Intro Index Section 1

Table of Contents:

Section 1 - Hardware

1.0 Introduction 1
1.1 Central Processing Unit (CPU) 1
1.2 Memory Layout 2
1.3 Main Board I/O Channels 3
1.4 Expansion Bus I/O Channels 5
1.5 Direct Memory Access (DMA) 5
1.5.1 DMA Page Registers 6
1.5.2 DMA Initialization 7
1.6 System Interrupts 7
1.6.1 Interrupt Levels 8
1.6.2 Interrupt Controller Initialization 8
1.6.3 NMI Mask Control 9
1.7 Programmable Interval Timers 9
1.7.1 Timer Configuration 10
1.7.2 Counter 1 initialization 10
1.8 System Status and Control 10
1.8.1 Port B - System Control 11
1.8.2 Port A - Status-1 Input / Keyboard Code 12
1.8.3 Port C - Status-2 Input 13
1.8.4 Write System Status-1 14
1.8.5 Write System Status-2 14
1.8.6 System Reset 14
1.9 Real Time Clock 15
1.10 Parallel Printer Port 15
1.10.1 Printer Data Latch 16
1.10.2 Printer Control Latch 16
1.10.3 Printer Status Channel 17
1.11 The Internal display Adapter18
1.11.1 Colour Alpha Display 19
1.11.2 Colour Graphics Display 21
1.11.2.1 Low Resolution Graphics21
1.11.2.2 Medium Resolution Graphics 22
1.11.2.3 High Resolution (640 X 200) Graphics Mode 23
1.11.3 Monochrome Display 23
1.11.4 BIOS Modes 24
1.11.5 Colour Mode Registers. 25
1.11.5.1 CGA Mode Control Register 25
1.11.5.2 Colour Select Register26
1.11.5.3 CGA Status Register 27
1.11.5.4 CGA Mode CRTC initialization. 27
1.11.5.5 Set and Clear Light Pen Latch 29
1.11.5.6 Operation Control/Status Register 29
1.11.5.7 CRTC Index Readback 30
1.11.5.8 CRTC Data Readback 30
1.11.6 Monochrome Mode Registers.31
1.11.6.1 MDA Mode Control Register 31
1.11.6.2 MDA Status Register 32
1.11.6.3 Monochrome CRTC initialization. 32
1.12 Floppy Disk Controller 34
1.12.1 FDC Hardware Conditions 34
1.13 RS232C Asynchronous Serial Port 35
1.13.1 Serial Channnel Interface 35
1.13.2 Serial Channnel Pin Arrangement 36
1.14 Parallel Printer Interface 36
1.15 Keyboard Interface 38
1.15.1 Serial Clock and Serial Data 38
1.15.2 Keyboard to Main Board Interface 38
1.15.3 Main Board to Keyboard Interface 38
1.15.4 Keycodes 39
1.16 Modem Interface 39
1.16.1 Modem Connector 39
1.17 Light Pen Connector 40
1.18 Expansion Interface Connectors 41
1.19 Video Connector 44
1.20 Power Connectors 45
1.20.1 The Adapter Power Connector45
1.20.2 The Display Power Connector45
1.21 PPC Switch Settings 46
 
2.0 Firmware 47
2.1 Power-Up Initialization and Self Test 47
2.2 Power-Up Self Tests 52
2.2.1 Test Procedure. 52
2.2.2 Test Methods. 53
2.2.3 ROS Checksum Test. 53
2.2.4 Direct Memory Access Controller test. 54
2.2.5 Programmable Interval Timer test. 54
2.2.6 Programmable Peripheral Interface test. 54
2.2.7 Real Time Clock test. 54
2.2.8 Asynchronous Communications Element test. 54
2.2.9 Printer Parallel Port test.54
2.2.10 System RAM test. 54
2.2.11 Programmable Interrupt Controller test. 55
2.2.12 Disk test. 55
2.2.13 Keyboard Interface test. 55
2.3 ROM Firmware Interrupts. 55
2.3.1 Interrupt 2: Parity Error (NMI). 55
2.3.2 Interrupt 5: Print Screen. 56
2.3.3 Interrupt 8: System Clock Interrupt 56.
2.3.4 Interrupt 9: Keyboard Interrupt. 57
2.3.4.1 Special Key Actions 61
2.3.5 Interrupt 14: Floppy Disk Controller. 62
2.3.6 Interrupt 16: Video I/O. 62
2.3.7 Interrupt 17: System Configuration. 71
2.3.8 Interrupt 18: Memory Size. 72
2.3.9 Interrupt 19: Disk I/O. 72
2.3.9.1 Hard Disk Call Parameters and Registers 77
2.3.10 Interrupt 20: Serial I/O. 79
2.3.11 Interrupt 22: Keyboard I/O.83
2.3.12 Interrupt 23: Printer I/O.87
2.3.13 Interrupt 24: System Restart. 88
2.3.14 Interrupt 24: Disk Bootstrap. 89
2.3.15 Interrupt 26: System Clock & Real Time Clock. 89
2.3.16 Interrupt 27: Keyboard Break Interrupt. 93
2.3.17 Interrupt 28: External Ticker Interrupt. 93
2.3.18 Interrupt 29: Video Parameter Table. 93
2.3.19 Interrupt 30: Disk Parameter Table. 95
2.3.20 Interrupt 31: Video Matrix Table. 95
2.4 System RAM Variables. 96
2.5 Non Volatile RAM. 103
2.6 ROS Messages. 104
2.6.1 Non-Fatal ROS Messages. 104
2.6.2 Fatal ROS Messages. 105
 
3.0 Reference Information. 106
3.1 Language Links. 106
3.2 Processor Memory Usage. 106
3.3 Asynchronous Communications Element (8250) Registers. 107
3.4 High Performance Programmable DMA Controller
(8237A-4) Registers		 110
3.5 Programmable Interrupt Controller (8259A-2)
Command Words.		 112
3.6 Programmable Interval Timer (8253) Registers. 115
3.7 Real Time Clock (HD146818) Registers 116
3.7.1 Time, Calendar and Alarm Locations 117
3.7.2 RTC Register Locations 119
3.8 Floppy Disk Controller (uPD765A). 121
 
Appendix 1:
MS-DOS System Configuration		 137
Appendix 2:
Country Dependent Information for MS-DOS 3		 144
Appendix 3:
RS232C Connections		 145
Appendix 4:
Printer Lead (PL-2) Wiring Specification		 153
Appendix 5:
PPC Power Usage		 155
Appendix 6:
ROM Character Set		 156
Appendix 7:
Keyboard Keycodes		 158
Appendix 8:
Keyboard Layouts		 159
Appendix 9:
The LINKER Program		 164
Appendix 10:
COMMAND.COM		 179
Appendix 11:
The DEBUG Utility Program (DEBUG)		 180
Appendix 12:
The EXE2BIN Utility Program		 202
Appendix 13:
The EXIT Command		 204
Appendix 14:
The RECOVER Utility Program		 205
Appendix 15:
The SHARE Utility Program		 206
Appendix 16:
The FDISK Utility Program		 207
Appendix 17:
The BACKUP Command		 218
Appendix 18:
The RESTORE Command		 221
Intro Index Section 1