User Manual for the Harvard Mark 1 Electro-Mechanical Computer (1946) | Hacker News Reader

User Manual for the Harvard Mark 1 Electro-Mechanical Computer (1946)

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32 pointseigenvalue8 comments

This is a really fascinating document. It was written by the lead designer (Howard Aiken) and Grace Hopper, who is well known in CS circles. What I like most about the machine is that it feels easier to understand how it operates in an intuitive way, particularly because it is all in decimal as opposed to binary. And the machine was accurate to a very high number of decimal places, and could also directly produce high-quality printed tables of mathematical tables (the first big job it worked on was to prepare large tables of Bessel functions).

What we really want is audio of a relay computer working. It must have been quite the sound!!

Here is one from 1958 in Japan that has been preserved. The whole video is worth watching, but here is a demo of a running calculation: https://youtu.be/_j544ELauus?t=1027.

That was a great watch, thanks for sharing!

One of my favorite YouTube channels. Marc has tons of amazing vintage computer content. The Apollo guidance computer series in particular is great.

Yes, it made a racket! There is a description of the Harvard Mark I crashing in Beyer's "Grace Hopper and the Invention of the Information Age":

> Hopper, Campbell, and Bloch invested substantial energy in developing practices and procedures for debugging. Like physicians, they identified symptoms, made diagnoses, and prescribed treatments. Sometimes symptoms were obvious, as when Mark I would come to a crashing halt: “The crash of that thing sounded as if a plane had run into the building,” Hopper recalled. ”You never heard such a crash in your life.”

Is that where the term of a computer "crashing" comes from?

Similar to how the term debugging may or may not have been "reinforced" by the finding of an actual moth on the Mark II (it wasn't its origin, according to Wikipedia: https://en.wikipedia.org/wiki/Debugging#Etymology ).

Perhaps debugging comes from a mathematical joke in base 6 encoding.

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