I don't think the comparison to a microwave oven or being a circuit really applies here.
* The microwave doesn't come with a slot to insert and run new or different programs into it. * The circuit analogy doesn't hold up either, since the user can change the operation just by inserting a new or different program - It's more like a computer in that case just like I can come along & insert a new CD into mine and boot a new or different version of, say, Trisquel. I recognize some of the references in this thread as coming from a page on fsf.org and the exceptions they mention are intended to be used cases where none of these points are true.
