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Comment by fernly | Hacker News Reader

This article has a striking absence, that being the name "John Atanasoff"[0], whose electronic digital calculator was seen and examined by Mauchly in 1941, and who spoke to Mauchly multiple times during the years when ENIAC was being built.

It was this connection that ultimately blocked Eckert and Mauchly from patenting the idea of the digital computer.[1]

[0] https://en.wikipedia.org/wiki/John_Vincent_Atanasoff [1] https://en.wikipedia.org/wiki/John_Vincent_Atanasoff#Patent_...

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…and whose digital calculator was _just_ a calculator (not a general purpose computer) that read values from a mechanical drum (so not fully electronic), and sat in a basement until it was later disassembled. That this device managed to qualify as prior art is mostly just an exhibit of how the trial system isn’t especially good at divining truth. So annoying that the ABC is a permanent barnacle on the ENIAC story.

The ABC's memory was not mechanical, even if the drum was driven directly by an electric motor. It was a self-refreshing series of capacitors using the same general mechanism as modern, non-persistent memory (self-regenerating I think?). It's was one of the other parts of the ABC that invalidated the Eniac patents, in addition to the ABC's binary adders. But the memory itself was entirely digital.

Sorry, I shortened to the point of inaccuracy - I should have said not fully electronic _speed_. Not meant to say that it was mechanically reading and writing values per se, just that the slow rotation of a mechanical drum was essential for its operation and ultimately had a limiting effect on the speeds it could compute. Thus the electronic storage and compute was rather defeated by inclusion of a mechanical element in the “critical path”, so to speak. I think that’s accurate to say?

Not any more accurate than it is to say the electronic storage and compute of any computer is defeated by the latency of its memory. Virtually all early memory devices were deeply limited.

Really the ABC was most limited by its use of a custom I/O device which used electrically burned holes in special paper to input the initial problem state and output the solution. Atanasoff never got it working reliably, which is the main reason the ABC was never fully functional before WWII.

In any case, the fixed nature of the ABC is often why its considered the first "digital electronic computer" and the ENIAC the first "general purpose digital electronic digital computer" (or later, the first "programmable digital electronic digital computer", after it was rebuilt in '46 - '47 to operate more like a modern computer).

Unfortunately I'm not familiar enough with Zuse's computers or the Colossus to say if those statements are really accurate.

> It was this connection that ultimately blocked Eckert and Mauchly from patenting the idea of the digital computer.

Why would a connection be relevant? A patent can be blocked by prior art, but that theoretically happens whether you know about the prior art or not.

Knowledge is relevant to how guilty you are over infringing an existing patent, and it's relevant to copyright, but I didn't think it was relevant to patentability.

I heartily recommend both (if you can find them) "The First Electronic Computer: The Atanasoff Story" (for a technical look at the computer itself, by Arthur and Alice Burks) and "Who Invented The Computer?" (for a history of the ABC as it applies to the patent trial, by Alice Burks).

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