Advanced Amiga BASIC

1986·41.3 MB·English

by  Halfhill, Tom R

Tom R. Halfhill and Charles Brannon
This guide reveals the advanced techniques
and commands you need to write your own
sophisticated programs in Amiga BASIC,
Numerous example programs, utilities, and
complete applications are fully explained and
ready to type in and use.
COMPUTE!
LIBRARY
SE LECTION

Advanced
Amiga
BASIC
Tom R. Halfhill and Charles Brannon
COMPUTE! Publicationsjnc.a3
PartofABCConsumerMagazines.Inc.
OneoftheABCPublishingCompanies
Greensboro, North Carolina
Dedication
To our parents
Copyright 1986, COMPUTE!Publications, Inc. Allrightsreserved.
Reproductionortranslationofany partofthisworkbeyondthatpermittedby Sections 107and 108 ofthe
UnitedStatesCopyrightActwithoutthepermissionofthe copyrightownerisunlawful.
Printedinthe United StatesofAmerica
10 98765432
ISBN 0-87455-045-9
Theauthorsandpublisherhavemadeeveryeffortinthepreparationofthisbooktoinsuretheaccuracyoftheprogramsand
information.However,theinformationandprogramsinthisbookaresoldwithoutwarranty,eitherexpressorimplied.Nei
thertheauthorsnorCOMPUTE!Publications,Inc.,willbeliableforanydamagescausedorallegedtobecauseddirectly,in
directly,incidentally,orconsequentiallybytheprogramsorinformationinthisbook.
TheopinionsexpressedinthisbookaresolelythoseoftheauthorsandarenotnecessarilythoseofCOMPUTE!Publications,
Inc.
COMPUTE! Publications, Inc., PostOfficeBox5406, Greensboro, NC 27403, [phone], is partofABC
ConsumerMagazines, Inc., one oftheABC PublishingCompanies, and isnotassociatedwithany manufac
turerofpersonal computers. Amigais a trademarkofCommodore-Amiga, Inc.
Contents
Foreword v
Introduction vii
1. Overview of Amiga BASIC 1
2. Introduction to Amiga Graphics 23
3. Programming Graphics 53
4. Object Animation 83
5. Sound and Music 129
6. Speech Synthesis 161
7. Designing a User Interface 201
8. Programming Peripherals 249
9. Library Calls 295
10. Putting It All Together 359
Appendices 387
A.Quick BASIC Reference 389
B. ISO Printer Codes 433
C. Memory Management 437
D.Subprograms 441
E.The Amiga Character Set 453
Index 459
Disk Coupon 465

Foreword
The Amiga is the first personal computer that comes with speech capability as
a standard feature. This, along with its powerful graphics chips, gives you the
opportunity to create programs of a sophistication never before possible on a
home computer. Advanced Amiga BASIC will help you take advantage of it and
all the other special capabilities that your Amiga offers.
Written by two expert programmers, Advanced Amiga BASIC guides you
logically with numerous step-by-step examples, utilities, and stand-alone pro
grams. After an overview of BASIC, you'll move rapidly along, learning how to
incorporate sound and graphics into your own programs. Then, after extensive
treatment of such topics as file handling, subprograms, library calls, and pro
gramming peripherals, the last chapter presents a fully developed graphics pro
gram, "MouseSketch," complete with detailed comments so that you can see
exactly how it all fits together.
There's a lot to learn, but you'll find that with Advanced Amiga BASIC at
your side, you'll have all you need to move into the ranks of advanced pro
grammers. Before you know it, you'll be writing programs that truly make the
most of your Amiga.

Introduction
Advanced Amiga BASIC is a book for intermediate Amiga BASIC pro
grammers who want to become advanced programmers. Perhaps the
more descriptive title Amiga BASICfor Intermediate BASIC Program
mers Who Wish to Become Advanced BASIC Programers would have been better.
But such a long title would have required a two-foot-wide cover.
Nevertheless, that title sums up our admittedly ambitious goal for Ad
vanced Amiga BASIC. We've written the book to reach three different types of
readers:
• Those for whom the Amiga is their first personal computer, and who have
now progressed beyond beginning BASIC programming and want to make the
leap toward advanced programming.
• Those who have already acquired BASIC programming experience on another
personal computer, and who now want to learn the unique features of Amiga
BASIC. h
• Those who have a fairly firm grasp of BASIC commands, but who'd like to
sharpen their skills and learn how to put all those commands together to
build practical, powerful applications.
Thus, Advanced Amiga BASIC spans the range from intermediate to ad
vanced programming—and is intended to help you cover that range, too. For
instance, the first two chapters, "Overview of Amiga BASIC" and "Introduction
to Amiga Graphics," lay the groundwork for deeper topics to follow: "Program
ming Graphics" presents a sketchpad program in embryonic form, and "Object
Animation" gives an in-depth look at Amiga BASIC'S provisions for animated
graphics. Other chapters take a similar approach toward sound, speech synthe
sis, file handling, and peripherals.
Chapter 7, "Designing a User Interface," goes beyond the nuts and bolts
of programming to discuss the philosophy behind the Amiga's visual link with
the user and how that philosophy may affect the way you design your own
programs.
Chapter 9, "Library Calls," is the most advanced chapter in the book. By
explaining how to directly access routines within the Amiga's operating system,
it shows that you're not limited to the commands which were provided in
Amiga BASIC. Furthermore, this chapter can be a springboard toward even
more advanced programming in C and machine language.
Vll
Chapter 10, "Putting It All Together/' takes the sketchpad program in
troduced in Chapter 3, incorporates many of the techniques covered throughout
the book, and expands it into a full-fledged application. Numerous comments
inserted in the listing explain in great detail how the program works on a line-
by-line basis.
Finally, the appendices cover additional topics of value to the upwardly
mobile Amiga BASIC programmer: ISO printer codes, memory management,
and subprograms. And there's a complete BASIC reference section plus tables
of characters and error codes.
But the strongest point of Advanced Amiga BASIC, we feel, lies in its pro
gram listings. In addition to demonstrating the numerous techniques covered in
the chapters, many of the programs are useful utilities that will help you write
your own Amiga BASIC applications in the years to come. And if the task of
typing in the listings seems too daunting, there's a disk available from COM
PUTE! Books which contains all of the major programs found between these
covers (ordering information for the disk is at the end of the book).
There's a lot to learn in Amiga BASIC—over 200 commands, statements,
and functions. But when your first major application emerges from the video
screen, we think you'll agree that it was worth the effort.
A Note on Typing In Programs
You'll notice that each complete program line has a return mark (<) at the end.
You cannot type this character—there's no left arrow character on the Amiga
keyboard. It simply marks the end of a logical line and indicates that you
should press the RETURN key. Do not press RETURN at the end of a line un
less you see the return mark. Only a few program lines break across the right
margin, but when they do, the remainder of the line is indented to the same
level of indention. This is just for the sake of readability—you would type the
line continuously, of course. A return mark alone on a line means to press the
RETURN key to insert a blank line—handy for separating program segments.
'nwft'fex
viii