Introduction

The Acorn Atom is perhaps one of the best machines on the market for learning machine and assembly language, based on the 6502 microprocessor. This is especially true if there is a disassembly and hex dump facility, plus improved BASIC. We believe that the DISATOM SUPER ROM is the best available on the market to date. This is a 4K ROM that immensely enhances the power of the Atom at machine level, and provides many extra words and utilities for BASIC. A more detailed specification of this toolkit is given in appendix 1. When constructing this toolkit, it was noticed that there is very little data available concerning the routines in the Atom's ROMs, or the uses that can be made of them. These routines are highly valuable to anyone writing in or learning machine language with the Atom.

We have collected and explained all the addresses, and also provided a thorough index to the routines individually. In addition you will see several chapters concernign important aspects of the machine's operation, and others on how you can turn this knowledge to your advantage. It really makes the machine 'transparent, and is recommended by Acorn. For those without a DISATOM, we provide software source code for memory dump/edit in hex.

Please note that this book is not intended to teach you machine code, but can be a great help to serious beginners.

Conventions used in this book:

(x) : The two-byte vector starting at address x.

?x : The contents of memory location x.

<x> : Key x on the Atom's keyboard.

In general, any notation used in the Atom manual, or by its assembler, may be used here.