The STV5342 is a HCMOS integrated circuit which performs all the processing of logical data within a 625 lines system teletext decoder. It is designed to operate in conjunction with one-chip : the SAA5231 integrated chip which extracts Teletext information embedded in a composite video signal. Up to 4 pages of display data can be stored in internal memory. A complete system also comprises a microprocessor controlling the STV5342 via a 2-wires serial bus. An on-chip ROM memory contains the character sets. The STV5342 performs automatic selection of one of up to six natural languages. Data bytes may be decoded in either 7-Bit plus parity or in full 8-Bit formats. The chip set also supports facilities for reception and display of higher-level protocol data.