His very old, frozen up Perkins Brailler which I should try oiling in case it's needed. It's missing the handle on the side, too. I suspect my grade-school teacher, sister let her little monsters at school at it.
The rules for using one are the same as for the modern Japanese abacus and after not too much time practicing, I was surprised to find that it's a lot easier and faster to use than a calculator, for the four common operations. Someone online pointed out that most of the countries that beat the pants off of the United States for math scores made extensive use of the abacus in elementary school level mathematics. Yeah, I know, I'd figured they'd gone to electronic calculators too but, according to what I'm reading, no.
Considering my limited experience with this, it's an appalling scandal that the United States isn't teaching basic arithmetic using an incredibly cheap, simple and far more efficient technology than electric calculators. Though, of course, it's not patented so no huge corporations are likely to make money producing them, probably a big reason the sighted United States didn't do what the blind United States apparently did more than 50 years ago.
Bought a used Japanese style abacus for less than a dollar, on which the beads move freely and which works perfectly, big surprise, huh? It's what I'll be doing my every day figuring with. My father's fingers must have been like iron bands the way he moved those beads. Two of them, anyway.
Update: I showed this to my brother and he wondered what happened to our father's talking calculator that someone gave him. I'd forgotten all about it because, unlike his abacus, it broke rather quickly and became unusable. I don't remember him using it much, though I do remember his sighted family members using it when they couldn't find a calculator that was working. He wasn't all that impressed with it.