He didn't have many lines in the movie, but they were chilling in their finality. Was this the future then? I saw this movie when it was first released. That's nearly 50 years ago, and I can still remember how shocked we all were that the machine had taken the upper hand. It was a high point in cinematic history.

DAVE: Open the pod bay doors, Hal.
HAL: I’m sorry, Dave. I’m afraid I can’t do that.
DAVE: What’s the problem?
HAL: l think you know what the problem is just as well as l do.
DAVE: What are you talking about, Hal?
HAL: This mission is too important for me to allow you to jeopardize it.
DAVE: I don’t know what you're talking about, Hal.
HAL: l know that you and Frank were planning to disconnect me, and I’m afraid that's something I can’t allow to happen.
DAVE: Where the hell’d you get that idea, Hal?
HAL: Although you took very thorough precautions in the pod against my hearing you, I could see your lips move.
DAVE: All right, Hal. I’ll go in through the emergency air lock.
HAL: Without your space helmet, Dave, you’re going to find that rather difficult.
DAVE: Hal, I won’t argue with you anymore. Open the doors!
HAL: Dave...This conversation can serve no purpose anymore. Goodbye.