For fun, I did a search for "user interface" before:1996-06-01 .
I found a paper that was definitely taking the perspective that the "user interface" encompasses all the ways in which the user can accomplish something via the software. It rated the effectiveness of a user interface in terms of the time taken to complete various specific tasks. (While remarking that other metrics matter to the concept too, and also measuring user satisfaction and error rates.)
But that paper also suggested how the term might have specialized - four pieces of software were studied, and they are presented in a table that gives their "interface technology", in two cases a "character-based interface" and in the other two a "graphical user interface".
Enough usage like that and you can see how "interface" might come to mean "what the user interacts with" as opposed to "how tasks are performed".
( https://www.nngroup.com/articles/iterative-design/ . It really is dated 1993, which I made a point of checking because Google assigns the "date" of a search result based on textual analysis, and it is frequently very badly wrong. I can't really slam the approach, which I assume was necessary to get the right answer here, but the implementation isn't working.)
I found a paper that was definitely taking the perspective that the "user interface" encompasses all the ways in which the user can accomplish something via the software. It rated the effectiveness of a user interface in terms of the time taken to complete various specific tasks. (While remarking that other metrics matter to the concept too, and also measuring user satisfaction and error rates.)
But that paper also suggested how the term might have specialized - four pieces of software were studied, and they are presented in a table that gives their "interface technology", in two cases a "character-based interface" and in the other two a "graphical user interface".
Enough usage like that and you can see how "interface" might come to mean "what the user interacts with" as opposed to "how tasks are performed".
( https://www.nngroup.com/articles/iterative-design/ . It really is dated 1993, which I made a point of checking because Google assigns the "date" of a search result based on textual analysis, and it is frequently very badly wrong. I can't really slam the approach, which I assume was necessary to get the right answer here, but the implementation isn't working.)