1.0	Introduction	1
1.1	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	DMA	5
1.5.1	DMA Page Registers	6
1.5.2	DMA Initialisation	7
1.6	System Interrupts	7
1.6.1	Interrupt Levels	8
1.6.2	Interrupt Controller initialisation	8
1.6.3	NMI Mask Control	9
1.7	Programmable Interval Timers	9
1.7.1	Timer Configuration	10
1.8	System Status and Control	10
1.8.1	Port B - System Control	10
1.8.2	Port A - Status-1 Input/Keyboard Code	11
1.8.3	Port C - Status-2 Input	12
1.8.4	Write System Status-1	13
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	16
1.10.1	Printer Data Latch	16
1.10.2	Printer Control Latch	17
1.10.3	Printer Status Channel	18
1.11	The Internal Graphics Adapter	19
1.11.1.1	Color Alpha Display	21
1.11.1.2	Monochrome Alpha Display	23
1.11.2.1	Color Graphics Display	24
1.11.2.2	Low Resolution (320x200) Graphics	25
1.11.2.3	Medium Resolution (640x200) Graphics Mode	26
1.11.2.4	High Resolution (640x350) Graphics Mode	26
1.11.2.5	IGA BIOS Modes	27
1.11.3	IGA Control Registers	28
1.11.4	IGA BIOS EGA Mode Initialization	63
1.11.5	Color Graphics Adpater Compatible Registers	64
1.11.5.1	CGA Mode Control Register	64
1.11.5.2	CGA Color Select Register	66
1.11.5.3	CGA Status Register	67
1.11.5.4	CGA Mode 6845 CRTC Emulation	67
1.11.5.5	CRTC Display Addressing	67
1.11.6	Monochrome Graphics Adapter Compatible Registers	69
1.11.6.1	MDA Mode Control Register	69
1.11.6.2	MDA Status Register	70
1.11.6.3	6845 CRTC Emulation	70
1.11.7	Hercules Compatible Emulation	71
1.11.7.1	HMGA Mode Control Register	71
1.11.7.2	HMGA Status Register	71
1.11.7.3	6845 CRTC Emulation	74
1.12	Floppy Disk Controller	76
1.12.1	FDC Hardware Conditions	76
1.13	RS232C Asynchronous Serial Port	77
1.13.1	Serial Channel Interface	77
1.13.2	Serial Channel Pin Arrangement	78
1.14	Parallel Printer Interface	78
1.15	Keyboard Interface	80
1.15.1	Serial Clock and Serial Data	80
1.15.2	Keyboard to Main Board Interface	80
1.15.3	Main Board to Keyboard Interface	80
1.15.4	Keycodes	81
1.15.5	Keyboard Connector	81
1.16	Mouse Interface	82
1.16.1	Mouse Connector	82
1.17	Joystick Interface	84
1.17.1	Joystick Connector	84
1.18	Light Pen Connector	85
1.19	Expansion Card Interface	86
1.20	Video Connector	89
1.21	Power Connector	90
1.22	Display Selector Switch Settings	91

2.0	Firmware	93
2.1	Power-Up Initialisation and Self Test	94
2.2	Power-Up Self Tests	98
2.2.1	Test Procedure	99
2.2.2	Test Methods	100
2.2.3	ROS Checksum Test	100
2.2.4	Direct Memory Access Controller Test	100
2.2.5	Programmable Interval Timer Test	100
2.2.6	Programmable Peripheral Interface Test	101
2.2.7	Real Time Clock Test	101
2.2.8	Asynchronous Communications Element Test	101
2.2.9	Printer Parallel Port Test	101
2.2.10	Mouse X and Y Count Register Test	101
2.2.11	System RAM Test	102
2.2.12	Programmable Interrupt Controller Test	102
2.2.13	Disk Test	102
2.2.14	Keyboard Interface Test	102
2.3	ROM Firmware Interrupts	102
2.3.1	Interrupt 2: Parity Error (NMI)	102
2.3.2	Interrupt 5: Print Screen	103
2.3.3	Interrupt 6: Mouse Button Control	103
2.3.4	Interrupt 8: System Clock Interrupt	104
2.3.5	Interrupt 9: Keyboard Interrupt	105
2.3.5.1	Special Key Actions	108
2.3.6	Interrupt 14: Floppy Disk Controller	110
2.3.7	ROS Interrupt 16: '6845 Compatible' Video I/O	111
2.3.8	IGA Interrupt 16: 'EGA Compatible' Video I/O	121
2.3.9	Interrupt 17: System Configuration	136
2.3.10	Interrupt 18: Memory Size	136
2.3.11	Interrupt 19: Disk I/O	137
2.3.11.1	Hard Disk Call parameters and registers	140
2.3.12	Interrupt 20: Serial I/O	143
2.3.13	Interrupt 21: Enhanced Function Interrupt	147
2.3.14	Interrupt 22: Keyboard I/O	149
2.3.15	Interrupt 23: Printer I/O	151
2.3.16	Interrupt 24: System Restart	153
2.3.17	Interrupt 25: Disk Bootstrap	153
2.3.18	Interrupt 26: System Clock & Real Time Clock	154
2.3.19	Interrupt 27: Keyboard Break Interrupt	158
2.3.20	Interrupt 28: External Ticker Interrupt	158
2.3.21	Interrupt 29: VDU Parameter Table	159
2.3.22	Interrupt 30: Disk Parameter Table	160
2.3.23	Interrupt 31: VDU Matrix Table	161
2.4	System RAM Variables	161
2.5	Non-Volatime RAM	169
2.6	ROS Messages	170
2.6.1	Non-Fatal ROS Messages	170
2.6.2	Fatal Messages	171

3.0	Reference Information	172
3.1	Language Links	172
3.2	Processor Memory Usage	173
3.3	Keyboard and Key Codes	174
3.4	ACE (8250) Registers	176
3.5	DMA Controller (8237A-4) Registers	179
3.6	PIC (8259-A) Command Words	182
3.7	Programmable Interval Timer (8253) Registers	185
3.8	Real Time Clock (HD146818) Registers	186
3.8.1	Time Calendar & Alarm Locations	187
3.8.2	RTC Register Locations	189
3.9	Floppy Disk Controller (uPD765A)	191

Appendix 1:	Mouse Software Interfaces	208
Appendix 2:	MS-DOS System Configuration	220
Appendix 3:	Country Dependent Information for MS-DOS 3.2	226
Appendix 4:	RS232C Connections	227
Appendix 5:	Printer Lead (PL-2) Wiring Specification	236
Appendix 6:	Power Supply Requirements	237
Appendix 7:	ROM Character Set	238
Appendix 8:	Keyboard Keycodes	240
Appendix 9:	Keyboard Layouts	241
Appendix 10:	The Linker Program (MS-LINK)	247
Appendix 11:	System Commands Processor (COMMAND.COM)	264
Appendix 12:	The DEBUG Utility Program (DEBUG)	265
Appendix 13:	The EXE2BIN Utility Program	290
Appendix 14:	The EXIT Command	291
Appendix 15:	The RECOVER Utility Program	292
Appendix 16:	The SHARE Utility Program	293

Intro

Index

Section 1

Table of Contents:

Section 1 - Hardware