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Contents

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1 System Calls 1

 1.1 Introduction 3
 1.2 Standard Character Device I/O 4
 1.3 Memory Management 5
 1.4 Process Management 7
 1.5 File and Directory Management 9
 1.6 Microsoft Networks 14
 1.7 National Language Support 15
 1.8 Miscellaneous System-Management Functions 16
 1.9 Old System Calls 17
 1.10 Using the System Calls 21
 1.11 Interrupts 35
 1.12 Function Requests 53

2 MS-DOS Device Drivers 323

 2.1 Introduction 325
 2.2 Format of a Device Driver 326
 2.3 How to Create a Device Driver 328
 2.4 Installing Device Drivers 329
 2.5 Device Headers 330
 2.6 Request Header 334
 2.7 Device Driver Functions 337
 2.8 The Media Descriptor Byte 351
 2.9 Format of a Media Descriptor Table 351
 2.10 The CLOCK Device 353
 2.11 Anatomy of a Device Call 354
 2.12 Two Sample Device Drivers 355

3 MS-DOS Technical Information 383

 3.1 Introduction 385
 3.2 MS-DOS Initialization 385
 3.3 The Command Processor 386
 3.4 MS-DOS Disk Allocation 387
 3.5 MS-DOS Disk Directory 387
 3.6 File Allocation Table (FAT) 390
 3.7 MS-DOS Standard Disk Formats 392

4 MS-DOS Control Blocks
 and Work Areas 395

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Contents

 4.1 Introduction 397
 4.2 Typical Contents of an MS-DOS Memory Map 397
 4.3 MS-DOS Program Segment 398

5 National Language Support 403

 5.1 Introduction 405
 5.2 National Language Support Calls 405
 5.3 Font Files 406

6 .Exe File Structure and Loading 411

 6.1 Format of a File Header 413
 6.2 The Relocation Table 414

7 Microsoft Relocatable
 Object Module Formats 417

 7.1 Introduction 419
 7.2 Module Identification and Attributes 423
 7.3 Conceptual Framework for Fixups 425
 7.4 Record Sequence 431
 7.5 Introducing the Record Formats 433
 7.6 Microsoft Type Representations
  for Communal Variables 460

8 Programming Hints 463

 8.1 Introduction 465
 8.2 Interrupts 465
 8.3 System Calls 466
 8.4 Device Management 467
 8.5 Memory Management 468
 8.6 Process Management 468
 8.7 File and Directory Management 469
 8.8 Miscellaneous 471


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Figures

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Figure 1.1 Example of the 8088 Registers 25

Figure 1.2 Sample Program with Common Skeleton 26

Figure 2.1 Sample Device Header 330

Figure 2.2 Attribute Word for Character Devices 333

Figure 2.3 Attribute Word for Block Devices 333

Figure 2.4 Request Header 335

Figure 2.5 Format of a Boot Sector 352

Figure 2.6 Format of a Clock Device 354

Figure 4.1 Program Segment Prefix 402

Figure 5.1 Font File Structure 407

Figure 7.1 Location Types 427



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Tables

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Table 1.1 Standard Character I/O Function Requests 4

Table 1.2 Memory Management Function Requests 5

Table 1.3 Process-Management Function Requests 7

Table 1.4 Predefined Device Handles 9

Table 1.5 File-Related Function Requests 10

Table 1.6 File-Sharing Function Requests 11

Table 1.7 Device-Related Function Requests 12

Table 1.8 Directory-Related Function Requests 12

Table 1.9 File Attributes 13

Table 1.10 Microsoft Networks Function Requests 14

Table 1.11 National Language-Support Function Requests 15

Table 1.12 Miscellaneous System-Management Function Requests 16

Table 1.13 Old System Calls and Their Replacements 17

Table 1.14 Format of the File Control Block (FCB) 18

Table 1.15 Error Codes Returned in AX 22

Table 1.16 MS-DOS Interrupts, Numeric Order 27

Table 1.17 MS-DOS Interrupts, Alphabetic Order 27

Table 1.18 MS-DOS Function Requests, Numeric Order 28

Table 1.19 MS-DOS Function Requests, Alphabetic Order 31

Table 1.20 Bit values for Function 29H 133

Table 1.21 Sharing Mode Bit Values 174

Table 1.22 Access Code Bit Values 175

Table 1.23 MS-DOS Data Bit Values 193

Table 1.24 Contents of the Parameter Block 239

Table 1.25 Contents of the Parameter Block 243

Table 1.26  250

Table 1.27 Allocation Strategy 263

Table 2.1 For Character Devices: 331

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  Contents

Table 2.2 For Block Devices: 331

Table 3.1 MS-DOS Standard Removable-Disk Formats 393

Table 3.2 MS-DOS Standard Removable Disk Formats (High-Density) 393

Table 7.1 Object Module Record Formats 419

Table 7.2 Combination Attribute Example 438



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