he thinks he's been using the same one for a decade

I've heard a lot of older people say things like "using the computer" when it'd be more natural to say "using computers", and I think it's often a sign that these people date back to the time when the company had a computer, and it clanked and whirred, and people were terrified of it, and went on earnest but incomprehensible internal training courses with titles such as "Doing Payroll -- Using The Computer".

Peter