Teletext default graphics mode (mode 7) was based on Teletext display, and the computer could be used to create and serve Teletext-style pages over a modem connection. With a suitable adapter, the computer could receive and display teletext pages, as well as software over the BBC's Ceefax service, for a time. The Philips P2000 home computer's video logic was also based on a chip designed to provide teletext services in TVs. Prestel was a British information-retrieval system based on teletext protocols. However, it was essentially a different system, using a modem and the phone system to transmit and receive the data,
Teletext systems mounted a large market trial in Los Angeles in partnership with NBC and Public Broadcasting Service (PBS) Public television. Services premiered simultaneously on station KNXT (now KCBS-TV), KNBC and KCET in Los Angeles. All three services included an array of local news and information services. KCET's service also included service components for use in schools. Later, an official North American standard of teletext, called NABTS (North American Broadcast Teletext Specification) was developed in the early 1980s by Norpak, a Canadian company. NABTS provided improved graphic and text capability over WST, but was quite short-lived. This was mainly due to the