[teleforce]

Since Multics is written for modern or next-generation time-sharing OS at the time hence it must support multi-process and multi-user capability. This capability is represented by the multiplex terminology. In the early days of analog and digital communication, multiplex is the scheme to transmit and receive multi-user information in time or frequency domain.

If you think about it, much of the complexity of Multics come from its multi-user requirement with overly complex access control matrix, multitude of file types including design for multi-user support, etc. Thus the Unix name metaphor or pun is to make it the latter simple by requirement and design. Remember that Unix was started as a skunkwork and even the original PDP-7 that being used originally was donated by other department of AT&T if I remember correctly it was the sound signal processing department [1]. If it is an official project, the multi-user requirement will be there from the start since arguably AT&T is the largest technical company at the time and they will want multi-user from the get-go.

But after some time and considerable success of Unix, the designers probably looks childish due to the naming since they did introduce multi-user at the later stage, and toned down the exact meaning of Unix. What is the opposite of multi, it is uni.

[1] The Strange Birth and Long Life of Unix:

https://spectrum.ieee.org/the-strange-birth-and-long-life-of...

[remram]

Your reference doesn't claim that the OS was single-user, only that it was developed for a single person (Thompson). There is no evidence that it was ever a single-user system or that it was named after that.

> Because the new operating system supported only one user (Thompson), he saw it as ...

This has a lot more good references too: https://retrocomputing.stackexchange.com/questions/10907/was...

[teleforce]

My previous reference is for the skunkworks not for multi-user. Since it's a skunkworks project there is no requirement for the OS to have multi-user so basically Ken is free to design the Unix system as simple as he wished. That's why initially Unix is a single user, flat file, etc [1]. It's not only for single user but also only support single task or process initially. This design of original Unix is the antithesis to the Multics (thus the name Unix) and the latter was designed from the start as per requirements as multi-process and multi-user hence the inherent complexity. Ken is still alive today perhaps you should ask him directly about this fact and I've no reason to believe otherwise.

[1] Unix:

https://en.wikipedia.org/wiki/Unix