I used to work at AlphaSmart on the Danas and Neos. I worked on the teacher software for downloading/uploading data to 30 of them at a time using the special cart and a big USB hub. If you have any particular questions on them I can probably get an answer. AlphaSmart was purchased by Renaissance Learning back in 2005? which is when I left, after the stock options were actually worth something.
I think the last person I knew working there has just recently left but I'm still in touch with the founders and the rest of the engineering team so we might be able to help if you decide to hack one apart.