This may be the first example many people will look at so imho it deserves some love. Do you prefer very small grained PRs or dumping smaller things into this thread?

Anyway, the first issue that hit me is that "ln" and "log" do nothing. "ln" should be unary and adding it to the uops is straightforward and works as expected. "log" appears to be intended as binary and I can not see why it does not work.

Also the whole logic of the calculator suffers a bit from the problem that "basic" and "scientific" calculators almost always use different logic of evaluation: "basic" won't honour arithmetic precedence rules, scientific will. So it may be an idea to concentrate on the scientific branch and make it real good.