In 1985 it would seem MXR employed the team at ART (Applied Research & Technology) to produce a digital reverb, based on the ART 01A, and it even had ART listed as the manufacturer on the front panel.
Released in 1985
ART 01A Digital Reverb
The ART 01A is a digital reverb from around 1985, that was also licensed to MXR and sold with the same 01A name on the front panel, but refereed to as the Model 191 on the rear.