A sci-fi book from the 70's

I am looking for the title of a 1970's sci-fi book that describes a world with planet wide internet whereas people are connected to the internet through a brain implant. They also have direct democracy in that they can vote on all new laws or project from the governments. They also have to "unplug" from the net because many people develop an "overdose" of internet connection and need to be treated - or simply disconnect- from internet overload. The book also predicted the large use of the internet for pornography.

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