Calc Is High-tech For 1970’s Homebrew

Just one look at that banner image and you’ve got to be thinking “that’s old”! This 1970’s era home made calculator used a 4-function calculator IC that was quite advanced for its time. The only problem is that the chip couldn’t do anything other than calcuations, which left it up to the maker of this dinosaur to get the display and keypad working. Circuit boards were made by drawing on copper clad with resist marker. These controlled the VFD digits for the IC’s output and also fed it the user inputs.

[Thanks Brian]

19 thoughts on “Calc Is High-tech For 1970’s Homebrew

  1. That’s pretty cool how people used to be able to get the bare essentials done with some elbow grease and know-how.

    I doubt he could get a UL listing these days with the wooden case, though.

  2. Most people forget, or don’t know, THIS is the reason we have processors today!!

    As I remember, somebody wanted a single chip calculator. Then once they were produced, the company didn’t want them or couldn’t afford them. But somebody else figured out they would be good as general purpose “calculator” chips.

    So, the 4004 was born….. (or it’s predecessor, I can’t remember)

    I built something similar to this long ago too. Except I used a phone dial to enter numbers, and used relays. And I didn’t have “digit” displays, so I ended up using rows of bulbs to represent the numbers (ya know, if 8 bulbs were lit, it was the number eight).

    And didn’t look NEARLY this good!! (but I was just a kid at the time too!)

    This is some fantastic work for that time period. For the “hobby” level, this is some really fine work.

  3. @George Johnson

    “I built something similar to this long ago too. Except I used a phone dial to enter numbers, and used relays. And I didn’t have “digit” displays, so I ended up using rows of bulbs to represent the numbers (ya know, if 8 bulbs were lit, it was the number eight).”

    Now THAT I would like to see on hack a Day, you still don’t have it do you? Pictures mabye

  4. “Except I used a phone dial to enter numbers, and used relays.”

    My father did something similar to that back in the early 80’s. Using an intel 8085 based microcomputer, a voice synthesizer chip, and a DTMF decoder. He could call his apartment, wait for the circuit to answer. The voice synth chip would actually talk to him on the phone, so he could hit the number 5 and it would respond “Your air conditioning is now on”. I wish I was alive to see it work :-)

  5. It’s still state of the art. Almost nobody makes digital calculators or watches that use any display technology that isn’t seven segment.

    40 years later and the displays are the same.
    What is really sad is when applications running on high resolution displays feel a need to use a font that resembles 60’s/70’s digital display technology.

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