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1^*1 TI-99/4A BASIC Reference Manual 1S> Carol AnnCasciato and DonaldJ. Horsfall are the principals in InternationalTech nical Communications, Inc., a computer systems research and consulting firm in the Philadelphia area. For the last 12years, they have done managementand systems con sulting, research, and writingforavariety ofFortune 500clients. Their first exposure to professional writing came when they produced more than 25 G^n manuals for a large technical documentation project. Since that time, they have written in-depth computer industry research reports, detailed technical product analyses, and manualsfor microcomputermanufacturers. When not reading, writing, or consultingoncomputers, Carol Ann prepareselaborate chocolate desserts and cares for her large collection of exotic plants. Don's interests includesciencefiction, restoringhis Victorian home,andcollectingspaceart. TI-99/4A BASIC Reference Manual Carol Ann Casciato and DonaldJ. Horsfall $£3 Houjard UU. Sams & Co., Inc. 4300 WEST 62ND ST. INDIANAPOLIS. INDIANA 46268 USA (cid:127)pn Copyright© 1984by CarolAnnCasciato and DonaldJ. Horsfall FIRSTEDITION FIRSTPRINTING—1984 All rightsreserved. No partofthisbook shallberepro duced, stored inaretrievalsystem,ortransmittedbyany means, electronic, mechanical, photocopying, recording,or otherwise, without written permission fromthepublisher. No patent liabilityisassumedwith respecttotheuseofthe informationcontained herein.While everyprecautionhas beentakeninthe preparationofthis book, the publisher assumesno responsibility for errorsoromissions. Neitheris any liabilityassumed fordamages resulting fromtheuseof theinformationcontainedherein. International StandardBookNumber: 0-672-22246-9 LibraryofCongressCatalog CardNumber: 83-51181 Editedby: Don Silengo Illustratedby: D. B. demons Printedinthe UnitedStatesofAmerica. 'SB Preface This is a TI-99/4A BASIC Language Reference Manual. We wrote this book to make the TI BASIC commands and statements more easily acces sible toyou (and tous). The organizationisintended tomake programming theTI-99/4Ain BASIC a more pleasant, rewarding, and productive expe rience for you. Chapter 1 is an introduction to BASIC, with a short review of the as, expandedcapabilitiesoffered byExtended BASIC. InChapters 2and3youwillfindacompleteinvestigationofTI BASIC, the rules for formulation of expressions, and information on file processing. »(cid:127) But, by far the largest and the most important part of this book is Chapter 4, the reference section. This chapter contains detailed descrip tions ofall the commandsand statements inTI BASIC. They are arranged inalphabetical order withcompleteexamplesanderror analysis. r* There are more than 130sample programs included to illustrate the use ofthe TI BASIC commands and statements. We encourage you to enter andruntheexample programsonanyBASICinstructionsthatyoumaybe having trouble understanding. Takethe program as presented and make pn changes to it, some of which we suggest to you. You will know you understand whatisgoing on when you can successfullyalter a programto make itdo whatyou want. If you are interested in the internal workings of the TI BASIC inter preter, Chapter 5 provides some technical insight into what is going on when you run a BASIC program. Finally, the Appendices provide a quick reference to detailed informa tion required by many BASIC instructions. This includes colorand sound tables, derived trigonometric functions, and, in the last Appendix, error analysis designed to help you recognize and correct the programming errors that inevitably appearineventhe best programmer'scode. CarolAnn Casciato DonaldJ. Horsfall We thank Anna Marie Casciato-Sekerke for preparing the figures and for testingsomeofthe sampleprograms in this book. ^S1 J (Ks F* t"^ •;*5E1 "1^™) Contents CHAPTER1 Introduction toTI BASIC 9 BASICBackground—TI BASICFeatures—ExtendedBASIC CHAPTER2 Data in BASIC 13 Introduction—Data Types—Data in Programs—Constants and Variables— TI BASICExpressions CHAPTER3 Using BASIC 35 TI BASIC Elements—Entering TI BASIC Programs—Editing TI BASIC S3 Programs—FilesinTI BASIC CHAPTER4 ^81 TI BASIC Statements, Commands, and Functions 55 How Each BASIC Element Is Described—Tables and Figures—Examples— Notation—Commands, Statements, and Functions r CHAPTERS TI BASICTechnical Information 258 Introduction to Hexadecimal—Internal Data Storage Formats—Inside a TI BASICProgram APPENDIXA BASIC Statements, Commands, FunctionsSummary 269 APPENDIXB Glossary 277 APPENDIXC ReservedWords 281 APPENDIXD Editing Keys 282 APPENDIXE ASCII Codes 284 APPENDIXF Graphics 285 APPENDIXG Joysticks 287 APPENDIXH Sound 289 APPENDIXI DerivedTrigonometric Functions 291 APPENDIXJ TI BASICErrors 293 Introduction—TIBASICErrors Index 303 WSJ USHil 1 iJj*5J CHAPTER Introduction to TI BASIC Thischaptergives youa briefhistory of theBASIC languageand tells why it's a good languagefor home computers and beginning programmers. We tellyou abouttheTIBASIC thatis intheTI-99/4A ROM and howyoucaneasily writeprogramsthatusetheTIsoundandgraphics features. WepointoutwhereyoureachthelimitsofTI BASICandtell you(briefly)whatyoucandowithExtendedBASIC. BASICBACKGROUND BASIC, BeginnersAll PurposeSymbolicInstructionCode, is the pro gramming language mostoftenusedonhome computers today. Likeany programming language, BASIC isa setof instructions andrulesthatare used to tell yourcomputerwhat to do. Virtuallyall home computerscome with BASICas their standard pro gramming language. BASIC is relatively easy to learn, yet powerful enoughthatyoucanwritesubstantial programs init. Itisusuallybuiltinto the machine in the form of a ROM-based (Read Only Memory) BASIC interpreter.This makes BASICa permanentpart of the computer and it means that you need noother parts(likea disk drive)to write, or to run programs written in BASIC. Why BASIC? Why notLOGOorCorPL/7orFORTRAN? The answer is the same as you will findin manyareasof computerstandardization. BASIC was in the right place at the right time. BASIC was developed at Dartmouth College for students learning to programon a time-sharing mainframecomputer.Becauseitwasdesigned to be mainly a teaching tool, it was very strong in error detection and diagnosis. Since it had to support many students simultaneously, it was kept simple and was implemented as an interpreter rather than as a com r piler. An interpreter is a good deal easier to write and much easierto use than a compiler.