While part of HAL's hardware is shown toward the end of the film, he is mostly depicted as a camera lens containing a red and yellow dot, with such units located throughout the ship.

HAL speaks in a soft, calm voice and a conversational manner, in contrast to the crewmen, David Bowman and Frank Poole.

[1][2] In addition to maintaining the Discovery One spacecraft systems during the interplanetary mission to Jupiter (or Saturn in the novel), HAL has been shown to be capable of speech synthesis, speech recognition, facial recognition, natural language processing, lip reading, art appreciation, interpreting emotional behaviours, automated reasoning, spacecraft piloting, and computer chess.

[2] In 2001: A Space Odyssey (1968), HAL is initially considered a dependable member of the crew, maintaining ship functions and engaging genially with his human crew-mates on an equal footing.

In the film, astronauts David Bowman and Frank Poole consider disconnecting HAL's cognitive circuits when he appears to be mistaken in reporting the presence of a fault in the spacecraft's communications antenna.

When Bowman, without a space helmet, uses another pod to attempt to rescue Poole, HAL locks him out of the ship, then disconnects the life support systems of the other hibernating crew members.

Dave begins to revive his hibernating crew mates, but is foiled when HAL vents the ship's atmosphere into the vacuum of space, killing the awakening crew members and almost killing Bowman, who is only narrowly saved when he finds his way to an emergency chamber which has its own oxygen supply and a spare space suit inside.

In the film, HAL's central core is depicted as a crawlspace full of brightly lit computer modules mounted in arrays from which they can be inserted or removed.

HAL finally reverts to material that was programmed into him early in his memory, including announcing the date he became operational as 12 January 1992 (in the novel, 1997).

In the 1982 novel 2010: Odyssey Two written by Clarke, HAL is restarted by his creator, Dr. Chandra, who arrives on the Soviet spaceship Leonov.

Therefore, HAL made the decision to kill the crew, thereby allowing him to obey both his hardwired instructions to report data truthfully and in full, and his orders to keep the monolith a secret.

In the film, HAL functions normally after being reactivated, while in the book it is revealed that his mind was damaged during the shutdown, forcing him to begin communication through screen text.

In Clarke's 1987 novel 2061: Odyssey Three, Heywood Floyd is surprised to encounter HAL, now stored alongside Dave Bowman in the Europa monolith.

The earliest draft depicted Socrates as a roughly humanoid robot, and is introduced as overseeing Project Morpheus, which studied prolonged hibernation in preparation for long term space flight.

Athena refuses to allow him to leave the ship, citing "Directive 15" which prevents it from being left unattended, forcing him to make program modifications during which time the antenna drifts further.

[7][1] After the film was released, fans noticed HAL was a one-letter shift from the name IBM and there has been much speculation since then that this was a dig at the large computer company,[27][28] something that has been denied by both Clarke and 2001 director Stanley Kubrick.

[1] Clarke addressed the issue in his book The Lost Worlds of 2001: ...about once a week some character spots the fact that HAL is one letter ahead of IBM, and promptly assumes that Stanley and I were taking a crack at the estimable institution ... As it happened, IBM had given us a good deal of help, so we were quite embarrassed by this, and would have changed the name had we spotted the coincidence.

"[32] The former president of HAL Communications, Bill Henry, has stated that this is a coincidence: "There was not and never has been any connection to 'Hal', Arthur Clarke's intelligent computer in the screen play '2001' — later published as a book.

Kelly's voice recorder synthesizer vocoder recreated the song "Daisy Bell", with musical accompaniment from Max Mathews.

Marvin Minsky, director of the MIT Computer Science and Artificial Intelligence Laboratory (CSAIL) and one of the most influential researchers in the field, was an adviser on the film set.

For example, AI pioneer Herbert A. Simon at Carnegie Mellon University had predicted in 1965 that "machines will be capable, within twenty years, of doing any work a man can do".

[39][40] Michael Fassbender has also cited HAL as an inspiration for his performances as android characters such as David (Prometheus) and Walter (Alien: Covenant).