Tony Iommi recently spoke to Planet Rock about BLACK SABBATH's decision to part ways with the malfunctioning Ozzy Osbourne in 1979 and replace him with Ronnie James Dio.

"I think the major problem started from drugs," Iommi recalled about the events that led to the split with Osbourne. "We'd been about for a while at that point and done a lot of touring — a lot of touring. It came to a point where we [needed] to do another album. And off we go to Los Angeles to do another album. And we had a house in L.A. that we were there for 11 months to rehearse in the house. We'd never done anything, basically. We came up with a lot of riffs and stuff, but we'd never actually done much as far as putting songs together. Because the whole thing was falling apart. Everybody's going in their own individual rooms. And at the end of the day, it just was disastrous — we just weren't producing anything. It was very difficult, because I can say, 'Ozzy was the first one to have to go,' but it was hard. We had to do something. It was me that used to take the stuff to the record company, and they're going, 'How's the rehearsals? How's the writing going?' 'Oh, great.' Lie. "When can we hear some stuff?' 'Oh, fairly soon.' We hadn't got anything. We got some music ideas, but not much vocal ideas. And Ozzy was going through probably a really awkward stage… We just got pressurized so much into, 'We've gotta do something.' Money was going out the window. It was costing a fortune staying there. Everything was coming to a head, and we had to say, 'Well, what are we gonna do? We're either gonna call it a day or break up or we've gotta try and find another singer.' We'd already had this problem slightly before we we went as well. And Ozzy left for a short while and came back. But in L.A., it just came to a crunch and it all came to an end."

Asked if BLACK SABBATH was close to breaking up at that time, Iommi said: "It certainly wouldn't have continued at that point. It was getting worse and worse. We were all so down then. We needed something to really boost us up. And so when we replaced Ozzy with Dio, it really did start us off again. We had somebody that's come in that's had some input. And he would sing to the riffs we'd got. 'Cause it's a bit disappointing when you come up with all these riffs and nothing is done with them. And you start thinking, 'What are we gonna do?' So when Ronnie came in and I played him a couple of riffs, immediately he started singing 'em. We were all living in the same house in Bel Air. In the garage, we turned it into a studio — we built a studio there. So we'd go in there and play. When Ronnie came up, we played it live, and it was great — he just sang away and it was brilliant. And it was a totally different approach. As soon as Ronnie got involved, the writing changed as well, because I was able to play a different way, for some reason. Whereas Ozzy would sing a lot on the riffs and follow the riff, Ronnie would sing in between stuff — he didn't always sing on riffs, and he'd sing on chords. And we were trying to also talk to him about singing on the riff as well, which he did on a couple of the things. But more or less, it was good, because you could approach the songs differently. And here you are with a singer that you don't know where he's gonna go. And it's quite exciting, because you can play something and you can hear him go into a place that you wouldn't ordinarily recognize… Later on, he started suggesting ideas. Not so much right in the beginning, because he was obviously new and he didn't wanna upset the boat. I think 'Children Of The Sea' was the first one he sang. And we had that riff for a bit, and he just sort of sang it. And it was really good — the first things he did."

With Ronnie at the mic, SABBATH released two consecutive classic metal albums, "Heaven And Hell" and "Mob Rules". Meanwhile, Ozzy had a string of solo hits and became force to be reckoned with in his own right.

