Back in the days before cheap electronics, businessmen and engineers used good old clacking, whirring, mechanical calculators to get their computing done. The image you see above is from Mark Glusker's expansive and amazingly well-kept collection of the appliances, captured by San Francisco-based photographer Kevin Twomey. Looking at the machines stripped open, you really get an appreciation for how intricate and precise these things are, and the price tags show it — many of them sold for upwards of $1,000 in 1960s money (over $7,000 today). To get a sense of how far the world of computing has come in 50 years, compare the image above with this one from iFixit's teardown of the new iPad:

For those looking to see the mecha-calculators in action, a video featuring Glusker and his collection in all of its whizz-clunk glory can be found on Twomey's website.