Unit 1

What is a computer?

When you read the following text, you will probably meet words and expressions that are new to you. First try to understand their meaning from the context – read the same passage a few times. When you have read the whole text, check new words in a dictionary.

A computer is a machine with an intricate network of electronic circuits(Điện xoay chiềuthat(1) (!computer) operate switches or magnetize tiny metal cores. The switches (nút?), like the cores, are capable of being in one of two possible states, that is, on or off, magnetized or demagnetized. The machine is capable of storing and manipulating numbers, letters, and characters. The basic idea of a computer is that we can make the machine do what we want by inputting signals that turn certain switches on and turn other off, or that magnetize or do not magnetize the cores.

The basic job of computers is the processing (xử lí?) of information. For this reason, computer can be defined as devices (thiết bị?) which(2) (!devices) accept information in the form of instructions called a program and characters called data, perform mathematical and/or logical operations on the information, and then supply results of these operations. The program, or part of it(3), which(4) tells the computers what to do and the data, which provide the information needed to solve the problem, are kept inside the computer in a place called memory.

Computers are thought to have many remarkable powers. However, most computers, whether large or small have three basic capabilities. First, computers have circuits (mạch) for performing arithmetic (số học) operations (các thao tác), such as: addition, subtraction, division, multiplication and exponentiation. Second, computers have a means of communicating with the user. After all, if we couldn’t need information in and get results back, these machines wouldn’t be of much use. However, certain computers (Commonly minicomputers and microcomputers) are used to control directly things such as robots, aircraft navigation systems, medical instruments, etc.

Some of the most common methods of inputting information are to use punched cards, magnetic tape, disks, and terminal. The computer’s input device (which might be a card reader, a tape drive or dirk drive, depending on the medium used in inputting information) reads the information into the computer.

For outputting information, two common devices used are a printer which(5) prints the new information on paper, or a CRT display screen which(6) shows the results on a TV-like screen.

Third, computers have circuits which(7) can make decisions. The kinds of decisions which computer circuits can make are not of the tape: “Who would win a war between two countries?” or “Who is the richest person in the world?”. Unfortunately, the computer can only decide three things, namely: Is one number less than another? Are two numbers equal? And, is one number greater than another?

A computer can solve a series of problems and make hundreds, even thousands, of logical decisions without becoming tired or bored. It(8) 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(9) has no originality; it works according to the instructions given to it and cannot exercise any value judgments. There are times when a computer seems to operate like a mechanical “brain”, but its achievements are limited by the minds of human beings. A computer cannot do anything unless a person tells it(10) what to do and gives it the appropriate information; but because electric pulses can move at the speed of light, a computer can carry out vast numbers of arithmetic-logical operations almost instantaneously. A person can do everything a computer can do, but in many cases that person would be dead long before the job was finished.

Words and expressions
circuit
core
device
program
data
memory
punched card
magnetic tape
disk
terminal
input device
tape drive
disk drive
CRT display
instruction

Exercises

I. Main idea
Which statement best expresses the main idea of the text? Why did you eliminate the other choices?
Computers have changed the way in which many kinds of jobs are done.
Instructions and data must be given to the computer to act on.
Computers are machines capable of processing and outputting data.
Without computers, many tasks, would take much longer to do.

II. Understanding the passage
Decide whether the following statements are true or false (T/F) by referring to the information in the text. Then make the necessary changes so that the false statement become true.
A computer can store or handle any data even if it hasn’t received information to do so.
All computers accept and process information in the