Since entering software engineering, I picked up the habit of saying "machine" when talking about a computer. Most of my colleagues seem to do the same. However, when I use this idiom in everyday conversation, people get a bit confused.
Obviously, a computer is a machine. However, most machines are not computers. So it's a bit non-obvious why we do that.
So what is the history behind this practice? Where does this come from?
When computing machines were invented, the term "computer" already existed as the job description of a person whose job it is to compute things. Computing machines were called "machines" because they were machines, as opposed to the computers they replaced, which were people.
Jorg's explanation that the term computer was originally an occupational description for a person is interesting.
However, the existence of such roles has receded from living memory (certainly inside the workplace), and nowadays it cannot be discounted that "machine" is just two syllables and "computer" is three, and thus machine is a form of occupational jargon that is preferred for its brevity and ease of articulation.
I haven't known people to become confused by the word in appropriate context, unless the context itself would be confusing and unfamiliar to people not accustomed to working with IT.
Let's not forget the Turing Machine, and also, from Wikipedia
Charles Babbage began to construct a small difference engine in c. 1819[4] and had completed it by 1822 (Difference Engine 0).[5] He announced his invention on 14 June 1822, in a paper to the Royal Astronomical Society, entitled "Note on the application of machinery to the computation of astronomical and mathematical tables".[6]
So, precursors of computers were called machines as far back as at least 1822.
The early computers were used to perform calculations, particularly to crack secret messaging at times of war, thus they were called computers. As the number of applications increased, the term computer became less appropriate and was replaced by the more generic term machine, which better suits the general purpose character of the thing.
