MY103842A - Rapid access teletext decoder arrangement. - Google Patents

Abstract

A TELETEXT DECODER INCLUDES A BACKGROUND OR BUFFER MEMORY (45) OPERATING AS A FIRST-IN, FIRST-OUT (FIFO) MEMORY. THE BUFFER MEMORY (45) IS USED FOR STORING A LARGE NUMBER OF TELETEXT PAGES. A GIVEN VIDEO LINE THAT CONTAINS TELETEXT INFORMATION IS IDENTIFIED AS SUCH BY THE DETECTION OF PART OF A CLOCK RUN-IN SEQUENCE FOLLOWED BY THE FRAMING CODE. THE VIDEO LINE IS THEN STORED IN THE BACKGROUND MEMORY (45). AFTER A USER PAGE REQUEST OCCURS, THE BACKGROUND MEMORY (45) IS READ-OUT BY A DATA PROCESSOR (30) OPERATING IN A FULL CHANNEL MODE OF OPERATION FOR OBTAINING THE INFORMATION OF THE REQUESTED OAGE. AS LONG AS THE READ-OUT OPERATION HAS NOT BEEN TERMINATED, INCOMING TELETEXT DATA IS STORED IN THE BACKGROUND MEMORY (45). THIS ENABLES TELETEXT DATA RECEIVED PRIOR TO TERMINATION OF THE READ-OUT OPERATION TO BE READ OUT AND PROCESSED BY THE DATA PROCESSOR.@@(FIG. 2)