Sadly,cart machines have just about disappeared from radio stations-they want to use those computer touch screen studio systems for storing commercials,songs,and promos.But is there a backup in case the system crashes?It WILL crash-the question is WHEN?Other things of course that have disappeared from radio stations-live music programs,RR tape machines and Turntables along with record boards or racks full of records.Even AM transmitters are now solid state and have switching power supplies.Encountered a 1Kw AM solid state Transmitter that took up only half of astandard rack.Usual size is about that of a home fridge for one with tubes.You can now get SS 50Kw AM-and even larger--and SS TV,FM transmitters.I still like the ones that glow in the dark-just easier to fix.Least have an idea how long transmitting tubes last.But with SS the device could last 20 years or only 2 weeks-you just don't know.