-matrix, laser, ink-jet, and thermal.
Dot-Matrix Printer Dot-matrix printers can produce a page of text in less than 10 seconds and are highly reliable. They form characters or images using a series of small pins on a print head. The pins strike an inked ribbon and create an image on paper. Printers are available with print heads of 9, 18, or 24 pins. One disadvantage of this type of printer is noise.
Laser Printer The laser printer creates dot-like images on a drum, using a laser beam light source. [3] The characters are treated with a magnetically charged ink-like toner and then are transferred from drum to paper. A heat process is used to make the characters adhere. The laser printer produces images with excellent letter and graphics quality.
Ink-Jet Printer An ink-jet printer sprays small droplets of ink at high speed onto the surface of the paper. This process not only produces a letter-quality image but also permits printing to be done in a variety of colors.
Thermal Printer A thermal printer uses heat elements to produce images on heat-sensitive paper. Color thermal printers are not as popular because of their cost and the requirement of specifically treated paper. They are a more special use printer that produces near photographic output. They are widely used in professional art and design work where very high quality color is essential.
Plotters Plotters are special-purpose output devices for producing bar charts, maps, architectural drawings, and even three-dimensional illustrations. Plotters can produce high-quality multicolor documents and also documents that are larger in size than most printers can handle. There are four types of plotters: pen, ink-jet, electrostatic, and direct imaging.
Voice-Output Devices Voice-output devices make sounds that resemble human speech but actually are pre-recorded vocalized sounds. Voice output is used as a reinforcement tool for learning, such as to help students study a foreign language. It is used in many supermarkets at the checkout counter to confirm purchases. Of course, one of the most powerful capabilities is to assist the physically challenged.
Words
| adhere | v. | 黏附，附着，坚持 |
| architectural | adj． | 建筑上的，建筑学的 |
| arithmetic | n. | 算术，运算 |
| assemble | v. | 集合，聚集，装配 |
| cabinet | n. | 橱柜，机箱 |
| checkout | n. | 检验，收款处 |
| chip | n. | 芯片 |
| crystal | adj. | 结晶状的 |
| n. | 晶体 | |
| cushion | n. | 垫子，软垫，衬垫 |
| droplet | n. | 小滴 |
| duplicate | n. | 复制品，副本 |
| electromagnetic | adj. | 电磁的 |
| flexible | adj. | 柔韧的，易弯曲的 |
| impurity | n. | 杂质，混杂物，不洁，不纯 |
| immense | adj. | 极广大的，无边的 |
| megabyte | n. | 兆字节 |
| metallic | adj. | 金属的 |
| molecule | n. | 分子 |
| multiplication | n. | 乘法，增加 |
| mylar | n. | 聚酯薄膜 |
| neon | n. | 氖，氖光灯，霓虹灯 |
| optical | adj. | 光学的，眼的，视力的 |
| oxide | n. | 氧化物 |
| plasma | n. | 等离子体，等离子区 |
| plotter | n. | 绘图仪 |
| reinforcement | n. | 增援，加强，加固，援军 |
| sensitive | adj. | 敏感的，灵敏的，感光的 |
| sterile | adj. | 贫脊的，不育的，消过毒的，无菌的 |
| spray | v. | 喷射，喷溅 |
| temporarily | adv. | 暂时地，临时地 |
| thermal | adj. | 热的，热量的 |
| toner | n. | 调色剂，调色者，碳粉 |
| vocalize | v. | 成为有声 |
| volatile | adj. | 挥发性的，可变的，不稳定的 |
Phrases
| dot-matrix printer | 点阵式打印机 |
| head crash | 磁头划伤 |
| ink-jet printer | 喷墨式打印机 |
| laser printer | 激光打印机 |
| line up | 排列，（使）排成行，（使）对齐 |
| thermal printer | 热敏式打印机 |
Abbreviations
| ALU（Arithmetic-Logic Unit） | 算术—逻辑单元 |
| EL（Electroluminescent） | 电致发光 |
| LCD（Liquid-Crystal Display） | 液晶显示器 |
Notes
[1] 例句：The purpose of storage hardware is to provide a means of storing computer instructions and data in a form that is relatively permanent, that is, the data is not lost when the power is turned off—and easy to retrieve when needed for processing.
分析：句中means是“方法”的意思。when needed for processing是状语从句when they are needed for processing的省略形式。为了简洁起见，有的状语从句（如时间状语从句、条件状语从句等）有时可省略从句的主语和部分谓语（尤其是当从句主语与主句主语一致，且从句谓语包括有动词be时）。例如，He kept silent when (he was) asked why he was late. 当被问及为什么迟到时，他一言不发。
译文：存储硬件的作用是以一种相对持久的方式提供存储计算机指令和数据的方法，即当切断电源时不会丢失数据，且当需要处理数据时又容易恢复。
[2] 例句：An electric field causes the molecules to line up in a way that alters their optical properties.
分析：句中line up意思是“排成行”，that alters their optical properties是定语从句，修饰way。
译文：电场使得这些分子排成一行，这种排行改变着它们的光学特性。
[3] 例句：The characters are treated with a magnetically charged ink-like toner and then are transferred from drum to paper.
分析：句中treat with意思是“用……处理”，then后面省略了主语the characters。
译文：字符先被用磁化的带电的像墨一样的碳粉处理，然后被从磁鼓传送到纸上。
Exercises
Ⅰ. Put "true" or "false" in the brackets for the following statements according to the passage.
1. ( ) The CPU is the processor of a computer.
2. ( ) The memory of a computer can hold data and information permanently.
3. ( ) Diskettes are flexible, flat, circular pieces of mylar plastic that rotate within a jacket, and they can be bent easily.
4. ( ) Hard disks are instruments extremely sensitive to pollution, so magnetic tape is an effective compensation for making a backup of your programs and data.
5. ( ) Input devices accept people readable data and programs, and convert them to machine readable form; while output devices reverse the process.
6. ( ) Direct entry doesn't need keyboard to input data and information into computer.
7. ( ) Mouse, touch screen, light pen, digitizer and plotter are all direct entry devices.
8. ( ) Thermal printer must use specialized paper.
9. ( ) Laser printer can produce images with excellent letter and graphics quality, and it can also print large size documents.
10. ( ) Voice output devices can mimic human speech immediately.
Ⅱ. Fill in the blanks according to the passage.
1. The CPU itself has two parts:and.
2. The ALU performs two operations:and.
3. The basic math operations are:, , , .
4. Image scanner, fax-machine and bar-code reader are all.
5. LCD, EL and gas-plasma are alldisplays.
6. Output devices convertinformation intoform.
7. LCDs are difficult to read inor other.
8. One disadvantage of dot-matrix printer is.
9. Plotters are special-purpose output devices, for producing, , , and evenillustrations.
10. Voice-output devices make sounds that resemble human speech but actually are.
Ⅲ. Translate the following words and expressions into Chinese.
1. arithmetic-logic unit
2. volatile
3. optical disk
4. electromagnetic charges
5. time-consumig
6. direct entry
7. voice-input
8. inked ribbon
9. letter-quality
10. heat sensitive
Flash memory is a non-volatile computer memory that can be electrically erased and reprogrammed. It is a technology that is primarily used in memory cards and USB flash drives (as shown in Figure 1.5) for general storage and transfer of data between computers and other digital products. It is a specific type of EEPROM (Electrically Erasable Programmable Read-Only Memory) that is erased and programmed in large blocks; in early flash the entire chip had to be erased at once. Flash memory costs far less than byte-programmable EEPROM and therefore has become the dominant technology wherever a significant amount of non-volatile, solid state storage is needed. Example applications include PDAs (personal digital assistants), laptop computers, digital audio players, digital cameras and mobile phones. It has also gained popularity in the game console market, where it is often used instead of EEPROMs or battery-powered SRAM for game save data.
Figure 1.5 A USB flash drive. The chip on the left is the flash memory. The microcontroller is on the right
Flash memory is non-volatile, which means that no power is needed to maintain the information stored in the chip. In addition, flash memory offers fast read access times (although not as fast as volatile DRAM memory used for main memory in PCs) and better kinetic shock resistance than hard disks. These characteristics explain the popularity of flash memory in portable devices. Another feature of flash memory is that when packaged in a "memory card", it is enormously durable, being able to withstand intense pressure, extremes of temperature, and even immersion in water.
Although technically a type of EEPROM, the term "EEPROM" is generally used to refer specifically to non-flash EEPROM which is erasable in small blocks, typically bytes. Because erase cycles are slow, the large block sizes used in flash memory erasing give it a significant speed advantage over old-style EEPROM when writing large amounts of data.
Flash memory was invented by Dr. Fujio Masuoka while working for Toshiba circa 1980. According to Toshiba, the name "flash" was suggested by Dr. Masuoka's colleague, Mr. Shoji Ariizumi, because the erasure process of the memory contents reminded him of a flash of a camera. Dr. Masuoka presented the invention at the IEEE 1984 International Electron Devices Meeting (IEDM) held in San Francisco, California.
Words
| circa | prep. | 大约 |
| console | n. | ［计］控制台 |
| durable | adj. | 持久的，耐用的 |
| enormously | adv. | 非常地，巨大地 |
| immersion | n. | 沉浸 |
| kinetic | adj. | （运）动的，动力（学）的 |
| maintain | v. | 维持，维修，继续 |
| Toshiba | n. | 日本东芝公司 |
Phrases
EEPROM (Electrically Erasable Programmable Read-Only Memory） 电可擦除只读存储器
计算机硬件有四个组成部分：中央处理器和内存、存储硬件、输入硬件和输出硬件。
CPU 计算机运行程序的部分被称为处理器或中央处理单元。在微型计算机中，CPU在系统单元或系统机箱内的单独电子元件，即微处理器芯片上。CPU本身具有两个部分：控制单元和算术—逻辑单元。在微型计算机中，这两个部分都在微型机芯片上。
控制单元 控制单元告诉计算机系统的其他部分如何完成程序指令。它指挥着电子信号在内存和算术—逻辑单元之间的移动。它也控制着CPU和输入／输出设备之间的控制信号。
算术—逻辑单元 通常被称为ALU，完成两类运算——算术和逻辑。算术运算是基本的数学运算：加、减、乘、除。逻辑运算是由比较（运算）构成的。也就是说，对两个数据进行比较，以看其中一个是否是等于、小于或大于另外一个。
内存 内存也被称为主存储器、内部存储器，它临时存储数据、程序指令和信息。关于内存需要重点了解的是它所保存的内容只是临时的。换句话说，这些内容只有在计算机开着时才能被保存。当关闭机器时，其内容会立即消失。在内存中所存储的信息是不稳定的并会很快消失。
存储硬件 存储硬件的作用是以相对持久的方式提供存储计算机指令和数据的方法，即当切断电源时不会丢失数据，且当需要处理数据时又容易恢复。目前有四种存储硬件：软盘、硬盘、光盘和磁带。
软盘 软盘又被称为软磁盘、可弯曲磁盘、软盘或简单地称为磁盘。在磁盘封套内是柔韧的圆形聚酯塑料盘片，它们在封套内旋转。程序和数据以电磁荷的形式存储在聚酯塑料片表面的金属氧化物薄膜上。
硬盘 硬盘由金属盘片而不是塑料盘片组成。它们被紧紧地密封起来，以防止外界东西进入。硬盘是非常灵敏的设备。读写头浮在大约0.000 001英寸厚的空气气垫上。空气垫非常薄，以至于烟粒、指印、灰尘或者头发都可能引起磁头划伤。磁头划伤对于硬盘来讲是灾难性的，它意味着磁盘上的数据部分或全部丢失。硬盘在无菌条件下安装并且密封在远离杂质的永久的容器内。
光盘 光盘用于存储大量的数据。一个光盘可能容纳650兆字节的数据——相当于数以百计的软盘。并且，光盘使得大量的信息可用于微机上。在光盘技术中，激光束改变塑料或金属盘的表面来表示数据。为了读取数据，激光扫描这些区域并且将这些数据送给计算机芯片以便转换。
磁带 磁带可有效地备份（即复制、拷贝）程序和数据。我们曾提到如果硬盘磁头划伤，就会产生令人担忧的结果，因为这将会丢失部分或全部的程序或数据。当然，也可以将硬盘上的文件拷贝到软盘上。但这样很费时，并且需要很多张软盘。磁带是顺序访问存储的，能够解决上面所提到的问题。
输入硬件 输入硬件接收人们能读懂的程序和数据，并将其转换为计算机能处理的形式，这就是机器可读的电子信号0和1。输入硬件有键盘输入和直接输入两种。
键盘输入 数据通过形似打字机键盘但有附加键的键盘输入到计算机。用这种方式，用户一般读取被称为是源文件的初始文件，通过在键盘上打字输入文件。
直接输入 当数据输入到计算机时，是以机器可读懂的形式输入的，不需要键盘。直接输入设备分成三类：指针设备（如鼠标、触摸屏、光笔、数字化仪）、扫描设备（如图像扫描仪、传真机、条形码读器）和声音输入设备。
输出硬件 输出设备将机器可读的信息转换为人类可读的形式。一般的输出设备有监视器、打印机、绘图仪和声音输出设备。
监视器 监视器也被称为屏幕显示或视频显示终端。大多数放在桌面上的监视器的制作方法同电视机一样，它们被称为是阴极射线管。另一类监视器是平板显示器，包括液晶显示器、光电发光显示器和等离子显示器。液晶显示器自己不发射光，相反，是由晶体分子组成，电场使得这些分子排成一行，这种排行改变着它们的光学特性。遗憾的是，许多液晶显示器在太阳光或其他强光下很难读到。等离子显示器是平板显示器中最好的一种。与氖光灯泡一样，等离子显示器在电流存在的情况下使用一种发光的气体。
打印机 目前普遍使用的打印机有四种：点阵式、激光式、喷墨式和热敏式。
点阵式打印机 它能在不到几秒的时间内打印一页文本并且非常稳定。点阵式打印机利用在打印头上的一系列小针来形成字符或图像，这些针击打喷墨的色带并在纸上产生图像。目前有9针、18针和24针的打印机，这种打印机的缺点是它的噪声较大。
激光打印机 它使用激光束光源在磁鼓上产生小点一样的图像，并用磁化的带电的像墨一样的碳粉处理这些字符，然后从磁鼓传送到纸上，再使用热处理过程使这些字符粘贴。激光打印机打印的图像字符清晰，图像质量高。
喷墨式打印机 它能以很快的速度将小点状墨汁喷到纸面上。该类打印机不仅可用于印刷高质量的图像，而且能打印彩色图像。
热敏式打印机 它使用热元素在热感应纸上产生图像。由于价格高并需要特殊处理的纸张，彩色热敏打印机还不是很普及。热敏式打印机能产生逼真的输出。它们被广泛应用在要求高质量彩色输出的专业艺术设计工作中。
绘图仪 绘图仪是特殊用途的输出设备，用于产生条形图、地图、建筑绘图，甚至三维图表。绘图仪可以输出高质量的多种色彩的文档，并且文档的尺寸比大多数打印机能处理的大。目前有四种类型的绘图仪：钢笔、喷墨、静电和直接图像。
声音输出设备 声音输出设备可以发出类似于人类说话的声音，但实际上声音是事先被录制的。声音输出作为强化工具被用于辅助学习，例如帮助学生学习外语。它还被用于许多超市的收款台来确认购买。当然，它最强大的功能是帮助残障者。
闪存（Flash memory），是一种以电子方式擦除和重写的非易失性的存储器。这种技术主要用于存储卡与USB闪存驱动器（图1.5所示），进行一般性资料的储存，以及在计算机与其他数字产品间交换传输资料。闪存是一种类型特殊的、以大区块擦除与重写的EEPROM（电可擦除可编程的只读存储器），早期的闪存只能对整个芯片进行擦除。闪存的成本远比以字节为单位擦写的EEPROM低，其技术主要用于需要大量非易失性固态存储的场合。PDA（个人数字助手）、笔记本电脑、数字随身听、数字相机与手机上均可见到闪存。此外，闪存还较好地获得了游戏控制台的市场，借以取代储存游戏资料用的EEPROM或带有电池的SRAM。
闪存是非易失性的，也就是说没有电源也可以使得存储在芯片上的信息不被丢失。另外，闪存提供快速读取（但没有PC主存中使用的易失性DRAM那么快），而且与硬盘相比，闪存具有更佳的动态抗振性。这些特点使得闪存在便携式设备中得到广泛应用。闪存的另一个特性是：它被制成存储卡后非常耐用，可以承受高压力与极端的温度，甚至浸在水中也不会损坏。
虽然闪存在技术上属于EEPROM，但是“EEPROM”通常特指非快闪式、以小区块方式清除的EEPROM，它们的清除单位是字节。老式的EEPROM擦除循环相当缓慢，相比之下以大区块方式擦除的闪存在写入大量资料时则具有明显的速度优势。
闪存是Fujio Masuoka博士于1980年在为东芝公司工作时发明的。根据东芝公司的说法，Fujio Masuoka博士的同事Shoji Ariizumi先生将其命名为“闪”（flash），是因为这种新存储器删除内容的过程使他想起照相机的闪光灯。Masuoka博士于1984年在美国加州旧金山举行的IEEE国际电子设备会议上介绍了该项发明。