170 33 BASIC keywords This chapter contains a detailed description of every word that BASIC understands. These words are called ‘keywords’. Some parts of the description are intended for the novice user and others for the person who is familiar with BASIC. Note that your BBC Microcomputer is supplied with the latest version of BBC BASIC, known as BASIC II. If you are already familiar with the earlier version, you may wish to refer to chapter 49 before reading this chapter. Chapter 49 lists those BASIC keywords which exist only in BASIC II. Each keyword is described under a number of headings as follows: Keyword Sometimes followed by a few words explaining the derivation of the word.
Purpose A plain-English description of what the keyword does. This is intended for the person who is learning BASIC. The only technical terms used are ‘string’ and ‘numeric’ – if you don’t understand those two words then read chapter 9 first. The mathematical functions SIN , COS , TAN etc are not exlained for the absolute beginner – there just isn’t room to explain everything! This section gives a few one-line examples of the keyword (not complete programs). Some of the examples have a number at the start of the line. This number is an ‘example line number’. Examples The examples are only intended to be illustrative.
In some cases a line of BASIC program may overflow onto the next line as elsewhere in this book. Description In this section the keyword is described using normal computer jargon. Syntax The syntax of each keyword’s usage is given more by way of helpful explanation than for its strict accuracy. Purists will, rightly, complain at travesty of Backus- Naur form. Others may find the entries useful.