The Neo is a word processing keyboard which was created by former Apple Computer engineers in 1993. After several earlier models (which were named AlphaSmart after their new company) the Neo was introduced in 2004. I've created hundreds of book chapters and blogs using it and, though costlier such gadgets were created, consider the NEO best.
The NEO is powered by three AA batteries (which often last for a year) and is virtually indestructible. When turned off, the data is automatically saved, to be later transferred to a computer's word processing program for editing via a printer cable.
You can't beat their current (used) price of $15 to $25 on Ebay, I paying $200 for my new one years ago. Their current low cost derives from millions having been sold to schools that used them as a cheaper, more durable substitute for the laptop which slowly became reduced in price and provided internet connection which the NEO lacks.
A later AlphaSmart model, the DANA, had a larger screen and (now obsolete) internet connection though many regard the NEO as the better writing instrument because of its exceptional battery life, auto-save feature, and less glary screen. Neither has been manufactured for years and can buy a DANA for a few dollars more than the NEO. I own two of each.
The cult surrounding the NEO is well deserved. If a writer or a student, consider joining it.