Tagalong Todd Tutorial

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Revision as of 18:16, 3 January 2013 by Rickreynolds (talk | contribs) (The Progression)
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If you're looking to get into developing programs (presumably games) for the Intellivision platform, you can go through the Hello World tutorials and read a good bit about the CP1600 architecture and the AS1600 assembler syntax, etc., etc. But to start programming anything of any consequence, you typically hear that you should start by understanding what is going on in the very simple demonstration game Tagalong Todd. I've attempted that a couple of times and found it difficult. Finally, I just started attempting to understand the game by ripping it apart and seeing what changes/breaks. At that point, writing up a tutorial seemed like a good idea as that will help me to understand the code as well.

This tutorial will attempt to build up the Tagalong Todd example game from the title screen on up through a working "game" one bite-sized chunk at a time.

There are several versions of Tagalong Todd out there. There are at least three that are shipped with the SDK itself! This tutorial will work through the simplest one, the one found in the examples/tagalong directory within the SDK directory structure.


This tutorial will try not to duplicate documentation available elsewhere in the SDK documentation and/or on the Intelliwiki. As such it will not go into details about as1600 syntax, the architecture of the CP1600, etc. However, it will touch on those topics insomuch as they are related to the coding of the examples, of course.

The tutorial also assumes you've already worked through the "Hello World" tutorials, and will pretty much pick up where those left off. E.g. it is assumed you understand how to overwrite text on the title screen, can assemble and run that example code and not much more.

The Progression

The plan for this tutorial is to take the very basic Tagalong Todd "game" that comes with the SDK and break it down into small chunks that can build upon each other until the entire game is understood. As such, the tutorial will follow this progression:

  • Part 1: Start with code that can display the title screen and then draw the player figure.
  • Part 2: Add code to move the figure around the screen programmatically.
  • Part 3: Add code to read controller input and move the figure around the screen in response.
  • Part 4: Add code to draw Todd on the screen.
  • Part 5: Add code to cause Todd to chase the player.

At that point, the game should be very close to the one that comes with the SDK.