Here are two programming interface implementations.

Origianlly Posted by Jtrapass (Post#20) https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/74147-ultima-electronic-ignition#post1703764

27 September 2009

Ultima Programmer Project

First, here's my disclaimer:
I have no interest in making more of these and marketing them. Dyna/Ultima is doing that fine. I made one for myself, and I'm satisfied with that. I also take no responsibility for damage to your computer or your bike if you try this and it doesn't work. if you're not comfortable building circuits, get help from somebody (not me) who is.

Schematic of this circuit:

Most of the parts should be available at any electronics store. I actually ended up using a 2N3904 instead of the transistor I listed above. Any reasonable NPN BJT should work fine. And for the resisters, they don't need to be exact, either. Anything close should be fine. You also don't need a pull up resister on that final output that connects to voes line because the voes port on the programmer has its own built in pull up resister of 1k. But you can add one if it gives you a warm and fuzzy or makes your circuit easier to test before clipping it on your bike.

It should end up looking like this:

And again, download the hd curvemaker software and manuals here: http://www.dynaonline.com/skins/downloads/

Happy hacking. :)