Technology in the 1950's was based on the use of vacuum tubes. These tubes, consisting of various wires and metals in specific configurations were pretty large, some as big as a light bulb. In addition to taking up a lot of room, they were very fragile, and needed to be kept apart. They also generated a lot of heat. The large cabinets were necessary to protect the glass tubes and absorb the heat without catching fire. Up into the 1960's, many hardware stores had large testing machines that you could use to see if your radio or television tubes were okay, or whether they had burnt out, then you could purchase the appropriate ones to replace them. Today, the tube has been replaced with semi-conductors that are solid state, require very little power and therefore generate very little heat, and thousands of them are crammed into a postage stamp sized microchip.