NEC Advanced Personal Computer System Reference Manual

• 6

  Table of Contents
• 14

  Preface

16

Chapter 1 Hardware Overview

• 17

  System Block Diagram

20

Chapter 2 Processor Pcb

• 20

  Processor PCB
• 21

  Processor PCB Block Diagram
• 22

  Mother Board/Card Cage Interface
• 23

  Card Cage Socket Contact Assignments
• 23

  Interrupt Lines
• 27

  Processor Timing
• 29

  RFSH Signal Timing
• 31

  Device Interface Circuits
• 32

  Microprocessor
• 33

  Direct Memory Access
• 33

  DMA Instructions
• 35

  DMA Command and Mode Registers
• 36

  DMA Request and Mask Register
• 38

  Interval Timer
• 38

  DMA Status Register
• 38

  Interval Timer Block Diagram
• 39

  Interrupt Control
• 39

  Timer Commands
• 40

  Interrupt Control Block Diagram
• 41

  Interrupt Control Commands Summary
• 43

  Interrupt Initialization Command Words
• 44

  Interrupt Operation Command Words
• 45

  Memory
  • 45

    System Memory Map
  • 46

    Main Memory
  • 46

    Main Memory Block Diagram
  • 47

    Battery-Backed Memory
  • 47

    Battery-Backed Memory Block Diagram
  • 48

    Read Only Memory
• 48

  Parallel Printer Control
  • 48

    Interface
  • 48

    Programming Considerations
  • 49

    Parallel Printer Control Block Diagram
  • 50

    Parallel Printer Connectors Pin Assignments
  • 52

    Parallel Printer Interface Signals
  • 54

    Parallel Printer Controller Instruction
  • 55

    Parallel Printer Controller Interface Timing
  • 55

    Parallel Printer Controller Instruction Sequence
  • 56

    Parallel Printer Controller Interface at Paper Out Status
• 57

  Keyboard
  • 58

    2.8.1 Keyboard Layout and Scan Codes
  • 58

    Keyboard Layout
  • 60

    Interface
  • 60

    Keyboard Interface
• 61

  Calendar and Clock Generator
  • 61

    Keyboard Interface Lines
  • 62

    Circuit Description
  • 62

    Clock/Calendar Block Diagram
  • 63

    Clock/Calendar Instruction Format
  • 63

    Programming Considerations
  • 64

    Clock/Calendar Format
• 65

  Jumper Settings

66

Chapter 3 Controller Pcb

• 66

  Mother Board/Card Cage Interface
• 68

  Controller PCB Block Diagram
• 69

  Crt Display Control
  • 69

    Buffer Memory
  • 70

    Character-Code Representation in the Character Code
  • 70

    CRT Display Control Block Diagram
  • 70

    Display Buffer Memory
  • 71

    Attribute Description for Character Attribute Code
  • 72

    Controller PCB
  • 73

    Programming Considerations
  • 74

    GDC I/O-Address and Bit Map
  • 75

    Contents of the GDC Status Register
  • 83

    GDC Command Constants
• 85

  Crt Display Unit
• 86

  Flexible Disk Drive Controller
  • 88

    Bit Description of the FDC Main Status Register
  • 89

    Programming Considerations
  • 92

    FDC Commands