Jerry Kaplan's _StartUp_ is on sale again --- $2.99 at Amazon:
https://www.amazon.com/dp/B00L0M749M...=9780544391277
and may be available other places.
It's a remarkable story about the early days of personal computers as they transitioned from the desktop to being carried around, including information which well supplements the book _ThinkPad: A different shade of blue_ and covering the early days of pen/tablet computing and Go Corp. and PenPoint and Windows for Pen Computing.
The Goodreads page describes it well and has reviews:
https://www.goodreads.com/book/show/1171250.Startup