The Axio music controller designed by Brad Cariou at the University of Calgary back in the early 90s. From the YouTube description –
I designed the electronics and firmware for the chording keyboard in this alternative MIDI controller in the early 90’s. It was made using a set of Yamaha DX7 key contacts. These contacts have both make and break contacts which allow for velocity sensing. The firmware was done in 8031 assembler and the source code is posted on my website, www.MusicTechnologiesGroup.com The project was presented at various conferences and symposiums around the world.
Built with interactive programming mainstay Max/MSP the project resembles many experimental controllers we see introduced nowadays. Some additional info is available on the University of Calgary’s site