計(jì)算機(jī)專業(yè)英語相關(guān)素材.doc

“計(jì)算機(jī)專業(yè)英語”課程教學(xué)相關(guān)素材閱讀材料1Computer and MicrocomputerA computer is a machine with an intricate network of electronic circuits that operate switches or magnetized tiny metal cores. A total computer system includes both hardware and software. Hardware consists of the physical components and all associated equipment. Software refers to the programs that are written for the computers.It is possible to be familiar with various aspects of computer software without being concerned with details of how the computer hardware operates. It is also possible to design parts of the hardware without a knowledge of its software capabilities. However those concerned with computer architecture should have a knowledge of both hardware and software because the two branches influence each other.A program written by a user may be either dependent or independent of the physical computer that runs his program. For example, a program written in standard FORTRAN is machine independent.A computer can solve a series of problems and make hundreds, even thousands, of logical decisions without becoming tired or bored. It can find the solution to a problem in a fraction of the time it takes a human being to do the job. A computer can replace people in dull, routine tasks, but it has no originality; it works according to the instructions given to it and cannot exercise any value judgements. But a computer can carry out vast numbers of arithmetic logical operations almost instantaneously.Microcomputers, or micro for short, is a kind of computers. It was born in the early 1970s. The central processor of the micro, called the microprocessor, is built as a single semiconductor device; that is, the thousands of individual circuit elements necessary to perform all the logical and arithmetic functions of a computer are manufactured as a single chip. A complete microcomputer system is composed of a microprocessor, a memory and some peripheral equipment. The processor, memory and electronic controls for the peripheral equipment are usually put together on a single or on a few printed circuit boards. Systems using microprocessors can be hooked up together to do the work that until recently only minicomputer systems were capable of doing. Micros generally have somewhat simpler and less flexible instruction sets than minis, and are typically much slower. Different micros are available with 4-, 8-, 12-, 16-bit word lengths. Similarly, minis are available with much larger primary memory sizes. Micros are becoming more powerful and converging with minicomputer technology.翻譯1計(jì)算機(jī)和微型計(jì)算機(jī)計(jì)算機(jī)是一種具有復(fù)雜電路網(wǎng)絡(luò)的機(jī)器，其電路可控制開關(guān)或磁化微小的金屬磁心。一個(gè)完整的計(jì)算機(jī)系統(tǒng)應(yīng)包括硬件和軟件兩部分，硬件由物理元件和所有相關(guān)設(shè)備組成；軟件則是為計(jì)算機(jī)所寫的程序。即使不了解計(jì)算機(jī)硬件的工作細(xì)節(jié)，也可以通曉計(jì)算機(jī)軟件的各種特性；同樣，不懂計(jì)算機(jī)軟件也可以設(shè)計(jì)硬件部分。但是，一旦涉及計(jì)算機(jī)體系結(jié)構(gòu)，就必須同時(shí)具有硬件和軟件兩方面的知識(shí)，因?yàn)檫@兩個(gè)分支是相互影響的。用戶所寫的程序，可以依賴，也可以獨(dú)立于運(yùn)行這個(gè)程序的具體計(jì)算機(jī)。例如，用標(biāo)準(zhǔn)FORTRAN語言所編寫的程序就是獨(dú)立于機(jī)器的。計(jì)算機(jī)能夠解決一系列問題，作出成百甚至上千個(gè)邏輯判定而不感到疲勞和厭煩。計(jì)算機(jī)能夠在人類做這項(xiàng)工作所需的一小部分時(shí)間內(nèi)，就找到問題的答案。計(jì)算機(jī)可以代替人們做那些單調(diào)的日常工作，但是它沒有創(chuàng)造力；計(jì)算機(jī)根據(jù)給它的指令工作，而不能行使任何意義的判斷。但是計(jì)算機(jī)幾乎在瞬間就可以處理大量的算術(shù)邏輯運(yùn)算。微型計(jì)算機(jī)或簡稱微型機(jī)是計(jì)算機(jī)的一種。它誕生于70年代初期。稱為微處理器的微機(jī)中央處理器是單片半導(dǎo)體裝置。也就是說，實(shí)現(xiàn)計(jì)算機(jī)所有邏輯和算術(shù)功能所必不可少的成千上萬個(gè)單獨(dú)的電路元件都制造在一塊芯片上。完整的微機(jī)系統(tǒng)由微處理器、存儲(chǔ)器和外圍設(shè)備組成。處理器、存儲(chǔ)器和外圍設(shè)備的電子控制裝置通常一起放在一塊或幾塊印刷電路板上。使用微處理器的系統(tǒng)可以在一起來做迄今為止只有小型計(jì)算機(jī)系統(tǒng)才能夠做的工作。一般來說，微機(jī)的指令系統(tǒng)比小型機(jī)略為簡單，靈活度稍低，而且特別是比小型機(jī)慢得多。微型機(jī)的字長不同，有4位、8位、12位和16位的。同樣，小型機(jī)字長可達(dá)32位。盡管小型機(jī)可以裝上較大的主存，但是微型機(jī)變得功能越來越強(qiáng)，并與小型機(jī)技術(shù)結(jié)合起來了。閱讀材料2Types of MemoryThe memory unit is an essential component in any digit computer since it is needed for storing the programs that are executed by the CPU. A very small computer with a limited application may be able to fulfill its intended ask without the need of additional storage capability. However, most computers would run more efficiently if they are supplied with additional storage beyond the capacity of the main memory.There is just not enough space in one memory unit to accommodate all the systems programs written for a typical computer. Moreover, most computer installations accumulate and continue to accumulate large amounts of information.Not all computers have the same type of memory. The memory of the first computers was made up of a kind of grid of fine vertical and horizontal wires. At each intersection where the wires crossed, there was a small ferrite ring called a core (hence the name core memory) which was capable of being either magnetized or demagnetized. Every intersection had its unique address; consequently, when an electrical current was passed through the wires, the magnetized as well as the demagnetized cores were identified by their respective address. Each core represented a binary digit of either 0 or 1, depending on its state. Early computers had a capacity of around 80000 bits; whereas now, it is not surprising to hear about computers with a memory capacity of millions of bits. This has been made possible by the advent of transistors and by the advances in the manufacture of miniaturized circuitry. As a result, mainframes have been reduced in both size and cost. Throughout the 1950s, 1960s and up to the mid-1970s, core memory dominated the market.In the 1970s, there was a further development which revolutionized the computer field. This was the ability to etch thousands of integrated circuits onto a tiny piece (chip) of silicon, which is a non-metallic element with semiconductor characteristics. Chips have thousands of identical circuits, each one capable of storing one bit. Because of the very small size of the chip, and consequently of the circuits etched on it, electrical signals do not have to travel far; hence, they are transmitted faster. Moreover, the size of the components containing the circuitry can be considerably reduced, a step which has led to the introduction of both minis and micros. As a result, computers have become smaller, faster, and cheaper. There is one problem with semiconductor memory, however, when power is removed, information in the memory is lost, unlike core memory, which is capable of retaining information during a power failure.Another development in the field of computer memories is bubble memory. The concept consists of creating a thin film of metallic alloys over the memory board. When this film is magnetized, it produces magnetic bubbles, the presence or absence of which represents one bit of information. These bubbles are extremely tiny, about 0.1 micrometer in diameter. Therefore, a magnetic bubble memory can store information at a greater density than existing memories, which makes it suitable for micros. Bubble memories are not expensive, consume little power, are small in size, and are highly reliable.Magnetic disk storage looks rather like a juke-box but instead of records, which have only one track on each side, the disks are metal and coated on each side with magnetic material and have as many as 500 concentric tracks per side, each track usually stores one block.The disks are mounted on a vertical shaft with spaces between them to allow the insertion of an arm with two read / write heads, one for the upper disk and the other for the lower. The shaft and disks rotate at about forty revolutions per second. 翻譯2存儲(chǔ)器的種類任何一臺(tái)數(shù)字計(jì)算機(jī)都需要存儲(chǔ)CPU（中央處理器）所執(zhí)行的程序，因此，存儲(chǔ)器是計(jì)算機(jī)最重要的部件之一。一臺(tái)應(yīng)用于有限范圍的很小的計(jì)算機(jī)，不擴(kuò)充其存儲(chǔ)容量，也可以滿足進(jìn)一步的請(qǐng)求。但是，大多數(shù)計(jì)算機(jī)在擴(kuò)充原有主存儲(chǔ)容量后，運(yùn)行效率更高。對(duì)一臺(tái)典型的計(jì)算機(jī)而言，一個(gè)存儲(chǔ)器的空間不足以容納其全部系統(tǒng)程序。而且，大多數(shù)計(jì)算機(jī)越來越聚集了大量的信息。并不是所有的計(jì)算機(jī)都有同樣類型的存儲(chǔ)器。最初的計(jì)算機(jī)存儲(chǔ)器是由纖細(xì)的橫豎導(dǎo)線組成的格柵構(gòu)成。每兩根導(dǎo)線的交叉點(diǎn)處有一個(gè)稱為磁心的小鐵氧環(huán)（所以取名為磁心存儲(chǔ)器）。磁心能夠被磁化或去磁。每一個(gè)交叉點(diǎn)有自己特定的地址。因而當(dāng)電流通過導(dǎo)線時(shí)，被磁化以及被去磁的磁心根據(jù)它們自己的地址而被識(shí)別出來。每個(gè)磁心代表一個(gè)二進(jìn)制數(shù)，不是0就是1，依它的狀態(tài)而定。早期計(jì)算機(jī)的存儲(chǔ)量大約為80000位。而現(xiàn)在，聽到計(jì)算機(jī)的存儲(chǔ)量為上百萬位是不足為奇的。晶體管的出現(xiàn)和小型化電路生產(chǎn)的改進(jìn)已使之成為可能。其結(jié)果是主機(jī)的體積減小且成本降低了。在整個(gè)50年代、60年代一直到70年代中葉，磁心存儲(chǔ)器的銷路占很大優(yōu)勢。在70年代，計(jì)算機(jī)有了進(jìn)一步的發(fā)展，使計(jì)算機(jī)領(lǐng)域發(fā)生了一場革命。這就是將上萬個(gè)集成電路蝕刻在一小塊硅（芯）片上的能力。硅片是具有半導(dǎo)體特性的非金屬元件。芯片上具有成千上萬個(gè)相同的電路。每個(gè)電路能存儲(chǔ)一位。由于芯片很小，且電路蝕刻在芯片上，電信號(hào)無需行進(jìn)很遠(yuǎn)，因此它們傳輸?shù)幂^快。此外，裝有電路的部件體積可以大大減小，這一進(jìn)步已導(dǎo)致了小型機(jī)和微型機(jī)的引入。其結(jié)果是計(jì)算機(jī)體積變小，速度加快，價(jià)格更便宜。可是半導(dǎo)體存儲(chǔ)器有一個(gè)問題。當(dāng)電源切斷時(shí)，存儲(chǔ)器里的信息就丟失了，而不像磁心存儲(chǔ)器，在斷電時(shí)還能保留信息。計(jì)算機(jī)存儲(chǔ)器領(lǐng)域里的另一發(fā)展是磁泡存儲(chǔ)器，它的原理是在存儲(chǔ)板上形成一層金屬合金薄膜。當(dāng)這層膜被磁化時(shí)，就生成磁泡。磁泡的出現(xiàn)和消失代表一位信息的狀態(tài)，這些磁泡非常小，直徑大約為0。1微米。所以，磁泡存儲(chǔ)器能以比現(xiàn)在的存儲(chǔ)器更大的密度常常信息，這使它適用于微型機(jī)。磁泡存儲(chǔ)器造價(jià)不高，電能消耗小，體積小，可靠性高。磁盤存儲(chǔ)器看起來很像一個(gè)投幣式的自動(dòng)點(diǎn)唱機(jī)，但它裝的不是唱片。唱片每面只有一道唱紋，而磁盤則是用金屬制成的，兩面都涂有磁性材料，每面的同心磁道多達(dá)500道，而一道通常存儲(chǔ)一個(gè)字塊。這些磁盤片安裝在一個(gè)豎軸上，盤片與盤片之間留有間隙，以便一個(gè)取數(shù)臂伸入其間。每一取數(shù)臂上裝有兩個(gè)讀/寫頭，一個(gè)用于上面盤，一個(gè)用于下面盤。豎軸和磁盤每秒鐘大約旋轉(zhuǎn)40轉(zhuǎn)。閱讀材料3Buses: Connecting I/O Devices to Processor and MemoryIn a computer system, the various subsystems must have interfaces to one another. For example, the memory and processor need to communicate, as do the processor and the I/O devices. This is commonly done with a bus. A bus is a shared communication link, which uses one set of wires to connect multiple subsystems. The two major advantages of the bus organization are versatility and low cost. By defining a single connection scheme, new devices can easily be added, and peripherals can even be moved between computer systems that use the same kind of bus. Furthermore, buses are cost effective, because a single set of wires is shared in multiple ways.The major disadvantage of a bus is that it creates a communication bottleneck, possibly limiting the maximum I/O throughput. When I/O must pass through a single bus, the bandwidth of that bus limits the maximum I/O throughput. In commercial systems, where I/O is very frequent, and in supercomputers, where the I/O rates must be very high because the processor performance is high. Designing a bus system capable of meeting the demands of the processor as well as connecting large numbers of I/O devices to the machine presents a major challenge.One reason bus design is so difficult is that the maximum bus speed is largely limited by physical factors: the length of the bus and the number of devices. These physical limits prevent us from running the bus arbitrarily fast. Within these limits, there are a variety of techniques we can use to increase the performance of the bus; however, these techniques may adversely affect other performance metrics. For example, to obtain fast response time for I/O operations, we must minimize the bus latency by streamlining the communication path. On the other hand, to sustain high I/O data rates, we must maximize the bus bandwidth. The bus bandwidth can be increased by using more buffering and by communicating larger blocks of data, both of which increase the bus latency! Clearly, these two goals, low latency and high bandwidth can lead to conflicting design requirements. Finally, the need to support a range of devices with widely varying latencies and data transfer rates also makes bus design challenging.A bus generally contains a set of control lines and a set of data lines. The control lines are used to signal requests and acknowledgments, and to indicate what type of information is on the data lines. The data lines of the bus carry information between the source and the destination. This information may consist of data, complex commands, or addresses. For example, if a disk wants to write some data into memory from a disk sector, the data lines will be used to indicate the address in memory in which to place the data as well as to carry the actual data from the disk. The control lines will be used to indicate what type of information is contained on the data lines of the bus at each point in the transfer, some buses have two sets of signal lines to separately communicate both data and address in a single bus transmission. In either case, the control lines are used to indicate what the bus contains and to implement the bus protocol.翻譯3總線：連接I/O設(shè)備到處理器和存儲(chǔ)器在一個(gè)計(jì)算機(jī)系統(tǒng)中，各種各樣的子系統(tǒng)必須有接口相互連接。例如，存儲(chǔ)器和處理器間需要通信，處理器和I/O設(shè)備間也一樣。這通常由一條“總線”來完成?？偩€是共享的通信鏈路，它用一束通信線來連接多個(gè)子系統(tǒng)。總線結(jié)構(gòu)的兩個(gè)最主要的優(yōu)點(diǎn)是：靈活性和廉價(jià)性。通過定義一種連接方式，可以很容易地增加新設(shè)備，甚至也可將外圍設(shè)備在兩個(gè)使用同種總線的計(jì)算機(jī)系統(tǒng)間搬動(dòng)。此外，總線能被有效地使用，因?yàn)橐粭l總線可以多種方式共享。總線的最大缺點(diǎn)是它產(chǎn)生通信瓶頸，可能限制最大的I/O流量。當(dāng)I/O必須經(jīng)過一條總線時(shí)，總線帶寬限制了最大I/O流量。在I/O很頻繁的商用系統(tǒng)中和因處理器的高性能而要求I/O速率也很高的超級(jí)計(jì)算機(jī)中，設(shè)計(jì)一個(gè)既能滿足處理器要求、又能連接大量I/O設(shè)備的總線系統(tǒng)是一個(gè)重要的課題?？偩€設(shè)計(jì)如此困難的一個(gè)原因是，總線的速度很大程度上受物理因素限制：總線長度和設(shè)備數(shù)量。這些物理因素使我們不能以任意高速使用總線。在這些限制下，盡管我們可用許多技術(shù)來提高總線的性能，但是，這些技術(shù)也會(huì)相反地影響其它性能。例如，為獲得較快的I/O響應(yīng)時(shí)間，我們必須用流水線化通信路徑來最小化總線延時(shí)。另一方面，為維持高速I/O數(shù)據(jù)速率，我們必須最大化總線寬度。使用更多的緩沖和用更大的數(shù)據(jù)塊通信能增加總線寬度，但兩者都增加總線的延時(shí)。顯然，這兩個(gè)目標(biāo)，低延時(shí)和高帶寬，會(huì)導(dǎo)致設(shè)計(jì)要求的沖突。最后，支持具有不同延時(shí)和數(shù)據(jù)傳送速率的一定范圍的設(shè)備的需要，也使總線設(shè)計(jì)成為困難。一條總線一般包括一束控制線和一束數(shù)據(jù)線。控制線被用于標(biāo)記請(qǐng)求和應(yīng)答，并且指出數(shù)據(jù)線上信息的種類?？偩€的數(shù)據(jù)線在源地和目的地間運(yùn)送信息。這種信息可以包括數(shù)據(jù)、復(fù)雜命令和地址。比如，磁盤想要從某個(gè)扇區(qū)往內(nèi)存中寫數(shù)據(jù)，數(shù)據(jù)線就用于指明內(nèi)存中的哪個(gè)地址用于存放數(shù)據(jù)，并且在實(shí)際上將數(shù)據(jù)從磁盤運(yùn)輸?shù)絻?nèi)存，控制線用于指出傳送的每一時(shí)刻數(shù)據(jù)線上都包括哪種類型的信息。一些總線有兩束信號(hào)線，在一個(gè)總線傳送中獨(dú)立地傳送數(shù)據(jù)和地址。在任何一種情況下，控制線都用于指出總線包括什么并且執(zhí)行總線協(xié)議。閱讀材料4MonitorMonitors maybe are one of the most important output devices. Computers only use monitors to show you exciting operation results or marvelous and vivid pictures. Monitors also are the best windows for conversation between users and computers. So, many users select monitors carefully. Which parameters or indexes ought be paid attention to when you select a monitor? We provide some here for your reference.Element DistanceThe distance between two picture elements in horizontal direction is called element distance here and its current value in most PC monitors is 0.28mm. if the value is smaller, the screen is more distinct.Video BandwidthIt is an important concept in monitor technology. It is related to the highest work frequency of the monitor. It is from tens MHz to hundreds MHz. Here is a formula for you to calculate the video bandwidth:Video bandwidth = row number column number frame-refreshed rateHere, row number = picture element number in one column; column number = picture element number in one row; frame-refreshed rate = frame change times per second.Example: let row number = 768, column number = =1024, frame-refreshed rate = 85 then video bandwidth = 768102485=66.85MHz.Vertical Scan Rate and Horizontal Scan FrequencyVertical scan sate is equal to frame-refreshed rate; horizontal scan frequency is what its name tells. The relationships between vertical scan rate, horizontal scan frequency and video bandwidth in non-interlace monitors are as follows:Vertical scan rate = video bandwidth / column number / row numberHorizontal scan frequency = video bandwidth / column number.So, only horizontal scan frequency is enough to measure the property of a monitor and it is between 50KHz and 90KHz.SolutionIt is an another important parameter of a monitor. Its higher, the view on a screen is clearer. Solution means the sum of all picture elements on a screen. The solution is 640 480 for 14inch monitors and 1024 768 for 17 inch monitors commonly.Scan StyleThe scan style of a electron gun in a tube is divided into two styles: interlace and non-interlace. In interlace style, electron-beam sweeps elements in odd rows first time and does elements in even rows second time. A frame to be renewed needs sweeping two times. In non-interlace style, electron-beam sweeps all elements only in one time. In non-interlace work style, the monitor works better and gives clear pictures without flash.翻譯4顯示器顯示器可能是最重要的輸出設(shè)備之一。計(jì)算機(jī)只能用它們來顯示有趣的結(jié)果和神奇生動(dòng)的畫面。顯示器也是人機(jī)對(duì)話的最好窗口，所以很多用戶選擇顯示器時(shí)非常小心。當(dāng)選擇顯示器時(shí)應(yīng)該注意哪些參數(shù)和指標(biāo)呢？這兒我們給出一些參數(shù)供你參考。像素距離兩個(gè)像素水平方向的距離稱為像素距離。目前大多數(shù)PC的流行像素距離是0.28毫米。這個(gè)值越小、屏幕越清晰。視頻帶寬它是監(jiān)視器技術(shù)中一個(gè)很重要的概念，它關(guān)系到監(jiān)視器的最高工作頻率。它的范圍從幾十兆赫茲到幾百兆赫茲。這里有個(gè)用來計(jì)算視頻帶寬的公式：視頻帶寬 = 行數(shù) 列數(shù) 刷新率其中，行數(shù)等于每列中像素的個(gè)數(shù)，列數(shù)等于每行中像素的個(gè)數(shù)，刷新率等于每秒鐘畫面的變化次數(shù)。例：設(shè)列數(shù)=768，行數(shù)=1024，刷新率=85，則視頻帶寬 = 768 1024 85 = 66.85MHz垂直掃描和水平掃描頻率垂直掃描頻率等于刷新率，水平掃描頻率就是它名字所提示的。二者與視頻帶寬的關(guān)系在非隔行監(jiān)視器下如下：垂直掃描頻率=視頻帶寬 / 列數(shù) / 行數(shù)水平掃描頻率=視頻帶寬 / 列數(shù)所以，僅用水平掃描頻率就足以度量監(jiān)視器的性能，它的范圍從50KHz到90KHz分辨率它是監(jiān)視器的另一個(gè)重要參數(shù)，它的值越高，屏幕上的圖像越清晰。分辨率表示一個(gè)屏幕上全部像素的總和。一般而言，14英寸的監(jiān)視器的分辨率為640480，17英寸的監(jiān)視器的分辨率為1024768。掃描方式顯像管中的電子槍的掃描方式有兩種：隔行和非隔行。在隔行方式中，電子射槍首先掃描奇數(shù)項(xiàng)中的像素，第二次再掃描偶數(shù)項(xiàng)中的像素。一幀畫面的更新需掃描兩次。在非隔行的方式中，電子射槍一次完成掃描全部像素。在這種工作方式中，監(jiān)視器工作得更好而且圖像清晰、不閃光。閱讀材料5Hard DiskEvery user has used hard disks and liked them very much since they have gigantic storage capacity and work fast, especially since operating systems grow larger and larger. One example is Win98, with its full installation needing 300MB memory, long application programs and multimedia development need more and more storage space, etc. All of these spur the development of hard disks. The hard disk storage capacity almost is doubled every year and the hard disk works faster and faster.Ultra DSP is great advance in hard disk technology. Ultra DSP means Ultra Digital Signal Processor, the working speed of which is 1050 times as fast as the speed of CPU. It ameliorates hard disk functions and promotes hard disk speed and reliability much more.Cache technology is another advanced technology applied in hard disks. The CPU can read data directly from the cache and improved the access speed tremendously. The cache storage capacity is now between 512KB to 2MB.The average seek times is another significant index. The shorter it is, the better the hard disk. Users should prefer those with an index generally below 10 ms. The internal data transfer rate should also be paid attention to. The rate will affect the whole hard disk working speed.翻譯5硬盤每個(gè)用戶都用過硬盤而且很喜歡它，因?yàn)樗芯薮蟮拇鎯?chǔ)容量和快速的工作速度，特別是在操作系統(tǒng)愈來愈大的時(shí)代。如Windows 98，它的全部安裝需要300MB存儲(chǔ)空間，長的應(yīng)用程序和多媒體的發(fā)展需要的存儲(chǔ)空間愈來愈大等，所有這些都刺激了硬盤的發(fā)展。硬盤存儲(chǔ)容量幾乎每年都加倍增長而且工作速度越來越快。Ultra DSP是硬盤技術(shù)中很先進(jìn)的技術(shù)。Ultra Digital Signal Processor的意思是超級(jí)數(shù)字處理器。它的工作速度510倍于CPU的工作速度。它改進(jìn)了硬盤的性能且大大提高了硬盤的速度和可靠性。硬盤的另一個(gè)先進(jìn)技術(shù)是高速緩沖技術(shù)。CPU能直接從高速緩沖器中讀取數(shù)據(jù)并大大提高訪問速度。現(xiàn)在的高速緩沖的存儲(chǔ)量為512KB到2MB。平均尋道時(shí)間是另一個(gè)重要指標(biāo)，它愈短，硬盤愈好。用戶應(yīng)選擇該指標(biāo)低于10ms的產(chǎn)品。也應(yīng)注意內(nèi)部數(shù)據(jù)傳輸率，它直接關(guān)系到硬盤的工作速度。閱讀材料6Keyboard and DisplayThe basic input device on most microcomputer systems is a keyboard. As characters are typed, they are stored in main memory, and then copied from the memory to the basic output device - a display screen. The screen, often called a monitor, serves as a window on main memory, allowing the user to view its contents.Through the keyboard you “talk” to a computer. That is, it allows you to input information, instructions, or data to the computer. Keyboards vary considerably from system to system, but most look a lot like a standard typewriter keyboard. Many also have a numeric keypad on the right, which looks like the keypad on a 10-key adding machine. The keypad makes it easy to input large amounts of numerical data into the computer