TECHNICAL REFERENCE SERIES

• System BIOS for IBM® PCs, Compatibles, and EISA Computers, Second Edition

The Complete Guide to ROM-Based System Software

P H O E N I X T E C H N O L O G I E S L T D .

J

TT Addison-Wesley Publishing Company, Inc. Reading, Massachusetts Menlo Park, California New York

Don Mills, Ontario Wokingham, England Amsterdam Bonn Sydney Singapore Tokyo Madrid San Juan

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Table of Contents

Preface xv

1 The ROM BIOS

Overview 1

Interrupts 3

BIOS Interrupt Service Routines 5

BIOS Device Service Routines 5

Unexpected-Interrupt Handlers 7

Summary: BIOS Services 8

2 XT, ISA, and EISA Hardware

Overview 15

Microprocessor 16

Math Coprocessor 18

XT, ISA, and EISA Buses 19

I/O Devices 23

Timers and Counters 26

Programmable Interrupt Controllers 28

Direct Memory Access 29

EISA Bus Master Support 32

Miscellaneous Additional Logic 34

System BIOS for IBM PCs, Compatibles, and EISA Computers V

Table Of Contents, Continued

3 System RAM Data

Overview 35

Interrupt Vector Table 36

BIOS Data Area 39

Extended BIOS Data Area 46

4 CMOS RAM Data

Overview 47

Standard or Extended CMOS RAM Data Definitions 48

EISA CMOS RAM Data 52

5 ROM BIOS Data

Overview 53

Compatibility Segment 54

System Configuration Table 57

Diskette Parameters Table 59

ISA and EISA Fixed Disk Parameters Table 61

XT Fixed Disk Parameters Table 66

Baud Rate Initialization Table 68

6 I/O Ports

Overview 69

I/O Port List 70

Video I/O Port Lists 92

vi System BIOS for IBM PCs, Compatibles, and EISA Computers

Table of Contents, Continued

7 Power-On Self Test

Overview 95

Standard Tests and Initializations 97

Initialization of Option ROMs 98

Reentry into POST 100

Error Reporting 101

System Boot Procedure 101

8 Nonmaskable Interrupt Service

Overview 103

NMI Handling 105

NMI Handling in EISA Systems 106

External Math Coprocessor Exceptions 107

INT 02h Nonmaskable Interrupt ISR 108

INT 75h Math Coprocessor Exception ISR 108

9 Keyboard Services

Overview 109

Theory of Operation 110

Character Code Tables 112

INT 09h Keyboard ISR — Translate Scan Code 124

INT 16h Keyboard DSR 127

INT 16h Function 00h — Read Keyboard Input 128

INT 16h Function Olh — Read Keyboard Status 130

INT 16h Function 02h —Return Shift Hag Status 131

INT 16h Function 03h — Set Typematic Rate and Delay 132

INT 16h Function 05h — Store Key Data 133

System BIOS for IBM PCs, Compatibles, and EISA Computers VÜ

Table Of Contents, Continued

9 Keyboard Services, confd

INT 16h Function lOh — Read Extended Keyboard Input 134

INT 16h Function l lh — Return Extended Keyboard Status 135

INT 16h Function 12h — Return Extended Shift Flags 136

10 Video Service

Overview 137

Theory of Operation 138

Video Modes 142

INT 10h Video DSR 144

INT 10h Function 00h — Set Video Mode 145

INT 10h Function Olh —Set Cursor Type 146

INT 10h Function 02h — Set Cursor Position 148

INT 10h Function 03h — Read Current Cursor Position 149

INT 10h Function 04h — Read Light Pen Position 150

INT 10h Function 05h — Select New Video Page 151

INT 10h Function 06h — Scroll Current Page Up 152

INT 10h Function 07h — Scroll Current Page Down 153

INT 10h Function 08h — Read Character/Attribute from Screen 154

INT 10h Function 09h — Write Character/Attribute to Screen 155

INT 10h Function OAh — Write Character Only to Screen 157

INT 10h Function OBh — Set Color Palette 158

INT 10h Function OCh — Write Pixel 159

INT 10h Function ODh — Read Pixel 160

INT 10h Function OEh — Write Teletype to Active Page 161

INT 10h Function OFh — Return Video Status 163

INT 10h Function 13h — Write String 164

ViH System BIOS for IBM PCs, Compatibles, and EISA Computers

Table Of Contents, Continued

11 Diskette Service

Overview 165

Theory of Operation 166

INTOEh Diskette ISR 171

INT 13h Diskette DSR 172

Error Handling 173

INT 13h Function OOh —Reset Diskette System 175

INT 13 Function Olh — Read Diskette Status 176

INT 13h Function 02h —Read Diskette Sectors 177

INT 13h Function 03h —Write Diskette Sectors 178

INT 13h Function 04h —Verify Diskette Sectors 179

INT 13h Function 05h — Format Diskette Track 180

INT 13h Function 08h — Read Drive Parameters 182

INT 13h Function 15h — Read Drive Type 183

INT 13h Function 16h —Detect Media Change 184

INT 13h Function 17h —Set Diskette Type 185

INT 13h Function 18h — Set Media Type for Format 186

12 Fixed Disk Service

Overview 189

Theory of Operation 190

INT 13h Fixed Disk DSR 194

Error Handling 195

INT 13h Function OOh —Reset Fixed DiskSystem 197

INT 13h Function Olh — Read Disk Status 198

INT 13h Function 02h — Read Disk Sectors 199

INT 13h Function 03h —Write Disk Sectors 200

INT 13h Function 04h — Verify Disk Sectors 201

INT 13h Function 05h —Format Disk Cylinder 202

System BIOS for IBM PCs, Compatibles, and EISA Computers ix

Table Of Contents, Continued

12 Fixed Disk Service, conf d

INT 13h Function 06h — Format Bad Track 203

INT 13h Function 07h — Format Drive 204

INT 13h Function 08h — Read Drive Parameters 205

INT 13h Function 09h — Initialize Drive Parameters 206

INT 13h Function OAh — Read Long Sector 207

INT 13h Function OBh — Write Long Sector 208

INT 13h Function OCh — Seek to Cylinder 209

INT 13h Function ODh — Alternate Reset Fixed Disk 210

INT 13h Function OEh — Diagnostics 1: Read Test Buffer 211

INT 13h Function OFh — Diagnostics 2: Write Test Buffer 212

INT 13h Function 10h — Test for Drive Ready 213

INT 13h Function l lh — Recalibrate Drive 214

INT 13 Functionl2h — Controller RAM Diagnostic 215

INT 13h Function 13h — Controller Drive Diagnostic 216

INT 13h Function 14h — Controller Internal Diagnostic 217

INT 13h Function 15h — Read Disk Type 218

13 Serial Communications Service

Overview 219

Theory of Operation 220

INT 14h Serial Communications DSR 221

Error Handling 222

INT 14h Function 00h — Initialize Serial Adapter 223

INT 14h Function Olh — Send Character 225

INT 14h Function 02h — Receive Character 226

INT 14h Function 03h — Return Serial Port Status 227

X System BIOS for IBM PCs, Compatibles, and EISA Computers

Table Of Contents, Continued

14 System Services

Overview 229 INT 15h System Services DSR 231 INT 15h Function 4Fh — Keyboard Intercept 232 INT 15h Function 80h — Device Open 233 INT 15h Function 81h —Device Close 234 INT 15h Function 82h —Program Termination 235 INT 15h Function 83h — Set Event Wait Interval 236 INT 15h Function 84h —Joystick Support 237 INT 15h Function 85h —System Request Key 238 INT 15h Function 86h — Wait 239 INT 15h Function 87h — Move Block 240 INT 15h Function 88h — Read Extended Memory Size 245 INT 15h Function 89h — Switch to Protected Mode 246 ГАТТ 15h Function 90h — Device Busy 248 INT 15h Function 91h — Interrupt Complete 249 INT 15h Function COh — Return

System Configuration Parameters Address 250 INT 15h Function Clh — Return

Extended BIOS Data Area Segment Address 251 INT 15h Function C2h — Pointing Device Interface 252 INT 15h Function C3h — Fail-Safe Timer Control 260 INT 15h Function D8h — Access EISA System Information 261

15 Parallel Printer Service

Overview 279 Theory of Operation 280 INT 17h Function 00h —Print Character 283

System BIOS for IBM PCs, Compatibles, and EISA Computers Xi

Table of Contents, Continued

15 Parallel Printer Service, cont'd

INT 17h Function 01h —Initialize Printer 284

INT 17h Function 02h — Read Printer Status 285

16 Time-of-Day Service

Overview 287

Intel 8254 Programmable Interval Timer 288

Motorola MC146818A Real Time Clock 289

INT lAh Time-of-Day DSR 290

INT 1 Ah Function 00h — Read System Time Counter 291

INT lAh Function 01h —Set System Time Counter 292

INT 1 Ah Function 02h — Read Real-Time Clock Time 293

INT 1 Ah Function 03h — Set Real-Time Clock Time 294

INT 1 Ah Function 04h — Read Real-Time Clock Date 295

INT 1 Ah Function 05h — Set Real-Time Clock Date 296

INT 1 Ah Function 06h — Set Real-Time Clock Alarm 297

INT 1 Ah Function 07h — Reset Real-Time Clock Alarm 298

INT 08h System Timer ISR 299

INT 70h Real-Time Clock ISR 300

INT ICh Timer Tick ISR 301

INT4Ah Alarm ISR 301

17 Single-Function Services

Overview 303

INT 05h Print Screen DSR 304

INT 11h Equipment Check DSR 306

XÜ System BIOS for IBM PCs, Compatibles, and EISA Computers

Table Of Contents, Continued

17 Single-Function Services, cont'd

INT 12h Memory Size DSR 307 INT 18h Process Boot Failure DSR 307 INT 19h Bootstrap Loader DSR 308

A ISA/EISA Error Codes and Messages

Introduction 311 IBM BIOS POST and Boot Messages 312 PhoenixBIOS ISA/EISA POST Messages 313 PhoenixBIOS Run-Time Messages 325

В XT BIOS Error Messages

Introduction 327 IBM XT BIOS POST Messages 328 Phoenix XT BIOS POST and Boot Messages 329 Phoenix XT BIOS POST and Boot Messages, Continued 330 Beep Code 331

Phoenix XT BIOS Run-Time Messages 331

Glossary 333

Selected Bibliography 345

Index 351 System BIOS for IBM PCs, Compatibles, and EISA Computers xiii