EXTENDING DOS EXTENDING DOS Edited by Ray Duncan RayDuncan Charles Petzold M. Steven Baker Andrew Schulman Stephen R. Davis Ross P. Nelson Robert Moote A TT Addison-WesleyPublishing Company, Inc. Reading,Massachusetts MenloPark,California NewYork Don Mills,Ontario Wokingham,England Amsterdam Bonn Sydney Singapore Tokyo Madrid SanJuan Many ofthe designations used by manufacturers and sellers todistinguish their products are claimed as trademarks. Where those designations appear in this book and Addison-Wesley was aware of a trademark claim, the designations havebeenprintedin initial capitalletters. Copyright©1990by RayDuncan All rights reserved. No partof this publicationmaybe reproduced,storedin are trieval system, or transmitted, in anyform or by any means, electronic,mechani cal, photocopying, recording, or otherwise,without the prior written permission of the publisher. Printed in the United States of America. Published simulta neouslyin Canada. ProductionEditor: AmorettePedersen ManuscriptEditor: Kate LeeJohnson TechnicalConsultant: AndrewSchulman CoverDesignby: CopenhaverCumpston Illustrators: EddieO'Brienand Kathy Turok Setin 10.5-pointPalatinoby BenchmarkProductions ABCDEPG-MW-943210 First Printing,April1990 ISBN 0-201-55053-9 Windowsisaregistered trademarkofMicrosoftCorporation. MicrosoftC,MS-DOS,Presenta tionManager,andWindows386aretrademarksofMicrosoftCorporation. DESQviewandQEMM-386aretrademarksofQuarterdeckOfficeSystems. Paradox,TurboC,andSidekickareregistered trademarksofBorlandInternational. dBASEisaregisteredtrademarkofAshton-TateInc.dBASEIVisatrademarkofAshton-Tate,Inc. WordPerfectisatrademarkofWordPerfectCorporation. Lotusand 1-2-3areregistered trademarksofLotusDevelopmentCorporation. PC/AT,IBM,andPS/2 areregisteredtrademarksofInternationalBusinessMachinesCorpora tion.OS/2andPC-DOCare trademarksofInternationalBusinessMachinesCorporation. NeWsisa trademarkofSunMicrosystems,Inc. AutoCADis a trademarkofAutodesk, Inc. PARCisa trademarkofXeroxCorporation. UNIXisa trademarkofAT&TBellLaboratories. Clipper isatrademarkofNantucket, Inc. Appleand Macintosharetrademarks ofAppleCorporation. Compaqand SystemProaretrademarksofCompaqComputerCorporation. CompuServeisaregisteredtrademark ofCompuServeCorporation. Hewlett-Packardisaregistered trademarkofHewlett-PackardCorporation. INTELisaregistered trademarkofIntelCorporation. MacDrawisaregistered trademarkofCLARISCorporation. 386AMaxis a trademarkofQualitas,Inc. Phar Lapisa registeredtrademark ofPhar LapSoftwareInc. 386IVMM and 3861DOS ex tenderare trademarksofPharLap Software,Inc. NeXTis a trademarkofNeXt,Inc. ORACLEisaregistered trademarkofOracle Corp. Informixisaregistered trademarkofInformixSoftware,Inc. PICKisaregistered trademarkofPickSystems,Inc. OSF/Motifisatrademarkofthe OpenSoftwareFoundation. CHIPSisaregistered trademarkofChipsandTechnologies,Inc. Watcomisa trademarkofWatcomSystems,Inc. Instant-CisatrademarkofRationalSystems,Inc. GoldenCommonLispisaregistered trademarkofGold HillComputers,Inc. TOPSisaregisteredtrademarakofSun Microsystems. LogitechisatrademarkofLogitech, Inc. CommonviewisatrademarkofGlockenspiel. ZortechC++is a trademarkofZortech,Inc. MetaWare,Hich-C,and ProfessionalPascalaretrademarksof MetaWare,Inc. LMIFORTHisatrademarkofLaboratoryMicrosystems,Inc. 1167and3167aretrademarksofWeitekCorp. 68881isatrademarkofMotorolaCorp. PocketSoftis a trademarkofPocketSoft,Inc. Table ofContents Introduction xi About the Contributors xv Chapter 1 TheIBMPCProgramming Architecture 1 ByRoss P. Nelson IBM's First PersonalComputer 3 The 8086Becomesa Family 5 SolvingReal Problems 8 Using ProtectedMode 13 DOSExtenders 20 Intel's 32-bitMicroprocessors 21 Operating Environments 27 WhatAboutOS/2? 28 ChoosingYourMarket 29 Chapter 2 ExpandedMemory and the EMS 31 ByRayDuncan Components ofExpanded Memory 33 ObtainingAccess to Expanded Memory 35 vii viii EXTENDING DOS UsingExpanded Memory 39 EMSPitfallsfor Drivers and TSRs 44 EMSEmulators 46 EMSExample Program 49 Chapter3 Extended Memory and the XMS 79 ByRayDuncan Reaching Extended Memoryin RealMode 81 The ROMBIOSExtended Memory Functions 82 Primitive Extended MemoryManagement 88 The extendedMemorySpecification(XMS) 93 LOADALL:The BackDoor to Extended Memory 100 Chapter4 80286-based Protected-Mode DOS Extenders 109 ByAndrew Schulman Whydevelopfor the 286? 110 Protected-ModeMS-DOS 112 How does it work? 116 MoreThanOne Int21H 122 An In-DepthLook at theDOS/16MToolkit 124 Isn't there anyworkinvolved? 134 Bugs! 146 #ifdefDOS16M: The DOS/16M Library 147 OS/286 and the Two-MachineModel 154 Performance 162 Programming Project 169 ByAndrew Schulman ExploringProtected Mode withInstant-C 169 Chapter5 80386-based Protected-Mode DOS Extenders 193 ByM. StevenBakerandAndrewSchulman 386DOS Extenders in theMarketplace 194