Closed caption encoder for inserting caption and text data on line 21 of the NTSC signal. It will insert four channels of data that are multiplexed into the vertical interval on line 21 of field one. The four channels of line 21 are described as caption channel 1, caption channel 2, text channel 1, and text channel 2. It also processes data on line 21 of field two to meet the new revised FCC specifications. To meet future requirements, the PCE 845 is capable of inserting data on lines 10 through 25. A single internal jumper selects correct line placement. The unit is compatible with PAL closed caption, and caption data is usually inserted on Line 22 of field one. Line voltage operation is recommended for 115/240Vac, 50/60Hz, internally selected. The input signals are composite video, S/VHS, or Y, R-Y, B-Y. There are two composite video outputs. If a component format is used, the delay of each signal path is carefully matched, providing transparent thru-put. An RS-232C Input/output data port is provided on the rear panel that operates from 600 to 4800 baud (jumper selected). A second data port can accommodate an external modem. A switch on the front panel labeled test places a test message on line 21 to confirm proper operation of the encoder. A modem and computer can be connected to the PCE-845 simultaneously to receive local and remote caption data.