Comment by monerozcash

It's a legal term, has nothing to do with technical protections.

Practically any device connected to the internet is a "protected computer". The only case I can think of where the defendant prevailed on their argument that the computer in question was not a "protected computer" was US v Kane. In that case the court held that an offline Las Vegas video poker machine was not sufficiently connected to interstate commerce to qualify as a "protected computer".