The 15-pin D-sub connector itself was apparently a combination of analog and digital. It had to be, since MIDI is digital (it’s right there in the name: Musical Instrument Digital Interface). TIL it wasn’t all digital.
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.
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.
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.
Its on the sound card because it’s a midi port. Its designed for connecting a keyboard (as in electronic piano). Most people used it for gamepads but that’s not what it was there for.
Big keyboard jack, serial for mouse, parallel for printer
Don’t forget the serial input for gamepads and joysticks in the dedicated sound board for some reason
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.
Wow, 30 years later and I’m just learning this now. Thank you
More info: https://en.wikipedia.org/wiki/Game_port
The 15-pin D-sub connector itself was apparently a combination of analog and digital. It had to be, since MIDI is digital (it’s right there in the name: Musical Instrument Digital Interface). TIL it wasn’t all digital.
huh, i thought it was just because “owning a sound card” and “likely to play games” was the biggest overlap of the Venn circles.
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.
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.
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.
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.
Its on the sound card because it’s a midi port. Its designed for connecting a keyboard (as in electronic piano). Most people used it for gamepads but that’s not what it was there for.
And because the PC only have 1 serial port, you disconnect the printer and use a parallel to serial adapter.
Yes, this is where my PC master gaming started.