Introduced in the UK 1983, thus agreeing with the Prof's memory, Diet Coke uses an entirely different formula from regular Coke.
However, Tab was the Diet brand of the Coca Cola Company from 1963 onwards. The Coca-Cola Company refused to use the Coca-Cola brandname, fearing that its flagship brand might suffer by being used on another product, the long-term viability of which was uncertain.
Its rival Pepsi had no such qualms, and after the long-term success of its sugar-free brand Diet Pepsi, launched in 1964, became clear, Coca-Cola decided to launch a new sugar-free brand under the Coca-Cola name to compete with Diet Pepsi.
It still tastes like over sweetened cack though.
