EXOS 2.1 Kernel Specification

---

Contents:

1. Introduction

2. Overview of the EXOS Environment

2.1 The EXOS Input / Output System

2.2 Memory Allocation

2.2.1 Memory Segments and Pages

2.2.2 User Segment Allocation

2.2.3 EXOS RAM usage and Channel RAM

2.3 System Extensions (ROM and RAM)

3. System Initialization and Warm Reset

3.1 Cold Reset Sequence

3.2 Warm Reset Sequence

4. Applications Program Interface

4.1 EXOS System Calls - General

4.2 Hardware and Software Interrupts

4.2.1 User Hardware Interrupt Routine

4.2.2 Software Interrupts

4.3 The STOP key

5. Segment Allocation

5.1 User and Device / Extension Segments

5.2 System Segments and the EXOS Boundary

5.3 The Shared Segment and User Boundary

5.4 System Segment Usage

6. Device Descriptors

6.1 The Device Chain

6.2 Details of Device Descriptors

6.3 Extension ROM Devices

6.4 User Devices

7. Device Drivers

7.1 Device Driver Routines - General

7.2 Device Initialisation Routine

7.3 Channel RAM Allocation

7.4 The Buffer Moved Routine

7.5 Device Interrupt Routines

7.6 Device Channel Calls

7.6.1 Open Channel and Create Channel Routines

7.6.2 Block Read and Write Routines

8. EXOS Variables

9. System Extension Interface

9.1 Calling System Extensions - General

9.2 Action Codes

9.2.1 Action code 1 - Cold Reset

9.2.2 Action code 2 - Command string

9.2.3 Action code 3 - Help string

9.2.4 Action code 4 - EXOS variable

9.2.5 Action code 5 - Explain error code

9.2.6 Action code 6 - Load module

9.2.7 Action code 7 - RAM allocation

9.2.8 Action code 8 - Initialisation

9.3 Starting a New Applications Program

10. Enterprise File Format and EXOS Loading Functions

10.1 Enterprise File Format

10.1.1 Module Header Types

10.2 Loading Enterprise Format Files

10.3 Relocatable Data Format

10.3.1 Location Counter and Run Time Page

10.3.2 Relocatable Words and Absolute Bytes

10.3.3 End of Module Item

10.4 User Relocatable Modules

10.5 Relocatable and Absolute System Extensions

10.6 New Applications Programs

11. EXOS Function Calls in Detail

11.1 Device Name and Filename String Syntax

11.2 Function 0 - System Reset

11.3 Function 1 - Open Channel

11.4 Function 2 - Create Channel

11.5 Function 3 - Close Channel

11.6 Function 4 - Destroy Channel

11.7 Function 5 - Read Character

11.8 Function 6 - Read Block

11.9 Function 7 - Write Character

11.10 Function 8 - Write Block

11.11 Function 9 - Channel Read Status

11.12 Function 10 - Set and Read Channel Status

11.13 Function 11 - Special Function

11.14 Function 16 - Read, Write or Toggle EXOS Variable

11.15 Function 17 - Capture Channel

11.16 Function 18 - Re­direct Channel

11.17 Function 19 - Set Default Device Name

11.18 Function 20 - Return System Status

11.19 Function 21 - Link Device

11.20 Function 22 - Read EXOS Boundary

11.21 Function 23 - Set User Boundary

11.22 Function 24 - Allocate Segment

11.23 Function 25 - Free Segment

11.24 Function 26 - Scan System Extensions

11.25 Function 27 - Allocate Channel Buffer

11.26 Function 28 - Explain Error Code

11.27 Function 29 - Load Module

11.28 Function 30 - Load Relocatable Module

11.29 Function 31 - Set Time

11.30 Function 32 - Read Time

11.31 Function 33 - Set Date

11.32 Function 34 - Read Date