Task: Purchase or Download the Atari 8-Bit Programming Reference Book “Mapping the Atari”
Needed: Web Browser
Time: 5-10 mins
Any serious programming on the Atari 8-bit computers requires interacting with various memory locations on the Atari. Some of these memory locations are free for you to use as part of your program and some store programmable data used by the hardware for various functions. For example, page six of memory (i.e. starting at location 1536 = 6 * 256) contains 256 bytes of RAM which can be used by the programmer to store game data or assembly routines. Further, memory location 704 stores the color of player and missile 0 as part of player-missile graphics. Memory locations can be written to and read using the POKE and PEEK statements in BASIC, respectively. In assembly language you can write to a memory location by loading the accumulator with a decimal value (e.g. LDA #8) and then storing it in the memory location (e.g. STA 704). To read a value you would load the accumulator with the contents of the memory location (e.g. LDA 704).
The hard part is knowing where the free memory is and what all the useful locations are for interacting with the hardware. One of the most useful and most popular Atari 8-bit computer books to own is “Mapping the Atari” by Ian Chadwick and published by Compute!. This book lists all the memory location with an explanation about what they do. Some of the entries go into some detail and even provide coding examples. This is a bible for Atari programmers, and I personally keep a copy close by on my desk whenever I am coding.
The first edition came out in 1983 and covered the 400/800 line. The revised edition came out in 1985 and covered the XL/XE computers with their expanded memory. These are readily available in hard copy or PDF.
Ebay is a great source for hard copies of the book. At the time of this posting there were eight copies available and most were in the $50 range. Well worth the expense for this one!
The book is also available for free online. Here is a web resource of the revised edition on Atari Archives. Here is the first edition as a PDF from Archive.org. Here is the revised edition as a PDF from Archive.org.
A must have book for Atari enthusiasts! Here is an overview of the book from Antic Magazine.