Neat thing is its interface - plain old USB, no drivers needed, it emulates a keyboard. Usable on any device that recognizes USB keyboards. Open a blank document or whatever on the device, and push a button on the AlphaSmart, and it "types" out the current file you're working on. Totally OS agnostic, and future-proof-ish as long as devices support USB.
They were all made in the late nineties / early noughties and the company that made them is long gone, but they made a whole lot of them (mainly for schools) and they're pretty cheap used. Built solid too so unless they were thrown in a wood chipper they should last.