IBM PC Technical Reference Manual

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IBM PC Technical Reference Manual
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CONTENTS
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1-1 SECTION 1. HARDWARE OVERVIEW
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1-4 System Block Diagram


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2-1 SECTION 2. HADRWARE
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2-3 System Board
2-6 System Data Flow
2-8 I/O Channel
2-9 I/O Channel Diagram
2-10 System Board I/O Channel Diagram
2-13 System Board Component Diagram
2-14 Keyboard
2-15 Keyboard Interface Block Diagram
2-16 Keyboard Diagram
2-17 Keyboard Scan Codes
2-18 Keyboard Interface Connector Specifications
2-19 Cassette User Interface
2-19 Cassette Jumpers
2-19 Cassette Block Diagram
2-21 Cassette Interface Connector Specifications
2-22 Speaker Interface
2-22 Speaker Drive System Block Diagram
2-23 I/O Address Map
2-25 System Memory Map
2-28 System Board And Memory Expansion Switch Settings
2-29 5 1/4" Diskette Drives Switch Settings
2-29 Monitor Type Switch Settings
2-30 System Board Memory Swith Settings
2-31 32/64 KB Memory Expansion Option Switch Settings

2-33 Power Supply
2-34 Power Supply Location
2-34 Input Requirements
2-34 DC Output
2-34 AC Output
2-35 Power Supply Connectors And Pin Assignments
2-36 Important Operating Characteristics
2-36 Over Voltage/Current Protection
2-36 Signal Requirements

2-37 IBM Monochrome Display and Parallel Printer Adapter
2-37 Parallel Interface Description
2-38 IBM Monochrome Display Adapter Block Diagram
2-39 System Channel Interface
2-39 Lines Used
2-39 Loads
2-39 Special Timming
2-39 Data Rates
2-39 Interrupt and DMA Response Requirements
2-40 Modes of Operation
2-41 Programming Considerations
2-41 Programming the 6845 CRT Controller
2-41 Sequence of Events
2-41 Memory Requirements
2-42 DMA Channel
2-42 Interrupt Levels
2-42 I/O Address and Bit Map
2-43 IBM Monochrome Display
2-43 Operating Characteristics
2-44 IBM Monochrome Display Drive Interface and Pin Assignment

2-45 Color/Graphics Monitor Adapter
2-47 Color/Graphics Monitor Adapter Block Diagram
2-48 Major Components Definitions
2-48 Motorola 6845 CRT Controller
2-48 Mode Set and Status Registers
2-48 Display Buffer
2-48 Character Generator
2-48 Timming Generator
2-48 Composite Color Generator
2-49 Modes of Operation
2-49 Alphanumeric Mode
2-49 Color TV
2-50 Color Monitor
2-51 IBM Monochrome Display Adapter Vs. Color/Graphics Adapter Attribute Relationship
2-51 Color/Graphics Modes
2-52 Graphics Storage Map
2-54 Description of Basic Operations
2-55 Summary of Available Colors
2-55 Programming Considerations
2-55 Programming The 6845 Controller
2-56 6845 Register Description
2-57 Programming the Mode Control and Status Register
2-57 Color Select Register
2-58 Mode Select Register
2-58 Mode Register Summary
2-59 Status Register
2-59 Sequence of Events
2-60 Memory Requirements
2-60 Interrupt Level
2-61 I/O Address and Bit Map
2-62 Color/Graphics Monitor Adapter Direct Drive, and Composite Interface Pin Assignment
2-63 Color/Graphics Monitor Adapter Auxiliary Video Conectors

2-65 Parallel Printer Adapter
2-66 Parallel Printer Block Diagramm
2-67 Programming Considerations
2-69 Parallel Printer Adapter Interface Connector Specifications
2-70 IBM 80 CPS Matrix Printer
2-71 Printer Specifications
2-72 Setting the DIP Switches
2-72 Functions and Conditions of DIP Switch 1
2-73 Functions and Conditions of DIP Switch 2
2-73 Parallel Interface Description
2-74 Connector Pin Assignment and Description of Interface Signals
2-77 Parallel Interface Timming Diagrams
2-78 ASCII Coding Table
2-79 Control Codes

2-89 5 1/4" Diskette Drive Adapter
2-90 5 1/4" Diskette Drive Adapter Block Diagram
2-91 Functional Description
2-91 Digital Output Register
2-91 Floppy Disk Controller
2-94 Programming Considerations
2-94 Symbol Descriptions
2-96 Command Summary
2-100 Command Status Registers
2-103 Programming Summary
2-103 DPC Registers
2-104 Drive Constants
2-104 Comments
2-104 System I/O Channel Interface
2-106 Drive A and B Interface
2-106 Adapter Outputs
2-107 Adapter Inputs
2-108 5 1/4" Diskette Drive Adapter Internal Interface Specifications
2-109 5 1/4" Diskette Drive Adapter External Interface Specifications
2-110 5 1/4" Diskette Drive
2-111 Diskettes
2-112 Mechanical and Electrical Specifications

2-113 Memory Expansion Options
2-113 Operating Characteristics
2-114 Memory Module Description
2-114 Memory Module Pin Configuration
2-115 Switch Configurable Start Address

2-117 Game Control Adapter
2-117 Game Control Adapter Block Diagram
2-118 Functional Description
2-118 Address Decode
2-118 Data Bus Buffer/Driver
2-118 Trigger Buttons
2-118 Joystick Positions
2-119 I/O Channel Description
2-119 Interface Description
2-121 Joystick Schematic
2-122 Game Control Adapter (Analog Input) Connector Specifications

2-123 Asynchronous Communications Adapter
2-124 Asynchronous Communications Adapter Block Diagram
2-125 Modes of Operation
2-125 I/O Decode for Comunications Adapter
2-126 Interrupts
2-126 Interface Description
2-127 Curent Loop Interface
2-128 Voltage Interchange Information
2-129 INS 8250 Functional Pin Description
2-129 Input Signals
2-132 Output Signals
2-133 Input/Output Signals
2-133 Programming Considerations
2-133 Asynchronous Communications Reset Functions
2-134 INS 8250 Accessable Registers
2-134 INS 8250 Line Control Register
2-135 INS 8250 Programmable Baud Rate Generator
2-137 Line Status Register
2-139 Interrupt Identification Register
2-140 Interrupt Enable Register
2-142 Modem Control Register
2-143 Modem Status Register
2-144 Receive Buffer Register
2-145 Transmitter Holding Register
2-146 Selecting The Interface Format
2-147 Asynchronous Communications Adapter Connector Interface Specifications


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3-1 SECTION 3. ROM and SYSTEM USAGE
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3-2 ROM BIOS
3-2 Use of BIOS
3-2 Parameter Passing
3-3 Interrupt Vector Listing
3-5 Vectors With Special Meaning
3-5 Interrupt ICH - Timer Tick
3-5 Interrupt 1DH - Video Parameters
3-5 Interrupt 1EH - Diskette Parameters
3-6 Interrupt 1FH - Graphics Character Extensions
3-6 Other Read/Write Memory Usage
3-6 BIOS Programming Tip
3-7 BIOS Memory Map

3-8 BIOS Cassette Logic
3-8 Interrupt 15
3-8 Cassette Write
3-9 Cassette Read
3-10 Data Record Architecture
3-10 Error Recovery

3-11 Keyboard Encoding and Usage
3-11 Encoding
3-11 Character Codes
3-13 Extended Codes
3-13 Extended Functions
3-14 Shift States
3-15 Shift Key Priorities
3-15 Special Handling
3-15 System Reset
3-16 Break
3-16 Pause
3-16 Print Screen
3-17 Keyboard Usage
3-19 BASIC Screen Editor Special Functions
3-19 DOS Special Functions

3-21 Low Memory Maps
3-21 0-7F Interrupt Vectors
3-22 BASIC and DOS Reserved Interrupts (80-3FF)
3-22 Reserved Memory Locations (400-5FF)
3-23 BASIC Workspace Variables


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A-0 APPENDICES
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A-1 Appendix A: ROM BIOS Listing
B-1 Appendix B: Assembly Instructions Set Reference
C-1 Appendix C: Of Characters Keystrokes and Color
D-1 Appendix D: Logic Diagrams
E-1 Appendix E: Unit Specifications
G-1 Glossary
Bib-1 Bibliography
I-1 Index


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FIGURE LISTING
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1 System Block Diagram 1-4
2 System Board Data Flow 2-6, 2-7
3 I/O Channel Diagram 2-9
4 System Board Component Diagram 2-13
5 Keyboard Interface Block Diagram 2-15
6 Keyboard Diagram 2-16
7 Cassette Interface Read Hardware 2-19
8 Cassette Interface Write Hardware 2-20
9 Cassette Motor Control 2-20
10 Speaker Drive System Block Diagram 2-22
11 System Memory Map 2-25
12 System Memory Map (Increments of 16 KB) 2-26
13 Power Suply and Connectors 2-35
14 IBM Monochrome Display Adapter Block Diagram 2-38
15 Color/Graphics Monitor Adapter Block Diagram 2-47
16 Parallel Printer Adapter Block Diagram 2-66
17 Location of (Printer) DIP Switches 2-72
18 Parallel Interface Timing 2-77
19 5 1/4" Diskette Driver Adapter Block Diagram 2-90
20 Game Control Adapter Block Diagram 2-117
21 Joystick Schematic 2-121
22 Asynchronous Communications Adapter Block Diagram 2-124
23 Current Loop Interface 2-127
24 Selecting The Interface Format 2-146
25 BIOS Memory Map 3-7


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TABLE LISTING
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1 Keyboard Scan Codes 2-17
2 6845 Initialization Parameters 2-41
3 Monochrome Vs. Color/Graphics Attributes 2-51
4 Color/Graphics Modes 2-51
5 Summary of Available Colors 2-55
6 6845 Register Description 2-56
7 Printer Specifications 2-71
8 Functions and Conditions of DIP Swich 1 2-72
9 Functions and Conditions of DIP Swich 2 2-73
10 Connector Pin Assignment and Description of Interface Signls 2-74
11 ASCII Coding Table 2-78
12 DC1/DC3 and Data Entry 2-82
13 Symbol Description 2-94
14 Status Register 0 2-100
15 Status Register 1 2-101
16 Status Register 2 2-102
17 Status Register 3 2-103
18 Mechanical and Electrical Specifications 2-112
19 Memory Module Pin Configuration 2-114
20 DIP Module Star Address 2-115
21 I/O Decodes (3F8-3FF) 2-125
22 Asynchronous Communications Reset Functions 2-133
23 BAUD Rate at 1.843 Mhz 2-137
24 Interrupt Control Functions (Asynchronous) 2-140
25 Character Codes 3-11
26 Keyboard Extended Functions 3-14
27 Keyboard - Commonly Used Functions 3-17
28 Basic Screen Editor Special Functions 3-19
29 DOS Special Functions 3-19
30 0-7F Interrupt Vectors 3-21
31 Basic & DOS Reserved Interrupts (80-3FF) 3-22
32 Reserved Memory Locations (400-5FF) 3-22