Text № 7 what is a computer language?

Instructing a computer is done with a computer language. A computer language is a set of words, symbols and commands that a computer can “understand”. Think of this example: if you study French you learn words and rules of grammar that another speaker of French can understand. If you study computer language, you learn words and rules that a computer can understand. Most French words are not familiar to you when you first see them. But many computer languages use words that are mostly English ones, such as PRINT, ENTER and SHIFT. These words have special meanings in a computer language.

Computer languages are not spoken to the computer (except in some experimental systems with limited vocabularies). Instead, you type the computer language on the keyboard. The computer then translates what you have typed into electrical impulses that represent 0’s and 1’s – the form in which the computer can understand and carry out your instructions. To translate your instructions, the computer needs a language processor that is either built into the computer itself or loaded into it form a disc. The language processor acts as a human interpreter.

There are many different computer languages. You may have heard of BASIC, Logo, Pascal, FORTRAN, Delphi and others. The reason for so many languages is that every language works well for different kinds of tasks.

Черкаський політехнічний технікум

Текст № 7

для студентів III курсу, 6 семестр (ПС)

Викладач Горпинко В.П.

Text № 8 structured languages

You’ve learned that different languages are designed for different purposes. BASIC is an all-purpose language, meaning that you can do almost anything in BASIC. But some things will be rather hard to do in it.

Logo is a structured language which is available for many microcomputers. You may be familiar with Logo because many schools use it to do “turtle graphics”. A turtle is a cursor on the screen. It’s called so because it’s often shaped like one. The turtle can move left, right, up and down, or turn a certain number of degrees, it can draw on the screen.

Logo is a language that can also help you to write structured programs. For example, you can tell a turtle to carry out a set of commands that will draw a rectangle on the screen. Then you can call that set of commands “box”. Each time you tell the turtle to “DO BOX”, it’ll draw the rectangle. “BOX” has become a module of a program. You can create a whole series of routines that draw different shapes or parts of pictures. Then you can combine them all in one statement and call the whole thing “house”. Then you can make “house” part of another routine, and so on. Your whole program can consist of a series of statements defining different routines and then a few statements calling theses routines in correct order.

Logo doesn’t just do turtle graphics, it’s a complete language. But whether you use the language to draw a house or computer mathematical functions, the modular structure of the language is the same.

Pascal is also a structured language. Pascal has some features that make structured languages easier. It allows to indent the statements in a loop so that you can see the beginning and the end of each loop. Pascal also has certain requirements that make you plan your program carefully. For example, it requires you to define all your variables before you begin.

One disadvantage of Pascal is that it often a compiled language, i.e. it must be translated by a compiler into a code that the computer can understand before the program can be run.

Черкаський політехнічний технікум

Текст № 8

для студентів III курсу, 6 семестр (ПС)

Викладач Горпинко В.П.