November 17th, 2009


Antique database technology

So tonight on NCIS there's an episode that starts out with people taking out an ISP and then doing something to trigger a widespread power grid failure--and suddenly our intrepid investigators must go back to old methods.

All of a sudden I was reminded of an early database package of sorts. I'm not sure whether I saw it in an Edmund Scientific catalog or maybe even, of all places, a Lafayette Electronics catalog--that's a vague memory I don't think I should trust. After all, the whole point was that no electricity was required.

The hardware? A bunch of stiff cards that you wrote information on. Each card had holes punched around the border, and each hole corresponds to a predicate. Actually, you could go either way--having the hole cut out to the edge could either represent the predicate being true or being false, and you could even set up negative logic, a la logic circuits, if it would make certain common queries faster.

Let's say we go with "hole = false, slot = true". Then you use rods through the holes/slots for the predicates you're interested in. Simplest query: select all records for which p is true. Stick one rod through the deck at the spot corresponding to p; all cards that fall off have the hole cut through to the edge, and hence have p. p is false? Stick the rod through; all those that stay on the rod are those for which not-p. p and q? Rods through two holes; those that fall off have both cut through, and hence p and q are both true. And so forth. Really kind of clever for the era if you can't afford a 407 accounting machine.

UPDATE: That's the term! Edge-notched cards.
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