Rupert Lane has started a blog series about Stanford's WAITS operating system for the PDP-10.
https://timereshared.com/stanford-waits/
In photos, upper right: Gareth Loy at an III display. Lower left: Jeff Rubin (standing) and Ralph Gorin (sitting) - two programmer wizards - at the KL10 console. Lower right: Les Earnest - pointing a FINGER, get it? - at a Data Disc display.

@larsbrinkhoff
From time to time I wandered onto the Stanford campus and used a freely-given account on WAITS. I thought it was supposed to be very much like ITS, but I found it confusing.

But I found ITS confusing too; I was a Unix guy in a strange land.

Later I spent enough time on TOPS-20 such that *it* was not confusing. It helps with operating systems to have lots of exposure, need to use, documentation, and community, in my experience.

@dougmerritt WAITS is more like TOPS-10. I guess from a Unix or ITS perspective, quite a lot alike. But there are also some differences.