Immediately upon completing the cable, I quickly:
- booted the Apple IIe to the BASIC prompt
- connected the cable between the iPhone and IIe
- wrote a few lines of REM statements
- launched the Voice Memo app on the iPhone
- pressed “Record” in the app
- typed “SAVE” from BASIC
- waited for the BASIC prompt to come back
- pressed “Stop” in the app
- unplugged the iPhone
- listened to what was recorded and…
All I could hear in the recording was myself typing on the IIe and rustling about in my nylon jacket. So obviously the iPhone was using its internal microphone instead of the line-in. After verifying all the connections were valid along the cable and behind the IIe, I decided to pray to the Internet.
The Internet told me that the iPhone expects a particular amount of impedance on the microphone pin before it will be recognized. Otherwise the iPhone will default to using the built-in microphone. About 1600 ohms is needed.
So without knowing what that really meant I decided to add two resistors I found in my junk pile, a 1k and 620 ohm in series along the line and things are back on track.
I am now able to record to the iPhone.
You may wish to turn down your computer’s speaker volume before clicking on this link. There will be 10 seconds of mind-numbing tone followed by another long run of “was-once-my-mind-but-is-now-jelly”-numbing tone before the data part starts to warble out.
Apple II Cassette Audio Test (recorded using the cable above and the Apple iPhone Voice Memo app)
But then, as it is with computers, I hit Snag #2…