INTRODUCTION

This chapter explains CBM BASIC Language keywords. First we give you an easy to read list of keywords, their abbreviations and what each letter looks like on the screen. Then we explain how the syntax and operation of each keyword works in detail, and examples are shown to give you an idea as to how to use them in your programs.

As a convenience, Commodore 64 BASIC allows you to abbreviate most keywords. Abbreviations are entered by typing enough letters of the keyword to distinguish it from all other keywords, with the last letter or graphics entered holding down the <SHIFT> key.

Abbreviations do NOT save any memory when they're used in programs, because all keywords are reduced to single-character "tokens" by the BASIC Interpreter. When a program containing abbreviations is listed, all keywords appear in their fully spelled form. You can use abbreviations to put more statements onto a program line even if they won't fit onto the 80-character logical screen line. The Screen Editor works on an 80-character line. This means that if you use abbreviations on any line that goes over 80 characters, you will NOT be able to edit that line when LISTed. Instead, what you'll have to do is (1) retype the entire line including all abbreviations, or (2) break the single line of code into two lines, each with its own line number, etc.

A complete list of keywords, abbreviations, and their appearance on the screen is presented in Table 2-1. They are followed by an alphabetical description of all the statements, commands, and functions available on your Commodore 64.

This chapter also explains the BASIC functions built into the BASIC Language Interpreter. Built-in functions can be used in direct mode statements or in any program, without having to define the function further. This is NOT the case with user-defined functions. The results of built-in BASIC functions can be used as immediate output or they can be assigned to a variable name of an appropriate type. There are two types of BASIC functions:

1. NUMERIC
2. STRING