The storage devices write data and programs onto or read them from storage media（）

Secondary Storage Media

  

辅助存储介质

  Secondary storage or external memory may sound at first like a misnomer, since there are at least two or three faster forms of memory in every machine. Secondary memory is clearly slower than either registers or main memory, so why not tertiary memory? In practice, registers are not generally thought of as storage devices more like working locations. Main memory is the primary storage location of data during execution of a program. Cache memory^[1]is a relatively recent invention (also one that is frequently invisible to the programmer in most models of computation). External memory is secondary to RAM^[2]as an important visible depository of data. It sits at one end of the memory hierarchy: usually at least a few orders of magnitude larger than main memory, several orders of magnitude slower, and an order or two less expensive. The first and last of these properties provide its principal advantage; the middle property, its principal disadvantage.

  Secondary memory has two features that can not be provided by RAM memory as discussed up to this point. First, while RAM memory may not be large enough to hold all of the data that a program needs, secondary storage can be arbitrarily large. One million bytes of RAM sounds like a considerable quantity. However, consider a matrix designed to hold relationships between any two of 5000 data items.

  One advantage of a computer is that once data have been entered, they can be stored on the machine and accessed repeatedly. Generating address labels for a magazine is a good example. Instead of retyping all the labels for each edition, subscriber data are input once, stored, and then dumped from storage whenever necessary. Programs provide another example. Like the subscriber data, they are stored on the computer and accessed on demand.

  Where exactly are the data and the programs stored? The obvious answer is main memory, but main memory is expensive, and the supply on most machines is limited. Another problem is its volatility; main memory loses its contents when the power is cut. We need a fast, accurate, inexpensive, high-capacity, nonvolatile extension of main memory. and secondary storage fills this need.

  

Ⅰ. Semiconductor Memory Storage

  Semiconductor memory uses semiconductor-based integrated circuits to store information. A semiconductor memory chip may contain millions of tiny transistors or capacitors. Both volatile and non=volatile forms of semiconductor memory exist. In modern computers, primary storage almost exclusively consists of dynamic volatile semiconductor memory or dynamic random access memory. Since the turn of the century, a type of non- volatile semiconductor memory known as flash memory has steadily gained share as off-line storage for home computers. Non-volatile semiconductor memory is also used for secondary storage in various advanced electronic devices and specialized computers. Examples of semiconductor memory include static random access memory (RAM), which relies on transistors, and dynamic random access memory, which uses capacitors to store the bits.

  Flash memory^[3]is a non-volatile computer memory that can be electrically erased and reprogrammed. It is a technology that i.s primarily used in memory cards and USB^[4]flash drives for general storage and transfer of data between computers and other digital products. It is a specific type of EEPROM^[5](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 i.s needed. Example applications include PDAs^[6](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^[7]for game save data.

  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^[8]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^[9], " it is enormously durable, being able to withstand intense pressure, extremes of temperature, and even immersion in water.

  U-Disk is a flash memory card and is superior to the similar types of flash memory cards such as Compact Flash, Smart Media and so forth. U-Disk International Association consists of 89 IT companies around the world. With the promotions done by U-Disk International Association, U-Disk will create a new standard in the world' s mini-memory storage market.

  

Ⅱ. Paper Data Storage

  Paper data storage refers to the storage of data on paper. This includes writing, illustrating, and the use of data that can be interpreted by a machine or is the result of the functioning of a machine. A defining feature of paper data storage is the ability of humans to produce it with only simple tools and interpret it visually. Though it is now mostly obsolete, paper was once an important form of computer data storage.

  The earliest use of paper to store instructions for a machine was the work of Basile Bouchon^[10]who, in 1725, used punched paper rolls to control textile looms. This technology was later developed into the wildly successful Jacquard loom^[11]. The 19th century saw several other uses of paper for data storage. In 1846, telegrams could be prerecorded on punched tape.

  The data tabulation industry and computer revolution of the 20th century led to several more uses of paper as a data storage medium. Hollerith^[12]'s company later became IBM and his cards were widely used with computers through the 1970s. Other technologies were also developed that allowed tabulating machines and computers to work with marks on paper instead of punched holes. This technology was widely used for tabulating votes and grading standardized tests. Barcodes made it possible for any object that was to be sold or transported to have some computer readable information securely attached to it.

  

Ⅲ. Magnetic Storage

  Magnetic storage and magnetic recording are terms from engineering referring to the storage of data on a magnetized medium. Magnetic storage uses different patterns of magnetization in a magnetizable material to store data and is a form of non-volatile memory. The information is accessed using one or more read/write heads. As of 2007, magnetic storage media, primarily hard disks, are widely used to store computer data as well as audio and video signals. In the field of computing, the term magnetic storage is preferred and in the field of audio and video production, the term magnetic recording is more commonly used. The distinction is less technical and more a matter of preference.

  · Magnetic Cassette

  The least expensive of the secondary storage media is magnetic cassette, one of the most common backup media. Data are output to a tape recorder. By playing the "recording" back, the material is restored to main memory. Cassettes are inexpensive and compact, but they are also relatively slow and error prone. They are used on some small home computer systems or for archival storage.

  ·Diskette

  The most common microcomputer secondary storage medium is diskette or floppy disk, a thin circular piece of flexible polyester coated with a magnetic material. Data are recorded on one or both flat surfaces. Because contact with dust, or even a human finger can destroy the data, each diskette has its own protective jacket. A diskette drive works much like a record turntable. The round hole in the center of the disk allows the drive mechanism to engage and spin it; an access mechanism, analogous to the tone arm^[13], reads and writes the surface through the window visible near the bottom.

  The data are recorded on a series of concentric circles called tracks. The access mechanism steps from track to track, reading or writing one at a time. The tracks are subdivided into sectors; it is the contents of a sector that move between the diskette and main memory. To distinguish the sectors. they are addressed by numbering them sequentially 0, 1,2, and so on.

  Although diskette is certainly faster than cassette, data access still means a delay of at least a fraction of a second. Many common personal computer applications involve only limited disk access, so the delay is hardly noticeable. On other applications, however, the delay can be intolerable. The solution is often a hard disk.

  ·Hard Disk

  A diskette drive spins only when data are being read or written. The drive must be brought up to operating speed before the read/write heads can be moved and the data accessed, and that^[14]takes time. A hard disk, in contrast, spins constantly. Since it is not necessary to wait for the drive to reach operating speed before moving the access mechanism, seek time is significantly reduced, often to a few thousandths of a second. Further improvements are gained by spinning the disk more rapidly (5000 revolutions per minute or more) , which reduces rotational delay. Data stored on hard disk can be accessed far more rapidly than data stored on diskette.

  Another advantage of hard disk is its storage capacity. A typical double-sided diskette might hold 1440,000 characters. A hard disk for a microcomputer system might store 1 to 10 billion characters.

  With slow diskette drives, the access mechanism rides directly on the disk surface. At 1000 revolutions per minute, however, any physical contact between the disk surface and the read/write head would quickly destroy both: thus, a hard disk's access mechanism rides on a cushion of air, a few millionths of an inch above the surface. (Shaped like an airfoil, the read/write head literally files) Because such pollutants as a smoke particle, dust, or a human hair won't fit between the head and the surface, a hard disk is normally encased in an airtight container to protect it from the environment.

  

Ⅳ. Optical Storage

  Initially, optical discs were for storing music and computer software. The laser disc format stored analog video signals, but, commercially, lost to the VHS^[15]videotape cassette, mainly due to its high cost and non-recordability, other first-generation disc formats are designed solely to store digital data.

  Most first-generation disc devices had an infrared laser reading head. The minimum size of the laser spot is proportional to its wavelength, thus wavelength is a limiting factor against great information density, and too little data can be stored. Second-generation optical discs were for storing great amounts of data, including broadcast-quality digital video. Such discs usually are read with a visible-light laser (usually red); the shorter wavelength and greater numerical aperture allow a narrower light beam, permitting smaller pits and lands in the disc. In the DVD^[16]format, this allows 4.7GB storage on a standard 12cm, single-sided, single-layer disc; alternately, smaller media, such as the MiniDisc^[17]and the DataPlay formats, can have capacity comparable to that of the larger, standard compact 12cm disc.

  Third-generation optical discs are in development, meant for distributing high- definition video and support greater data storage capacities, accomplished with short- wavelength visible-light lasers and greater numerical apertures. The Blu-ray disc^[18]uses blue-violet lasers of greater aperture, for use with discs with smaller pits and lands, thereby greater data storage capacity per layer. In practice, the effective multimedia presentation capacity is improved with enhanced video data compression codes.

  Notes

  [1] cache memory高速缓冲存储器。

  [2] RAM(random access memory)随机访问存储器，可由CPU或其他硬件设备读或写的半导体存储器。

  [3] flash memory闪电内存或闪存，一种非易失性的内存。它在功能上与EEPROM相似，但是它必须按块擦除，而EEPROM则可以一次只擦除一个字节。闪电内存通常用在便携机中作为硬盘的补充或替代品。

  [4] USB(Universal Serial Bus)通用串行总线架构

  [5] EEPROM (electrically erasable programmable read only memory)电可擦除可编程只读存储器。用于断电情况下对数据的长期稳定存储，同时允许重编程。EEPROM包含的存储器比RAM少，重编程时间长，而且在其有效使用期内只允许有限次的重编程。

  [6] PDA(Personal Digital Assistant)个人数字助理。它是一种轻便的掌上型计算机，既有通信功能，又有个人组织功能(包括日历、笔记、数据库、计算器等)。更高级的型号中还提供了多媒体功能。

  [7] SRAM (static RAM)静态随机存储器，半导体存储器(RAM)的一种，由触发器逻辑电路构成，只要有足够的电力使之运行，信息就会一直保持。通常用作缓存。

  [8] DRAM (dynamic RAM)动态随机存储器。动态RAM将信息存储在包含电容器的集成电路中。由于电容器的电荷会随时间丢失，因此动态RAM板上必须包括一个连续刷新(再充电)RAM芯片的逻辑电路。

  [9] memory card存储卡，用于扩展RAM存储容量，或者代替诸如膝上型电脑、笔记本电脑或手提式电脑等便携式计算机的硬盘的存储模块。

  [10] The earliest use of paper to store instructions for a machine. 最早期的存储媒介——打孔纸卡，是最早的数据存储媒介，在1725年由法国纺织工人鲁修(Basile Bouchon)发明出来，用来保存印染布上的图案。

  [11] Jacquard loom提花机，法国人Jacquard (1752-1834)发明的衣布织机。

  [12] Hollerith霍勒里思·赫尔曼(1860-1929)，美国发明家，他发明了能够在穿孔卡片上贮存和再现信息的系统(1880年)并创建了后来发展为IBM的公司(1924年)。

  [13] tone arm唱臂，在留声机唱盘上支持唱片的臂状物。

  [14] that指前面提到的“the drive must be brought up to operating speed before the read/write heads can be moved and the data accessed.”.

  [15] VHS (Video Home System)家用录像系统。它是由日本JVC公司在1976年开发的一种家用录像机录制和播放标准。

  [16] DVD(digital video disc)数字视频磁盘，第二代光盘存储技术，它使用数字视频磁盘技术，可以将视频、音频、及计算机数据编码到光盘(CD)上。

  [17] MD(MiniDisc)迷你光碟，也是对MD碟片及使用MD碟片设备的通称。MD碟片直径为6.4cm，外有一个略大于盘面的矩形塑料外壳保护。

  [18]蓝光(Blu—ray)或称蓝光盘(Blu—ray Disc，缩写为BD)利用波长较短(405nm)的蓝色激光读取和写入数据，并因此而得名。而传统DVD需要光头发出红色激光(波长为650nm)来读取或写入数据，通常来说波长越短的激光，能够在单位面积上记录或读取更多的信息。

Another trend of the 1990s in the computer industry is toward multimedia formats, as the market for conventional types of computer--those that have computation and data processing as their major functions--has begun to become saturated. Multimedia computers are systems that can process graphics, sound, video, and animation in addition to traditional data processing. Videocassette recorders, televisions, telephones, and audiocassette players have recently undergone a change in technology from analog to digital formats. Television images, for example, can be processed by computer programs once they have been converted to digital signals, while those in conventional analog signals cannot. In other words, digital video images can be zoomed up or down, reshaped, or rearranged by the appropriate software. Also, due to advances in video-signal compression technology, the memory space required for storing a video program has been greatly reduced.

Multimedia has important applications for consumer products and for business needs. Video scenes that are captured by camcorders can be combined with text, sound, and data and can be viewed on television sets in homes, schools, or offices. These multimedia presentations are becoming useful educational and commercial tools. For example, there are available encyclopaedias that contain video programs depicting animal behavior, geomorphic processing, and other natural phenomena. Automobile mechanics can watch videos that demonstrate how to repair new models. In business applications, documents can be annotated with 7oice or video. New consumer products can be more effectively marketed by demonstrating how they can be used. CD-ROMs of numerous other subjects have been recently published; all of them can be viewed on TV monitors using multimedia computers. These multimedia computer systems can, in turn, be incorporated into computer networks, enhancing the effectiveness of communication.

This multitude of new products and capabilities has been made possible by the tremendous progress of microprocessor technology. Because of the advances in this area, personal computers have become more powerful, smaller, and less expensive, which has enabled computer networks to proliferate. Many of the tasks that were traditionally performed by mainframes have been transferred to personal computers connected to communications networks. Although the mainframe. continues to be produced and serves a useful purpose, it has been used more often as one of many different computers and peripheral devices connected to computer networks. In this new role, the function of mainframes as powerful processors of database systems is becoming important, and, as a result, massively parallel computers with hundreds or thousands of microprocessors are being produced. In addition to being powerful, the microprocessors used for this purpose must be inexpensive, but low costs can be achieved only if they are mass-produced. Throughout the world, more than 100, 000, 000 personal computers and 500, 000 workstations are in use, whereas only several hundred supercomputers are in operation; the numbers of mainframes and minicomputers fall somewhere between those of supercomputers and workstations. Because of such high-volume production, microprocessors for personal computers or workstations tend to be inexpensive and are available for use in massively parallel computers as well.

Multimedia computers ______.

A．can process anything but digital data

B．can even process television images

C．are rarely used in education

D．have few business applications

Somedatastorageandtransfermediahavefixed-lengthphysicalrecords.Whenthedatarecordsareshort，morethenonecanbestoredinasingle，physicalrecordtousethestoragespaceefficiently.Considerthisdata：1119Smith1120Yvonne1121Albert1130ThomasWhichtwostatementscanyouusetoloadthedataintotheEMPtable？（）

A.A

B.B

C.C

D.D

Laura Holshouser's favorite video games include Halo, Tetris, and an online training game developed by her employer. A training game? That's right. The 24-year-old graduate student, who manages a Cold Stone Creamery ice-cream store in Riverside, Calif. , stumbled across the game on the corporate Web site in October.

It teaches portion control and customer service in a cartoon-like simulation of a Cold Stone store. Players scoop cones against the clock and try to avoid serving too much ice cream. The company says more than 8,000 employees, or about 30% of the total, voluntarily downloaded the game in the first week. "It's so much fun," says Holshouser. "I e-mailed it to everyone at work."

The military has used video games as a training tool since the 1980s. Now the practice is catching on with companies, too, ranging from Cold Stone to Cisco Systems Inc. to Canon Inc. Corporate trainers are betting that games' interactivity and fun will hook young, media-savvy employees like Holshouser and help them grasp and retain sales, technical, and management skills. "Video games teach resource management, collaboration, critical thinking, and tolerance for failure," says Ben Sawyer, who runs Digitalmill Inc. , a game consultancy in Portland, Me.

The market for corporate training games is small but it's growing fast. Sawyer estimates that such games make up 15% of the "serious," or nonentertainment market, which also includes educational and medical training products. Over the next five years, Sawyer sees the serious-games market more than doubling, to $100 million, with trainers accounting for nearly a third of that. It's numbers like those that prompted Cyberlore Studios Inc. , maker of Playboy: The Mansion, to refocus on training games—albeit based on its Playboy title. And training games will be top of mind at the Game Developers Conference in San Jose, Calif. , this month.

Companies like video games because they are cost-effective. Why pay for someone to fly to a central training campus when you can just plunk them down in front of a computer? Even better, employees often play the games at home on their own time. Besides, by industry standards, training games are cheap to make. A typical military game costs up to $10 million, while sophisticated entertainment games can cost twice that. Since the corporate variety don't require dramatic, warlike explosions or complex 3D graphics, they cost a lot less. BreakAway Games Ltd., which designs simulation games for the military, is finishing its first corporate product, V-bank, to train bank auditors. Its budget? Just $500,000.

Games are especially well-suited to training technicians. In one used by Canon, repairmen must drag and drop parts into the right spot on a copier. As in the board game Operation, a light flashes and a buzzer sounds if the repairman gets it wrong. Workers who played the game showed a 5% to 8% improvement in their training scores compared with older training techniques such as manuals, says Chuck Reinders, who trains technical support staff at Canon. This spring, the company will unveil 11 new training games.

Games are also being developed to help teach customer service workers to be more empathetic. Cyberlore, now rechristened Minerva Software Inc. , is developing a training tool for a retailer by rejiggering its Playboy Mansion game. In the original, guests had to persuade models to pose topless. The new game requires players to use the art of persuasion to sell products, and simulates a store, down to the carpet and point-of-purchase display details.

Don Field, director of certifications at Cisco, says games won't entirely replace traditional training methods such as videos and classes. But he says they should be part of the toolbox. Last year, Cisco rolled out six new training games—some of them designed to teach technicians how to build a computer network. It's hard to imagine a drier subject. No

A．The advantages of online training game have been exploited by many companies to save money.

B．Video games have been used as training tool for the military.

C．Companies tend to use online game as the marketing tool.

D．Online training game will become a major industry in the following years.

Its the holiday season and that means kids by the millions are asking Santa for the opportunity to blow away enemy soldiers and aliens on the Xbox or PlayStation. Would parents be worried about【M1】______ buying such gifts? Violent video games are now an established part of our culture; recent releases of games such as Call of Duty: Modern Warfare and Skyrim have setting sales records for media【M2】______ releases(topping even blockbuster movies)and garnishing lavish reviews for their artistic merits. Ten years ago, scholars and politicians raised the possibility such games might contribute to【M3】______ school shootings or other youth violence. Our modern fears over Violent video games appear to be in line with prior moral panics over media as diversely as jazz music,【M4】______ comic books and Harry Potter. Granted, too much passive activity, including video games, can contribute to obesity. Unlike【M5】______ anything else, gaming should be enjoyed in moderation, balanced with outdoor activity, allowed enough time for family and【M6】______ schoolwork. A very small number of kids exhibit signs of pathological gaming. And regarding concerns about aggression, it【M7】______ appears to be that, fairly early on, children learn to distinguish between fantasy and reality, and their brains dont treat these phenomena the same. Santa Claus is a primary example. Despite【M8】______ that not only their parents but all of society conspiring to lie to【M9】______ children about the reality of this fellow, children can reason out the improbability of its existence by the mid-elementary years. With【M10】______ those kinds of reasoning powers, kids can handle a video game that doesnt even claim to be real.

【M1】

What is the woman asking the man for?

A．His opinions on juvenile crime.

B．His opinions on social system.

C．His opinions on the prevention of young people crime.

D．His opinions on the behaviors of media and school.