Microsoft, founded by the billionaire entrepreneur Bill Gates, is to invest $220m (pounds 140m) over five years for a half-share in the cable unit, to be called MSNBC Cable. Expected to begin operations within six months, the venture will represent the first serious challenge to Ted Turner's CNN.
The two companies will meanwhile have equal shares also in MSNBC Online, which will package the news for distribution on the Internet. The Online service will provide both text and graphics, incorporating video from NBC, and will be fully interactive.
The companies said that they expected to invest an additional $200m between them, also over five years, for the development of the two services. MSNBC Cable will be managed by NBC solely, while MSNBC Online will be jointly managed, with NBC retaining exclusive responsibility for news content.
"Both of the companies are saying we believe in the world of interactivity but we're bringing this world into broadcast," Mr Gates said. "We'll be working with NBC to create an integrated media experience". The move is intended to steal a march on ABC, shortly to become a unit of Disney, which earlier this month announced plans for a 24-hour news channel starting in 1997. Rupert Murdoch also vowed recently to embark on a non-stop news channel.
Andrew Lack, NBC's head of news programming, said the deal represented, "a giant leap for electronic journalism into the next century". The online service will be boosted by the introduction of modem technology next year allowing full video to be shown on personal computers on the Internet.
Users of the service will be able to tailor exactly which stories in the day's news they wish to view and, equally, to highlight specific elements in a single story that may interest them.
In Europe the MSNBC Cable service will be delivered to viewers by NBC's existing cable and satellite operation, SuperChannel/CNBC.Reuse content