A multiplexing circuit uses parallel-configured pairs of resistors and signal sources in a voltage divider network in such a way that a single analog-to-digital input can be used to specify the state of more than one signal source. The player includes a front plate formed of metal and having an opening configured to receive a media unit. Each CPU may embed an operating system including a kernel comprising a protocol stack. The operator can be an automated operator, a manual operator, or a private branch exchange, for example.