This is another Twitter bot that I’ve made that you might find interesting. VL-Tonifier makes ADSR settings for Casio VL-1’s.
Basically the VL-1 takes its synth input via a sequence of 8 numbers. These control the basic sound and then the ADSR envelope. If you’re interested in knowing more you can find a PDF of the Casio VL-1 manual Casio VL-1. And, if you’re really keen you can find VL-Tones on eBay here.
And he’s a little video of when there used to be a VL-1 on the app store: