Radio Shack TRS-80 Model 100 User guide

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MODEL 100
BASIC
LANGUAGE LAB
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Model 100
BASIC Language Lab
ADIVISION OF TANDY CORPORATION
FORT WORTH, TEXAS 78102

Model 100 BASIC Language Lab Program:
©1983 Tandy Corporation
All Rights Reserved.
Model 100 BASIC Language Lab Program Manual:
©1983 Tandy Corporation
All Rights Reserved.
Reproduction or use, without express written permission from
Tandy Corporation, uf 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 contained herein.
109 8 7 6 5 4 3 2 1

Contents
Introduction. .......................................................... 1
"
Lesson #1 Introduction to BASIC. ....................................... 3
Lesson
#2 Saving Programs. .......................................... .. 15
Lesson #3 Interest Calculations .. ...................................... .. 31
Lesson #4 Sales Commissions ......................................... .. 45
Lesson #5 Day, Time and Date ........................................ .. 57
Lesson
#6 Using the Editor. 69
Lesson #7 Sales Trend ............................................. .. .. 87
Lesson #8 Plot Your Data 99
Lesson #9 Functions 111
Lesson # 10 Data Files ' , 123
Lesson # 11 Average Sales 131
Lesson #12 Sound &Simulation 145
Lesson # 13 Function Keys 155
Lesson #14 Using the COM Option 165
Lesson #15 TELCOM Applications 175
Application # 1 Calculator 185
Application #2 Memory Master Game 189
Application #3 Descriptive Statistics 195
Index 203

Introduction
If you've used your TRS-80 Model 100 just once, you know how simple, versatile,
and powerful acomputer it is. Its built-in application programs allow you
to perform
normally complex computer operations with ease. This includes data manipulation,
computer-to-computer communications, word processing, and more.
However,
as you become more familiar with your Model 100, you can make the
computer even more useful by customizing it to suit your own special needs. This
is
done through BASIC, the built-in programming language.
For instance, from BASIC, you can:
•Re-define the Function Keys
(fj) through (lID.
•Communicate with information services and other computers.
•Write programs for awide range
of applications such as forecasting sales trends and
performing interest or mortgage calculations.
•Make use
of the computer's graphic and sound capabilities.
and ahost
of other operations!
This course will show you how
to perform operations such as these by explaining in
detail the BASIC section
of your Model 100 Owner's Manual. This means that by the
time you've finished this course. you'll be writing your own programs and using the
built-in application programs more effectively.
Since most
of the application programs not built-in will be written in BASIC, and
since BASIC interacts with the other built-in programs, you'll find it
is definitely to
your advantage
to become familiar with BASIC.
So sit back and get ready to enjoy your Model 100 even more. You're about to find
out how powerful acomputer it really
is!
1
it'

Lesson #1 Introduction to BASIC
To use the BASIC capabilities of the Model 100, you must first learn how to
communicate with your Computer. Essentially, this involves typing instructions on the
keyboard and watching the display for responses from the Computer.
While you can type anything you wish on the keyboard, the Model 100 only responds
to words written in its own "language." This "language"
is BASIC. If you type
something which the Model
100 does not recognize as aBASIC word, it will respond
with an error message.
In this lesson, you will learn afew BASIC commands
to communicate with your
Computer and write simple programs.
It should be mentioned at this point, that even when you type aBASIC word, the
Model 100 will not respond until the ENTER key (located in the right side of the
keyboard)
is pressed. After pressing (ENTER), the line just typed is placed in memory
for processing by the Computer.
Throughout this Manual, the phrase "enter this command" will be used often. This
simply means that you should press
~ after typing the command or instruction.
Also, when
we tell you to press ~, you should press both (SHIFT) and (PAUSE)
together.
Accessing BASIC
Prior to typing or editing aBASIC program, you must access the BASIC interpreter of
the Model 100.
When you Power-Up the Computer, you will see the Main Menu, which shows all the
''files'' that exist in the Model 100's memory. Think of these computer files simply as
file folders that may hold text or programs.
If you haven't created any files, the Main Menu displays the built-in application
programs:
11:06:08 (C)Microsoft
TEL COM ADDRSS
20897 Bytes free
On initial Power-Up, the Main Menu Cursor -the large, dark rectangle -is
positioned over the word
"BASIC." The Cursor can be placed on any other Menu
word by pressing the Cursor Movement Keys
«(3 ,G ,rn ,or rn).
3

To access the BASIC interpreter, simply position the Cursor over the word BASIC
and press
CEmR.l. The Display will then look like this:
TRS-8~ Model 100 Software
(cpr. 1983 Microsoft
21190 Bytes free
Ok
The number 2 11 9 QI indicates the number of free bytes for creating any programs and
it may vary depending upon the capacity
of your machine and whether any other files
have been created and saved.
The word 0 kand the flashing cursor symbol below it, indicate that you are in the
Command Mode of BASIC and ready to begin programming.
Experiment #1 Entering aCommand
Acommand is an instruction to the Computer ordering it to do something
immediately. In this experiment you will learn how to enter asimple command.
First you will attempt to have the Model 100 print out aname on the display. Type
the name:
JOHN SMITH
You may use any other name. Now, press ~. As soon as you do this, the
Computer displays the message:
?8N Error
This message indicates that an error, specifically asyntax error, has been made. The
syntax error occurred because the Computer doesn't recognize John Smith
as part of
its vocabulary (also known as the Instruction Set).
The correct way to instruct the Computer to print the name
is to type:
PR I NT II JOHN 8M I TH II (ENTER)
Be sure to press ~ at the end of the line. The key word PRINT and the
quotation marks enclosing the name are recognized as part
of the Computer's
vocabulary. This way no syntax error occurs and the name appears printed right below
the command.
4

PRINT "JOHN SMITH"
JOHN SI'1 I TH
Ok
•
Use the PRINT command to print your own name if you haven't already done so.
Also, try printing other phrases. For example, to print How now brown cow, type:
PR INT II HOW NOW BROWN COW II (ENTER)
Notice that the phrase is printed exactly as it appears within the quotation marks,
including spaces.
Experiment #2 What is aBASIC Program?
ABASIC program is alist of instructions (or statements) that the Computer
executes, one at atime, in asequential order. An instruction differs from acommand
in that it is preceded by aline number.
Here is asimple BASIC program:
10 PRINT "JOHN SMITH"
This program, consisting of only one statement, the PRINT statement, accomplishes
the same thing
as the command:
PRINT "JOHN SMITH" CENnID
But because the word PRINT is being used in aprogram and preceded by aline
number, it is now called astatement. The number
H'J which is typed before the PRINT
statement is called aline
number. Every line in aBASIC program must have aline
number, even ifthe program contains only asingle line.
Type line 10 as it appears above. Notice that nothing happens this time when you
press
(ENTER). Unlike acommand, which instructs the Computer to perform atask
immediately, aprogram does nothing until the Computer is instructed to execute it.
This is accomplished with the command:
RUN
Type the RUN command.
Don't forget to press (ENTER) after typing it.
After entering the RUN command, the program
is executed and the name is displayed.
5

10 PRINT "JOHN SMITH"
RUN
JOI·-lN SM I TH
Amore economical way of instructing the Computer to execute your program is to
press the RUN Function Key,
~. This accomplishes the same thing as typing RUN
(ENTER).
Now try aslightly more ambitious program. Enter the following two-line program:
10 PRINT "RADIO SHACK MODEL 100"
20 GDTO 10
The second statement in this program begins with line number 20, indicating that this
instruction should
be executed after the first line which has asmaller line number.
There
is nothing special about the line numbers used in this program. The important
thing
is that the PRINT instruction has asmaller line number than the GOTO
instruction.
Execute the program with the RUN command or
by pressing ~.
As you can see, unlike the first single line program, this second program prints the
name within quotation marks repeatedly. This is known
as an "infinite loop"
program because the GOTO statement in the second line of the program simply
transfers control back to the first line which prints the
"string" (a group of characters
and/or numbers) again on the next line.
Because of this continuous transfer, the program has
no way of terminating and so it
must be terminated manually by you. To
"break" the program, press (BREAK)
«(SHIFT) ~).
When you press ~, the Computer will display amessage to show where the
program stopped when it was "broken."For example:
in 10
6

Note that the program you wrote "scrolls up and off" the screen as the program
began printing.
If you wish to see the program as you wrote it again, enter the
command:
LIST
or simply press the LIST Function Key, CEID. In either case, the program will appear
on the Display again.
List
10 PRINT "RADIO SHACK MODEL 100"
20 GOTO 10
Ok
•
Execute this program again with the RUN command or by pressing (f!l.
After letting the program run afew seconds, terminate it by pressing ~.
This time after pressing ~, enter the command:
CONT
As you can see, the program resumes execution. The CONT command is used to
CONTinue execution after the program has been "broken." Execution will start at the
same place where the program was interrupted.
Experiment #3 Simple Editing
Here's the program from the previous experiment:
1121 PRINT "RADIO SHACK MODEL 1121121"
2121 GOTO 1121
Suppose you want to change line 10 so that the message reads:
I LOVE MY MODEL 1121121
This can be done by retyping line 10 entirely:
1121 PRINT "I LOVE MY MODEL 1121121" (ENTER)
7

Now, when you list the program with the LIST command or with the (f5) Function
Key, the following is displayed:
10 PRINT "I U)VE MY 110DEL 101Zl"
2l2l GOTO 1l2l
Ok
•
Execute this program to verify that the new phrase is displayed. Now, instead of
pressing (BREAK) to interrupt execution, press the (PAUSE) key. This will cause the
program
to stop momentarily. To continue execution, simply press the (PAUSE) key
again. Pausing aprogram may be useful when you want
to read what is being
displayed before it scrolls off view.
Of course this program must still be terminated by
pressing
(BREAK) because it still is in an infinite loop.
Try a
few other experiments with the PRINT command. Type in the following
program:
10 PRINT "MY NAME IS"
20 PRINT "LEE"
Run this program. The output should be:
M\/ NAJvIE IS
LEE
Ok
•
Now, retype line 10 to insert aspace between the word "IS" and the quotation mark.
Also, add asemicolon
at the end of line 10. The changed program should look like
this
10 PRINT "MY NAME IS ";
20 PRINT "LEE"
8

Execute this program. The output should appear as:
MY NAME IS LEE
Ok
•
The printing appears all in one line because the semicolon instructs the Computer to
continue printing immediately after the first line is printed. The space after "IS" in
the first line
was added so that the words "IS" and "LEE" would not run together.
If you wanted to space the name further apart, you could add more spaces after "IS"
or you could add spaces before "LEE" in line 20.
Another way
to space the printing is to use acomma instead of asemicolon. Retype
line
10 so that it reads:
10 PRINT "MY NAME IS ",
Now list the program and it should read:
LIST
10 PRINT "MY NAME IS "
20 PRINT "LEE"
Ok
Run this program. The output should appear as:
NAME IS L.EE
This time "IS" and "LEE" are spaced several columns apart. The comma in the first
line means "begin printing in the next field" (more on fields later).
9

Enter the following program:
1121 PRINT "HOW ", "NOW ";
2121 PRINT "BROWN"; "COW"
Would you guess what the output of this program will produce? When executed, the
display will show:
Hm~
Ok
1\IOlr-J BFWWI\ICOW
The comma in line 10 caused the two strings HOW and NOW to be spaced several
columns apart. The semicolon between the two words
"BROWN" and "COW"
caused them to print without aspace. Now if line 10 is retyped so that the comma is
changed to asemicolon and the semicolon at the end of the statement is omitted,
1121 PRINT "HOW"; "NOW"
2121 PRINT "BROWN"; "COW"
the output would be
HOW NOW
BROWNCOW
The second PRINT statement produces output on the second line because the carriage
return after the first PRINT statement has not been suppressed with asemicolon or
comma.
If you wanted to print the words on one line, neatly spaced one column apart,
you could rewrite your program
as follows:
1121 PRINT "HOW"; "NDW ";
2121 PRINT "BROWN"; "CDW"
10

When it is executed, it produces, as expected, the following:
NOW BROWN COW
ABASIC program can be edited aline at atime simply by retyping the entire line as
you have been doing.
To delete an entire line from aprogram, all you have
to do is to type the line number
of the statement you wish
to delete and press ~.
For example, list the current program:
PRI NT "HOW "? "NOW ";
PRINT "BROWN "; "COW"
Now type
20~
If you list the program again, you will see that line 20 has been effectively deleted:
1~ PRINT "HOW"; "NOW";
Ok
I
Retype line 20 to restore your program to its previous form:
10 PRINT "HOW "; "NOW";
20 PR I NT "BROWN "j "COW"
11

A new line can be added to aBASIC program at any time simply by typing it with the
appropriate line number.
If you want to add astatement before line 10, give it a
number less than
10 (the smallest line number allowed is 1). If you want to add aline
between the two lines, give it anumber between
10 and 20 (e.g., 15).
Line numbers
10 and 20 were used to allow insertion of new lines. If successive line
numbers had been used, for example
15 and 16, then no new lines could have been
inserted.
It is agood practice to use line numbers that are multiples of 10 (or at least
5).
Here's your program again:
10 PRINT "HOW" j "NOW" j
20 PRINT "BROWN II j "COW"
Suppose you want to insert aline between 10 and 20. Simply type:
15 PRINT "SPLENDID "; ~
When you list the program now, it will show:
PRINT "HOW"; "NOW";
PRINT "SPL.ENDID "i
PRINT "BROWN !I; "COW"
Even though line 15 was typed after lines 10 and 20, it takes its correct place in the
program because its line number falls between
10 and 20.
Execute this program. The following output will result:
NOW SPL.ENDID BROWN COW
It should be clear by now that any BASIC program can be edited easily with the use
of the line numbers. You can add, delete, insert, and change lines and that is all you
ever need
to do.
12

Experiment #4 Writing Your Own Programs
By now you should be able to write simple BASIC programs using the two
instructions PRINT and GOTO.
Before you go on experimenting with the spacing in PRINT statements using the
comma and the semicolon, you should be aware
of another useful command, the
NEW command.
When you enter the NEW command, any program that has been previously typed and
is currently residing in working memory will be erased automatically.
Before you begin typing in anew program, you should always use the NEW
command to clear out the old program. Otherwise, you may end
-up with a
combination
of your new and old programs.
Assume that your old program still resides in memory:
10 PRINT "HOW"; "NOW";
is PRINT "SPLENDID ";
20 PRINT "BROWN "; "COW"
Now, without deleting this program, enter the following new program:
10 PRINT "MY COMPUTER IS A ";
20 PRINT "TOOL."
If you list the program, you will find it is:
LIST
10
PRINT "MY COMPUTER IS A ";
15 PRINT "SPLENDID ";
20 PRINT "TOOL."
K
Note that line 15 still exists because that line number was not used in the new
program.
So remember, before typing anew program, clear the memory with the
command NEW. This won't be necessary, however,
if you are certain that no program
exists
in memory.
What you have learned:
In this lesson you have learned some commands to write and execute asimple BASIC
program. The PRINT and GOTO statements have been used to display simple
messages. Editing aBASIC program can be
accompli~hed by retyping existing line~ or
typing new lines. The NEW command is used
to delete an entire program from
memory.
13