I don't think anybody referred to Acorn Computers as PCs (so, no, not only Apple). PC means different things according to the context, but the main ones are a

I don't think anybody referred to Acorn Computers as PCs (so, no, not only Apple). PC means different things according to the context, but the main ones are a) IBM-compatible PC. Which means Windows/MS-DOS. b) Personal computer, which means Mac The 'I'm a PC' advertising campaign, while quite entertaining, seems a bit outdated now IMO. Probably because compatibility issues aren't much of a headache these days for Mac/PC owners, who primarily just go on Facebook and check their email. Seems weird that Windows users would still think of themselves as 'PC' people.