I just ran across this and thought the calculating machine enthusiasts in the community might like this. 

Keith Houston is working on a book about the era of calculators, due out next year: Announcing a new book: Empire of the Sum – Shady Characters

I discovered Houston via his first book, Shady characters, a delightful book about punctuation (where did the ampersand and pilcrow come from originally?). His books tend to be very well researched and include tons of little bits of obscure trivia, which you can see in his latest blog post (back to punctuation): Miscellany № 96: EPA – Shady Characters