Yep, I had a problem here (and I may change my mind back again) as to what to call this. I made the (in retrospect) obvious decision to title the post with what I was writing about. That being said, I’ll still talk about computation later, but I think in a separate topic covering things like logic, complexity, etc.
So we have a nice clean definition of what we are going to talk about – computers. So, what is a computer? Whoops, problems already. Loosely, we can say somewhat circularly, it is anything that computes. So is a pencil and paper, accompanied by the human holding the pencil a computer? That’s stupid, you say, but that is exactly what the (mostly women) at Bletchley Park did and were called. That’s unsatisfactory to me, and it’s my blog, so that ain’t happenin’. (Much, much more about that and them later, but if you want to read ahead, see the references – but no extra credit on the final grade.) So is it something mechanical/electrical that aids in mathematics? In one sense that’s too narrow – we probably want to include any “machine” that processes information. In another sense it’s too broad – is an abacus a computer? Again just a thingie with a carbon-based I/O system. Or even the Egyptians with 3 sticks tied together in lengths of 3, 4, and 5, so they could run around creating right angles? I think not.
I’m taking the coward’s way out here – to paraphrase U.S. Supreme Court Justice Potter Stewart re pornography. “I know it when I see it.” Suffice it to say, we will see all kinds of embodiments of “computers”, some of which will make you say. “Huh?”, and post a scathing comment. To those of you who feel like doing that all I can say is. “Bring it on!!!” I thrive on controversy.
So let’s get started: what was the first “computer” (I will henceforth drop the quotes with the understanding that there could (will) be some disagreement)? Let me propose the Jacquard loom (~1800). Another “Huh?” moment. I chose this because it is the first device I know of whose behavior was “programmable” – that is, it didn’t just kind of stand there waiting for some one to tell it what to do. Note the distinction here, someone is telling it what to do. An abacus needs fingers (and nimble ones, at that) to do any computing. Here in the case of the loom, instructions were prepared off-line, loaded into the machine, and the “GO” button pushed. In its simplest manifestation, the pattern to be woven was encoded into a set of punched cards. Without a full Weaving 101 class, the basic idea was that the cards told the loom what to do with the various threads that were being woven, whether to go over or under, or some such. But, Martin Davis points out, that’s how a player piano works, and no one pretends that it’s any sort of a computer, so we’re back to square one. As a side note, Napoleon I stuck his two cents in here, as he did with so many scientific ventures.
Next up, Charles Babbage’s Analytic Engine.
Weave, weave, weave me the sunshine out of the falling rain
Bletchley Park – The Secret Lives of Codebreakers by Sinclair McKay
Colossus: The secrets of Bletchley Park’s code-breaking computers by B. Jack Copeland
Jacquard’s Loom – Jacquard’s Web: How a hand-loom led to the birth of the information age by James Essinger