The original design used two projector screens, one for each wall, alternating with left- and right- eye views, with the user wearing shutter glasses keeping the vision in sync, while wearing a head tracker. They did use 7 SGIs (6 VGX workstations and a Personal Iris) for the system.

Full details at https://dl.acm.org/doi/epdf/10.1145/129888.129892 .

Later designs included displays on 4 walls plus floor for near immersive VR.

This seems to be one of the few: https://www.webwire.com/ViewPressRel.asp?aId=11400