Titlebook: Beginning BASIC with the ZX Spectrum; Judith Miller Textbook 1985Latest edition Macmillan Publishers Limited 1985 BASIC.computer science.p

HPA533

Introduction,The system is composed of three main parts as illustrated below:

发电机

Interlocking

Correcting mistakes,In unit 1 you learned that a letter could be removed by pressing CAPS SHIFT and DELETE. Sometimes mistakes are not noticed immediately and you may have typed in a whole sentence before realising that a mistake has been made. In order to correct this mistake it is not necessary to delete the whole sentence.

议程

Making a program,The whole sentence plus the number and the keyword PRINT appears at the top of the screen. The computer is now making a . by storing the information for later use.

诽谤

More about numbering lines,Program lines are usually numbered in intervals of ten; for example, 10, 20, 30, 40 etc. The reason for this is that when a program is first made lines are often missed out by mistake. Having intervals of ten between lines enables a further nine lines to be inserted later if necessary. For example

巨头

栏杆

,Testing your knowledge—questions on the Introduction and Units 1–5,Try to answer from memory as many questions as you can. Look up those you do not know in the appropriate unit — the questions are divided into sections. Check your answers at the back of the book.

indicate

Numeric or simple variables,A numeric or simple variable is a storage space in the computer’s memory which is given a name. The storage space stores only numbers, hence its name. The easiest way to imagine this is to think of a box that has a name and contains a number. The example below shows a box called ‘A’ storing the number 15.

needle

String variables, are the letters of the alphabet, the numbers 0 to 9, punctuation marks and special symbols as +, -, *.

闪光你我

Using the computer as a calculator,For arithmetic you use four main operators: add, subtract, multiply and divide. BASIC language has the same operators although two are printed differently.