(It commodore

COMPUTER
FIRST EDITION THIRD PRINTING-1983
Copyright @ 1982 by Commodore Business Machines, All rights reserved.
This manual is copyrighted and contains proprietary information. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, eledronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of COMMODORE BUSINESS MACHINES, Inc. ii

TABLE OF CONTENTS

INTRODUCTION. What's Included?.

Reference

Guide. "

Commodore

ApplicationsGuide.

xii xvii

Commodore Information Network.
1. BASIC PROGRAMMING RULES

Introduction

. Screen Display

Codes (BASIC Character

The Operating System(OS) Programming Numbers and Variables Integer, Floating-Point and String Constants. Integer, Floating-Point and String Variables.
Integer, Floating-Point and String Arrays
. Expressionsnd Operators. a
Arithmetic Expressions. Arithmetic Operations.

Relational

Logical

Operators

Hierarchy of Operations.

Stri ng Operations

String

Expressions

Programming

Techniques

Data Conversions.
Using the INPUT Statement

Using the GET Statement.

How to Crunch BASIC Programs

2. BASIC LANGUAGE

VOCABULARY..
BASIC Keywords, Abbreviations, and Function Types
Description of BASIC Keywords (Alphabetical)
. The Commodore 64 Keyboard and Features. Screen Editor.
3. PROGRAMMING GRAPHICS ON THE

COMMODORE64

Graphics Overview Character Display

Bit Map Modes Sprites

GraphicsLocations

101 102

VideoBankSelection.

Screen Memory

ColorMemory

.1.. 103

Character Memory.

Standard Character Mode.

Character Definitions Programmable Characters Multi-Color Mode Graphics Multi-Color Mode Bit Extended Background Color Mode
. BitMapped Graphics. '".
Standard High-Resolution Bit Map Mode..

121 122

HowIt Works.
Multi-Color itMap Mode. B
. Smooth Scrolling. Sprites

128 131

Defining a Sprite 131 Sprite Poi nters. 133 Turning Sprites On 134 Turning Sprites Off. 135 Colors. 135 Multi-Color Mode 135
Setting a Sprite to Multi-Color Mode.
Expanded Sprites Sprite Positioning
Sprite PositioningSummary.
SpriteDisplay Priorities.

Collision Other

Detects Features

150 151

Graphics
Screen Blanking Raster Reg ister

Color Combinations.

Interrupt Status Register.
Suggested Screen and Character iv
Programming Sprites-Another Look Making Sprites in BASIC-A Short Program. Crunching Your Sprite Programs Positioning Sprites on the Screen

Sprite Priorities

156 157
Drawing a Sprite 162 Creati ng a Sprite. Step by Step 163 Moving Your Sprite on the Screen. 165

VerticalScrolling.

The Dancing Mouse-A
Sprite Program Example. 166
EasySpritemakingChart. 176 SpritemakingNotes. 177
PROGRAMMING SOUND AND MUSIC ON YOUR COMMODORE 64

Volume Control

Frequencies of Sound Waves.

UsingMultiple Voices.

Controlling Multiple Voices

Changing

187 191
Waveforms. Understanding aveforms. W.

The EnvelopeGenerator.

Filtering

Advanced Techniques.

Synchronization and Ring Modulation
5. BASICTOMACHINE LANGUAGE
What is Machine Language?

What Does Machine Code

Look Like?
Simple Memory Map of the Commodore 64 The Registers Inside the 6510 Microprocessor How Do You Write Machine Language Programs? 64MON

Hexadecimal Notation..

Your First Machine Language Instruction Writing Your First Program. Addressing Modes. Zero Page The Stack.

221 222

Indexing Indirect Indexed Indexed Indirect

Branches and Testing.

Subroutines Useful Tips for the Beginner

228 229

Approaching a Large Task.
MCS6510 Microprocessor Instruction Set-

Alphabetic Sequence

"'.

269 270

Instruction Addressing Modes and

Related Execution Times.

Memory Management on the Commodore 64
The KERNAL. KERNAL Power-Up Activities. How to Use the KERNAL.
User Callable KERNALRoutines Error Codes Using Machine Language From BASIC Where to Put Machine Language Routines. How to Enter Machine Language
. Commodore 64 Memory Map. 310 Commodore 64 Input/Output Assignments. 320 6. INPUT/OUTPUT GUIDE..

307. 309 309

Output to the TV
Output to Other Devices. Output to Printer.

Output to Modem

336 337
Working WithCassette Tape.

339 340

Data Storage on Floppy Diskettes.

The Game Ports

Paddles Light Pen RS-232 Interface Description General Outline Opening an RS-232 Channel Getting Data From an RS-232 Channel Sending Data to an RS-232 Channel Closing an RS-232 Data Channel Sample BASIC Programs.
Receiver/Transmitter Zero-Page
Buffer Base Location Pointers
Memory Locations and Usage Memory Locations and Usage
for RS-232 System Interface.

Nonzero-Page

for RS-232 System Interface. The User Port.

Port Pin Description

The Serial Bus.. Serial Bus Pinouts
. Z-80Microprocessor artridge. C

Expansion Port

Using Commodore CP/M@. Running Commodore CP/M@ APPENDICES
. 373 A. Abbreviations for BASICKeywords. 374
B. Screen Display Codes 376

C. D. E. F.

ASCIIand CHR$ Codes. Screen and Color MemoryMaps. Music Note Values. Bibliography.
G. VIC Chip Register Map H. Deriving Mathematical Functions

391 394

Pinouts for Input/Output Devices.
Converting Standard BASIC Programs to Commodore 64 BASIC

K. Error Messages.

L. 6510 Microprocessol Chip Specifications M. 6526 Complex Interface Adapter (CIA)

419 436

Chip Specifications. N. 6566/6567 (VIC-II)Chip Specifications.
O. P. 6581 Sound Interface Device (SID) Chip Specifications. Glossary
COMMODORE 64 QUICK REFERENCE CARD
SCHEMATIC DIAGRAM OF THE COMMODORE 64. 491

INTRODUCTION

The COMMODORE64 PROGRAMMER'SREFERENCE GUIDE has been developed as a working tool and reference source for those of you who want to maximize your use of the built-in capabilities of your COMMODORE64. This manual contains the information you need for your programs, from the simplest example all the way to the most complex. The PROGRAMMER'SREFERENCE GUIDE is designed so that everyone from the beginning BASIC programmer to the professional experienced in 6502 machine language can get information to develop his or her own creative programs. At the same time this book shows you how clever your COMMODORE 64 really is. This REFERENCEGUIDE is not designed to teach the BASIC programming language or the 6502 machine language. There is, however, an extensive glossary of terms and a "semi-tutorial" approach to many of the sections in the book. If you don't already have a working knowledge of BASIC and how to use it to program, we suggest that you study the COMMODORE 64 USER'SGUIDE that came with your computer. The USER'SGUIDE gives you an easy to read introduction to the BASICprogramming language. If you still have difficulty understanding how to use BASIC then turn to the back of this book (or Appendix N in the USER'S GUIDE) and check out the Bibliography. The COMMODORE 64 PROGRAMMER'SREFERENCEGUIDE is just that; a reference. Like most reference books, your ability to apply the information creatively really depends on how much knowledge you have about the subject. In other words if you are a novice programmer you will not be able to use all the facts and figures in this book until you expand your current programming knowledge.

What you can do with this book is to find a considerable amount of valuable programming reference information written in easy to read, plain English with the programmer's jargon explained. On the other hand the programming professional will find all the information needed to use the capabilities of the COMMODORE64 effectively.

WHAT'S INCLUDED?

. Our complete "BASIC dictionary" includes Commodore BASIC language commands, statements and functions listed in alphabetical order. We've created a "quick list" which contains all the words and their abbreviations. This is followed by a section containing a more detailed definition of each word along with sample BASIC programs to illustrate how they work. If you need an introduction to using machine language with BASIC programs our layman's overview will get you started. A powerful feature of all Commodore computers is called the KERNAL. It helps insure that the programs you write today can also be used on your Commodore computer of tomorrow. The Input/Output Programming section gives you the opportunity to use your computer to the limit. It describes how to hook-up and use everything from lightpens and joysticks to disk drives, printers, and telecommunication devices called modems. You can explore the world of SPRITES,programmable characters, and high resolution graphics for the most detailed and advanced animated pictures in the microcomputer industry. You can also enter the world of music synthesis and create your own songs and sound effects with the best built-in synthesizer available in any personal computer. If you're an experienced programmer, the soft load language section gives you information about the COMMODORE64's ability to run CP/M* and high level languages. This is in addition to BASIC.
Think of your COMMODORE64 PROGRAMMER'S REFERENCE GUIDE as a useful tool to help you and you will enjoy the hours of programming ahead of you.
.CP/M is a registered x INTRODUCTION

trademark

of Digital Research,

HOW TO USE THIS REFERENCEGUIDE
Throughout this manual certain conventional notations are used to describe the syntax (programming sentence structure) of BASIC commands or statements and to show both the required and optional parts of each BASIC keyword. The rules to use for interpreting statement syntax are as follows: 1. BASIC keywords are shown in capital letters. They must appear where shown in the statement, entered and spelled exactly as shown. 2. Items shown within quotation marks (" ") indicate variable data which you must put in. Both the quotation marks and the data inside the quotes must appear where shown in each statement. 3. Items inside the square brackets ([ ]) indicate an optional statement parameter. A parameter is a limitation or additional qualifier for your statements. If you use an optional parameter you must supply the data for that optional parameter. In addition, ellipses (. ) show that an optional item can be repeated as many times as a programming line allows. 4. If an item in the square brackets ([ ]) is UNDERLINED,hat means t that you MUST use those certain characters in the optional parameters, and they also have to be spelled exactly as shown. 5. Items inside angle brackets indicate variable data which you provide. While the slash ( / ) indicates that you must make a choice between two mutually exclusive options.
EXAMPLE OF SYNTAX FORMAT:
OPEN<file-num> ,<device> name>] [,<mode>]" [,<address>], ["<drive>: <file-
EXAMPLES OF ACTUAL STATEMENTS:
10 OPEN 2,8,6,"0:STOCK FOLlO,S,W" 20 OPEN 1,1 ,2,"CHECKBOOK" 30 OPEN 3,4 When you actually apply the syntax conventions in a practical situation, the sequence of parameters in your statements might not be exactly the same as the sequence shown in syntax examples. The examples are not meant to show every possible sequence. They are intended to present all required and optional parameters.

INTRODUCTION xi

Programming examples in this book are shown with blanks separating words and operators for the sake of readability. Normally though, BASIC doesn't require blanks between words unless leaving them out would give you an ambiguous or incorrect syntax. Shown below are some examples and descriptions of the symbols used for various statement parameters in the following chapters. The list is not meant to show every possibility, but to give you a better understanding as to how syntax examples are presented. SYMBOL <file-num> <device> <address> EXAMPLE 15 DESCRIPTION

A logical file number

A hardware device number A serial bus secondary device address number A physical disk drive number The name of a data or program file Literal data supplied by the programmer Any BASIC data variable name or constant Use of a string type variable required Use of a numeric type variable required An actual program line number An integer or floating-point variable

<drive> <file-name> <constant> <variable> <string> <number> <line-number> <numeric>

"TEST. DATA"

" ABCDEFG" X145 AB$ 1.5E4
COMMODORE 64 APPLICATIONS GUIDE
When you first thought about buying a computer you probably asked yourself, "Now that I can afford to buy a computer, what can I do with it once I get one?" The great thing about your COMMODORE 64 is that you can make it do what YOU want it to do! You can make it calculate and keep track of home and business budget needs. You can use it for word processing. You can make it play arcade-style action games. You can make it sing. Youcan even create your own animated cartoons, and more. The best part of owning a COMMODORE 64 is that even if it did only one of the things listed below it would be well worth the price you paid for it. But the 64 is a complete computer and it does do EVERYTHINGlisted and then some!

xii INTRODUCTION

By the way, in addition to everything here you can pick up a lot of other creative and practical ideas by signing up with a local Commodore Users' Club, subscribing to the COMMODOREnd POWER/PLAY a magazines, and joining the COMMODOREINFORMATIONNETWORKon

CompuServe

APPLICATION

COMMENTS/REQUIREMENTS

ACTION PACKED GAMES
You can get real Bally Midway arcade games like Omega Race, Gorf and Wizard of Wor, as well as "play and learn" games like Math Teacher I, Home Babysitter and Commodore Artist. Hook your COMMODORE64 to a TV, put it in a store window with a flashing, animated, and musical message and you've got a great point of purchase store display. Commodore's Sprite Graphics allow you to create real cartoons with 8 different levels so that shapes can move in front of or behind each other. The COMMODORE 64 HOME BABYSITTER cartridge can keep your youngest child occupied for hours and teach alphabet/ keyboard recognition at the same time. It also teaches special learning concepts and relationships. Your COMMODORE 64 USER'SGUIDE and the TEACH YOURSELF PROGRAMMING series of
books point. and tapes offer an excellent starting
ADVERTISING & MERCHANDISING

ANIMATION

BABYSITTING

BASIC PROGRAMMING

BUSINESS SPREADSHEET
The COMMODORE 64 offers the "Easy" series of business aids including the most powerful word processor and largest spreadsheet for any personal computer. available Enter the fascinating world of computer "networking." If you hook a VICMODEM to your COMMODORE 64 you can communicate with other computer owners all around the world.

COMMUNICATION

Not only that, if you join the COMMODORE INFORMATIONNETWORK on CompuServe you can get the latest news and updates on all Commodore products, financial information, shop at home services, you can even play games with the friends you make through the information systems you join. COMPOSING SONGS The COMMODORE 64 is equipped with the most sophisticated built-in music synthesizer available on any computer. It has three completely programmable voices, nine full music octaves, and four controllable waveforms. look for Commodore Music Cartridges and Commodore Music books to help you create or reproduce all kinds of music and sound effects. Commodore offers a CP/M* add-on and access to software through an easy-to-Ioad cartridge. Hand/Eye coordination

are aided by several

DEXTERITY TRAINING

and manual

dexterity
including "Jupiter simulation.

EDUCATION

lander"

and night driving

While working with a computer is an education in itself, The COMMODORE Educational Resource Book contains general information on the educational uses of computers. We also have a variety of learning cartridges designed to teach everything from music to math and art to astronomy. The COMMODORE 64 programmable character set lets you replace the standard character set with user defined foreign language characters. In addition to the Sprite Graphics mentioned above, the COMMODORE 64 offers highresolution, multi-color graphics plotting, proof Digital Research, Inc.

FOREIGN

LANGUAGE

GRAPHICS AND ART

.CP/M is a Registered trademark
grammable characters, and combinations of all the different graphics and character display modes.

INSTRUMENT

CONTROl
Your COMMODORE 64 has a serial port, RS-232 port and a user port for use with a variety of special industrial applications. An IEEE/488 cartridge is also available as an optional extra. The COMMODORE 64 will soon offer an exceptional word processing system that matches or exceeds the qualities and flexibilities of most "high-priced" word processors available. Of course you can save the information on either a 1541 Disk Drive or a Datassette TM recorder and have it printed out using a VICPRINTERor PLOTTER. Applications requiring the use of a lightpen can be performed by any lightpen that will fit the COMMODORE 64 game port connector. Your COMMODORE 64 PROGRAMMER'S REFERENCE GUIDE includes a machine language section, as well as a BASIC to machine code interface section. There's even a bibliography available for more in-depth study. The COMMODORE 64 can be programmed to handle a variety of entry-type business applications. Upper~lower case letters combined with C64 "business form" graphics make it easy for you to design forms which can then be printed on your printer. The COMMODORE 64 interfaces with a variety of dot matrix and letter quality printers as well as plotters. You can store your favorite recipes on your COMMODORE 64 and its disk or cassette storage unit, and end the need for messy recipe cards that often get lost when you need them most.

INTRODUCTION xv

JOURNALS AND CREATIVE WRITING

LlGHTPEN CONTROL

MACHINE CODE PROGRAMMING
PAYROLL & FORMS PRINTOUT

PRINTING

RECIPES

SIMULATIONS

Computer simulations let you conduct dangerous or expensive experiments at minimum risk and cost.

SPORTS DATA

The Source and CompuServe both offer sports information which you can get using your COMMODORE64 and a VICMODEM. With a VICMODEM and a subscription to any of the appropriate network services, your COMMODORE64 becomes your own private stock ticker.

STOCK QUOTES

These are just a few of the many applications for you and your COMMODORE64. As you can see, for work or play, at home, in school or the office, your COMMODORE64 gives you a practical solution for just about any need. Commodore wants you to know that our support for users only STARTS with your purchase of a Commodore computer. That's why we've created two publications with Commodore information from around the world, and a "two-way" computer information network with valuable input for users in the U.S. and Canada from coast to coast. In addition, we wholeheartedly encourage and support the growth of Commodore Users' Clubs around the world. They are an excellent source of information for every Commodore computer owner from the beginner to the most advanced. The magazines dnd network, which are more fully described below, have the most up-to-date information about how to get involved with the Users' Club in your area. Finally, your local Commodore dealer is a useful source of Commodore support and information. POWER/PLAY
The Home Computer Magazine
When it comes to entertainment, learning at home and practical home is applications, POWER/PLAY THEprime source of information for Commodore home users. Find out wh,ere your nearest user clubs are and what they're doing, learn about software, games, programming techniques, telecommunications, and new products. POWER/PLAY your is personal connection to other Commodore users, outside software and hardware developers, and to Commodore itself. Published quarterly. Only $10.00 for a year of home computing excitement.

xvi INTRODUCTION

COMMODORE
The Microcomputer Magazine
Widely read by educators, businessmen and students, as well as home computerists, COMMODORE Magazine is our main vehicle for sharing exclusive information on the more technical use of Commodore systems. Regular departments cover business, science and education, programming tips, "excerpts from a technical notebook," and many other features of interest to anyone who uses or is thinking about purchasing Commodore equipment for business, scientific or educational applications. COMMODOREis the ideal complement to POWER/ PLAY. Published bi-monthly. Subscription price: $15.00 per year.
AND FOR EVEN MORE INFORMATION DIAL UP OUR PAPERLESS USER MAGAZINE
COMMODORE INFORMATION NETWORK
The magazine of the future is here. To supplement and enhance your subscription to POWER/PLAY and COMMODOREmagazines, the COMMODORE INFORMATIONNETWORK-our "paperless magazine"-is available now over the telephone using your Commodore computer and modem. Join our computer club, get help with a computing problem, "talk" to other Commodore friends, or get up-to-the-minute information on new products, software and educational resources. Soon you will even be able to save yourself the trouble of typing in the program listings you find in POWER/PLAY COMMODOREy downloading direct from the or b Information Network (a new user service planned for early 1983). The best part is that most of the answers are there before you even ask the questions. (How's that for service?) To call our electronic magazine you need only a modem and a subscription to CompuServe, one of the nation's largest telecommunications networks. (To make it easy for you Commodore includes a FREE year's subscription to CompuServe in each VICMODEM package.) Just dial your local number for the CompuServe data bank and connect your phone to the modem. When the CompuServe video text appears on your screen type G CBM on your computer keyboard. When the COMMODORE INFORMATION NETWORK'Stable of contents, or "menu," appears on your screen choose from one of our sixteen departments, make yourself comfortable, and enjoy the paperless magazine other magazines are writing about.

INTRODUCTION xvii

For more information, visit your Commodore dealer or contact CompuServe customer service at 800-848-8990 (in Ohio, 614-457-8600).
Main Menu Description Direct Access Codes Special Commands User Questions Public Bulletin Board Magazines and Newsletters Products Announced Commodore News Direct Commodore Educational Dealers Resources
User Groups Descriptions Questions and Software Technical Directory

Answers

Tips Tips Descriptions