Douglas Rain, HAL 9000's voice in '2001: A Space Odyssey,' has died. He was 90.

“I’m sorry, Dave, I’m afraid I can’t do that.”

Douglas Rain, the actor who performed the voice of the computer Hal 9000 in Stanley Kubrick's film '2001: A Space Odyssey,' has died. He was 90 years old.

A transcript of the '2001' voice recording session in the Stanley Kubrick archives at the University of the Arts, London shows that Kubrick didn't give much direction to Rain, just a few brief notes like this:

— “Sound a little more like it’s a peculiar request.”

— “A little more concerned.”

— “Just try it closer and more depressed.”

From an archival New York Times article about the story that led to Rain being cast as the computer's voice in '2001' —

The “2001” historian David Larson said that “Kubrick came up with the final HAL voice very late in the process. It was determined during ‘2001’ planning that in the future the large majority of computer command and communication inputs would be via voice, rather than via typewriter.”

But artificial intelligence was decades from a convincing facsimile of a human voice — and who was to say how a computer should sound anyway?

To play HAL, Kubrick settled on Martin Balsam, who had won the best supporting actor Oscar for “A Thousand Clowns.” Perhaps there was a satisfying echo that appealed to Kubrick — both were from the Bronx and sounded like it. In August 1966, Balsam told a journalist: “I’m not actually seen in the picture at any time, but I sure create a lot of excitement projecting my voice through that machine. And I’m getting an Academy Award winner price for doing it, too.”

Adam Balsam, the actor’s son, told me that “Kubrick had him record it very realistically and humanly, complete with crying during the scene when HAL’s memory is being removed.”

Then the director changed his mind. “We had some difficulty deciding exactly what HAL should sound like, and Marty just sounded a little bit too colloquially American,” Kubrick said in the 1969 interview. Mr. Rain recalls Kubrick telling him, “I’m having trouble with what I’ve got in the can. Would you play the computer?”

Kubrick had heard Mr. Rain’s voice in the 1960 documentary “Universe,” a film he watched at least 95 times, according to the actor. “I think he’s perfect,” Kubrick wrote to a colleague in a letter preserved in the director’s archive. “The voice is neither patronizing, nor is it intimidating, nor is it pompous, overly dramatic or actorish. Despite this, it is interesting.”

On Twitter, 'Baby Driver' director Edgar Wright remembered Rain as "One of the best performances in film, with just his voice."