It's the second volume in a set of books about the history of keyboards, text entry, the user experience of working with text on various devices. This volume got into more modern history. Sometimes I was learning stuff, but other times I was just wallowing in nostalgia. Or maybe "nostalgia" isn't the right word. What's the word for when you find out that you misunderstood what was going on at the time? Decades ago, I thought I cured my repetitive strain injury by making sure I used different types of keyboard at home and at work. Now, reading this book, I figured out that what really cured my RSI is that the new "different" keyboard I bought for home was thinner than older keyboards, and thus didn't encourage my wrists to bend so much.
(OK, there was regular ol' nostalgia, too. Talking about Japanese text entry, I remembered how the then-newfangled Canon WordTank was so much easier to use than my Nelson's paper kanji dictionary. At the time, such a game-changer. Nowadays, the idea of a separate dictionary device seems absurd, tho.)
Anyhow, there's modern keyboard history, how keyboards migrated onto our phones, then (alas) to our phone screens. There are a couple of chapters about modern keyboard enthusiasts who soup up their keyboards with custom designed keys, custom-built boards… Uhm, I didn't really try to follow those chapters too closely because I already have enough hobbies. (Also, I would feel bad if I spilled snacks on a nice keyboard, so that's a deal-breaker.)