Apropos the story of MTS running on tiny hardware, I've been musing about what it would take for modern software to consider itself a spiritual heir to the MTS online conferencing system Confer, written by Bob Parnes. I spent a lot of time on Confer in my misspent college days, and most of what I think about online communications is somehow influenced by that system.
Confer is a structured communications system, in that there is a definite distinction between the first message in a conversation thread (the "item") and the subsequent responses. Items and responses have numbers, so that you can refer unambiguously to 6:23 and someone can go back and read that. Conferences have names, and membership in a conference is controlled down to the individual level if the organizer so desires.
A typical Confer conference either had a very narrow, focused point of view with a set of people trying to tackle some specific issue, or a general point of view open to all comers with very little restriction on the topics. A conference might be open ended, or it could be shut down after a decided on period of time when the work was concluded.
It's possible to use weblogs like Confer, sorta kinda, but they give relatively too much power to the blog owner (the person who authors posts, or "items") in shaping the discussion. My words are always at the top of the page, which doesn't always make for good dialog. Group blogs help somewhat, though there's still an editorial focus that doesn't feel like a conference.
Private Facebook groups, especially those that are carefully tended, come closer to Confer behavior. You have the same item and response structure, and a similar level of control over who participates. The biggest issue is that old Facebook posts scroll off into the mists of time, and it's hard to have a lot of conversations going on at once without overwhelming the board. This contrasts with Confer where judicious use of the "forget" command could keep one noisy item from overwhelming the whole thing.
Finally, of all things, the Github "issues" board has a very similar structure to Confer, with items ("issues") and responses neatly threaded. It has some of the less-used abilities of Confer to categorize and organize items, plus a well thought-out cross reference facility so that a link to another issue is easy to turn into something that you can click through.
We've gone from an era of computing scarcity to an era of embarrassing plenty. What's missing from everything is the sense that this mainframe that you were typing at was the only thing that was absorbing everyone's online attention, and that there really wasn't anything else that had the same density of local contacts and connections. The Internet is chockablock with online discussion and sharing systems looking to capture a piece of your daily energy, with more coming all the time. The era of the centralized mainframe with the centralized discussion board is over, no matter how compelling the features of its time seemed to be.