Unit 3 Computer
It was probably the worst prediction in history. Back in the 1940s, Thomas Watson, boss of the giant ШМ Corporation, reputedly forecast that the world would need no more than «about five computers». Six decades later and the global population of computers have now risen to something like one billion machines!
To be fair to Watson, computers have changed enormously in that time. In the 1940s, they were giant scientific and military behemoths commissioned by the government at a cost of millions of dollars apiece; today, most computers are not even recognizable as such: they are embedded in everything from microwave ovens to cellphones and digital radios. What makes computers flexible enough to work in all these different appliances? How come they are so phenomenally useful? And how exactly do they work?
A computer is an electronic machine that processes informa- tion — in other words, an information processor: it takes in raw information (or data) at one end, stores it until it's ready to work on it, chews and crunches it for a bit, then spits out the results at the other end. All these processes have a name. Taking in information is called input, storing information is better known as memory, chew- ing information is also known as processing, and spitting out results is called output.
Imagine if a computer were a person. Suppose you have a friend who's really good at math. She is so good that everyone she knows posts their math problems to her. Each morning she goes to her let- terbox and finds a pile of new math problems waiting for her atten- tion. She piles them up on her desk until she gets around to looking at them. Each afternoon she takes a letter off the top of the pile, studies the problem, works out the solution, and scribbles the answer on the
back. She puts this in an envelope addressed to the person who sent her the original problem and sticks it in her out tray, ready to post. Then she moves to the next letter in the pile. You can see that your friend is working just like a computer. Her letterbox is her input; the pile on her desk is her memory; her brain is the processor that works out the solutions to the problems; and me out tray on her desk is her output.
Once you understand that computers are about input, storage, processing, and output, all you have on your desk makes a lot more sense. Your keyboard and mouse, for example, are just input units — ways of getting information into your computer that it can process. If you use a microphone and voice recognition software, that's another form of input. Your computer probably stores all your documents and files on a hard-drive: a huge magnetic memory. But smaller, computer-based devices like digital cameras and cellphones use other kinds of storage such as flash memory cards. As for output, your computer almost certainly has a screen and probably also stereo loudspeakers. You may have an inkjet printer on your desk too to make a more permanent form of output. Your computer's processor (sometimes known as the central processing unit) is a microchip buried deep inside. It works amazingly hard and gets incredibly hot in the process. That's why your computer has a lhtle fan blowing away — to stop its brain from overheating!
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Monitor
Printer
Mouse
Input
t I
Processor chip
Processing
Output
image brighter. So, once again, the problem boils down to numbers and calculations.
What makes a computer different from a calculator is diat it can work all by itself. You just give it your instructions (called a program) and off it goes, performing a long and complex series of operations all by itself. Back in me 1970s and 1980s, if you wanted a home computer to do almost anything at all, you had to write your own little program to do it. For example, before you could write a letter on a computer, you had to write a program that would read me letters you typed on me keyboard, store them in the memory, and display them on the screen. Writing the program usually took more time than doing whatever it was that you had originally wanted to do (writing die letter). Pretty soon, people started selling programs like word processors to save you the need to write programs yourself.
Artwork caption: A computer works by combining input, storage, processing, and output. All the main parts of a computer system are involved in one of these four processes.
The first computers were gigantic calculating machines and all they ever really did was «crunch numbers»: solve lengthy, difficult, or tedious mathematical problems. Today, computers work on a much wider variety of problems — but tiiey are all still, essentially, calculations. Everything a computer does, from helping you to edit a photograph you've taken with a digital camera to displaying a web page, involves manipulating numbers in one way or another.
Suppose you're looking at a digital photo you just taken in a paint or photo-editing program and you decide you want a mirror image of it (in other words, flip it from left to right). You probably know that the photo is made up of millions of individual pixels (col- oured squares) arranged in a grid pattern. The computer stores each pixel as a number, so taking a digital photo is really like an instant, orderly exercise in painting by numbers! To flip a digital photo, the computer simply reverses the sequence of numbers so they run from right to left instead of left to right. Or suppose you want to make the photograph brighter. All you have to do is slide the little «brightness» icon. The computer dien works through all the pixels, increasing the brightness value for each one by, say, 10 percent to make die entire
Today, most computer users buy, download, or share programs like Microsoft Word and Excel. Hardly anyone writes programs any more. Most people see their computers as tools that help them do jobs, rather than complex electronic machines they have to pre-pro- gram — and that's just as well, because most of us have better diings to do man computer programming. The beauty of a computer is mat it can run a word-processing one minute — and men a photo-editing program fivcseconds later. In odier words, although we don't really think of it mis way, the computer can be reprogrammed as many times as you like. This is why programs are also called software. They're «soft» in me sense that they are not fixed: mey can be changed eas-
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ily. By contrast, a computer's hardware — the bits and pieces from which it is made (and the peripherals, like the mouse and printer, you plug into it) — is pretty much fixed when you buy it off the shelf. The hardware is what makes your computer powerful; the ability to run different software is what makes it flexible. That computers can do so many different jobs is what makes them so useful — and that's why millions of us can no longer live without them!
Photo caption: Computers can crack tricky mathematical problems much faster than humans.
Exercises
A. Comprehension
1. Answer these questions:
What is a computer?
What comparison of a computer is given in me text? In what way?
How can a computer be characterized from the point of view of its constituent parts? Give brief characteristics of each one.
Why is a computer said to simulate a calculator? How do they differ?
What makes a computer powerful and flexible?
2. Summarize the text using the words from Vocabulary Exercises.
B. Vocabulary
3. Give Russian equivalents of the following words and expressions:
raw information; rise; flexible; screen; bury; input; permanent; chew; crunch; solution; fair; appliance; embed; loudspeaker; output; tedi- ous; share; ink-jet printer; pile up; huge; keyboard; flip; tricky; edit; hard-drive; orderly; get around to; tool; instant; bury.
4. Translate these words and word combinations into English:
сотовый телефон справедливый
спрессовывать (данные) легко приспосабливаемый
решение вставлять
постоянный обдумывать
клавиатура сложный
редактировать, создавать струйный принтер мгновенный вернуться (к чему-л.) после
перерыва ввод, входной аппарат, прибор
экран увеличиваться в объеме,
возрастать огромный жёсткий диск, дисковод,
винчестер скрывать инструмент
разделять утомительный
отображать зеркально систематический
акустическая система делать, совершать
S. Find synonyms of the following expressions among the words and word combinations of the previous exercises:
monitor, display;
complicated, difficult, complex;
revise, check over, amend, improve, correct;
boring, dull, monotonous; wearisome;
device, implement, instrument;
piece of equipment, machine;
set in, insert, implant;
way out, result, explanation;
immediate, direct, instantaneous;
go halves, divide, contribute to;
enormous, massive, vast, gigantic;
collect, amass, load;
hide, conceal, put out of sight;
adaptable, variable, compliant;
just, fair-minded, rational;
systematic, methodical, organized;
enduring, lasting, eternal, stable.
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С. Reading and Discussion
6. Read the text and answer the questions: 1) What distinction of the term «computer» can be made in its original and modern meanings? 2) How do we call a list of instructions given to a computer? 3) What are the types of instructions? 4) What is a program execution similar to? Summarize the text using the words given below.
Originally, the term «computer» referred to a person who per- formed numerical calculations (a human computer), often with the aid of a mechanical calculating device (me abacus, the slide rale and arguably the astrolabe and the Antikythera mechanism). However, none of those devices fit the modern definition of a computer because they could not be programmed.
Nowadays a computer is a machine which manipulates data ac1 cording to a list of instructions.
Modern computers take numerous physical forms and are based on comparatively tiny integrated circuits and are millions to billions of times more capable while occupying a fraction of me space. Today, simple computers may be made small enough to fit into a wrist watch and be powered from a watch battery. Personal computers in various forms are icons of the information age and are what most people think of as «a computer». However, the most common form of computer in use today is by far the embedded computer. Embedded computers are small, simple devices that are often used to control other devices — for example, they may be found in machines ranging from fighter aircraft to industrial robots, digital cameras, and even children's toys.
The ability to store and execute lists of instructions called programs makes computers extremely versatile and distinguishes them from calculators. The Church—Turing thesis is a mathematical statement of this versatility: any computer with a certain minimum capabil- ity is, in principle, capable of performing the same tasks that any other computer can perform. Therefore, computers with capability and complexity ranging from that of a personal digital assistant to a supercomputer are all able to perform the same computational tasks given enough time and storage capacity.
In most cases, computer instructions are simple: add one number to another, move some data from one location to another, send a mes- sage to some external device, etc. These instructions are read from the computer's memory and are generally carried out (executed) in the
order they were given. However, mere are usually specialized instruc- tions to tell the computer to jump ahead or backwards to some other place in the program and to carry on executing from there. These are called «jump» instructions (or branches). Furthermore, jump instruc- tions may be made to happen conditionally so that different sequences of instructions may be used depending on the result of some previous calculation or some external event. Many computers directly support subroutines by providing a type of jump that «remembers» the loca- tion it jumped from and another instruction to return to me instruction following that jump instruction.
Program execution might be likened to reading a book. While a person will normally read each word and line in sequence, they may at times jump back to an earlier place in the text or skip sections that are not of interest. Similarly, a computer may sometimes go back and repeat the instructions in some section of the program over and over again until some internal condition is met. This is called me flow of control within the program and it is what allows the computer to perform tasks repeatedly without human intervention.
In practical terms, a computer program might include anywhere from a dozen instructions to many millions of instructions for some- thing like a word processor or a web browser. A typical modern computer can execute billions of instructions every second and nearly never make a mistake Over years of operation.
Large computer programs may take teams of computer program- mers years to write and the probability of the entire program having been written completely in the manner intended is unlikely. Errors in computer programs are called bugs. Sometimes bugs are benign and do not affect the usefulness of the program, in other cases they might cause the program to completely fail (crash), in yet other cases there may be subtle problems. Sometimes otherwise benign bugs may be used for malicious intent, creating a security exploit. Bugs are usu- ally not the fault of the computer. Since computers merely execute me instructions they are given, bugs are nearly always the result of programmer error or an oversight made in the program's design.
In most computers, individual instructions are stored as machine code with each instruction being given a unique number (its opera- tion code or opcode for short). The command to add two numbers together would have one opcode, the command to multiply them would have a different opcode and so on. The simplest computers
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are able to perform any of a handful of different instructions; the more complex computers have several hundred to choose from— each with a unique numerical code. Since the computer's memory is able to store numbers, it can also store the instruction codes. This leads to the important fact that entire programs (which are just lists of instructions) can be represented as lists of numbers and can themselves be manipulated inside the computer just as if they were numeric data. The fundamental concept of storing programs in the computer's memory alongside the data they operate on is the crux of the von Neumann, or stored program, architecture. In some cases, a computer might store some or all of its program in memory that is kept separate from the data it operates on. This is called the Harvard architecture after the Harvard Mark I computer. Modern von Neumann computers display some traits of the Harvard architecture in their designs, such as in CPU caches.
refer, aid, fit, tiny, wrist, execute, versatility, add, conditionally, previous, subroutine, skip, bug, benign, malicious, intent, fault, multiply, crux
7. Reproduce the text in English emphasizing the new information not mentioned in the English texts. Use the words given at the bottom.
Компьютер (англ. computer — «вычислитель») — машина для проведения вычислений. При помощи вычислений ком- пьютер способен обрабатывать информацию по заранее опре- деленному алгоритму. Кроме того, большинство компьютеров способны сохранять информацию и осуществлять поиск инфор- мации, выводить информацию на различные виды устройств выдачи информации. Свое название компьютеры получили по своей основной функции — проведению вычислений. Однако в настоящее время полагают, что основные функции компь- ютеров — обработка информации и управление.
Основные принципы: выполнение поставленных перед ним задач компьютер может обеспечивать при помощи перемещения каких-либо механических частей, движения потоков электронов, фотонов, квантовых частиц или за счет использования эффектов от любых других хорошо изученных физических явлений.
Наибольшее распространение среди компьютеров получили так называемые электронно-вычислительные машины, ЭВМ. Собственно, для подавляющего большинства людей, слова «электронно-вычислительные машины» и «компьютеры» стали словами-синонимами, хотя иа самом деле это не так. Наиболее распространенный тип компьютеров — электронный персональ- ный компьютер.
Архитектура компьютеров может непосредственно моде- лировать решаемую проблему, максимально близко (в смысле математического описания) отражая исследуемые физические явления. Так, электронные потоки могут использоваться в качестве моделей потоков воды при моделировании дамб или плотин. Подобным образом сконструированные аналоговые компьютеры были обычны в 60-х годах XX века, однако сегодня стали достаточно редким явлением.
В большинстве современных компьютеров проблема сначала описывается в математических терминах, при этом вся необходимая информация представляется в двоичной форме (в виде единиц и нулей), после чего действия по ее обработке сводятся к применению простой алгебры логики. Поскольку практически вся математика может быть сведе- на к выполнению булевых операций, достаточно быстрый электронный компьютер может быть применим для решения большинства математических задач (а также и большинства задач по обработке информации, которые могут быть легко сведены к математическим).
Было обнаружено, что компьютеры все-таки могут решить не любую математическую задачу. Впервые задачи, которые не могут быть решены при помощи компьютеров, были описаны английским математиком Аланом Тьюрингом.
Результат выполненной задачи может быть представлен пользователю при Помощи различных устройств ввода-вывода информации, таких, как ламповые индикаторы, мониторы, принтеры и т. п.
Начинающие пользователи и особенно дети зачастую с трудом воспринимают идею того, что компьютер — просто машина и не может самостоятельно «думать» или «понимать» те слова, которые он показывает. Компьютер лишь механически отображает заданные программой линии и цвета при помощи
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2. Зак. 496 —"— 33 —■—
устройств ввода-вьгаода. Человеческий мозг сам признает в изображенном на экране образы, числа или слова и придает им те или иные значения.
Впервые трактовка слова «компьютер» появилась в 1897 го- ду в Оксфордском английском словаре. Его составители тог- да понимали компьютер как механическое вычислительное устройство. В 1946 году словарь пополнился дополнениями, позволяющими разделить понятия цифрового, аналогового и электронного компьютеров.
Первые компьютеры создавались исключительно для вы- числений (что отражено в названиях «компьютер» и «ЭВМ»). Даже самые примитивные компьютеры в этой области во много раз превосходят людей (если не считать некоторых уникальных людей-счетчиков). Не случайно первым высокоуровневым языком программирования был Фортран, предназначенный исключительно для выполнения расчетов.
Вторым крупным применением были базы данных. Прежде всего, они были нужны правительствам и банкам. Базы данных требуют уже более сложных компьютеров с развитыми систе- мами ввода-вьгаода и хранения информации. Для этих целей был разработан язык Кобол. Позже появились СУБД со своими собственными языками программирования.
Третьим применением было управление всевозможными устройствами. Здесь развитие шло от узкоспециализирован- ных устройств (часто аналоговых) к постепенному внедрению стандартных компьютерных систем, на которых запускаются управляющие программы. Кроме того, все большая часть тех- ники начинает включать в себя управляющий компьютер.
Наконец, компьютеры развились настолько, что компьютер стал главным информационным инструментом как в офисе, так и дома, т. е. теперь почти любая работа с информацией осуществляется через компьютер — будь то набор текста или просмотр фильмов. Это относится и к хранению информации, и к ее пересылке по каналам связи.
Наиболее сложным и слаборазвитым применением ком- пьютеров является искусственный интеллект — применение компьютеров для решения таких задач, где нет четко определен- ного более или менее простого алгоритма. Примеры таких-за- дач — игры, машинный перевод текста, экспертные системы.
алгоритм г- algorithm;ctfbftar*электронов — electron stream; квантовая частица — quantum particle; электронно-вычисли- тельная машина — electronic computer; дамба — dam; плоти- не — dike; аналоговый компьютер — analogue computer; дво- ичный — binary; единица (натуральное число) — unit; булева операция —Boolean operation; ламповый индикатор —valve/tube indicator; составитель —compiler,author; высокоуровневый — higher-level, high-level; узкоспециализированный — highly tailored; управляющий компьютер — LCU control
8. Talking points.
The definition of a computer, its origin and constituent parts.
Computer programming.
Computer usage.
UNIT 4
Types of Computers
-. 1. The Mainframe Computer — These are computers used by 1здр», organizations'Шее meteojrological surveys and statistical insti- tutes for performing bulk mathematical computations. They are core computers which are used for desktop functions of over one hundred people simultaneously.
2. The Microcomputer — These are the most frequently used computers better known by the name Of «Personal computers». This is the type of computer meant for public use. Other than Desktop Computer the choice ranges as follows:
Personal Digital Computer
According to the classification based on operational principle the types of computers: analog and hybrid.
Analog Computers: The Analog computer is almost an extinct type of computer these days. It is different from a digital computer in respect that it can perform numerous mathematical operations simultaneously. It is also unique in terms of operation as it utilizes continuous variables for the purpose of mathematical computation. It utilizes mechanical, hydraulic, or electrical energy or operation.
Hybrid computers: These types of computers are, as the name suggests, a combination of both Analog and Digital computers. The Digital computers which work on the principle of binary digit system of «0» and «1» can give very precise results. But the problem is that they are too slow and incapable of large scale mathematical operation. In the hybrid types of computers the Digital counterparts convert the analog signals to perform Robotics and Process control.
Apart from mis, computers are also categorized on the basis of physical structures and the purpose of their use. Based on capacity, speed and reliability they can be divided into three categories of computers:
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Hand-held (HPC) PDA Tablet PC
-4 и ■
?n Laptop Desktop
t:
is
Notebooks are impractical or unwieldy, or do not provide the needed nationality.
. t JA workstation is a desktop computer that has a more powerful
processor, additional memory and enhanced capabilities for performing
«^special group of task, such as 3D Graphics or game development.
л : 3. The Mini computer — Mini computers like the mainframe
i computers are used by business organization. The difference
■» being that it can support die simultaneous working of up to
if, 100 users and is usually maintained in business organizations
for the maintenance of accounts and finances.
Yet another category of computer is the Super Computers. It is
somewhat similar to mainframe computers and is used in economic
forecasts and engineering designs. Today life without computers is
inconceivable. Usage of different types of computers has made life
both smooth and fast paced.
A desktop is a PC that is not designed for portability. The ex- pectation with desktop systems is that you will set the computer up in a permanent location. Most desktops offer more power, storage and versatility for less cost dian meir portable brethren.
Laptops, also called notebooks, are portable computers that inte- grate the display, keyboard, a pointing device or trackball, processor, memory and hard drive all in a battery-operated package slightly larger than an average hardcover book.
Palmtops, more commonly known as Personal Digital Assistants (PDAs), are tightly integrated computers that often use flash memory instead of a hard drive for storage. These computers usually do not have keyboards but rely on touchscreen technology for user input. Palmtops are typically smaller than a paperback novel, very lightweight with a reasonable battery life. A slightly larger and heavier version of the palmtop is the handheld computer.
A tablet PC is a notebook or slate-shaped mobile computer, first introduced by Pen Computing in the early 90s with their PenGo Tablet Computer and popularized by Microsoft. Its touchscreen or graphics tablet/screen hybrid technology allows the user to operate the computer with a stylus or digital pen, or a fmgertip, instead of a keyboard or mouse. The form factor offers a more mobile way to interact with a computer. Tablet PCs are often used where normal
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Exercises