Easy Programming with the TI-99/4A

196 Pages·1984·6.309 MB·English

by  Richard Guenette, James Vogel (auth.)

Easy Programming
with the TI-99/4A
Easy Programming
with the TI-99/4A
Richard Guenette
and
James Vogel
Birkhiiuser
Boston -Basel - Stuttgart
Library of Congress Cataloging in Publication Data
Guenette, Richard.
Easy programming with the TI-99/4A
Bibliography: p.
Includes index.
1. TI 99/4A (Computer)-Programming. 2. Basic (Computer program language)
m.
I. Vogel, James, 1952- II. Title. Title: Easy programming with the
T.I.-99/4A.
QA76.8.TI33G83 1983 001.64'2 83-15714
ISBN-13: 978-1-4615-9815-2 e-ISBN -13: 978-1-4615-9813-8
DOl: 10.1007/978-1-4615-9813-8
All rights reserved. No part of this publication may be reproduced, stored in a
retrieval system, or transmitted, in any form or by any means, electronic, mechanical,
photocopying, recording or otherwise, without prior permission of the copyright
owner.
© Birkhiiuser Boston, Inc., 1984
ABCDEFGHIJ
ISBN-13: 978-1-4615-9815-2
Contents
Foreword ...................................................................... v
Chapter 1 Microcomputers in Brief. ........................................... ..
Of Bits and Bytes ................................................ .
Storing Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1
Elementary Computer Architecture. . .. . . . . . .. . . . . . .. .. .. .. . . . . . . . . ... 2
Computer Languages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4
Chapter 2 Cas~ette Deck Notes ................................................. 5
Cassette Decks .................................................... 5
Cassette Interface Cable .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 5
Loading and Saving Programs ...................................... , 6
Chapter 3 Keyboard Guide. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 8
Enter Key ........................................................ 8
Shift and Alpha Lock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9
Special Symbols .................................................. 10
Mathematical Operators ........................................... 10
Control Keys .................................... " ............... 10
Function Keys.. . . .. . .. . .. . .. .. . .. .. .. . .. . . .. . .. .. . . .. .. . . .. . .. ... 11
Automatic Repetition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 12
Using the Screen Editor .......................... , ......... , ... '" 12
Chapter 4 Introducing TI BASIC .............................................. 15
Commands, Functions, and Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 16
Immediate Mode ............................................... 16
Using the PRINT Command ..................................... 17
CALL Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . .. 17
Command Mode Calculator ...................................... 19
Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 19
Functions ....................................................... , 20
Math Functions ................................................ 20
TAB Function .................................................. 21
Statement and Program Lines .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 22
GOTO .......................................................... 23
Chapter 5 Tools for Building Programs ......................................... 26
Line Numbering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 26
RESEQUENCE .................................................. 28
Editing Programs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 30
LIST .......................................................... 30
Edit Mode .... '.' . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 30
Starting and Stopping Programs .................................... 32
Diamond Track ................................................ 33
RUN ........................... '" ........................... 34
CONtinue ..................................................... 34
BREAK and UNBREAK ........................................ 34
END and STOP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 36
REMark Statements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 36
Chapter 6 Working with Numbers .............................................. 37
Order of Arithmetic Operations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 38
Relational Expressions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 39
Chapter 7 Variables .......................................................... 40
Numeric Variables ................................................ 40
Naming Numeric Variables ......................................... 42
String Variables .................................................. 43
The Role of Variables in Programming .............................. 43
Chapter 8 Using PRINT ...................................................... 45
The PRINT System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 45
Quotation Marks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 45
Print Separators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 47
The TAB Function ............................................... 49
The Sick Rose. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 50
Chapter 9 Branching Statements ............................................... 52
The Unconditional Branchers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 53
GOTO ........................................................ 53
GOSUBroutine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 54
Conditional Branching Statements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 56
ON-GOTO .................................................... 56
ON-GOSUB ................................................... 58
IF-THEN-ELSE ................................................ 59
Chapter 10 Data Anyone? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 62
INPUT .......................................................... 62
The READ/DATA Statements ...................................... 65
Setting Up a Data Bank. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 67
Checking Variable Status .......................................... 68
Multiple-Variable READ/DATA Statements .......................... 69
RESTORE ....................................................... 70
Using Counters To Manipulate Data ................................ 73
Using Data Flags ................................................. 74
Chapter 11 The FOR-NEXT Loop .............................................. 77
Entering Data with FOR-NEXT Loops .............................. 78
Defining Loops With STEP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 79
Nested Loops .................................................... 81
Chapter 12 Debugging Programs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 85
Error Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 86
TRACE and UNTRACE .......................................... 87
PRINT Debug ................................................... 88
Chapter 13 Numeric Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 90
INTeger ......................................................... 90
RANDOMIZE and the Random Number Function - (RND(X» ......... 90
Other Numeric Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 93
ABS(X) ....................................................... 93
ATN(X) ....................................................... 93
COS(X) ....................................................... 93
SIN(X) ........................................................ 94
TAN(X) ....................................................... 94
EXP(X) ....................................................... 94
LOG(X) ....................................................... 94
SQR(X) ....................................................... 94
SGN(X) ....................................................... 94
User-Defined Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 94
Chapter 14 Computer Sound and Music. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 98
Tpe Sound Chip. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 98
CALLing Sound. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 100
Noise Settings ................................................... 100
Negative Duration Values ......................................... 101
Programming a Song for One Voice ............................... 102
RESTORE for Repeats ........................................... 104
A Song for Three Voices ......................................... 105
Sound Effects ................................................... 108
Chapter 15 BASIC Graphics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 110
The Screen ..................................................... 110
BASIC Graphics Statements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. III
CALL CHAR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. III
CALL CLEAR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 113
CALL HCHAR and CALL VCHAR. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 113
CALL COLOR ............................................... 115
CALL SCREEN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 117
The RANDOM Character Generator ............................... 119
Combining Characters in Space: White Knight. . . . . . . . . . . . . . . . . . . . . .. 123
Combining Characters in Time: Running Man. . . . . . . . . . . . . . . . . . . . . .. 124
Chapter 16 Interacting with Your Computer: Keyboard and Joystick ................ 126
CALL KEYboard ................................................ 126
Key-Unit ...................................................... 127
Return Variable ............................................... 127
Status Variable ................................................ 128
Mazemaker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 130
CALL JOySTick ................................................ 133
Joystick Mazemaker ........................................... 134
Chapter 17 Arrays........................................................... 136
Subscripted Variables and Simple Arrays ............................ 137
Using READ/DATA To Load Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 139
OPTION BASE 1 and the DIM Statements ......................... 139
Two-Dimensional Arrays ......................................... 142
Chapter 18 String Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 147
ASCII VaIue-ASC .............................................. 147
Character-CHR$ ............................................... 148
Value-VAL .................................................... 150
String Number-STR$ ........................................... 151
Length-LEN ................................................... 152
Position-POS .................................................. 152
String Segment-SEG$ ........................................... 154
Chapter 19 More Graphics .................................................... 156
FOR-NEXT Looping. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 156
CALLing COLOR ............................................... 157
Strings and String Functions ...................................... 160
Using PRINT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 160
Using SEGment and LENgth String Functions ..................... 161
Printing Text with HCHAR ..................................... 162
Using Arrays in Graphics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 163
Chapter 20 Live Time on the Keyboard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 167
Links in a Chain ........................................ , ....... 171
Chapter 21 Your Home Computer as a Terminal ................................. 176
Chapter 22 Syste~ Options. . . . .. .. . . . .. . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . .. 179
Extended BASIC ................................................ 179
Speech Synthesizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 179
Peripheral Expansion Box ........................ '. ................ 180
RS232 Card ................................................... 180
Disk Drive Controller Card ..................................... 180
32K Memory Expansion Card ................................... 180
P-Code Card. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 180
Disk Drives ..................................................... 181
Printers ..•..................................................... 181
Telephone Modems .............................................. 182
The Fully Configured System. . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . ... 182
Alternatives to the Peripheral Expansion Box System ................. 182
Word Processing ................................................ 182
Microsoft Multiplan™ ............................................ 182
UCSD p-System™ .... , ........................................... 183
LOGO ......................................................... 183
Machine Language. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 183
FORTH ........................................................ 184
Voice Recognition ............................................. 184
Winchester Hard Disk .......................................... 184
Chapter 23 Resource List ..................................................... 185
Foreword
Welcome to the world of computer programming. Your Texas
Instruments TI-99/4A is a real 16-bit microcomputer, complete with
sound and color graphics. Making these features do what you want may
seem impossible at fIrst, but don't worry; there's nothing mysterious about
computer programming. Learning to program computers simply means
learning a new language-in this case, TI BASIC (for Beginner's All
purpose Symbolic Instruction Code), a version of the most popular
language used on today's microcomputers. This book will teach you,
step by step, how to tell your machine what you wish it to do-in other
words, how to program it.
But that's not all. You'll also find chapters on general microcomputer
principles, cassette deck use, the TI-99/4A as a terminal for much larger
systems, options for expansion, and a list of resources for getting the
most out of your home computer.
With the 99/4A you have access to a large library of programs, or
software, already written by someone else. Without knowing anything
about programming, you can use this software to play games, learn math,
or store addresses. But at some point you'll want to make your personal
computer really personal. You might want to create your own video game
or compose a tune. And that's when you'll want to learn programming.
Learning to program is like learning to ride a bicycle: you must over
come the fear of falling. Once you do, you move right along. Once you
overcome the fear of indecipherable computerese, you'll move right along
in programming, too. And, as with bicycle riding, you learn by doing.
To get the most out of this book, you'll need your computer, a TV
set (preferably color), a cassette tape recorder and connecting cable, your
User's Reference Guide, and the confidence that you can do it.
Remember: computers, personal or otherwise, are machines. They are
tools, extensions of the people who use them. Your TI-99/4A is an ex
tension of you, and the programs you write are extensions of your own
imagination. So let's begin.
Easy Programming
with the TI-99/4A
1 Microcomputers in Brief
This chapter introduces microcomputers: their structure, methods of
storing information, and languages. You'll find this information useful
but not absolutely necessary for understanding how to program your
TI-99/4A. If you're eager to grapple with the machine on your desk,
skip right ahead.
OF BITS AND BYTES
On the most basic level, computers process information using numbers
having only one digit. These numbers are called binary numbers; each
digit is called a bit (short for "binary digit''). The value of a single bit
can either be 1 or O. To the computer, a 1 means an electrical "on";
a 0 means "off." All computer operations are ultimately manipulations
of these binary numbers.
The basic building blocks, bits, are in turn assembled to form bytes.
A byte is a series of eight bits. Each byte is equivalent to a letter or
number, a keyboard symbol, or single character space in a page of text.
The word ''byte,'' for instance, would occupy four bytes. The byte
representing the letter "A" is composed of the bits 0100000 1. Every time
you press the letter "A" the computer translates it into this series of bits.
STORING INFORMATION
Computers store information in different kinds of memory. One kind
is called random access memory, or RAM. RAM is like a blank sheet
of paper that the computer allows you to write instructions, or programs,
on. There are two types of RAM, static and dynamic. Static RAM, found
1