[Test Desk]

So we have a crystal set, a wireless set, a television set and a handset. I never heard "radio set" but we still have the "goggle box" even though it's no longer box. A telephone handset consists of a transmitter and receiver combined, so "set" makes sense to me. I imagine "set top box" came from the US where they probably had cable TV before Betamax recorders, and as early TV sets were standalone items of furniture, the CATV control box would literally sit on top of the TV cabinet, thus becoming a "set top box". Then recorders came along and TV furniture had to adapt to accommodate extra bits of kit.