My 1998 album was called "Vokoder", because I have always liked this sound a lot! Here's Berhninger's new remake of a classic vocoder keyboard. It does sound different than digital vocoders, and it's not "Auto Tune" - that's something different. B - ) In this case, you play the notes and chords, and talk or sing into a microphone plugged into the machine to get these type of results.
Vocoders do tend to require precise adjustments to get the best "robot voice" sounds, but I easily got this working in minutes.