Why do we say someone is "on their computer"?
We don't say they are on the tv when watching TV, and we don't say they are on the radio when listening to the radio. But if someone is, like me right now, using their computer, they are ON the computer.
I just find it a strange way of wording it. Is there a reason why the preposition on is collocated with computer?
Solution 1:
I would suggest that there's a silent working there, and so the sentence is a contraction, as in:
I'm (working) on my computer.