This is a simple adding machine for use with the software Zillions of Games.
There really isn't much to say about it: all it does is add and subtract.
It can handle negative as well as positive numbers.

Use the sliders to set the number you want to add or subtract.
To add, move the right-hand lever up, then back to the middle.
To subtract, move the right-hand lever down, then back to the middle.
To clear the machine, just start a new game.

I made this adding machine as a project to amuse myself for a few hours one night.
I do not intend to add any new features, but you are welcome to if you want to.
You are also welcome to the code and/or graphics if you want to use them in your own project.