The MC144144 is a Line 21 closedcaption decoder for use in television receivers or settop decoders conforming to the NTSC standard. Capability for processing and displaying all of the latest standard Line 21 closedcaption format transmissions is included. The device requires a closedcaption encoded composite video signal, a horizontal sync signal, and an external keyer to produce captioned video. RGB and box signal outputs are provided, which along with the mode select, allow simple interfacing to either color or blackandwhite TV receivers.