When I was going to university there was great competition between the established HP and the upcomer TI, which made less expensive calculators that used algebraic notation. HP issued a marketing T-shirt, which simply said

Enter > =

where both Enter and = looked like the respective keys on the respective calculators. Same sort of argument you see between Apple and Windows today.

You must of had some extra bucks - my roomy had a TI - I had dad's slide rule!