Abstract: A projection television system which adapts automatically between from screen projection and rear screen projection upon insertion of the projector into a rear screen cabinet. A compact projection unit has a quick-disconnect electric connector and optical aligner which mate with connection elements in a projection cabinet upon insertion of the projector into an opening in the front of the cabinet. The cabinet has a two-mirror optical relay which inverts the projected picture. Upon completion of insertion, the electric connections automatically invert the image being projected by the projector. In another embodiment, insertion also automatically connects to audio equipment in the rear screen cabinet.

Abstract: A remote control transmitter, preferably a universal or reconfigurable remote control transmitter, is incorporated into a television receiver. Mounting a light emitting source such as a light emitting diode in a line of sight or a wired connection with an external tuning system such as that of a VCR or cable converter, and modification of the television tuning system to cause the transmission of activating signals to the remote control transmitter, allows functions which are channel associated and which are therefore generally suppressed when a remote tuning system is used to remain in force.

Abstract: In a contention polling arrangement wherein polling messages are transmitted by a central controller for simultaneously polling a group of remote stations, the polling message contains an address which defines the entire range of remote stations to be polled and the remote stations will respond if their addresses fall between the address contained in the polling message and an address resulting from converting any trailing 0's of the address in the polling message to 1's.