INTRODUCTION

Your Commodore computer is equipped with one of the most sophisticated electronic music synthesizers available on any computer. It comes complete with three voices, totally addressable, ATTACK/DECAY/SUSTAIN/ RELEASE (ADSR), filtering, modulation, and "white noise." All of these capabilities are directly available for you through a few easy to use BASIC and/or assembly language statements and functions. This means that you can make very complex sounds and songs using programs that are relatively simple to design.

This section of your Programmer's Reference Guide has been created to help you explore all the capabilities of the 6581 "SID" chip, the sound and music synthesizer inside your Commodore computer. We'll explain both the theory behind musical ideas and the practical aspects of turning those ideas into real finished songs on your Commodore computer.

You need not be an experienced programmer nor a music expert to achieve exciting results from the music synthesizer. This section is full of programming examples with complete explanations to get you started.

You get to the sound generator by POKEing into specified memory locations. A full list of the locations used is provided in Appendix O. We will go through each concept, step by step. By the end you should be able to create an almost infinite variety of sounds, and be ready to perform experiments with sound on your own.

Each section of this chapter begins by giving you an example and a full line-by-line description of each program, which will show you how to use the characteristic being discussed. The technical explanation is for you to read whenever you are curious about what is actually going on. The workhorse of your sound programs is the POKE statement. POKE sets the indicated memory location (MEM) equal to a specified value (NUM).

   POKE MEM,NUM

The memory locations (MEM) used for music synthesis start at 54272 ($D400) in the Commodore 64. The memory locations 54272 to 54296 inclusive are the POKE locations you need to remember when you're using the 6581 (SID) chip register map. Another way to use the locations above is to remember only location 54272 and then add a number from 0 through 24 to it. By doing this you can POKE all the locations from 54272 to 54296 that you need from the SID chip. The numbers (NUM) that you use in your POKE statement must be between 0 and 255, inclusive.