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Let’s Make a Game!

Introduction

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 websitecolorful.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:

Game Mockup

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:

 

 

 

 

 

 

 

 

Next Step >

 

 

 

 

 

 

Table of Contents for Let’s Make a Game!

Introduction

Goals for this tutorial.

Step 1: Generate a Stable Display

On other systems, the video chip generates the display; on the 2600, your program generates the display.

Step 2: Timers

Improve the display generation by using the built-in timer.

Step 3: Score and Timer Display

Using the playfield to display information.

Step 4: 2 Line Kernel

Draw the player objects (sprites) on screen (X & Y location).

Step 5: Automate Vertical Delay

Finish the Y positioning of the player objects (sprites).

Step 6: Spec Change

Revise our goals.

Step 7: Draw the Playfield

Display an arena (like the mazes in Combat).

Step 8: Select and Reset Support

Using the Game Select and Game Reset console switches.

Step 9: Game Variations

How to implement game variations (number of players, different mazes).

Step 10: “Random Numbers”

How to randomize your game.

Step 11: Add the Ball Object

Draw the ball on screen (X & Y location).

Step 12: Add the Missile Objects

Draw the missiles on screen (X & Y location)

Step 13: Add Sound Effects

Let’s make some noise!

Step 14: Add Animation

Make the humans run instead of glide.

 

 

 

 

Useful Links

Easy 6502 by Nick Morgan

How to get started writing 6502 assembly language. Includes a JavaScript 6502 assembler and simulator.

 

 

Atari Roots by Mark Andrews (Online Book)

This book was written in English, not computerese. It's written for Atari users, not for professional programmers (though they might find it useful).

 

 

Machine Language For Beginners by Richard Mansfield (Online Book)

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 Second Book Of Machine Language by Richard Mansfield (Online Book)

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.

 

 

6502 Instruction Set with Examples

A useful page from Assembly Language Programming for the Atari Computers.

 

 

6502.org

Continually strives to remain the largest and most complete source for 6502-related information in the world.

 

 

Guide to 6502 Assembly Language Programming by Andrew Jacobs

Below are direct links to the most important pages.

 

 

Stella Programmer's Guide

HTMLified version.

 

 

Nick Bensema's Guide to Cycle Counting on the Atari 2600

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.

 

 

How to Draw A Playfield by Nick Bensema

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.

 

 

Cart Sizes and Bankswitching Methods by Kevin Horton

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 Specifications

Atari 2600 programming specs (HTML version).

 

 

Atari 2600 Programming Page (AtariAge)

Links to useful information, tools, source code, and documentation.

 

 

MiniDig

Atari 2600 programming site based on Garon's "The Dig," which is now dead.

 

 

TIA Color Charts and Tools

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.

 

 

The Atari 2600 Music and Sound Page

Adapted information and charts related to Atari 2600 music and sound.

 

 

Game Standards and Procedures

A guide and a check list for finished carts.

 

 

Stella

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.

 

 

JAVATARI

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.

 

 

batari Basic Commands

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.

 

 

Atari 2600 BASIC

If assembly language is too hard for you, try batari Basic. It's a BASIC-like language for creating Atari 2600 games. It's the faster, easier way to make Atari 2600 games.

Try batari Basic

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Disclaimer

View this page and any external web sites at your own risk. I am not responsible for any possible spiritual, emotional, physical, financial or any other damage to you, your friends, family, ancestors, or descendants in the past, present, or future, living or dead, in this dimension or any other.

 

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