I finally picked up a Mac-101e keyboard for a negligible price. Of course when I got it I promptly took it apart. I'll post pictures of the circuit board at some point. Like most keyboards it is quite simple with what appears to be a custom controller chip and a couple of smaller off-the-shelf ICs that appear to be the same as that used in the Mac 128K-Plus keyboard. It has two ADB ports (one at each end) and an RJ-10 connector.
The most surprising thing was the DIP switch array, which is explained HERE.
Evidently the DIP switch is configured to route the signals to ADB or RJ-10 protocol. Surprisingly it is not easy to change (you have to pry off a cover), so switching back and forth between the two platforms would not be practical. Perhaps I am inferring too much here, but it seems that this happens after the keystrokes have been processed, meaning there should be a way to construct a simple converter to RJ-10 or ADB from any keyboard. Now that I know what the DIP switches do, I'll need to follow the traces to see what they connect to. Obviously any adapter would have to intercept the signal directly on the keyboard before it reaches the external connectors.
Possible issues: Is it possible that either or both Apple ADB & RJ-10 keyboards' keystroke ICs output the appropriate signal protocol rendering interception impossible? Would third party keystroke encoding be dramatically different from Apple's?
Observation: Considering Apple produced the Plus as long as it did the SE, it seems like they should have make the ADB keyboard a hybrid as well, producing one keyboard for both Macs to save money. That way they could have sold the Plus for even less, during the age of "optional" keyboards.
The most surprising thing was the DIP switch array, which is explained HERE.
Evidently the DIP switch is configured to route the signals to ADB or RJ-10 protocol. Surprisingly it is not easy to change (you have to pry off a cover), so switching back and forth between the two platforms would not be practical. Perhaps I am inferring too much here, but it seems that this happens after the keystrokes have been processed, meaning there should be a way to construct a simple converter to RJ-10 or ADB from any keyboard. Now that I know what the DIP switches do, I'll need to follow the traces to see what they connect to. Obviously any adapter would have to intercept the signal directly on the keyboard before it reaches the external connectors.
Possible issues: Is it possible that either or both Apple ADB & RJ-10 keyboards' keystroke ICs output the appropriate signal protocol rendering interception impossible? Would third party keystroke encoding be dramatically different from Apple's?
Observation: Considering Apple produced the Plus as long as it did the SE, it seems like they should have make the ADB keyboard a hybrid as well, producing one keyboard for both Macs to save money. That way they could have sold the Plus for even less, during the age of "optional" keyboards.