I found this 1984 video about MIT's Project Athena. A few VAXstation 100 are visible running some demos in a windowing system. Nothing exciting unfortunately, just a few seconds and no details visible. Since X was started in 1984, it could be a very early version we see here. I asked Jim Gettys, and he suggested it could also be W since it was apparently used before X in Project Athena. https://youtu.be/tG7i7HCD9g0?t=28 I checked the xdemo director in X10R3 (earliest available so far) for a match against the circle demo, but all samples are written in CLU...