Radio Shack® Cat. No. 26-3191

GETTING
STARTED
WITH
COLOR
BASIC

TRS-80™ COLOR COMPUTER

GETTING
STARTED
WITH
COLOR
BASIC

Getting Staried with COLOR BASIC: © 1980 Tandy Corporation, Fort Worth, Texas 76102 U.S.A. All Rights Reserved.

Reproduction or use, without express written permission from Tandy Corporation, of any portion of this manual is prohibited. While reasonable efforts have been taken in the preparation of this manual to assure its accuracy, Tandy Corporation assumes no liability resulting from any errors or omissions in this manual or from the use of the information obtained herein.

TRS-80 Color Computer System Software: © 1980 Tandy Corporation and Microsoft. All Rights Reserved.

The system software in the Color Computer micro- computer is retained in a read-only memory (ROM) format. All portions of this system soft- ware, whether in the ROM format or other source code form format, and the ROM circuitry, are copyrighted and are the proprietary and trade secret information of Tandy Corporation and Microsoft. Use, reproduction or publication of any portion of this material without the prior written authorization by Tandy Corporation is strictly prohibited.

10 9 8 7 6 5 4 3 2 1

INTRODUCTION

This book is for those of you who don’t know anything about Computers, and would like to be spared the long, technical explanations!

Using this as your guide, you'll be able to interact and enjoy your Computer right away. Later, you'll probably want to read some of our thorough and detailed books. For now, though, the easiest way to get started with your Computer is to use it and have fun doing it.

You'll find many of the things we have you do — especially in the first chapters — are games,. songs, or other fun-type programs. This is not to say your TRS-80 can’t be used for practical programs. It’s every bit as powerful as other computers its size. We start you off with the fun programs because it’s the easiest way for you to feel at ease with your Computer. Once you feel it’s truly an extension of yourself, you’ll find it much easier to write any kind of program you want.

So sit down and spend a couple of hours with it. Type away at it. Play with it. Try to make it do strange things. In other words…get to feeling comfortable with it. There’s an infinite number of things it can do for you.

TO GET STARTED …

Connect your Computer by referring to the Chapters on “Installation” and “Operation”, and to Figure 1 in your TRS-80 Color Computer Operations Manual¹⁾.

Then power up your Computer:

• Turn ON your television set
• Select channel 3 or 4
• Set the antenna switch to “COMPUTER”
• Turn ON the Computer. The POWER button is on the left rear of your keyboard (when you’re facing the front).

This message should appear:

COLOR BASIC v.r
© 1980 TANDY
OK

(v.r is two numbers specifying which version and release you have).

If you don’t get this message, turn the computer on and off again. Adjust the Brightness and Contrast on your T.V. set. Check all the connections. If you still don’t get this message, refer to “Troubleshooting and Maintenance” in the TRS-80 Color Computer Operations Manual.

Once you do get this message, you’re ready to begin.

HOW DO YOU TALK TO A COMPUTER?

In this book, you'll learn how to talk to your Computer. That’s all programming is, by the way. Once you learn how to communicate, you'll be able to get your Computer to do whatever you tell it. (well, almost). The Computer understands a language called COLOR BASIC. COLOR BASIC is form of BASIC — Beginners All-purpose Symbolic Instruction Code. There are lots of computer languages. COLOR BASIC just happens to be the language your Computer understands.

We'll introduce BASIC words in the order that it’s easiest to learn them. When you get mid-way in the book, you might forget what one of the words means. If this happens, simply look up the word in the back of the book or use your “Quick Reference Card” to find its meaning.

TABLE OF CONTENTS

CHAPTER 1: MEET YOUR COMPUTER
CHAPTER 2: YOUR COMPUTER NEVER FORGETS (unless you turn it off...)
CHAPTER 3: SEE HOW EASY IT IS?
CHAPTER 4: COUNT THE BEAT
CHAPTER 5: SING OUT THE TIME
CHAPTER 6: DECISIONS, DECISIONS
CHAPTER 7: GAMES OF CHANCE
CHAPTER 8: SAVE IT ON TAPE
CHAPTER 9: COLOR YOUR SCREEN
CHAPTER 10: ONE FANTASTIC TEACHER
CHAPTER 11: HELP WITH MATH
CHAPTER 12: A GIFT WITH WORDS
CHAPTER 13: BEAT THE COMPUTER
WHAT NOW?

APPENDIXES
A / MUSICAL TONES
B / BASIC COLORS
C / PRINT @ SCREEN LOCATIONS
D / GRAPHICS SCREEN LOCATIONS
E / ANSWERS TO EXERCISES
F / SAMPLE PROGRAMS
G / ERROR MESSAGES
H / BASIC SUMMARY

INTRODUCING
TRS
80

MEET YOUR COMPUTER

MEET YOUR COMPUTER

Is your Computer connected? Turned on? Ready to give it a first work-out?

In these first two Chapters, we’re going to introduce you to your Computer — the way it thinks, some of its many talents, and even a couple of little quirks it has. By the time you finish these chapters, you'll be ready to program … promise!

Type away on the keyboard and then press the (ENTER) key.

Don’t worry about anything but the last line of type on your screen. It should say:

OK

OK is the Computer’s “prompt”. It’s telling you — “OK, enough foolishness … as soon as you are ready …” (It patiently waits for your command.) You are the Master — you can tell the Computer to do anything you wish.

Give it your first command. Type this exactly as it is below:

PRINT "HI, I’M YOUR COLOR COMPUTER"

When you reach the end of the line on your screen, keep on typing. The last part of the message will appear on the next line.

Now check your line. Did you put the quotation marks where we have them? If you made a mistake, no problem. Simply press the (←) key and the last character you typed will disappear. Press it again and the next to the last will disappear (…and so on and so on…).

Ready? This should be on your screen:

OK
PRINT "HI, I'M YOUR COLOR COMPUT
ER"

Press the (ENTER) key and watch. Your screen should look like this:

OK
PRINT "HI, I'M YOUR COLOR COMPUT
ER"
HI, I'M YOUR COLOR COMPUTER
OK

“Hi, I’m Your Color Computer!”

Your Computer just obeyed you by printing the message you had in quotes. Give it another message to print. Type:

PRINT "2"

Press (ENTER)… The Computer again obeys you and prints your next message:

2

Try another one:

PRINT "2 + 2" (ENTER)

The Computer obeys you by printing²⁾:

2 + 2

You probably expect a lot more than just an electronic mimic… like maybe some answers! Well, try it without the quotation marks. Type:

PRINT 2 + 2 (ENTER)

Much better. This time the Computer prints the answer:

4

These quotation marks obviously must mean something. Try experimenting some more with them. Type each of these lines:

PRINT 5+4 (ENTER)
PRINT "5+4" (ENTER)
PRINT "5+4 EQUALS" 5+4 (ENTER)
PRINT 6/2 "IS 6/2" (ENTER)
PRINT "8/2" (ENTER)
PRINT 8/2 (ENTER)

Have you come up with any conclusions on what the quotes do?

A COLOR CALCULATOR, NO LESS!

Any arithmetic problem is a snap for your Computer. Let it do some long division. Type:

PRINT "3862 DIVIDED BY 13.2 IS" 3862/13.2 (ENTER)

Let’s do a multiplication problem:

PRINT 1589 * 23 (ENTER)

Notice that the Computer’s multiplication sign is an asterisk, rather than the X sign which you’ve always used in math. This is because the Computer is such a precise and literal creature that it would get the X multiplication sign mixed up with the X alphabetical character.

Try a few more problems:

PRINT "15 * 2 = " 15*2 (ENTER)
PRINT 18 * 18 "IS THE SQUARE OF 18" (ENTER)
PRINT 33.3/22.82 (ENTER)

Now it’s your turn. Write two command lines which will print these two problems as well as their answers:

157 /.13.2 =
95 * 43 =

If you used “correct” command lines, this is what the Computer should have printed on your screen:

157 / 13.2 = 11.8939394
95 * 43 = 4085

Ready for the answers:

PRINT "157 / 13.2 =" 157/13.2
PRINT "95 * 43 =" 95*43

IT HAS ITS RULES…

By now, the Computer has probably printed some funny little messages on your screen. If it hasn’t, type this line deliberately misspelling³⁾ the word PRINT:

PRIINT "HI"

The Computer prints:

?SN ERROR

SN ERROR stands for “syntax” error. This is the Computer’s way of saying “The command ‘PRIINT’ is not in my vocabulary …I have no earthly idea what you want me to do”. Anytime you get a SN error, it’s probably because you made some kind of typographical error.

The Computer will also give you error messages when it does understand what you want it to do, but you’re asking it to do something that it feels is illogical or impossible. For instance, try this:

PRINT 5/0 (ENTER)

The Computer prints:

?/0 ERROR

Which means “Don’t ask me to divide by 0 — that’s impossible!!”

If you get a strange error message you don’t understand, flip back to the Appendix. We’ve listed all the error messages there and what probably caused them.

IT'S A SHOW OFF, TOO

So far, all you’ve seen your Computer do is silently print on a green screen. But your color Computer enjoys showing off. Type:

CLS(3) (ENTER)

Now your screen is a pretty shade of blue with a green stripe at the top. Your typed command told the Computer to clear the screen and print color number 3 — blue.

But why the green stripe? The Computer cannot type on a blue background. Anytime it types something on the screen, it must type it on a green background. Try typing some more characters. Notice that the Computer gives these characters a green background also.

Colors other than green are for printing graphics illustrations. We'll spend lots more time with this color capability later.

Press (ENTER) so that you get the OK prompt on your screen. Type:

CLS(7)

Now you should have magenta (pinkish purple) on your screen with a green stripe at the top. Try some more colors if you like. Use any number from 0 to 8. Your color Computer has nine colors. Each color has a numeric code.

BUG: If you get a message saying MICROSOFT or an ?FC Error message, it’s because you are using a number other than 0 through 8.

Type CLS without a number code:

CLS (ENTER)

If you don’t use a number code, the Computer assumes you just want a clear green screen.

COMPUTER SOUND OFF — ONE, TWO…

“Sound Off!”

Type this:

SOUND 1, 100 (ENTER)

If you don’t hear anything, turn up the volume and try again.

What you are hearing is 6 seconds of the lowest tone the Computer can hum. How about the highest tone? Type:

SOUND 255, 100

OK, so it’s got quite a hum-range…hope you're suitably impressed. Try some other numbers. Hope you like the Computer’s voice (it’s the only one it’s got).

You want to know what the other number is for? (Or maybe you've already found out). The second number tells the Computer how long to hum the tone. You can use any number from 1 to 255. Try 1:

SOUND 128, 1 (ENTER)

and the Computer will hum the tone for about 6/100ths of a second. Try 10:

SOUND 128, 10 (ENTER)

The Computer sounds the tone for 6/10ths of a second. Try variations of both numbers, but stick to numbers between 1 and 255.

BUG: Again, if you get an ?FC Error message, it’s because you are using a number other than 1 through 255.

ONE MORE THING…

Press the (SHIFT) and (0) (zero) keys, holding both down at the same time. Now type some letters. The letters you type should now be green on a black background. If they’re not, try it again pressing (SHIFT) slightly before pressing (0). Be sure to hold both keys down at the same time.

Now, with the colors “reversed”, press (ENTER) and then type this simple com- mand line:

PRINT "HI" (ENTER)

The Computer gives you an ?SN ERROR. It doesn’t understand the command.

Press the (SHIFT) and (0) characters again and type some letters. They should be back to normal: black with the green background. Press (ENTER) and type the same command line again. This time, it'll work.

We just wanted to show you this in case you ever press (SHIFT) and (0) by a mistake. The computer can’t understand any commands you type with re- versed colors. If you ever find you’re typing with these reversed colors, press the (SHIFT) and (0) keys to get the colors back to normal.

LEARNED IN CHAPTER 1

We'll put a list like this at the end of each chapter. It'll help you make sure you didn’t miss anything.

NOTES:

CHAPTER 2

YOUR COMPUTER NEVER FORGETS
(…unless you turn it off… )

YOUR COMPUTER NEVER FORGETS
(. . . unless you turn if off . . .)

One of the things that makes your Computer so powerful is its ability to remember anything you ask it to. To make the Computer remember the number 13, type this:

A = 13 (ENTER)

Now type anything you want to confuse the Computer. When you’re done, press (ENTER). To see if the Computer remembers what A stands for, type:

PRINT A (ENTER)

Your Computer will remember 13 as long as you have it on … or until you do what we’re going to do next. Type:

A = 17.2 (ENTER)

Now if you ask it to PRINT A, it will print the number 17.2.

This is what just happened in your Computer’s memory:

You don’t have to use the letter A. You may use any letters from A to Z. (Asa matter of fact, you can use any two letters). Try typing this:

B = 15 (ENTER)
C = 20 (ENTER)
BC = 25 (ENTER)

Have it print all your numbers. Type:

PRINT A, B, C, BC

To get it to remember a string of letters or numbers, put a dollar sign next to the letter. Type:

A$ = "TRY TO:"
B$ = "REMEMBER"
C$ = "THIS YOU"
BC$ = "GREAT COMPUTER"

Let’s see how sharp your Computer is. Type: PRINT A$, B$, C$, BC$

To the Computer, a dollar sign means it’s a string.

Computer types call all these letters variables. So far, we’ve used these variables:

YOUR COMPUTER'S MEMORY

NUMBERS
A → 17.2
B → 15
C → 20
BC → 25

CHARACTERS
A$ → “TRY TO”
B$ → “REMEMBER”
C$ → “THIS YOU”
BC$ → “GREAT COMPUTER”

Try spot checking these variables to see if the Computer has remembered your information properly. For instance, type:

PRINT BC (ENTER)

To see if BC still contains 25.

You can think of these variables as little boxes where you can store your information. One set of boxes is for strings; the other set’s for numbers. You use these variables to label each box.

Do you think the Computer will accept these lines:

D = "6" (ENTER)
Z = "THIS IS STRING DATA" (ENTER)

With both of these lines, the Computer responds with ?TM ERROR. It’s telling you you've got to play according to its rules.

These are the rules you ignored:

To obey the Computer’s rules, we have to put a dollar sign after D and Z. Type:

D$ = "6" (ENTER)
Z$ = "THIS IS STRING DATA" (ENTER)

which the Computer accepts. Do you think the Computer will accept this?

D$ = 6 (ENTER)

These are the rules that this command ignored:

Type this, which the Computer will accept:

D = 6 (ENTER)
Z = 12 (ENTER)

You have now added this to your Computer’s memory.

YOUR COMPUTER’S MEMORY

NUMBERS
D → 6
Z → 12

STRINGS
D$ → “6”
Z$ → “THIS IS STRING DATA”

Now you can do something interesting with these letters. Type:

PRINT D * 2 (ENTER)

The Computer prints the product of D times 2.

Try this line:

PRINT Z/D

The Computer prints the quotient of Z divided by D.

Would this work:

PRINT D$ * 2 (ENTER)

Did you try it? This makes the Computer print the same ?TM ERROR. It cannot multiply string data.

Cross out the commands that the Computer will reject:

Finished? This is what the Computer will accept.

F = 22,9999999
DZ$ = “REMEMBER THIS FOR ME”
Z=F+F

LEARNED IN CHAPTER 2

Now that you’ve learned how the Computer thinks it will be easy to write some programs. But before going to the next chapter, how about a break?

NOTES:

Type:

NEW (ENTER)

This is just to erase anything that might be in the Computer’s “memory”.

Now type this line: Be sure you type the number 10 first — that’s pretty important.

10 PRINT “HI, I’M YOUR COLOR COMPUTER”

Did you press (ENTER)? Nothing happened, did it? Nothing that you can see, that is. What you just did is type your first program. Type:

RUN

The Computer obediently runs your program. Type RUN again and again to your heart’s content. The magic machine will run your program anytime you wish, as many times as you wish.

Since that worked so well, let’s add another line to the program. Type:

20 PRINT “WHAT IS YOUR NAME?”

Now type:

LIST

Your Computer obediently LISTs your entire program. Your screen should look exactly like this:

10 PRINT “HI, I’M YOUR COLOR COM
PUTER”
20 PRINT “WHAT IS YOUR NAME?”

What do you think will happen when you RUN this? Try it. Type:

RUN

The Computer prints:

HI, I'M YOUR COLOR COMPUTER
WHAT IS YOUR NAME?

Answer the Computer’s question and then press (ENTER) …….. What? There’s that SN Error. The Computer didn’t understand what you meant when you typed your name. In fact, the Computer can’t understand anything unless you talk to it in its own way.

So let’s use a word the Computer understands — INPUT. Type this line:

30 INPUT A$

This tells the Computer to stop and wait for you to type something, which it will label as A$. Add one more line to the program:

 40 PRINT “HI, ” A$

Now list the program again to see if yours looks like mine. Type:

LIST (ENTER)

Your program should look like this:

10 PRINT “HI, I'M YOUR COLOR COM
PUTER”
20 PRINT “WHAT IS YOUR NAME”
30 INPUT A$
40 PRINT “HI, ” AS

Can you guess what will happen when you RUN it? Try it:

RUN

That worked well, didn’t it? This is probably what happened when you ran the program (depending on what you typed as your name):

HI, I'M YOUR COLOR COMPUTER
WHAT IS YOUR NAME?
? JANE
HI, JANE

RUN the program again using different names:

The Computer doesn’t care what you want to call yourself. Here’s what line 30 did to your Computer’s memory each time you ran the program. (Assuming you gave it the same names we did):

There’s an easier way to run your program over and over without having to type the RUN command. Type this line:

50 GOTO 10

Now RUN it……. the program runs over and over again without stopping. GOTO told the Computer to go back up to line 10:

10 PRINT “HI, I'M YOUR COLOR COMPUTER™
20 PRINT “WHAT IS YOUR NAME”
30 INPUT A$
40 PRINT “HI, ” A$
50 GOTO 10

Your program will now run perpetually, because every time it hits line 50, the Computer goes up to line 10 again. We call this a “loop”. The only way you can stop this endless ioop is by pressing the (BREAK) key.

Change line 50 so we can give your name the kind of attention it deserves. How do we change a program line? Simply by typing it over again, using the same line number. Type:

50 GOTO 40

This is what the program looks like now:

10 PRINT “HI, I'M YOUR COLOR COMPUTER”
20 PRINT “WHAT IS YOUR NAME”
30 INPUT A$
40 PRINT “HI, ” A$
50 GOTO 40

Type RUN and watch what this loop does. Press the (BREAK) key when you’ve seen enough.

There’s a big change we can make simply by adding a comma or a semicolon. Try the comma first. Type line 40 again, but with a comma at the end:

40 PRINT A$,

RUN the program ….. The comma seems to print everything in two columns.

Press (BREAK) and try the semicolon. Type:

40 PRINT A$;

and RUN… . You probably won’t be able to tell what it’s doing until you press BREAK). See how the semicolon crams everything together?

Let’s play around some more with your Computer’s sound and color abilities. First clean out its memory. Remember how?

Now enter this program:

10 PRINT “TO MAKE ME CHANGE MY TONE”
20 PRINT “TYPE IN A NUMBER FROM 1 TO 255”
30 INPUT T
40 SOUND T, 50
50 GOTO 10

RUN through this program to get a sampling of some of the Computer’s tones.

BUG: If you get a ?FC Error when you run this program, it’s because you used a number other than 1 through 255. This error, like all errors, will make the Computer stop RUNning the program.

What would happen if we changed line 40 to:

40 SOUND 50, T

HINT: Look back in Chapter 1 where we talk about SOUND.

—

Did you figure it out? By making this change, the Computer hums the same tone every time, but hums it for a different length of time, depending on the number you type in.

Press (BREAK) first and then erase this program by typing NEW. Now see if you can write a program, similar to the one above, to make the Computer show a color you ask for. Remember, there are 9 colors, 0 through 8.

HINT: Line 40 could be:

40 CLS(T)

This is our program:

10 PRINT “TO MAKE ME CHANGE MY COLOR”
20 PRINT “TYPE A NUMBER BETWEEN 0 AND 8
30 INPUT T
40 CLS(T)
50 GOTO 10

Professional programmers would think that pressing the key was a rather sloppy way of getting the program to stop running. Why not get the Computer to politely ask us if we are ready to end it? Change Line 50 in the above program to:

50 PRINT “DO YOU WANT TO SEE ANOTHER COLOR”

and add these lines:

60 INPUT R$
70 IF R$ = “YES” THEN 20

and RUN the program … Type YES and the program will keep on running. Type anything else and the program will stop.

This is what the program looks like:

Let’s look at what these new lines did:

Line 50 simply printed a question.

Line 60 told the Computer to stop and wait for our answer – R$.

Line 70 told the Computer to go back to line 20 IF (and only IF) your answer (R$) was YES. If not, the program simply ended since there are no more lines in the program.

You’ve covered a lot of ground in this chapter. Hope we’re just whetting your appetite for more to come.

Don’t worry if you don’t understand everything perfectly yet. Just enjoy using your Computer.

NOTES:

In this Chapter we are going to do some experimenting with Computer sound effects. To do this, we have to first teach the Computer how to count.

Type this:

10 FOR X = 1 TO 10
20 PRINT "X = " X
30 NEXT X
40 PRINT "I HAVE FINISHED COUNTING"

RUN the program.

RUN the program several times, each time replacing line 10 with one of these lines:

10 FOR X = 1 TO 100
10 FOR X = 5 T0 15
10 FOR X = -2 T0 2
10 FOR X = 20 TO 24

Do you see what FOR and NEXT are making the Computer do? They are making it count. Let’s study the last program we suggested you try:

10 FOR X = 20 TO 24
20 PRINT "X = " X
30 NEXT X
40 PRINT "I HAVE FINISHED COUNTING"

Line 10 tells the Computer that the first number should be 20 and the last number should be 24. It uses X to label these numbers.

Line 30 tells the Computer to keep going back up to line 10 for the next Number—the NEXT X—until it reaches the last number (24).

Look at line 20. Since line 20 is between the FOR and NEXT lines, the Computer must PRINT the value of X every time it counts:

X = 20
X = 21
X = 22
X = 23
X = 24

Add another line between FOR and NEXT:

15 PRINT "... COUNTING ..." 

and RUN it. With every count, your Computer executes any lines you choose to insert between FOR and NEXT.

Write a program which will make the Computer print your name 10 times.

HINT: The program must count to 10.

Write a program which will print the multiplication tables for 9 (9*1 through 9*10).

HINT: PRINT 9*X is a perfectly legitimate program line.

Write a program which will print the multiplication tables for 9*1 through 9*25.

HINT: By adding a comma in the PRINT line, you can get all the problems and results on your screen at once.

everything after this point

“2, 4, 6, 8…”

Finished? These are our programs:

Program 4/A Program 4/B Program 4/C 10 FOR X = 17010 10 FOR X = 17010 10 FOR X = 1: T0.25 20 PRINT “THOMAS” 20 PRINT “9*”X“=“9*X = 20 PRINT “9*”X“=”9*X, 30 NEXT X 30 NEXT X 30 NEXT X

COUNTING BY TWOS

Now we'll make it count a little differently. Erase your program by typing NEW and then type our original program, using a new line 10:

10 FOR X = 2 TO 10 STEP 2

20 PRINT “X= “ X

30 NEXT X

40 PRINT “I HAVE FINISHED COUNTING”

RUN the program. . . Do you see what the STEP 2 did? It makes the Computer count by 2’s. Line 10 tells the Computer that:

@ the first X is 2

@ the last X is 10 oo AND STEP 2… .

@ all the Xs between 2 and 10 are 2 apart… that is 2, 4, 6, 8, and 10. (STEP 2 tells the Computer to add 2 to get each NEXT X.) '

To make the Computer count by 3’s, make all the Xs 3 apart. Try this for line 10:

10 FOR X = 3TO 10 STEP 3

RUN the program. It should print this on your screen:

X = 3 X = 6 Xx =9 

It passed up the last X (10) because 9 + 3 = 12. Try afew more FOR… STEP lines so you can see more clearly how this works:

10 FOR X = 5 TO 50 STEP 5 10 FOR X = 10 TO 1 STEP-1 10 FOR X = 1 TO 20 STEP 4

COUNTING THE SOUNDS

Now that you've taught the Computer to count, you can add some sound. Erase your old program and type this:

10 FOR X = 1 TO 255 20 PRINT “TONE ” X 30 SOUND X, 1

40 NEXT X

This program is making the Computer count from 1 to 255 (by ones). Each time it counts it does what lines 20 and 30 tell it to do:

e It PRINTs X, the current count (Line 20) @ It SOUNDs X’s particular tone (Line 30)

For example:

@ the first time the Computer got to FOR, in line 10, it made X equal to 1. @ then it went to line 20 and printed 1, the value of X.

@ then, line 30 had it SOUND tone #1.

@ then it went back up to line 10 and made X equal to 2

® etc.

What do you think the Computer will do if you make this change to line 10:

TO POR. X =. 255: TO 2 STEP —s

Did you try it? Using STEP, change line 10 so the Computer will sound tones from:

39 

40

(1) the bottom of its range to the top, humming every tenth note. (2) the top of its range to the bottom, humming every tenth note. (3) the middle of its range to the top, humming every fifth note.

Ready for the answers?

1° '255- STEP 10

10 FOR X = 10 FOR X = 255 TO 1 STEP —10 10 FOR X = 128 TO 255 STEP 5

Now see if you can write a program which makes the Computer hum:

-(1)_ from the bottom of its range to the top, and then (2) from the top of its range back to the bottom

The answer is in the back of this book. 

BUT CAN IT SING?

Yes. Although your Computer is slightly off pitch, it can warble out most songs. The next chapter will show you how to teach it some of your favorite

songs.

FOR) c:') F045 STER NEXT

NOTES:

SING OUT THE TIME

SING OUT THE TIME

You’re now ready to show your Computer how to do two things: tell time and sing (… well, as good as the Computer can sing. . .). Since they are actually closely related — especially to your Computer! — we're covering them both in the same Chapter.

Begin by typing this:

10 FOR Z = 1 TO 460 * 2 20 NEXT Z 30 PRINT “I COUNTED TO 920”

RUN the program. Be patient and wait a couple of seconds. Two seconds, to be precise. It takes your computer 2 seconds to count to 920.

Lines 10 and 20 set a timer pause in your program. By making the Computer count to 920, it keeps the Computer busy for 2 seconds.

As you can see, this gives us the makings of a stopwatch. Erase the program, and type this:

10 PRINT “HOW MANY SECONDS” 20 INPUT S

30 FOR Z = 1 TO 460*S

40 NEXT Z

50 PRINT S “ SECONDS ARE UP!!!”

43 

RUN it, inputting the number of seconds you want timed on your stopwatch.

It would be nice if the stopwatch could sound some kind of alarm. Add some lines to the end of the program to make it sound an alarm.

Here’s the program we wrote:

10 PRINT “HOW MANY SECONDS” 20 INPUT S

30 FOR Z = 1 TO 460 * S$ 40 NEXT Z

i ee Le 50 PRINT S “ SECONDS ARE UP!!!” This is how computerized timers — i‘< FOR T = 120 TO 180

Revie et eens 70 SOUND T, 1 80 NEXT T

90 FOR T = 150 TO 140 STEP -]

100 SOUND T, 1 110 NEXT T

120 GOTO 50 44 

Notice the GOTO line we added at the end of the program. This is so the message would print and the alarm would keep ringing over and over again

until the nervous programmer must press the (BREAK) or (SHIFT keys to turn it off.

COUNTING WITHIN THE TIME

Before we go any further on the clock, we’re going to have the Computer keep count within the time. This concept will become very clear to you shortly.

Type this new program:

10 FORX = 1T03 20!) PRINT “Xam 1K

30 FORY = 1T02 40 (PRINT, VS 40-¥ 50 NEXT Y

60 NEXT X

RUN it … This should be on your screen:

X=1 Y=1 Y=2 X= 2 y 1 Y 2 X = 3 Y=1 Y=2

Call it a count within a count or a loop within a loop — whatever you prefer. Programmers call this a “nested loop”. This is what the program does:

I. It counts X from 1 to 3. Every time it counts X, it does these things:

A. It PRINTs the value of X

Notice the comma in line 40. Try it without the comma. The comma

makes “Y = ” Y PRINT on the next column.

45 

With this groundwork, it is easy to make a full fledged clock:

10

20

30

~

40

60

70

a

80

90

⁴⁾'7-2

When the Computer sees a problem with more than one set of parenthesis, it

107 108

solves the inside parenthesis and then moves to the outside parenthesis. In other words, it does this:

ao — BR) / 2

es 6/2=3

ANANRRARRARRARAAVLAY

RULES ON PARENTHESIS

1. When the Computer sees a problem containing parenthesis, it solves the \ operation inside the parenthesis BEFORE solving the rest of the

operations. 2. If there are parenthesis inside parenthesis, the Computer solves the

innermost parenthesis first and works its way out. ¢

ARARARAAAAAAAAAAALA

AAA

Insert parenthesis in the problem below so that the Computer will PRINT 28 as the answer: ‘

Answer:

PRINT 30° '(97— (8° = (7 —“6)))

IS SAVING WORTH IT?

With what you’ve learned in this chapter, you can let the Computer do all the math by putting complicated math formulas in your subroutines. The program below uses two subroutines. It’s for those of you who save by putting the same amount of money in the bank each month:

10 INPUT “YOUR MONTHLY DEPOSIT”; D

20 INPUT “BANK'S ANNUAL INTEREST RATE”; I 30 I= 1/12* 01

40 INPUT “NUMBER OF DEPOSITS”; P

50 GOSUB 1000

PRINT “YOU WILL HAVE $” FV“ IN” P “ MONTHS” END

REM COMPOUND MONTHLY INTEREST FORMULA N=1+1]1

GOSUB 2000

FV = D* (E -— 1/1)

RETURN

REM FORMULA FOR RAISING A NUMBER TO A POWER E=1

FOR X = 1T0OP

E=E*N

NEXT X

IF P= OTHENE = 1

RETURN

Notice that we have one subprogram “calling” another subroutine. This is perfectly OK with the Computer as long as you have a GOSUB to send the Computer to each subroutine, and a RETURN in each subroutine to return the

“A PENNY SAVED…”

109 iio.

Computer to the BASIC word following each GOSUB.

If you will be using your Computer a lot to help with math or accounting, you might want to save all your math formulas on tape as subroutines. Then, when

you are writing a program that uses one of them, simply load the subroutine from tape — it’ll then be part of your program.

GOSUB RETURN REM

Cv) Order of operations

NOTES:

ae

A GIFT WITH WORDS

on me

A GIFT WITH WORDS

One of your Computer’s greatest skills is its gift with words. It can tirelessly twist, combine, or separate words to anything you want. Because of this gift, you can teach it to read, write, and even carry on a halfway decent conversa- tion.

For starters, see what you think of this:

10 PRINT “TYPE A SENTENCE”

20 INPUT S$

30 PRINT “YOUR SENTENCE HAS ” LEN(S$) ‘\ CHARACTERS” 40 INPUT “WANT TO TRY ANOTHER”; A$

50 IF AS = “YES” THEN 10

Impressed? LEN(S$) tells the Computer to compute the LENgth of the string S$— your sentence. Your obedient Computer counts every single character in the sentence, including spaces and punctuation marks.

Here’s another skill it has. Erase your program and type this to make it compose a poem (of sorts):

10, AS i=)>A. ROSE’

20 BS Say NS uy

30 C$ = “IS A ROSE”

40 DS = BS + C$

50 E$ = “AND SO FORTH AND SO ON” 60 FS = A$ + D$ + DS + BS + EG

70 PRINT F$ 113 114

Here the Computer combines strings. The plus sign tells it to do this. D$ combines B$ and C$ to get “IS A ROSE”, and you can see what strings are combined to form F$.

A word of caution about combining strings — add this line to your program and RUN it:

80 G$ = F$ + F$ + F$ + FS + FS + FS + FS

When you RUN this program, the Computer prints 70S ERROR IN 80. OS means Out of String Space. The Computer only reserves about 50 characters for working with strings. Add this line to the beginning of the program for reserving plenty of string space:

5 CLEAR 500

RUN the program again. This takes care of the first problem, but there’s still another.

This time the Computer prints 7LS ERROR IN 80. LS means string too long. Line 80 asks the Computer to form a string — G$ — with more than 255 characters. Your Computer simply can’t manage to remember a string with that many characters.

Now that the Computer has combined strings, let’s get it to take one apart. Type and RUN this program:

10 INPUT “TYPE A WORD”; W$ 20 PRINT “THE FIRST LETTER IS : ” LEFT$ (W$,1)

30 PRINT “THE LAST 2 LETTERS ARE : ” RIGHTS (W$,2) 40 GOTO 10

Here’s what your Computer is doing:

In line 10 you INPUT a string for W$. Let’s say the string is MACHINE:

COMPUTER MEMORY

W$ — > MACHINE

Your Computer then performs several calculations in lines 20 and 30 to get the first LEFT letter and the last 2 RIGHT letters of the string:

LEFT$ (W$,1) RIGHT$ (W$,2)

Try RUNning the program a few times until you get the hang of it. Add this line to the program:

5 CLEAR 500

So that your Computer will set aside plenty of space for working with strings. Now INPUT a sentence rather than a word.

Pee She hae ete 8 SUPT Se AR ee eee. BBO eh Ore Ne a) Gps eie, eS he] me he MEN ab ame 6.6.0 ewan g letuieleve, eR p.e7 0 ile te) Sioce. eo ellene tele: sre lee ie lalelecoieneiw bce te

How would you change lines 20 and 30 so that the Computer will give you the first 5 letters and the last 6 letters of your string?

Answers:

20 PRINT “THE FIRST FIVE LETTERS ARE :” LEFT$ (W$,5) 30 PRINT “THE LAST SIX LETTERS ARE :” RIGHT$ (W$,6)

PES IAT GS POO Se OR SB) 8 i658. OO Oe ee ee 6 8\'e (a8 eM) 80) 0 6h am A / eT Si. 6) 8) C0. ¥@ 16 ere) pole \al.e; (al eie\s V6 eF¥! &'@ opie lh ae 6.66026, 6 e18\ ep alee ple elie (e706 btere pile elenm

‘i oe 116

Remember how to erase a program? Type: NEW (ENTER

Erase your program and type this one:

10 20 30 40 50 60 70 80 90

CLEAR 500

INPUT “TYPE A SENTENCE”; S$

PRINT “TYPE A NUMBER FROM 1 TO ” LEN(S$)

INPUT X

PRINT “THE MIDSTRING WILL BEGIN WITH CHARACTER ” X PRINT “TYPE A NUMBER FROM 1 TO ” LEN(S$) — X + 1

INPUT Y

PRINT “THE MIDSTRING WILL BE” Y “CHARACTERS LONG” PRINT “THIS MIDSTRING IS :” MID$(S$,X,Y)

100 GOTO 20

RUN this program a few times to see if you can figure out how MID$ works. Here’s how the program works. Say you INPUT “HERE IS A STRING” for your

sentence:

YOUR COMPUTER’S MEMORY S$ ef» HERE IS A STRING

In line 30, the computer first calculates the LENgth of S$ — 16 characters. It then asks you to choose a number from 1 to 16. Let’s say you pick the number 6.

The Computer then, in line 60, asks you to pick another number from 1 to 11 (16-6) plus 1. Say you pick the number 4.

YOUR COMPUTER’S MEMORY

Xe 6 Y——> 4

In line 90, the Computer gives you a MID string of S$ which begins at character number 6 and is 4 characters long:

1 2 3 4 5 6 7 i Bi 10 26ll V2 ATS) AA SE EG A MERRY CE bea Sat Lo Ne G MID$(S$,6,4)

Here’s something else you can do with MID$. Erase your program and type:

10 INPUT “TYPE A SENTENCE”; S$

20 INPUT “TYPE A WORD IN THE SENTENCE”; W$ 30 L = LEN(W$)

40 FOR X = 1 TO LEN(S$)

50 IF MID$(S$,X,L) = W$ THEN 90

60 NEXT X

70 PRINT “YOUR WORD ISN’T IN THE SENTENCE” 80 END

90 PRINT W$ “–BEGINS AT CHARACTER NO.” X

RUN this program a few times. Here’s how it works.

Say you type in the above sentence, and the word you INPUT for W$ is “IS”. In line 30, the Computer then calculates the LENgth of W$ — 2 characters.

YOUR COMPUTER’S MEMORY

0 O S$ =⇒ HERE IS A STRING WS -—=—3 IS

L a 2

The Computer then goes through the FOR/NEXT loop (lines 40-90) counting each character in S$ beginning with character 1 and ending with character number LEN(S$) — 16.

These types of programs can be used

to sort through large files of informa- —

tion. For instance, by separating strings, you could look through a mailing list for TEXAS addresses.

117 

Every time it counts a new character, the Computer looks at a new MID string. Each MID string begins at character X and is L or 2 characters long.

For example, when X equals 1, the Computer looks at this MID string:

Sak SE 23> MID$(S$,1,2)

Ri E I S A S fa leceR:s il

The fourth time through the loop, when X equals 4, the Computer looks at this:

MID$(S$,4,,2)

It finally finds the MID string it is looking for when X equals 6.

YOUR COMPUTER CAN BE A TOUGH EDITOR

“#@b/&$!”

Are you beginning to get a picture of the Computer hacking away at your sentences with a red pen? You can program it to help refine your writing and save you hours of typing and rewriting.

Say you had a phrase you want to add to:

10 A$ = “CHANGE A SENTENCE.”

Add to this one-line program so that the Computer will insert these words at the beginning of the sentence:

IT’S EASY TO and PRINT the new sentence:

IT’S EASY TO CHANGE A SENTENCE 118 

This is our program:

10 A$ “CHANGE A SENTENCE.” 20 BS “IT'S: EASY TO”

30 C$ = BS ape NUE A$

40 PRINT C$

Now see if you can add to the program to get the Computer to:

1. Find the beginning location of the MID string: A SENTENCE

2. Delete the words A SENTENCE, forming a new string: IT’S EASY TO CHANGE

3. Add these words to the end of the new string:

ANYTHING YOU WANT

4. And PRINT the newly formed string:

IT’S EASY TO CHANGE ANYTHING YOU WANT

119 

HINT: To form the string IT’S EASY TO CHANGE, you need to get the LEFT portion of the string IT’S EASY TO CHANGE A SENTENCE.

CEs ine ewe: 6 wcare 0} wate, Siete.» le ele pues ib! %, His, bu 6 fale, shiek or/Ole: 6 allele 6 lo te: > Wie pe, Bre. e110 9) e)fei @: ois/ale 6 Stew) ejetie el S)roeWa eis) (overs) ae [ipirevenelfe: eee eye Fe S's (6: 81 8 1S: Sie: 4) 9) 6:

Answer: 10 A$ = “CHANGE A SENTENCE.” 20°: BS! = “EWS EASY: 107 30 C$ = BS + “” + AG 40 PRINT C$

50 Y = LEN (“A SENTENCE”)

60 FOR X = 1 TO LEN(C$) : 70 IF MID$ (C$,X,Y) = “A SENTENCE” THEN 90 80 NEXT X

85 END a

90 D$ = LEFT$ (C$,X - 1)

100 E$ = D$ + “ANYTHING YOU WANT”

110 PRINT E$

120 

IF YOU LIKE A CHALLENGE, TRY a ih Write a program in which:

1. The Computer asks you to INPUT: a. a sentence b. a phrase within the sentence to delete c. a new phrase to replace the deleted phrase

2. The Computer then PRINTs a new sentence with your change intact.

This may take a while, but you have everything you need to write it. Our answer is in the back of the book:

121 

LEN LEFT$ RIGHT$ MID$

NOTES:

122 

NOTES:

123 | aaa

Dense

i va

BEAT THE COMPUTER

BEAT THE COMPUTER

You'll find the Computer much more adept by getting it to constantly watch and react to everything you do. By “watching you”, we mean watching the keyboard to see if you are pressing something. The word INKEY$ makes this possible.

Type this:

10 A$ = INKEYS

20 IF A$ <>‘”’ GOTO 50

30 PRINT “YOU PRESSED NOTHING”

40 GOTO 10

50 PRINT “THE KEY YOU PRESSED IS—” AS

Press a key while RUNning this program.

INKEY$ tells the Computer to look at the keyboard to see if you have pressed anything. The Computer does this with super-speed. You will have pressed absolutely nothing for at least the first 20 times the Computer checks.

The Computer labels this key, or this non-key (“”), A$. Then the Computer makes its decision:

If A$ equals “” — nothing — the Computer prints “YOU PRESSED NOTH- ING” and goes back up to line 10 to check the keyboard again.

Remember what <> means? (It

means “not equal to”)

er)

means an empty string — nothing

125 

126

However, if A$ equals something, the Computer goes to line 50 and prints the key.

For a constant look-out, type this and RUN the program: 60 GOTO 10

No matter how quick you are, the Computer is much faster! Erase line 30 to see what keys you’re pressing.

AN ELECTRONIC PIANO

Try using INKEY$ to make a piano out of your keyboard. Look at that table in the Appendix, “Musical Tone Numbers’. It lists these as the tones for middle C through the next higher C:

C - 89 E-125 G - 147 B-170 D - 108 F - 133 A-159 C-176

We can tell the Computer that if you press a certain key it should SOUND one of these tones. Erase your program and type:

10 A$ = INKEY$

20 IF A$ = “” THEN 10

30 IF A$ = “A” THEN T = 89 40 IF A$ =“S” THEN T = 108 50 IF A$ =“D” THEN T = 125 60 IF A$ = “F” THEN T = 133 70 IF AS = “G” THEN T = 147 80 IF A$ = “H” THEN T = 159 90 IF A$ = “J” THEN T = 170 100 IF A$ = “K” THEN T = 176 110 IF T =O THEN 10

120 SOUNDT,5

130 T=0

140 GOTO 10 

RUN the program . . . Well, what are you waiting for? Play a tune. Type any of the keys on the third row down on your keyboard — from A to K.

Why wouldn’t the program work right if you use INPUT rather than INKEY$?

If you use INPUT the Computer will wait until you press (ENTER) before acknowledging what you type. With INKEY$, it sees everything you type.

There’s another way of writing this program using READ and DATA lines. Do you know how this would be done?

This is what we came up with:

10 A$ = INKEY$

20 FORX =1T08

30 READ B§, T

40 IF A$ = B$ THEN SOUNDT,5 50 NEXT X

60 RESTORE

70 GOTO 10

80 DATA A, 89, S, 108 90 DATA D, 125, F, 133 100 DATA G, 147, H, 159 110 DATA J, 170, K, 176

How would this change the program? 120 SOUND T, 1

Using these DATA and READ lines will make it easier for you to add more tones to your Computer’s repertoire.

127 128

BEAT THE COMPUTER Type this program:

10 X = RND(4)

20 Y = RND(4)

30 PRINT “WHAT IS” X “+” Y 40 T=0

50 A$ = INKEY$

60 T=T+1

70 SOUND 128, 1

80 IF T = 15 THEN 200 90 IF AS = ‘”’ THEN 50 100 GOTO 10

200 CLS(7) 210 SOUND 180, 30 220 PRINT “TOO LATE”

Here’s what the program tells the Computer to do:

Lines 10, 20, and 30 gets the Computer to pick two random numbers and ask you what their sum is.

Line 40 sets T to 0. We will use T as a timer.

Line 50 gives you your first chance to answer the question — in one minute split second.

Line 60 adds 1 to the timer. T now equals 1. The next time the Computer gets to line 60 it again adds 1 to the timer to make T equal 2. Everytime the Computer executes line 60 it will add 1 to T.

Line 70’s just there to make you nervous.

Line 80 tells the Computer you have 15 chances to answer. Once T equals 15, time’s up. The Computer will insult you with lines 200, 210, and 220.

Line 90 says if you haven’t answered yet to go back and give you another chance.

The Computer only gets to line 100 if you do answer. It will go back for another problem. 

How would you get the Computer to give you three times as much time to answer each question?

Answer: By changing this line: 80 IF T = 45 THEN 200

CHECKING YOUR ANSWERS

How would you get the Computer to check to see if your answer is correct? Would this work?

100 IF A$ = X + Y THEN 130

110 PRINT “WRONG”, X “+ Y “=“X + Y 120: GOTO 10

130 PRINT “CORRECT”

140 GOTO 10

If you RUN this program (and answer on time), you'll get this error message:

?TM ERROR IN 100

That’s because you can’t make A$, a string, equal to X + Y,numbers. You have

to somehow change A$ to a number.

Fortunately, your Computer has a way of doing this. Change line 100 by typing: 100 IF VAL(A$) = X + Y THEN 130

VAL(A$) turns A$ into its numeric VALue. If A$ equals the string “5”;

VAL(A$) equals the number 5. (However, if VAL(A$) equals the string “C”; VAL(A$) equals 0 since “C” has no numeric value.)

Remember the problem of mixing strings with numbers. Chapter 2 will refresh your memory.

129 130

For those that want to make the program a bit more challenging, change these

lines:

10 20 90 100

X = RND(49) + 4

Y = RND(49) + 4

BS = BS + A$

IF VAL(B$) = X + Y THEN 130

And add these lines:

45 95

B$ = ws IF LEN(B$) <> 2 THEN 50

A COMPUTER TYPING TEST

Here’s a program that will get the Computer to time how fast you type:

10 20 30 40 50 60 70 80 “90 “100 *110

120 130 140 150 160

CLS

INPUT “PRESS <ENTER> WHEN READY TO TYPE THIS PHRASE”; E$ PRINT “NOW IS THE TIME FOR ALL GOOD MEN” T=1

A$ = INKEY$

IF A$ = ‘“”’ THEN 100

PRINT A$;

BS = BS + A$

IF LEN(B$) = 32 THEN 120

T= T+ 1

GOTO 50

S = T/74 M = S/60 = 8/M PRINT PRINT “YOU TYPED AT —“R”’—WDS/MIN” 

Here’s how this program works: In line 40, we set the timer — T — to 1.

Line 50 gives you your first opportunity to type a key — A$. If you’re not quick enough, line 60 sends the Computer directly to line 100 and adds 1 to the timer.

Line 70 prints the key you typed.

Line 80 forms a string named B$. Each time you type a key (A$), it will be added to B$. For example, if the first key you type is “N”, then:

AS = “NY!

and BS = B$ + A$ B$ = wa + NGS B$ = “N’’

If the next key you type is “O”, then:

AS = MO!*

and BS = BS + A$ B$ = MAI + Me BS = “NO”

And if the third key you type is “W”, then:

A$ = “yw!

and BS = “NO” + “W’ BS = “NOW”

When the LENgth of B$ equals 32 characters (the length of “NOW IS THE TIME FOR ALL GOOD MEN”), the Computer assumes you've finished typing the phrase and goes to line 120 to compute your words per minute.

131 

Di isc We calculate the words per minute in lines 120, 130, and 140 by dividing T by BRO FESS 74 (to get the seconds), S by 60 (to get the minutes), and then dividing the 8

Change this program to get the Computer to check to see if you made a typographical error.

Our answer is in the back of this book.

INKEY$ VAL

: NOTES:

133  

Congratulations! By now, you should feel in full control of your Computer. You might be so busy writing programs that you don’t want to read anything else yet.

It’s only fair to tell you that there are other BASIC words we haven’t covered. They are all listed on your Quick Reference Card.

If you want more complete instructions on how to program, Radio Shack has plenty of good books:

BASIC Computer Language—catalog number 62-2016

BASIC Computer Programming—catalog number 62-2015

Level II Programming—catalog number 62-2061

Level II Programming Techniques—catalog number 62-2062

TRS-80 Assembly Language Programming—catalog number 62-2006 Understanding Digital Computers—catalog number 62-2027 Understanding Solid-State Electronics—catalog number 62-2035

These books are written at all different levels. Browse through them at your Radio Shack store to see which are best for you.

135 

136

MUSICAL TONES

Your Computer can come fairly close to matching (although it can’t exactly match) the musical tones shown below. You may either use the piano keyboard or the musical staff to produce electronic music.

If you’re using the piano keyboard, the Computer tone for each key is directly over the key. For example, the Computer tone number for Middle C is 89.

If youre using the musical staff, the tone number for each note is below the note. For example the tone number for:

is 108.

a Oo oO

6 EB) OD ani by gy SS BST Ss 3) 88.088 Rk me! BoB Se

Ww - o + ow © w © oOo - - - - - r _ - - + ~ - tr - - MIDDLE

Ee eB be (ee Ber oR Wel Ae DfEE

If the note is a flat, select the tone number immediately preceeding the note. For example:

is 99.

If the note is a sharp, select the tone number immediately following the note. For example:

ISsLL7:

Chapter 5 shows how to program the Computer to play a song.

eR oO bn OMI =< EOE <a SRA 9 o co - © w - a - N + © R/O a - WN o o °o o oO r rr xn N A N N Oo oO oO oO © |S eh i - aS A AN DW DW xn A WA A AW N NWN AA AA Nn AA AAW

137 138

BASIC COLORS

These are the codes for each of the 9 colors you can create on the TRS-80 COLOR COMPUTER:

0 - black

1 - green

2 - yellow

3 - blue

4 - red

5 - buff

6 - cyan

7 - magenta 8 - orange

The color might vary in shade from these, depending on your T.V.

Color 0 is actually an absence of color. When using SET for graphics, color 0 will leave the cell’s color unchanged.

PRINT @ SCREEN LOCATIONS

139 

GRAPHICS SCREEN LOCATIONS

140 A

ANSWERS TO EXERCISES

CHAPTER 4

SOUNDing tones from bottom of range to top and back to

bottom:

10 FOR X = 1 T0.255

20 SOUND X,1

30 NEXT X

AO. FOR: Ai =o 255) 70: Li STEP (—1 50 SOUND X,1

60 NEXT X

CHAPTER 5 Lines added to clock program:

92: FOR ‘T= 200'.T0,210)STEP'5 94 SOUND T, 1

95: NEXT)

97 FOR T = 210 TO 200 STEP —5 98 SOUND T, 1

99 NEXT T

Program which Shows 9 colors for 1 second each:

10 FOR C = 070 8 20 CLS(C)

30 FOR X = 1 TO 460 40 NEXT X

50 NEXT C

CHAPTER 7 Craps Game

10 CLS

20 A RND(6)

30 B RND(6)

40 R=A+.B

50 PRINT @ 200, A

60 PRINT @ 214, B

70 PRINT @ 394, “YOU ROLLED A” R

80

90

100 110 120 130 140 150 160 170

180 185 190 200 210 220 225 230 240 250 260 270 280

500 510 515 520 530 540

600 610 615 620 630

IF R = 2 THEN 500 IF R = 3 THEN 500

IF R = 12 THEN 500

IF R = 7 THEN 600

IF R = 11 THEN 600

FOR X = 1 TO 800

NEXT X

CLS

PRINT @ 195, “ROLL ANOTHER” R “AND YOU WIN‘ PRINT @ 262, “ROLL A 7 AND YOU LOSE” PRINT @ 420, “PRESS <ENTER> WHEN READY’ PRINT @ 456, “FOR YOUR NEXT ROLL” INPUT A$

X = RND(€)

Y = RND&(€)

Z=X+Y

CLS

PRINT @ 200, X

PRINT @ 214, Y

PRINT @ 394, “YOU ROLLED A” Z

IF Z = R THEN 500

IF Z = 7 THEN 600

GOTO 180

FOR X = 1 TO 1000

NEXT X

CLS

PRINT @ 230, “YOU'RE THE WINNER” PRINT @ 294, “CONGRATULATIONS!!!” GOTO 630

FOR X = 1 TO 1000

NEXT X

CLS

PRINT @ 264, “SORRY, YOU LOSE” PRINT @ 458, “GAME’S OVER”

141 

Russian Roulette program:

5 FOR N = 117010

10 PRINT “CHOOSE YOUR CHAMBER(1-10)” 20 INPUT X

30 IF X = RND(10) THEN 100

40 SOUND 200, 1

50 PRINT “—CLICK—”

60 NEXT N

65 CLS

70 PRINT @ 230, “CONGRATULATIONS!!!” 80 PRINT @ 265, “YOU MANAGED”

90 PRINT @ 296, “TO STAY ALIVE”

95 END

100 FOR T = 133 TO 1 STEP —5

110 PRINT “BANG!!!!1”

120 SOUND T, 1

130” “NEXT: 7

140 CLS

150 PRINT @ 230, “SORRY, YOU’RE DEAD” 160 SOUND 1, 50

170 PRINT @ 390, “NEXT VICTIM, PLEASE”

142

CHAPTER 10

Test

5

6

8 10 15 20 30 40 45 50 60 70 80 82 83 84 85 86 87 90 95 OF 98 o9 100 102 105 110

Your Arithmetic Program

CLS PRINT @ 230, “YOUR NAME”; INPUT N$ CLS ToS Tie X = RND(100) Y = RND(100) PRINT @ 228, “WHAT IS” X “4” Y; INPUT A IF A = X + Y THEN 82 PRINT @ 326, “THE ANSWER IS” X + Y PRINT @ 385, “BETTER LUCK NEXT TIME,” N$ GOTO 100 CLS(7) FOR M = 1104 SOUND 175, 1 SOUND 200, 1 NEXT M CLS PRINT @ 232, “CORRECT,” N$ “II!” C= iti4 1 PRINT @ 299, “THAT IS” PRINT @ 322, C “OUT OF” T “CORRECT ANSWERS” PRINT @ 362, C/T*100 “% CORRECT” PRINT @ 420, “PRESS <ENTER> WHEN READY” PRINT @ 458, “FOR ANOTHER” INPUT A$ GOTO 10 

CHAPTER 11 CHAPTER 13

Table of Squares Computer Typing Test D\/CLS 10; CLS 7 PRINT @ 38, “TABLE OF SQUARES” 20 INPUT “PRESS <ENTER> WHEN READY TO TYPE 8 PRINT THIS PHRASE”; E$ 10 P =2 30 PRINT “NOW IS THE TIME FOR ALL GOOD MEN” 20 FOR N =2 TO 10 40: T’=“1 25 GOSUB 2000 50 AS = INKEY$ 30: PRINT Nie Ae Ee. 60 IF A$ = ‘” THEN 100 40 NEXT N 70 PRINT A$; 50 END 80 BS = BS + A$ 2000 REM FORMULA FOR RAISING A NUMBER TO 90 IF LEN(B$) = 32 THEN 120 A POWER 100 T= 7T +51 20103 B= 110 GOTO 50 20200, FOR! X= Ji FOeP 120 S = T/74 20305 Eva 76: 2 oN 130 M = S/60 2040 NEXT X 140 R = 8/M 2050 IF P = 0 THEN E = 1 142 FOR X = 1 TO 32 2060 RETURN 144 IF MIDS(“NOW IS THE TIME FOR ALL GOOD MEN”,X,1) <> MID$(B$,X,1) THEN E = E + 1 CHAPTER 12 146 NEXT X Editing a Sentence 150 PRINT 160 PRINT “YOU TYPED AT—” R ‘“—WDS/MIN” 10 ‘PRINT. “TYPE A. SENTENCE ;’':;S$ 170 PRINT “WITH” E “ERRORS” 15 INPUT S$ 20 PRINT “TYPE A PHRASE TO DELETE” 23 INPUT D$

25 L = LEN(D$)

30 PRINT “TYPE A REPLACEMENT PHRASE”

35 INPUT R$

40 FOR X = 1 TO LEN(SS)

50 IF MID$(S$,X,L) = D$ THEN 100

60 NEXT X

70 PRINT D$ “— IS NOT IN YOUR SENTENCE”

80 GOTO 20

100 E = X — 1 + LEN(D$)

110 NS$ = LEFT$(S$,X—1) + R$ + RIGHTS(S$,LEN(S$) Sue

120 PRINT “NEW SENTENCE IS :” ad 130 PRINT NS$ APPENDIX F

SPEED READING MUSIC COMPOSER 20 INPUT “LENGTH(1-10)”; M

10 REM * SPEED READING * 25. M.=.M-*'4 20 CLS : PRINT @ 32, ‘HOW MANY WORDS PER MINUTE” 30 INPUT “TEMPO (1-4)”; T1 30 INPUT “DO YOU READ’; WPM 40 .IF Tl = 4 THEN 60 40 FOR X = 1 TO 23 50°. T.. = -TL =“GOT0::70 50 REM (23 LINES OF TEXT) 60: T= 8 60 READ A$ : PRINT @ 256, A$ 70° -FOR-K, =: 70) M*8 70 FOR Y = 1 TO (360/WPM) * 460 : NEXT Y 80 GOSUB 1000 80 REM Y LOOP SETS LINES/MINUTE 90: B. = -RNDG)* FT 90 NEXT X : END 100 SOUND P, B 100 DATA SCARLETT OHARA WAS NOT BEAUTIFUL 110 CLS(S) 110 DATA BUT MEN SELDOM REALIZED IT WHEN 120 NEXT K 120 DATA CAUGHT BY HER OWN CHARM AS THE 130 IF RND(10) ⇐8 THEN 150 130 DATA TARLETON TWINS WERE. IN HER FACE 140 SOUND 125, 16*T 140 DATA WERE TOO SHARPLY BLENDED 145 END 150 DATA THE DELICATE FEATURES OF HER 150 SOUND 90, 16*T 160 DATA MOTHER, A COAST ARISTOCRAT OF 160 END 170 DATA FRENCH DESCENT, AND THE HEAVY 1000 X = RND(100) 180 DATA ONES OF HER FLORID IRISH FATHER 1010 IF X ⇐ 20 AND X ⇐ 25 THEN P = 90:S = 1 190 DATA BUT IT WAS AN ARRESTING FACE, 1020 IF X > 20 AND X ⇐ 25 THEN P = 108: S = 2 200 DATA POINTED OF CHIN, SQUARE OF JAW 1030 IF X > 25 AND X ⇐ 40 THEN P = 125: 5S = 3 210 DATA HER EYES WERE PALE GREEN 1040 IF X > 40 AND X ⇐ 55 THEN P = 133: S = 4 220 DATA WITHOUT A TOUCH OF HAZEL, 1050 IF X > 55 AND X ⇐ 75 THEN P = 147:S = 5 230 DATA STARRED WITH BRISTLY BLACK 1060 IF X > 75 AND X ⇐ 85 THEN P = 159: S = 6 240 DATA LASHES AND SLIGHTLY TILTED 1070 IF X > 85 AND X ⇐ 95 THEN P = 176:S = 7 250 DATA THE ENDS, ABOVE THEM, HER THICK 1080 IF X > 95 THEN P = 58:S = 8 260 DATA BLACK BROWS SLANTED UPWARDS, 1090 RETURN

270 DATA CUTTING A STARTLING OBLIQUE LINE 280 DATA IN HER MAGNOLIA-WHITE SKIN—THAT 290 DATA SKIN SO PRIZED BY SOUTHERN WOMEN 300 DATA AND SO CAREFULLY GUARDED WITH 310 DATA BONNETS, VEILS, AND MITTENS

320 DATA AGAINST HOT GEORGIA SUNS.

144 —

READY, AIM, FIRE

10

20

30

40

50

60

70

80

90

100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 272 274 276 280 290 300 310 320 330 340 350

CLS : PRINT

PRINT “HIT ‘Z’ KEY TO AIM LEFT” PRINT “HIT Y’ KEY TO AIM RIGHT” PRINT “HIT SPACE BAR TO FIRE” FOR K = 1 TO 3000 : NEXT K CLS(0)

CA = 464

PRINT @ CA, “*”;

PRINT @ 495, “*” PRINT @ 32, “ ” F=0 PRINT @ 32 +1* 4,” i IF 1 > 6 THEN I = 0 I = I + RND(1O)/10 PRINT @ 32 + 1 * 4, \—>”; IF F = 0 THEN 500 RESET(MX,MY) MX = MX — MD MY = MY - 8 IF MX < 1 THEN 110 IF MX > 63 THEN 110 IF MY > 2 THEN SET(MX,MY,5) : GOTO 120 IF ABS(I*8-MX) > 4 THEN 110 FOR J = 1106 PRINT @ 32+4*], “**”;

FOR K = 1 TO 50

NEXT K

PRINT @ 32 + 1* 4 ™ u

FOR K = 1 TO 50

NEXT K

NEXT J

FOR K = 200 TO 10 STEP -3 SOUND K, 1

NEXT K

FOR K = 1 T0 7 : CLS(K)

FOR KK = 1 TO 50: NEXT KK NEXT K CLS(0)

360 GOTO 60

500 Y$ = INKEY$

510 IF F = 1 THEN END 520) TE Ye rhe THEN: 550 530 IF CA < 462 THEN 120 540 PRINT @ CA, CHR$(160); 545 CA = CA - 1

547 GOTO 580

550° IF Y$ <>'“Y” THEN 590 560 IF CA > 466 THEN 120 570 PRINT @ CA, CHR$(160); 575 CA = CA + 1

580 PRINT @ CA, “*”; : GOTO 120 BIO RAY Seer he THEN 120 600 F = 1: MD = 464 — CA: MY = 20 610 MX = 32 — 3 * MD: SET(MX,MY,3) : GOTO 120 620 END

KALEIDOSCOPE

10 CLS(O)

20 X = RND(32) —- 1

30 Y = RND(16) —- 1

40 Z = RND(Y) - 1

50 GOSUB 90

60 GOTO 20

90 IF Z = O THEN 150

95 IF RND(7) = 3 THEN 150 LOG: SETS) 164) 2)

110; SERGE X15 V 2)

12D SRT AK, 16 ¥)) 2)

150; SETG2+%; 15 'Y,, Z)

140 RETURN

150’: RESERGI— xX, 16+ Y)

160: RESET(31— X;,15.–Y)

170 RESET(32+X, 16+Y)

180 -RESETG2+X, 15~Y)

190 RETURN

145 146

ERROR MESSAGES

The shaded errors are the errors you are most likely to come across while going through this book. While you might get some of the non-shaded errors, they are usually caused by more advanced programming techniques.

AO Attempt to open a data file which is already open.

BS Bad subscript. The subscripts in an array are out of range. Use DIM to dimension the array. For example, if you have A(12) in your program, without a preceeding DIM line which dimensions array A for 12 or more elements, you will get this error.

CN Can’t continue. If you use the command CONT and you are at the END of the program, you will get this error.

DD Attempt to redimension an array. An array can only be dimensioned once. For example, you cannot have DIM A(12) and DIM A(50) in the same program.

DN Device number error. Only three devices may be used with OPEN, CLOSE, PRINT, or INPUT: 0, —1, or — 2. If you use another number you will get this error.

FD Bad file data. This error occurs when you PRINT data to a file, or INPUT data from the file, using the wrong type of variable for the corresponding data. For example, INPUT # —1, A, when the data in the file is a string, causes this error.

FM Bad file mode. This error occurs when you attempt to INPUT data from a file OPEN for OUTPUT (0), or PRINT data into a file OPEN for INPUT (I).

IE Input past end of file. Use EOF to check to see when you’ve reached the me of the file. When you have, CLOSE it.

NO File not open. You cannot input or output data to a file until you have OPENed it.

147

BASIC- SUMMARY

This appendix contains the BASIC words, keyboard characters, symbols, and operators that we’ve explained in this book. For a complete listing of them, see the COLOR BASIC Quick Reference Card.

BASIC WORDS

WORD CLOAD

CLS

CSAVE

DATA

END

FOR. .TO STEP/ NEXT

GOSUB

GOTO 148

PURPOSE

Loads the first program from cassette tape. You may specify the name of the program.

Clears the screen to green, or to the color code you specify. See Appendix B for a list of the color codes.

Saves a program on cassette tape. You may use a program name with up to 8 letters.

Stores data in your program. Use READ to assign this data to variables.

Ends your program.

..Creates a loop in your program

which the Computer must repeat from the first number to the

last number you specify. You may use STEP to specify how much to increment the number each time through the loop. If you omit STEP, 1 is the increment.

Sends the Computer to the subroutine beginning at the line number you specify.

Sends the Computer to the line number you specify.

CHAPTER

EXAMPLES DISCUSSED CLOAD 8 CLOAD “PROGRAM” CLS 1 CLS(2) CSAVE 8 CSAVE “PROGRAM” DATA 5, 3, PEARS 10 DATA PAPER, PEN END 6 FOR X = 2705 4&5

/NEXT X FOR A=1 TO 10 STEP5

/NEXT A FOR M = 30 TO 15 STEP —5

NEXT M GOSUB 500 11 GOSUB 5000 GOTO 300 3 

IF/THEN

INKEY$

INPUT

INT JOYSTK

LIST

NEW PEEK

PRINT

PRINT @

READ

Tests the relationship. If it is true, the Computer executes the instruction following THEN.

Strobes the keyboard and returns the key or non-key being pressed.

Causes the Computer to stop and await input from the keyboard.

Converts a number to an integer.

Returns the horizontal or

vertical coordinate of the left

or right joystick: 0—horizontal, left joystick 1—vertical, left joystick 2—horizontal, right joystick 3—vertical, right joystick

Lists the entire program, or the lines in the program you specify.

Erases everything in memory.

Returns the contents in the memory location you specify.

Prints the message you specify on the video screen.

Prints your message at the screen position you specify. See Appendix C for the screen positions.

Reads the next item in the DATA line and assigns it to the variable you specify.

IF A=5 THEN 300 IF BS=“YES” THEN PRINT “XYZ”

A$= INKEY$

INPUT X$ INPUT “NAME”; N$

X= INT(5.2)

M=JOYSTK(O) H = JOYSTK(2)

LIST

LIST 50-85 LIST 30 LIST —30 LIST 30-—

NEW A= PEEK(32076)

PRINT “HI” PRINT A$ PRINT A

PRINT “HI”, 256 PRINT A$, 331

READ A$ READ C, B

13

3&11

10

10

149 

REM

RESET

RESTORE

RETURN

RND

RUN

SET

SKIPF

SOUND

VAL

150

Allows you to insert a comment in your program. The Computer ignores everything on a REM line.

Erases the dot SET on the screen location you specify. See Appendix D for the screen locations.

Sets the Computer’s pointer back to the first item on the DATA lines.

Returns the Computer from the subroutine to the BASIC word following GOSUB.

Returns a random integer between 1 and the number you specify.

Executes a program.

Sets a dot at the screen location you specify, using the color you specify. See Appendix D for the screen locations and Appendix B for the color codes.

Skips to the end of the next program on cassette tape, or to the end of the program you specify.

Sounds the tone you specify for the duration you specify. Both the tone and the duration may be a number between 1 and 255.

Converts a string to a number.

REM THIS IS IGNORED

RESET(14,15)

RESTORE

RETURN

A=RND(10)

RUN

SET(14,13,3)

SKIPF SKIPF “PROGRAM”

SOUND 128, 3

A=VAL(B$)

11

10

tt

1&5

13 

KEYBOARD CHARACTERS BASIC OPERATORS

CHAPTER CHAPTER CHARACTER PURPOSE ; DISCUSSED OPERATOR PURPOSE DISCUSSED & Backspaces the cursor 1 + Combines strings 12 (the blinking light) He Addition 1 ENTER Tells Computer you’ve reached 1&3 re Subtraction 1 the end of your program line * Multiplication 1 or command line. / Division 1 ; = Equals 1 BREAK Stops execution of your program. 3 se Gééeater Than 9 Pauses execution of your program. 4 >= or ⇒ Greater than or equal to 9 Press any key to continue. ⇐ or =< Less than or equal to 9 Less than 9 <> or >< Not equal to 13 BASIC SYMBOLS CHAPTER SYMBOL EXPLANATION DISCUSSED Rei Indicates that the data in 1 quotes is a constant. Separates program “statements” 11 on the same line. G) Tells the Computer to perform 11

the operation in the inside parenthesis first.

151 

NOTES:

NOTES:

NOTES:

NOTES:

NOTES:

NOTES: |

NOTES:

The following are the terms and conditions of the Radio Shack Software License for copies of Radio Shack software either purchased by the customer, or received with or as part of hardware purchased by customer:

A. Radio Shack grants to CUSTOMER a personal, non-exclusive, paid up license to use the Radio Shack computer software programs received. Title to the media on which the software is recorded (cassette and/or disk) or stored (ROM) is transferred to the CUSTOMER, but not title to the software.

B. Inconsideration for this license, CUSTOMER shall not reproduce copies of such software programs except to produce the number of copies required for personal use by CUSTOMER (if the software allows a backup copy to be made), and to include Radio Shack’s copyright notice on all copies of programs reproduced in whole or in part.

C. CUSTOMER may resell Radio Shack’s system and applications software (modified or not, in whole or in part), provided CUSTOMER has purchased one copy of the software for each one resold. The provisions of this Software License (paragraphs A, B, and C) shall also be applicable to third parties purchasing such software from CUSTOMER.

IMPORTANT NOTE

All Radio Shack computer programs are licensed on an ‘‘as is’’ basis without warranty.

Radio Shack shall have no liability or responsibility to customer or any other person or entity with respect to any liability, loss or damage caused or alleged to be caused directly or indirectly by computer equipment or programs sold by Radio Shack, including but not limited to any interruption of service, loss of business or anticipatory profits or consequential damages resulting from the use or operation of such computer or computer programs.

Good data processing procedure dictates that the user test the program, run and test sample sets of data, and run the system in parallel with the system previously in use for a period of time adequate to insure that results of operation of the computer or program are satisfactory.

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TANDY CORPORATION

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