Teletext and to pad out the fixed packet. The vertical caption position is determined by the packet address. In the case of the Ceefax and ORACLE systems and their successors in the UK, the teletext signal is transmitted as part of the ordinary analog TV signal but concealed from view in the Vertical Blanking Interval (VBI) television lines which do not carry picture information. The teletext signal is digitally coded as 45-byte packets, so the resulting rate is 7,175 bits per second per used lines (41 7-bit 'bytes' per line, on each of 25 frames per second). A teletext page comprises
Teletext list of news headlines might appear on page 110; a teletext user would type "110" into the TV's remote control to view this page. The broadcaster constantly sends out pages in sequence. There will typically be a delay of a few seconds from requesting the page and it being broadcast and displayed, the time being entirely dependent in the number of pages being broadcast. More sophisticated receivers use a memory buffer to store some or all of the teletext pages as they are broadcast, allowing instant display from the buffer. This basic architecture separates from other digital information systems, such