The Intervision Song Contest was an international song competition organised by the International Radio and Television Organisation. It was the Eastern Bloc equivalent to the Eurovision Song Contest. It was transmitted to national broadcasters via the Intervision network. The contest took place in Czechoslovakia, and in the Forest Opera in Sopot, Poland.
The ISC was organised from 1965 to 1968 and again from 1977 to 1980. Since 1977, it replaced the Sopot International Song Festival that had been held in Sopot since 1961. From Wikipedia
