Detail of Input / Output
(All images, unless otherwise noted, were taken by Rocky Acosta and are CC-Attribution)
Gonna kick off the Visions of the Techpocalypse with a series of images of the Harvard Mark I electro-mechanical computer, or the IBM Automatic Sequence Controlled Calculator (ASCC).
From the IBM Archives:
“The Automatic Sequence Controlled Calculator (Harvard Mark I) was the first operating machine that could execute long computations automatically. A project conceived by Harvard University’s Dr. Howard Aiken, the Mark I was built by IBM engineers in Endicott, N.Y. A steel frame 51 feet (16 m) long and eight feet high held the calculator, which consisted of an interlocking panel of small gears, counters, switches and control circuits, all only a few inches in depth. The ASCC used 500 miles (800 km) of wire with three million connections, 3,500 multipole relays with 35,000 contacts, 2,225 counters, 1,464 tenpole switches and tiers of 72 adding machines, each with 23 significant numbers. It was the industry’s largest electromechanical calculator.”
From Wikipedia’s Harvard Mark I:
“The Mark I had 60 sets of 24 switches for manual data entry and could store 72 numbers, each 23 decimal digits long. It could do three additions or subtractions in a second. A multiplication took six seconds, a division took 15.3 seconds, and a logarithm or a trigonometric function took over one minute.
Detail of keypad
The Mark I read its instructions from a 24 channel punched paper tape and executed the current instruction and then read in the next one. It had no conditional branch instruction. This meant that complex programs had to be physically long. A loop was accomplished by joining the end of the paper tape containing the program back to the beginning of the tape (literally creating a loop).”
A couple more pictures:
