Comment by etaioinshrdlu

3 months ago

"Before microchips existed, computers were built with mechanical relays." Should probably say something about vacuum tubes as well!

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etaioinshrdlu

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analog31  3 months ago

And discrete transistors. Now that my curiosity is piqued, I found this nice timeline:

https://www.computerhistory.org/timeline/computers/

It looks like transistorized computers were dominant at the point when integrated circuits were introduced.

  • JKCalhoun  3 months ago

    Interesting: the entry for the Apollo Guidance Computer (AGC) indicates it used integrated circuits—I had remembered hearing it used RTL (resistor-transistor logic).

    It turns out both are true [1]. The "integrated circuits" were sort of "flat-packs" of RTL circuits. I had forgotten that early IC's were not quite what we envision today. Regardless I suppose ICs were RTL before they were TTL (before they were CMOS, etc.).

    [1] https://en.wikipedia.org/wiki/Apollo_Guidance_Computer#Logic...

  • hbrav  3 months ago

    And before that with gears! (With limited success.)

    • analog31  3 months ago

      Indeed, my dad was a research scientist at a large chemical company, and every scientist had a Friden mechanical calculator, which was capable of multiplying and dividing. But it was not a programmable computer.

      When the HP 35 came out, it was cheaper than the annual maintenance contract for the Friden. They bought one, and passed it around to try out for a week, then all of the Fridens went into the dumpster. Of course he brought one home, and we got to play with it.

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