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Computers are electronic devices that can follow instructions to accept input, process that input, and produce information. There are four types of computers: microcomputers, minicomputers, mainframe computers, and supercomputers.
Microcomputers, also known as personal computers, are small computers that can fit on a desktop. Portable microcomputers can fit in a briefcase or even in the palm of your hand. Microcomputers are used in homes, schools, and industry. Today nearly every field uses microcomputers.
One type of microcomputer that is rapidly growing in popularity is the portable computer, which can be easily carried around. There are four categories of portable computers.
Laptops: laptops, which weigh between 10 and 16 pounds, may be AC-powered, battery-powered, or both. The AC-powered laptop weighs 12 to 16 pounds. The battery-powered laptop weighs 10 to 15 pounds, batteries included, and can be carried on a shoulder strap. Figure 1.1 shows an example of a laptop.
Figure 1.1 A Modern Mid-range HP Laptop
Notebook PCs: notebook personal computers weigh between 5 and 10 pounds and can fit into most briefcases. It is especially valuable in locations where electrical connections are not available. Notebook computers are the most popular portable computers today.
Subnotebooks: subnotebooks are for frequent flyers and life-on-the-road types. [1] Subnotebooks users give up a full-size display screen and keyboard in exchange for less weight. Weighting between 2 and 6 pounds, these computers fit easily into a briefcase.
Personal Digital Assistants: much smaller than even the subnotebooks. Personal Digital Assistants (PDAs) weigh from 1 to 4 pounds. The typical PDA combines pen input, writing recognition, personal organizational tools, and communication capabilities in a very small package. Figure 1.2 shows an example of a PDA.
Figure 1.2 A PDA
Minicomputers, also known as midrange computers, are desk-sized machines. [2] They fall into between microcomputers and mainframes in their processing speeds and data-storing capacities. Medium-size companies or departments of large companies typically use them for specific purposes. For example, they might use them to do research or to monitor a particular manufacturing process. Smaller-size companies typically use microcomputers for their general data processing needs, such as accounting.
Mainframe computers are larger computers occupying specially wired, air-conditioned rooms and capable of great processing speeds and data storage. They are used by large organizations—business, banks, universities, government agencies—to handle millions of transactions. For example, insurance companies use mainframes to process information about millions of policyholders.
Supercomputers are special, high-capacity computers used by very large organizations principally for research purposes. Among their uses are oil exploration and worldwide weather forecasting. An example of a supercomputer is shown in Figure 1.3.
Figure 1.3 Mississippi State system administrators inspect the new Raptor supercomputer in the university's High Performance Computing Collaboratory
In general, a computer's type is determined by the following seven factors:
The type of CPU. Microcomputers use microprocessors. The larger computers tend to use CPUs made up of separate, high-speed, sophisticated components.
The amount of main memory the CPU can use. A computer equipped with a large amount of main memory can support more sophisticated programs and can even hold several different programs in memory at the same time.
The capacity of the storage devices. The larger computer systems tend to be equipped with higher capacity storage devices.
The speed of the output devices. [3] The speed of microcomputer output devices tends to be rated in terms of the number of characters per second (cps) that can be printed——usually in tens and hundreds of cps. Larger computers' output devices are faster and are usually rated at speeds of hundreds or thousands of lines that can be printed per minute.
The processing speed in millions of instructions per second (MIPS). The term instruction is used here to describe a basic task the software asks the computer to perform while also identifying the data to be affected. The processing speed of the smaller computers ranges from 7 to 40 MIPS. The speed of large computers can be 30 to 150 MIPS or more, and supercomputers can process more than 200 MIPS. In other words, a mainframe computer can process your data a great deal faster than a microcomputer can.
The number of users that can access the computer at one time. Most small computers can support only a single user, some can support as many as two or three at a time. Large computers can support hundreds of users simultaneously.
The cost of the computer system. Business systems can cost as little as $500 (for a microcomputer) or as much as $10 million (for a mainframe)—and much more for a supercomputer.
Words
| access | v. | 访问，存取 |
| accounting | n. | 会计学，统计 |
| agency | n. | 机构，办事处，代理店 |
| briefcase | n. | 公文包，公事包 |
| exploration | n. | 勘探，发掘，调查 |
| laptop | n. | 便携式电脑 |
| palm | n. | （手）掌，手心，掌状物 |
| policyholder | n. | 投保人，保险客户 |
| recognition | n. | 认出，识别，认可 |
| simultaneously | adv. | 同时地 |
| sophisticated | adj. | 精密复杂的 |
| strap | n. | （皮，布）带 |
| typically | adv. | 特有地，独特地，典型地 |
Phrases
| fall into | 属于 |
| in exchange for | 交换，来代替 |
| mainframe computer | 大型计算机 |
| portable computer | 便携式计算机 |
Abbreviations
| AC（Alternating Current） | 交流电 |
| PDA（Personal Digital Assistant） | 个人数字助理 |
Notes
[1] 例句：Subnotebooks users give up a full-size display screen and keyboard in exchange for less weight.
分析：in exchange for less weight是介词短语作目的状语，意思是“为了换取较轻的重量”。
译文：超小型笔记本电脑用户放弃了大尺寸的显示器和键盘，换来了重量的减轻。
[2] 例句：They fall in between microcomputers and mainframes in their processing speeds and data-storing capacities.
分析：句中They指的是小型计算机：短语fall in between意思是“介于两者之间”，in their processing speeds and data-storing capacities是介词短语作状语。
译文：小型计算机的处理速度和数据存储能力介于微型机和大型机之间。
[3] 例句：The speed of microcomputer output devices tends to be rated in terms of the number of characters per second (cps) that can be printed——usually in tens and hundreds of cps.
分析：句中tends to be rated…，意思是“倾向于用……度量”，tend to do sth. 意思是“倾向于／易于做某事”。例句：They tend to do badly in school. 他们通常在学校表现不好。In the end, everything tends to do what you would expect. 最后，所有的事情都会像你期望的那样运转。
译文：微机输出设备的速度倾向于用每秒钟能打印的字符数（cps）予以度量，通常为每秒几十个、几百个字符。
Exercises
Ⅰ. Put "true" or "false" in the brackets for the following statements according to the passage.
1. ( ) Computers are electronic devices that can perform tasks automatically.
2. ( ) Portable computers can fit in a briefcase or even in the palm of your hand.
3. ( ) Portable computers are AC-powered, battery-powered, or both.
4. ( ) All portable computers can fit in briefcases.
5. ( ) Subnotebooks have full-size display screens and keyboards.
6. ( ) The capacity of the storage devices is a main factor that affects the property of computers.
7. ( ) Most microcomputers are single-user systems.
8. ( ) According to the passage, supercomputers have storage devices with the largest capacity.
9. ( ) The term "instruction" used in the passage only describes a basic task that the software asks the computer to perform.
10. ( ) Ordinary users have chances to come into contact with supercomputers.
Ⅱ. Fill in the blanks according to the passage.
1. Computers aredevices that can followto accept input, process that input, and produce information.
2. Portable microcomputers can fit in aor even in theof your hand.
3. There are four types of computers:, , , .
4. Minicomputers fall into between microcomputers and mainframes in theirspeeds and data-storing.
5. Mainframe computers are used by large.
6. Insurance companies use mainframes to processabout millions of.
7. Supercomputers are special,computers.
8. Laptops may be, , or both.
9. The larger computer systems tend to bewith higher capacity.
10. Large computer can support hundreds of users.
Ⅲ. Translate the following words and expressions into Chinese.
1. electronic device
2. personal computer
3. processing speed
4. high-capacity
5. battery-powered
6. portable computer
7. writing recognition
8. storage device
9. supercomputer
10. mainframe
The title of forefather of today's all-electronic digital computers is usually awarded to ENIAC, which stood for Electronic Numerical Integrator and Calculator. ENIAC was built at the University of Pennsylvania between 1943 and 1945 by two professors, John Mauchly and the 24 years old J. Presper Eckert, who got funding from the war department after promising they could build a machine that would replace all the "computers", meaning the women who were employed calculating the firing tables for the army's artillery guns.
ENIAC filled a 20 by 40 foot room, weighed 30 tons, and used more than 18,000 vacuum tubes. ENIAC employed paper card readers obtained from IBM. When operating, the ENIAC was silent but you knew it was on as the 18,000 vacuum tubes each generated waste heat like a light bulb and all this heat (174,000 watts of heat) meant that the computer could only be operated in a specially designed room with its own heavy duty air conditioning system. Only the left half of ENIAC is visible in the first picture in Figure 1.4, the right half was basically a mirror image of what's visible.
Figure 1.4 Two views of ENIAC: the "Electronic Numerical Integrator and Calculator"
To reprogram the ENIAC you had to rearrange the patch cords that you can observe on the left in the prior photo, and the settings of 3000 switches that you can observe on the right. To program a modern computer, you type out a program with statements like:
Circumference＝3.14 * diameter
To perform this computation on ENIAC you had to rearrange a large number of patch cords and then locate three particular knobs on that vast wall of knobs and set them to 3, 1, and 4.
One of the most obvious problems was that the design would require 18,000 vacuum tubes to all work simultaneously. Vacuum tubes were notoriously unreliable. The idea that 18,000 tubes could function together was considered so unlikely that the dominant vacuum tube supplier of the day, RCA, refused to join the project (but did supply tubes in the interest of "wartime cooperation"). Eckert solved the tube reliability problem through extremely careful circuit design. He was so thorough that before he chose the type of wire cabling he would employ in ENIAC he first ran an experiment where he starved lab rats for a few days and then gave them samples of all the available types of cable to determine which they least liked to eat. Here's a look at a small number of the vacuum tubes in ENIAC:
Even with 18,000 vacuum tubes, ENIAC could only hold 20 numbers at a time. ENIAC's basic clock speed was 100,000 cycles per second. Today's home computers employ clock speeds of 1,000,000,000 cycles per second. Built with $500,000 from the U.S. Army, ENIAC's first task was to compute whether or not it was possible to build a hydrogen bomb (the atomic bomb was completed during the war and hence is older than ENIAC). The very first problem run on ENIAC required only 20 seconds and was checked against an answer obtained after forty hours of work with a mechanical calculator. After chewing on half a million punch cards for six weeks, ENIAC did humanity no favor when it declared the hydrogen bomb feasible. This first ENIAC program remains classified even today.
Eckert and Mauchly's next teamed up with the mathematician John von Neumann to design EDVAC, which pioneered the stored program.
Words
| artillery | n. | 炮 |
| bulb | n. | 植物的球茎，球茎状物，电灯泡 |
| forefather | n. | 祖先，祖宗 |
| funding | n. | 资金 |
| hold | n. | 握住，掌握，控制，容纳 |
| chew | v. | 咀嚼，认真考虑 |
| dominant | adj. | 有统治权的，占优势的，支配的 |
| extremely | adv. | 极端地，非常地 |
| involve | V. | 包括，涉及 |
| knob | n. | （门，抽屉等的）球形捏手，节，瘤，旋钮 |
| notoriously | adv. | 臭名远扬地，声名狼藉地，众人皆知地 |
| patch | n. | 片，临时电子线路 |
| pioneer | n. | 先驱，倡导者，先遣兵，先锋 |
| v. | 开辟，开拓，开创 | |
| prior | adj. | 优先的，在前的 |
| statement | n. | 声明，陈述，语句 |
| thorough | adj. | 彻底的，完全的，细心的 |
Phrases
| air conditioning | 空气调节装置 |
| heavy duty | 重型，重载 |
| University of Pennsylvania | 宾夕法尼亚州大学 |
| hydrogen bomb | 氢弹 |
| team up | （使）结成一队，合作，协作 |
Abbreviations
ENIAC（Electronic Numerical Integrator and Calculator）电子数字积分计算机
计算机是根据指令接收输入、处理输入数据并产生信息的电子设备。计算机有四种类型：微型机、小型机、大型机和巨型机。
微型计算机，也被称为个人计算机，是可以放在桌面上的小的计算机。便携式微型机可以放入手提箱，甚至手掌中。微型机被用于家庭、学校及工业中。如今几乎每一领域都在使用微型机。
便携式计算机是正在迅速普及的一种微型机，它易于四处携带。便携式计算机有四种类型。
膝上电脑：其重量在10～16磅之间，供电方式可以是交流供电、电池供电或两者均可。交流供电的膝上电脑重量在12～16磅之间。电池供电的膝上电脑的重量（包括电池）在10～15磅之间，可以用肩带背起来携带。图1.1是一个膝上电脑的例子。
笔记本个人电脑：其重量在5～10磅之间，可放入大多数公文包中，尤其适用于那些连接电源不方便的场所。笔记本电脑是如今最流行的便携式电脑。
超小型笔记本电脑：适合那些经常飞来飞去和将时间花在道路上的人使用。这些用户放弃了大尺寸的显示器和键盘，换来了重量的减轻。这种电脑重量在2～6磅之间，可以很容易地放入公文包中。
个人数字助手：它比超轻薄笔记本电脑还要小得多，其重量在1～4磅之间。典型的个人数字助手将钢笔输入、书写识别、个人编排工具和通信功能结合起来放入小包中。图1.2是一个PDA的例子。
小型计算机，也被称为中型机，是像书桌大小的机器。它们的处理速度和数据存储能力介于微型机和大型机之间。中型公司或大型公司的部门一般把它们用于特殊用途。例如，可以使用它们做研究或监视某一个生产过程。小型公司一般使用小型机进行日常的数据处理，比如说统计。
大型机是较大的计算机，放置在具有专线、空调的房间中，具有很快的处理速度和很大的数据存储量。它们通常被一些大的组织机构（商业部门、银行、大学、政府机构）用来处理数以百万计的数据。例如，保险公司使用大型机处理数以百万计的保险客户的信息。
巨型机是非常大的机构进行研究工作的大容量专用计算机。这些应用包括石油勘探和世界范围的天气预报。一个巨型机的例子如图1.3所示。
一般来说，计算机的类型由下列7个因素决定：
CPU的类型。微型计算机使用微处理器。较大的计算机趋向于使用由单独的高速复杂的零部件构成的CPU。
CPU能够使用的内存的总量。配备有大容量内存的计算机支持更复杂的程序，并且能同时容纳几个不同的程序运行。
存储设备的容量。较大的计算机系统趋向于配置较大容量的存储设备。
输出设备的速度。微机输出设备的速度用每秒钟能打印的字符数（cps）予以度量，通常为每秒几十个、几百个字符。较大计算机的输出设备的速度也较快，通常每分钟可打印几百或几千行。
用mips（每秒钟百万条指令）度量的处理速度。在这里用术语“指令”来描述软件要求计算机完成的基本任务，并且标识受到影响的数据。较小计算机的处理速度为7～40 mips。大型计算机的处理速度能达到30～150 mips或更多。巨型计算机的处理速度达200 mips以上。换句话说，大型计算机处理数据的能力要比微机快得多。
可以同时访问计算机的用户数量。大多数小型计算机某个时刻只能供单个用户使用，有些计算机可以同时由两个或三个用户访问，大型计算机则可同时由几百个用户访问。
计算机系统的价格。商用计算机系统的价格可低到500美元（一台微机）或者高达1000万美元（一台大型机），巨型计算机则花费更多。
现代电子计算机的祖先通常被认为是ENIAC, ENIAC是电子数字积分计算机的简称，英文全称为Electronic Numerical Integrator And Calculator。ENIAC于1943—1945在宾夕法尼亚大学由两个教授——John Mauchly和24岁的J. Presper Eckert制造。他们承诺可以建造一台机器代替所有的计算员（指雇佣来为军队的炮弹计算火力表的妇女），因此得到了美国陆军部的资助。
ENIAC占满了20×40英尺的房间，重30吨，并使用1.8万多个真空管。ENIAC使用来自IBM的纸卡阅读器。工作时，ENIAC是无声的，但我们知道它在工作，因为18000个真空管每个都像灯泡一样产生废热，这些热量（174000瓦特热）意味着计算机只能运行在一个特殊设计的有自己的重型空调系统的房间。在图1.4的第一张照片中只能看到左边一半ENIAC，右边的一半基本上是所看到内容的镜像。
为了修改ENIAC的程序，人们需要重新排列在图1.4中所看到的左边的连线，并设置右边的3000个开关。对一个现代计算机编程，可以输入如下语句的程序：
Circumference＝3.14 * diameter
为了在ENIAC上执行此计算，人们需要重新安排大量的跳线，然后在巨大的旋钮墙上找到三个特殊旋钮，并将其设为3、1和4。
其中最明显的问题是，该设计将需要18000个真空管同时进行工作。真空管是极不可靠的。18000个真空管同时工作的想法被认为是不可能的，当时主要的真空管供应商——RCA，拒绝参加该项目（但是为了“战时合作”的利益仍然提供了真空管）。Eckert认真设计电路，解决了真空管的可靠性问题。他非常专注，在选择应用于ENIAC的电线电缆类型时，先进行了一个实验。他把实验室的老鼠饿了几天，然后给它们所有可用电缆类型的样品，找出老鼠最不愿意吃的那一种。图1.4中是ENIAC中的一小部分真空管。
即使使用18000个真空管，ENIAC在某个时间也只能处理20个数据。ENIAC基本时钟频率为10万赫兹。今天的家用电脑使用的时钟频率是十亿赫兹。从美国军队接受了50万美元的经费，ENIAC的首要任务是计算是否有可能制造一个氢弹（原子弹是在战争期间完成的，因此比ENIAC早）。最初的问题在ENIAC运行仅需20秒，并与机械计算器工作四十小时后得出的答案进行核对。花费6个星期为50万纸卡打孔后，它宣布制造氢弹可行，ENIAC并没有为人类带来好处。这个最初的ENIAC程序至今仍然是保密的。
后来Eckert、Mauchly和数学家约翰·冯·诺依曼联合一起设计EDVAC，开创了存储程序计算机。