The "Brain Room" of the HAL 9000 computer from the end of 2001: A Space Odyssey and from the middle of 2010.
Arthur C. Clarke specifically says HAL stands for "Heuristically programmed ALgorithmic" computer -- and is NOT a letter-shift from IBM. Had he realized it would be interpreted as a letter-shift, he says, he would have named it something else.
Clarke initially wanted to call the computer Socrates, and to give it a robotic body so it could move around. In early script drafts, Socrates is asked early in the film to turn off the units for hibernating scientists Kaminski and Whitehead, but it cites the "First Law of Robotics" (never allow, or through lack of action allow, a human being to be harmed). This was a nod to the Rules of Robotics in Isaac Asimov's novels.
Clarke then gave the computer a female persona and named it Athena. In this script draft, Bowman tries to revive Dr. Whitehead after the death of Poole but Whitehead dies. Bowman then tries to realign the antenna outside the ship, and Athena tries to stop him from leaving.
The idea for having HAL's voice degrade as his memory is taken away came from a demonstration Clarke had seen of a voice synthesizer and how it could change speech.
Although the female persona was changed back to male prior to filming, Stanley Kubrick had actress Stefanie Powers provide the voice of HAL during rehearsals. Actor Nigel Davenport provided the voice of HAL on the set, but he was released after a while because Kubrick felt his voice was too British. First assistant director Derek Cracknell provided the voice of HAL on-set afterward, and even Kubrick fed the actors some of the more mundane lines. Kubrick cast Martin Balsam to dub HAL's lines in post-production, but replaced him with Douglas Rain after Kubrick concluded that Balsam had a voice that was "too American".
It's not clear who designed the HAL 9000 lens and faceplate that is seen throughout the movie. Eliot Noyes & Associates, a computer design firm, did early work on "Athena" for the film, but their concept was rejected.
The HAL 9000 faceplate features a Nikon Nikkor 8mm F8 lens. A red light projected behind the lens created the red glow effect.
The "Brain Room" of HAL 9000 was actually three stories high. Actor Keir Dullea was suspended from wires (which extended behind him, out of sight) to allow him to "drift weightlessly" toward the higher-level memory banks. Dullea moved slowly to mimic the effect of weightlessness.