Commodore VIC-20 User manual

Personal Computing on the
$5.95
a friendly computer guide
Z commodore
COMPUTER

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Published by
COMMODORE INTERNATIONAL, LTD.
Computer Systems Division
950 Rittenhouse Road
Norristown. PA 19403
U.S.A.
Copyright 1981 Commodore International and Avalanche Productions. AH rights re
served. No part of this publication may be reproduced, stored in a retrieval system, 01
transmitted in any form or Dy any means, electronic, mechanical, photocopying, recording
or otherwise without the prior written permission of Commodore International.
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PERSONAL
COMPUTING
ON THE
A friendly computer guide
COMMODORE INTERNATIONAL
AVALANCHE, INC.

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PREFACE c
You are about to meet a friendly computer! Friendly in price,
friendly in size, friendly to use and learn on and experience.
Most important — you don't have to be a computer r
programmer, or even a typist, to use it!
If you're a first time computerist, this manual will provide an
excellent introduction to computing. Unlike most instruction (
manuals, you don't have to read through this whole book to get
to the "good stuff." After reading Chapter 1 (GETTING
STARTED), you can go directly to a chapter that interests you
and start reading. If you're interested in animation turn to
Chapter 4. If you like music, try Chapter 5. Q
The first page of each chapter has a sample program to start (
you off. Just type the program exactly as shown ("Try Typing
This Program") and see what happens. The rest of the chapter C
explains what you did, and shows you how to do more. Chapter
7 summarizes some important programming concepts, and
explains the techniques used in the sample programs. (
If you're an experienced programmer, you can use the VIC like
any microcomputer. Familiarity with Commodore computers
will help, since the BASIC and graphics are nearly identical to
those used in the PET/CBM. Advanced reference material and
programming information are included in the Appendix. For
more sophisticated programming, see the VIC PROGRAMMERS r
REFERENCE GUIDE, available from your Commodore dealer.
If you're a noncomputerist and have no interest in
programming, per se, you should check out the VIC's growing £
library of plug-in cartridges and program tapes. VIC cartridges
plug directly into the back of the console and work
automatically. Programs are also provided on cassette tapes for r
use with the Commodore Cassette Tape Recorder.
Cartridges and tapes include exciting "arcade-type" games
such as "VIC INVADERS" as well as educational programs to |
help you develop special skills, and home utility programs to
help you solve problems and perform calculations.
Peripherals and accessories for the VIC include the VIC tape £
cassette recorder, single disk drive, telephone modem and
printer, to name a tew. (See Appendix A) C
Computers are becoming an increasingly important part of our
everyday lives — in our homes, at school and in business.
Those who become familiar with computers now will have an
important advantage in the coming months and years. The VIC r
not only introduces you to the world of computing, but also
gives you the features and flexibility you need to expand that
world.
Enjoy your new world!
II C

! TABLE OF CONTENTS
CHAPTER TITLE PAGE
£ PREFACE I)
UNPACKING AND CONNECTING THE VLC2Q V
One GETTING TO KNOW YOUR VIC 1
• Getting Started 3
• Your First Computer Program 7
Two USING THE SCREEN AND KEYBOARD 11
• Your First Graphic Character 14
( • A Tour of the VIC20 Keyboard 17
/ • Printing on theScreen 21
• The VIC20 Calculator 24
• Introduction to Color 25
Three COLOR AND GRAPHICS 27
• Programming in Color 30
( • The VIC Color Keys 32
s • Cftanging Screen and Border Colors 34
• Screen & Border Color Combinations 37
( • Coloring the Screen 37
* • Screen Locations 39
• Random Colors 40
< • Combining Sound and Color 45
• Keyboard Graphics 47
• Graphics in Headlines and Titles 48
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Four ANIMATION 51
• Flying Birds 53
• Bouncing Ball 57
• Controlling the Cursor 60
Animating with POKEs and PEEKs 61
•

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Five SOUND AND MUSIC 67
• Making Music 69
•The Four Voices of VIC 71
• The White Noise Generator 74 (
• Using the VIC as a Piano 76
• Playing Songs 78
• A Few Words About Poke 80 (
Six CONVERSING WITH YOUR VIC 61
•What's Your Name? 83
• Introducing Variables 86 {
• Choose a Note 88
•The GET Statement 89
Seven INTRODUCTION TO PROGRAMMING 93
• Your First BASIC Commands 95
• Random Numbers 103
TITLE PAGE
<
APPENDIX 105 (
A. VIC System Accessories 106
B. Working With Tape Cassettes 109
C. VIC BASIC Vocabulary 113 (
D. BASIC Command Abbreviations 133
E. Screenand Border Color Combinations 134
F. Musical Notes 135 (
G. Sample Sound Effects 136
H. Screen DisplayCodes 139
I. Screen Memory Map 143 (
J. Ascii and Character($) Codes 145
K. Deriving Mathematical Functions 148
L. Pinouts for Input/Output Devices 150 (
M. VIC Programs to Try 153
N. Error Messages 160
INDEX 162
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IV

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UNPACKING AND CONNECTING
THE VIC 20
Welcome to computing! The following sfep-by-step instructions show you how
to unpack the VIC, connect it to /our television sel and make sure it's working
properly.
Let's begin by taking a quick
look at the VIC 20:
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KEYBOARD
(used to type
information
and instructions
into the computer)
POWER LIGHT
(glows when your
VIC is turned on)
POWER CORD
SOCKET
(Attach power
supply here)
GAME PORT
(For joystick
and other
game control
devices)
ON/OFF
SWITCH
EXPANSION
PORT
(VIC Program
cartridges
plug in here)
USER PORT
(For special
accessories)
5 PIN
VIDEO
PORT
(For
connection
to TV set
or monitor)
SERIAL
PORT
(For special
accessories
like printer,
disk drive, etc.)
CASSETTE
PORT
(Tape
cassette
goes here)

1.
2.
3.
4.
5.
8.
Check the contents of your VIC container. You should find the
following items;
— VIC 20 Personal Computer
— Power Supply (large box with 2 cords coming out of it}
— RF Modulator (small metal box) and short cable*
— Video Cable
You will need 2 electrical outlets (sockets) — one for the VfC and
one for your television set.
Position the VfC and Television set so you can use the keyboard
comfortably while viewing the television screen...ideally, a tablelop
or desk.
Find the ON/OFF switch on
the rrght hand side of the VIC.
Make sure ifs in the "OFF"
position.
There are two cords coming
out of the power supply box.
Plug the power supply cord
into an electrical outlet and
plug the other cord into the
power cord socket on the side
of the VIC. NOTE: The power
supply remains "on" while
plugged in so you should
unplug
it when not in use.
Connect the video cable to
the back of the VIC and to the
RF Modulator box, as shown.
Make sure to connect it to the
video port and not to the 6-pin
serial port, which is next to it.
Connect the RF Modulator to
your television set. For this
you'll need a screwdriver. The
short TV connector cord runs
from the RF Modulator box to
the 2 VHF Antenna leads on
the back of your television.
Simply connect the two wires
to the VHF leads and tighten
the screws firmly."
Turn on the TV set.
VIDEO
PORT RF MODULATOR
c
o
VIDEO
PLUG
CONNECT
WJRE LEADS
TO ANTENNA
LEADS ON
you r tv
SET
VIDEO
CABLE
PEAR VIEW OF
TV SET
RF MODULATOR
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Note: Some VICs are provided wilti a "switchbox" which aitachea beiween ihe RF modulator and TV sei
The switcJibox contains a swiicn with skiing* Ipi "computer" end "TV and should be set to "computer"
when usmg Ihe ViC.
VI

TROUBLESHOOTING CHART
SYMPTOM
CAUSE
REMEDY
NO PICTURE VIC not "o
(POWER LIGHT OFF)
Make sure power switch
is in Mon" position
VIC not plugged in
Check power socket
next to power switch
Power supply not
plugged tn
Check connection with
wall outlet
Bad fuse in VIC
Take VIC to your
Authorized
Commodore
Service Center for
replacement of fuse*
NO PICTURE
(POWER LIGHT ON) (Try turning VIC off far a few secondsh then back on)
TV on wrong channel Check Channel 3 & 4 for
picture
Incorrect hookup
VIC hooks up to "VHF"
terminals on TV
Modulator not plugged
in
Check connection at
5-pin Video Port
Modulator on wrong
channel
Flip switch on Modulator
Video cable not
connected
Check connection on
modulator
PICTURE WITHOUT
COLOR |THY TV &
MODULATOR ON
CHANNEL 3 S 4)
Poorly tuned TV
RetuneTV
PICTURE WITH Bad color adjustment on Adjust color/hue/
POOR COLOR TV (see "picture without brightness controls on
color") TV
PICTURE WITH TV volume jp too high
EXCESS (see "picture without
BACKGROUND NOJSE color")
Adjust volume of TV
PICTURE OK,
BUT NO SOUND
TV volume too low
Adjust volume of TV
'The VIC uses a 3 amp SLO-BLO fuse.
VII

10.
11
12.
Turn on the VIC (the red
power light on the top of the
computer should come on). If
the power light does nol.
consult the accompanying
troubleshooting chart.
There is a switch on the RF
Modulator for selecting either
Channel 3 or 4. Choose the
channel with the weaker
reception in your area+ and set
both the TV and the
Modulator to lhat channel.
The fine tuning on your
television may need some
adjustment.
Here is what you should see
on the screen — sometimes it
takes a second or two lo
activate. If you don't get the
following display on your
screen, turn the computer off,
wait a few seconds and turn it
on again.
Adjusting the color and
tint/hue depends on the color
controls provided on your
television set — naturally,
sets with better controls yield
better color. Some sets show
some colors better than
others.
If you have trouble with any of
these steps, consult the
accompanying
troubleshooting chart.
NOW...you are ready to start using the VIC.
NOTE: You can use a monitor instead of a television set — in which case you
can go directly from the VIC to the monitor cable, without the RF
Modulator.
IF ALL ELSE FAILS-CALL THE TOLL-FREE
COMMODORE TECHNICAL HOTLINE...
1-800-523-5622
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VIII