This manual is about the ATARI Home Computer. It covers both the ATARI 400TM and the ATARI 800TM Computers. These two computers are electrically identical, differing only in mechanical features such as the keyboards and cartridge slots. The purpose of this manual is to explain in detail how to use all the features of the ATARI Computer. Because this is a complex and powerful machine, the explanations are accordingly rather long. Furthermore, they demand some expert Expertise on the part of the reader. This book is not intended for the beginning programmer. The reader should be thoroughly familiar with the BASIC Reference Manual, which is provided with the computer. Familiarity with assembly language is also essential. A glossary in the back defines and explains some of the less commonly encountered jargon. However, this glossary does not include terms that every serious personal computer programmer should already know.

Written as a training manual for professional programmers who use the ATARI Home Computer, this book may be modified for general use at some later date. It does not supplant the technical reference manual (ATARI part number C016555), which is a reference for programmers who already understand the system. This book is intended to be a tutorial that explains ideas and possibilities rather than defining registers and control codes.

The title, DE RE ATARI, is pronounced "Day Ray Atari". It is an obscure literary reference. Some Latin manuscripts in Roman and medieval times were entitled "De Re This" or "De Re That". Thus, "De Re Rustica" was a poem on farming and "De Re Metallica" described metallurgy. Loosely translated, "De Re" means "All About".

Most of the word processing for the book was carried out with Atari computers. A source file editor was used for text editing, and a modified version of FORMS (available from the Atari Program Exchange) was used to format and print the text. A letter-quality printer was used for output. Some sections were developed with a conventional word processor.

The Software Development Support Group wrote this book. Chris Crawford wrote Sections 1 through 6 and Appendices A and B. Lane Winner wrote Section 10 and Appendix D with assistance from Jim Cox. Amy Chen wrote Appendix C. Jim Dunion wrote Sections 8 and 9. Kathleen Pitta wrote Appendix E. Bob Fraser wrote Section 7. Gus Makreas prepared the Glossary. The final result has many flaws, but we are proud of it.