By Darrell Spice, Jr. (adapted by Duane Alan Hahn)
Original Blog Entry
For my Atari 2600 Homebrew presentation I've been giving a rundown of the challenges involved in writing an Atari game, namely the limited resources and capabilities of the hardware, as well as the tools (DASM, bB, Stella, Harmony, etc.) and resources (AtariAge, Mini Dig, etc.) that are available to help you.
I've been updating the presentation for each time I give it. On the most recent update, for the 2013 Houston Arcade Expo, I added code for a very simple 2600 program. You can see it here, starting with slide 51. You can also download the source and ROM from my website—colorful.zip.
The code addition went over very well so I've decided to expand upon it for my next presentation, which will be given the weekend of August 16th at the Classic Game Fest in Austin. I decided a very simple game would be the way to go and have worked up a mockup of what it might look like:
The game's going to be called Collect. It's a 1 player game and your objective is to collect as many boxes as you can before the timer runs out. My goals for code are to show:
Goals for this tutorial.
On other systems, the video chip generates the display; on the 2600, your program generates the display.
Improve the display generation by using the built-in timer.
Using the playfield to display information.
Draw the player objects (sprites) on screen (X & Y location).
Finish the Y positioning of the player objects (sprites).
Revise our goals.
Display an arena (like the mazes in Combat).
Using the Game Select and Game Reset console switches.
How to implement game variations (number of players, different mazes).
How to randomize your game.
Draw the ball on screen (X & Y location).
Draw the missiles on screen (X & Y location)
Let’s make some noise!
Make the humans run instead of glide.
This book was written in English, not computerese. It's written for Atari users, not for professional programmers (though they might find it useful).
This book only assumes a working knowledge of BASIC. It was designed to speak directly to the amateur programmer, the part-time computerist. It should help you make the transition from BASIC to machine language with relative ease.
The 6502 Instruction Set broken down into 6 groups.
Nice, simple instruction set in little boxes (not made out of ticky-tacky).
This book shows how to put together a large machine language program. All of the fundamentals were covered in Machine Language for Beginners. What remains is to put the rules to use by constructing a working program, to take the theory into the field and show how machine language is done.
An easy-to-read page from The Second Book Of Machine Language.
A useful page from Assembly Language Programming for the Atari Computers.
Continually strives to remain the largest and most complete source for 6502-related information in the world.
By John Pickens. Updated by Bruce Clark.
Below are direct links to the most important pages.
Goes over each of the internal registers and their use.
Gives a summary of whole instruction set.
Describes each of the 6502 memory addressing modes.
Describes the complete instruction set in detail.
Cycle counting is an important aspect of Atari 2600 programming. It makes possible the positioning of sprites, the drawing of six-digit scores, non-mirrored playfield graphics and many other cool TIA tricks that keep every game from looking like Combat.
Atari 2600 programming is different from any other kind of programming in many ways. Just one of these ways is the flow of the program.
The "bankswitching bible." Also check out the Atari 2600 Fun Facts and Information Guide and this post about bankswitching by SeaGtGruff at AtariAge.
Atari 2600 programming specs (HTML version).
Links to useful information, tools, source code, and documentation.
Atari 2600 programming site based on Garon's "The Dig," which is now dead.
Includes interactive color charts, an NTSC/PAL color conversion tool, and Atari 2600 color compatibility tools that can help you quickly find colors that go great together.
Adapted information and charts related to Atari 2600 music and sound.
A guide and a check list for finished carts.
A multi-platform Atari 2600 VCS emulator. It has a built-in debugger to help you with your works in progress or you can use it to study classic games.
A very good emulator that can also be embedded on your own web site so people can play the games you make online. It's much better than JStella.
If assembly language seems a little too hard, don't worry. You can always try to make Atari 2600 games the faster, easier way with batari Basic.
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