Frederick Brooks and the Definition of Computer Architecture
In The Mythical Man-Month, Frederick P. Brooks, Jr. uses the term “software architecture” to talk about “the complete and detailed specification of the user interface.” As I did some research I found an article (PDF) which states that he, together with Gene Amdahl and G. Anne Blaauw,
coined the term [computer architecture] to refer to those aspects of the instruction set available to programmers, independent of the hardware on which the instruction set was implemented.
After having thought about it for a while, I realized that it wasn’t as strange a change in usage as I first found it. According to a short bio of Brooks I found, the term was coined as early as 1957, at a time when the users spoke “machine language,” when the instruction set was the user interface.