
Build a No-Slot MIDI Interface on the Apple ][ Game I/O Socket - empressplay
https://paleotronic.com/2020/07/05/build-a-no-slot-midi-interface-on-the-apple-game-i-o-socket/
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danbmil99
Did similar stuff on Atari & Amiga. We actually had an app that could create
SMPTE timecode on a pin of a printer port. Then we could read the timecode
back (on an interrupt) and synchronize a MIDI score to a multi-track tape
recorder. Oh and we used another pin to output MIDI...

fun times

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dwheeler
I used to run my printer off my Apple II using the same kind of trick. Instead
of having a separate card, I used the game IO socket and some machine code.

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twoodfin
Had no idea that MIDI recommended/required (?) an opto-isolator as part of the
spec. Makes a ton of sense given the range (& expense!) of supporting devices
and the intended use.

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dhosek
I just had a flashback to the challenge of finding 150ohm dual axis variable
pots to have a joystick for an apple ][ because the ones that they sold at
Radio Shack were 100ohm.

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dan_hawkins
> The signals sent on your MIDI OUT port need to drive a phototransistor
> inside an opto-isolator in the MIDI IN circuit.

I would assume that MIDI OUT needs to drive LED in an opto-isolator.

