A recent comment on the Hackaday blog (https://hackaday.com/2017/06/24/a-goldmine-of-radio-shack-goodies-is-up-for-auction/#comment-3700073) turned me on to this sweet piece of hardware. I decided I should snap one up, certainly before NaNoWriMo season kicks into high gear and the price shoots up again.
It arrived today. There is great potential here, and largely untapped too - the sum total of knowledge about this device now lives on in this Flickr group: https://www.flickr.com/groups/alphasmart/discuss/
This device connects to a PC via USB. Without special drivers, it emulates a USB Keyboard when attached. Users can open Notepad, attach the NEO, then hit a key to "upload" their document by having it type out the letters one by one. There is also a NEO Manager application, and special drivers, which allow two-way communication. This is used to update firmware or flash new "SmartApplets", the name for programs that execute on the NEO.
There are multiple versions of AlphaSmart hardware: the 3000 is the oldest in the series, then the NEO, and the NEO 2 (which is like the NEO except it includes a proprietary radio system to link other NEO 2s in a classroom setting). There is also the Dana, which is actually a PalmOS device and very different.
All told, there hasn't been much done on the hacking front. Users do a fair bit of case modding by repainting with vinyl dye. Someone has cracked the font format and produced a font editor (http://tsoniq.com/software/legacy/neo-fonts/). Most SmartApplets are distributed by the now-defunct manufacturer: there are two commercial apps "Co:Writer" and "Inspiration Outliner" that have long since passed out of their customer service life, and not a lick of homebrew code to be found.