Cover Index Contents Preface This Technical Reference Manual is intended primarily to assist writers of software for the Amstrad PC1640, although in conjunction with the PC1640 Service Manual it will be of interest to designers of add-on hardware. It is assumed that the reader has a working knowledge of the Industry Standard architecture comprising of an 8086 (or 8088) with DMA, PIT, RTC and Interrupt Controller support chips; plus Extended Graphics Adapter (or Color Graphics Adapter) with Floppy Disk, Serial and Parallel Adapters. The information contained herein is largely unique to this document, with the exception of parts of the appendices which expand on the information contained in the PC1640 User Instructions and the Microsoft MSDOS Reference Manual. Whilst the PC1640 implements a superset of the Industry Standard, this manual makes no attempt to identify those areas of the PC1640 specification which exceed the Industry Standard. Users should, therefore, exercise caution when writing software for a range of manufacturers' PCs and only use the "Lowest Common Denominator" facilities if simple portability is required. © Copyright 1987 AMSTRAD Plc. Neither the whole nor any part of the information contained herein, nor the product described in this manual may be adapted or reproduced in any form except with the prior approval of AMSTRAD Plc. All information of a technical nature and particulars of the product are given by Amstrad in good faith. However, it is acknowledged that there may be errors or omissions in this manual. All correspondence should be addressed to: Amstrad Consumer Electronics Plc Brentwood House 169 Kings Road Brentwood ESSEX CM14 4EF All maintenance and service on the product must be carried out by Amstrad authorised dealers. Amstrad cannot accept any liability whatsoever for any loss or damage caused by service or maintenance by unauthorised personnel. This manual is intended to assist the reader in the use of the product, and therefore Amstrad shall not be liable for any damage or loss whatsoever arising from the use of any information or particulars in, or any error or omission in, this manual or any incorrect use of the product. Written by Bill Weidenauer, AMSTRAD plc. Published by Amstrad. First Published 1987. MS-DOS(R) is a registered trademark of Microsoft(R) Corporation AMSTRAD PC1640 is a registered trademark of AMSTRAD plc. AMSTRAD is a registered trademark of AMSTRAD plc. Unauthorised use of the trademark or the word AMSTRAD is strictly forbidden. Cover Index Contents Intro Index Section 1 Table of Contents: Section 1 - Hardware 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 Contents Index Section 2 AMSTRAD PC1640 TECHNICAL MANUAL 1.0 Introduction This manual provides a comprehensive description of the AMSTRAD PC1640 hardware and firmware. General information about the PC1640, GEM Desktop and the delivered operating system software is contained in the AMSTRAD PC1640 USER GUIDE. This manual is intended to satisfy the needs of advanced developers who must have access to the various resources available within the PC1640. Note that all address constants in this document are hexadecimal. In addition hexadecimal quantities are noted with small letter 'h' terminator to denote that they are in hexadecimal form.