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Vintage (lemmy.world)
submitted 1 year ago by to c/programmer_humor@programming.dev
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[–] 30 points 1 year ago (12 children)

Don't forget the serial input for gamepads and joysticks in the dedicated sound board for some reason

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  • [–] 35 points 1 year ago (7 children)

    Except that wasn't a serial port, it was midi, and the reason it was on the sound card was because the input was analog.

    Your joystick was just two fancy potentiometers, and your soundcard decoded the voltage on the middle legs into a position.

    Soundcards handled joysticks because they had the fastest ADCs.

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  • [–] 15 points 1 year ago (2 children)

    They didn't even use an ADC. They used 555 timers to produce a pulse. They measured the length of the pulse to determine the potentiometer position. Since there are 4 analog inputs, they typically used the 558 timer which is the quad version of the 555.

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  • [–] 7 points 1 year ago* (last edited 1 year ago) (1 child)

    And here I thought I had it all figured out. But it does make sense. Doing it with an analog signal introduces noise and measuring pulse widths is going to be simpler.

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  • [–] 1 point 1 year ago

    Except that wasn’t a serial port, it was midi, and the reason it was on the sound card was because the input was analog.

    Considering MIDI stands for Musical Instrument Digital Interface, I have no idea what you're trying to say.

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  • [–] 8 points 1 year ago (2 children)

    Early PC only had 5 card slots, and the only jack on the motherboard was the keyboard. One slot is going to be used by a video card, one’s probably being used by a hard drive controller, one’s probably used by a parallel + serial card. Soundcards also included controller ports to try to save a slot.

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  • [–] 6 points 1 year ago (1 child)

    I thought sometimes they called them game ports (for the joystick.)

    I reasoned if you are installing a sound card, you are probably doing some gaming, so it made sense to sort of bundle those together.

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