* PLATO at UIUC. Much more sophisticated graphics and extensive support for multiuser gaming, but requires custom (and expensive) terminals. Homegrown mainframe, then CDC hardware.
* Michigan Terminal System at University of Michigan and elsewhere. Runs on IBM mainframes.
* Multics, ITS, TOPS-10, and who knows what else at MIT. (Not Unix.) Mostly DEC hardware.
* Stanford's WAITS, a descendant of ITS. DEC hardware.
* Last but definitely not least, DTSS at Dartmouth, running on GE/Honeywell systems.
Of these, DTSS is by far the most widely used. Every Dartmouth undergraduate student is required to, at some point, write and debug a BASIC program. Terminals are everywhere on campus and almost everyone uses them for work (homework, research, and homegrown applications for registration and asset management for employees) and fun (games, email). Dartmouth's later BlitzMail is a natural extension of this mindset once things are decentralized to micros.
PLATO is widely available at UIUC but it is not proactively forced upon all students like DTSS. Based on The Friendly Orange Glow, some classes require its use but otherwise most seem to discover it from some unused terminal in the basement. No use by university employees.
From what little I know of MTS I think this is somewhere in between DTSS and PLATO in terms of adoption, at least at Michigan. Possibly more widespread/proactive at some other installations?
Stanford and MIT's systems are not for the masses, in the sense that students at large are not expected to use them. I don't think we're yet at the point where, for several years, anyone (affiliated with the university or not) can go to an MIT terminal (or connect remotely) and get an account. If not, you probably need to know someone in Course 6 or works at LCS. I think Stanford requires SAIL affiliation.
If Walter Bright reads this, he can tell us what Caltech is like.
Most other universities have computers by this time, of course, but almost always just batch-card systems.
Note that Unix is not listed above. I don't believe any university has students using it. Over the next decade there will be an explosion in multiuser, mostly driven by DEC hardware and, at first, DEC software, with Unix slowly, then suddenly, taking market share from DEC's own OSs despite outrage from DEC staff. DTSS, as widely used as it is, remains stuck in BASIC; in 1984 Dartmouth moves heavily into micros by becoming an early Macintosh adopter. PLATO remains isolated at UIUC; the ambitious CDC attempt to commercialize it almost kills the company, and anyway never goes beyond "drill and practice"-type software that wastes the graphical and social features. As mentioned, MIT is not a place where most students get exposure to computers, or otherwise an early pioneer in Unix. This suddenly changes in 1983 with Project Athena; within a few years MIT produces X and Kerberos.
About this time, my friend was working on his Ph.D. in Biology at Wayne State University and they had the MTS. It was pretty ubiquitous from what he’s told me.
I had a free account on MIT-AI at some point in the late 70s. I accessed it over the ARPANET!
My understanding is that, during the open access era, if you entered the wrong password the system would ask whether you wanted an account. Is that accurate?
How long did your account last? When did the mass revoking of non-MIT accounts occur? Or was there no such revoking, and accounts just expired from disuse?
You could login either using terminal through ARPAnet dial-in support, or later over network, and over time there was added a more concrete "tourist" policy.
DonHopkins seems to have an interesting writeup https://donhopkins.medium.com/mit-ai-lab-tourist-policy-f73b...
and of course there's PDP-10 org and its gather docs on github: https://github.com/PDP-10/its