"In 1963, at the "U-Dub," as it was called, I found myself in the
evolutionary transition between mechanical calculation and digital
computers. My first class in Numerical Analysis in 1964 was from a
professor in his 80s. This nice old gentleman was retiring, and not
too soon in my opinion, as he seemed quite feeble and at somewhat of a
loss of memory. He taught the trade of computing with Marchant
calculators.
A Marchant calculator is a big, black machine, about three times the
size of a typewriter. It has a giant carriage on top with about ten
holes with little mechanical numbers that pop up in the slots. There
are buttons all over the front with digits, decimal points, and keyed
symbols that multiply and divide to control this mechanical nightmare.
They used these Marchant calculators for Numerical Analysis, starting
in about the 1940's. A business would hire rows and rows of Marchant
calculator operators to compute so-called "Finite Differences." This
led to tables of figures that let you, for example, toss a mortar
precisely into your enemy's backyard.
You sat there and pushed those keys while the mechnicals made a host
of noises by cranking and grinding who-knows-what, until the rattling
stopped. You got a number. You put the number on a form, and
eventually, with enough numbers and forms, you got a result. Sometimes
the resulting number was correct."