By Robert M (adapted by Duane Alan Hahn)
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Table of Contents
This course assumes no prior knowledge of computer programming. While the examples given in the course are targeted at the 650X family of processors, the ideas presented will apply to assembly language programming and often programming in general.
Please feel free to posts comments or questions into the Lesson threads. If you wish to ask a private question don't hesitate to send me a PM.
The assembler we will be using for this course is DASM. We won't need the assembler for the first several sessions, I will provide links for downloading and installing DASM. DASM is available for DOS, Windows (in a DOS window), Amiga, and Macintosh (OS-9 or OS-X). So the development tools will be available on many platforms.
Imagine you have a black box with a single light bulb sticking out of it. Sometimes the light is on, sometimes it is off. Please answer these questions:
Until you can answer these questions, programming computers will never quite make sense. Everything else we do in this course will be built on this radical idea. Please take a moment to consider these questions. There are no wrong answers, its just a mental exercise to broaden your mind.
The key points that you need to take away from this exercise are:
1 or 0
YES or NO
"The Player is alive" or "The player is Dead"
"The Fire button is pressed" or "The fire button is not pressed"
So how does this relate back to the questions I asked above?
It means what ever you the programmer want it to mean is true.
The opposing condition for the meaning you give to the bit is true.
By common convention. the values 1 and 0 are used to represent the states of bits. One usually means on, yes, or true. Zero usually means off, no, or false. Notice that I said "by convention" and "usually". You could just as well use "A" and "B" or "Zip" and "Zap", but this makes it hard to talk with others about bits, so we will use 1 and 0 in this class.
This is the great secret of all computers and computer programming in general. When you program in assembly language, you have complete control/responsibility to provide the meaning of the values of the bits that make up your program. If you want a bit to mean "The Dragon is awake" when it is 1 and "The dragon is asleep" when it is zero, that is fine. Just understand that the meaning you give to the bit is completely your own invention and when the user pulls out cartridge with your program and puts another one in, that program will apply a completely different meaning to the EXACT SAME BIT.
Other Assembly Language Tutorials
Lesson 1: Bits!
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.
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.
Use any example programs at your own risk. I am not responsible if they blow up your computer or melt your Atari 2600. Use assembly language at your own risk. I am not responsible if assembly language makes you cry or gives you brain damage.