Check out the history of the Curta sometime. http://en.wikipedia.org/wiki/Curta_calculator
. Amazing. And anything which makes a guest appearance in a William Gibson novel is worth some extra attention on principle.
And to continue the literary vein, as it were, the Burroughs adding machine company was founded by an ancestor of William S. Burroughs, which explains the recurring references to adding machines in his writing ("...answer is always the same for given coordinates..."). Technology and weird writing go so well together, don't they?