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
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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
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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

Try typing this program:
Type this program exactly as shown and see
what happens!
This line tells
the VIC to print
what's between the
quotation marks.
This line tells the VIC
to go back to Line 1
and print it again.
Typing the word RUN
makes the program
run.
To stop the program, press the
key.
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GETTING STARTED—
EXPERIMENT A LITTLE
You made it! Your VIC is aglow with color and ready for you
to tell it what to do. The dark blue, blinking rectangle, called
the cursor, is a signal from the ViC that it is waiting for you.
VIC TIP:
II you type a character on the screen that you don't want, press the
key.
This key will erase the character immediately to the left of the blink
ing cursor.
Use this key as often as you like to delete unwanted characters.
Now, on with the tour! Begin by pressing the following keys:
See how the cursor moves over one position every time you
press a key? The cursor tells you where the next character is
going to appear on the screen. OK, now find the SHIFT key, it
looks like this:
There are two of them, both the same.
3

Hold the
press;
key down, and while it is being held.
You can release the | 'I key alter you press the
The screen should look like this:
key.
*** CSM BASIC V2"f
3583 BYTES FREE
READY.
PRINT"-)i(-
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Pressing the JJ key while holding down the
key caused the quotation mark to appear on the screen.
Let's continue. Now press the following keys:
Finally, hold down the
key once again. The screen
now shows:
key, and press the
CBM BASIC V2
3583 BYTES FREE .
READY,
PRINT "RAtNBOW"
'Note: if the number 2 appeared on the screen instead of the
" sign, you didn't hold down the shift key. Hit the
once to erase the 2 and try again.
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Look for this key:
Press the
key and look at the screen.
he cursor was here
when you pressed
the RETURN key.
The VIC typed these.
Pressing the [ BL^^^B j key told the VIC you were finished
typing. The VIC then looked at what you typed, recognized
that it was being asked to do something (actually, you told it
to print something). The VIC then PRINTed everything between
the two quotation marks (RAINBOW).
When the VIC finished PRINTing the word RAINBOW, it let
you know by displaying the READY message and blinking the
cursor.
It's your turn. Go ahead and enter some other PRINT
messages for your VIC to display. Try these or make up your
own: ,,
Remember, hold
the SHIFT down
to get this
character.

Experiment by using characters other than letters between the
quote marks: The VIC won't mind. Note: If you misspell the
word PRINT, the VIC will let you know by displaying this
message on the screen:
7SYNTAX
EfWOR
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Don't worry. There is absolutely no way you can hurt your VIC
by typing at the keyboard (unless, of course, you're an
elephant), but. if you make a mistake, the VIC will help you out
by
calling attention to the error. These error messages and
what they mean are listed in AppendixN. At this point, don't
worry about the "SYNTAX ERROR" message. Just keep
experimenting.
In no time your screen gets cluttered with all the stuff you've
been typing. The VIC has a handy way to CLeaR up this clut
ter. To tell the VIC to "clear" the screen, do the following:
key and press
Hold down the
the
The screen clears rnstantly; everything you and the VIC have
typed disappears. You are left with a clean white display area
and a blue cursor blinking away in the upper left hand corner.
Remember how you told the VIC to do this feat. Clearing up
the screen is one of the more frequent commands you'll be
using as you get to know your VIC.
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YOUR FIRST
COMPUTER "PROGRAM"
If your VIC performed well in displaying your messages, no
matter how bizarre they might have been, then your computer
is probably ready to do just about anything. Let's begin by
"entering" your first computer program.
STEP 1: Clear the screen by holding
down the I ; ■ key and
then pressing the
STEP 2: Type: [N
STEP 3: Type: [7] [o]
imi!l2][o]0E
and press ^ Use the
Wj and press the
STEP 4: Type: \2\ [O
Gl fol fTl |O
not type out-the letters of this word
—press the space bar (long key on the bottom of the VIC
When you finish, the screen looks like this:
You typed
this and
then
pressed
blink,
blink, blink.
The VIC
is waiting

VIC TIP: EDITING MISTAKES IN A PROGRAM
[f you make a mistake on a line, you have these editing options:
1, You can retype a line anytime and the VIC will automatically
substitute the new line for the old one. For example, it your pro
gram looks like this:
a lew limes and type:
10PRINN "VIC201
20 GOTO 10
You can skip down by hitting
10 PRINT "VIC20"
Now, the new line has replaced the old line and the program will
"run". To make sure, type jjjJQJEB ■ Replacing lines in a pro
gram is also a quick and easy way to experiment.
2. You can erase an unwanted line by typing the number of that line
and hitting I ■. ~.f- -, I. The entire line will be erased from
m s r~ o r -■ ■^■^■^■■S
3. you can edit a line by using the cursor keys to move to the
character(s) in the line of a program you want to change, typing in
a program over them and hitting
Note that quota
tion marks sometimes confuse the VIC—it you get unwanted
characters after quote marks, go back to the beginning ot the line
and type it over.
A. The INST key (get it by typing
lets you
insert characters by opening up spaces in a word or line you've
already typed.
5. The DELETE key (just type
diately to the left of the cursor.
) erases characters imme-
If everything looks all right to you, type the following word,
and press I i.-uj , t \ :
LHi El HH I ''"fi ' i nere
The screen should fill with VIC20. At times, it looks like small
animated letters traveling up the screen.
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VIC20VIC20VIC20VIC20VIC20VK
IC20VIC20VIC20VIC20VIC20VIC2CP
:20VIC20VIC20VJC20VIC20VIC20V
20VIC20VIC20VIC20VIC20VIC20V
3VIC20VIC20VIC20VIC20VIC20VI
MC20V!C20VIC20VIC20VIC20VIC20h
C20VIC20VIC20VIC20 VIC20 V1C20 V
20VIC20VIC20VIC20VIC20VIC20V
OVIC20VIC20VfC20VIC20VIC20VI
'IC20VIC20VIC20VIC20VIG20VIC20*
' IC20VIC20 VIC20VIC2GVIC20 VIC20^
'[C20VIC20VIC20VIC2QVIC20 VIC201
Want to slow down the program? Press the key on the left
side of the keyboard marked:
If you hold down the JUMH key, the program slows down.
Amazing! Your VIC is full of wonderful features. Here, with
just a single key, you are telling the VIC to reduce how fast it
is displaying stuff on the screen.
Yes, but how do you STOP the program? Good question. Look
around the keyboard until you find this key:
Press the jjyjjg key. The program should stop, and the
message:
BREAK IN 10
READY
should appear on the screen. (Don't worry, you didn't break
the VIC—"break" means "stop" in VIC language). Also, the
cursor should reappear. Did you notice that it was gone whife
it was printing?
Now, let's take a look at your program and see if it's still
there. Try typing this:
Your program (lines 10 and 20) will be displayed on the screen.
Now type RUN and the program will hlrun" again.

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You have just been introduced to several aspects of the VIC
that you will use in many of the later chapters. You have:
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• PRINTed messages on the screen.
• CLeaRed the screen {SHIFT CLR keys).
• Written your first program (VIC20) and created a moving
display.
• Slowed down (ConTRoLed) the program (the CTRL key).
• STOPed the program with the STOP key {RUN/STOP key).
• LISTed the program.
• Learned some easy ways to edit what you type.
As you explore the chapters of this guide, you will find many
uses for what you have seen here. Don't worry if you have
unanswered questions at this point. Just go ahead and experi
ment and most of your questions will be answered as you go
along.
This guide is designed so that you can go directly to any
chapter that looks interesting to you. You do not have to read
each chapter in order to get to know your VIC. Just be sure to
start from the beginning of each chapter. You will find that our
gradual introduction to each topic makes it easier for you to
learn how to create adventures of your own. Enjoy!
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