Letter: HAL's birthday

Sir: I have just read the article "Arthur C Clarke's brainchild" (Network, 13 January). Sunday, 12 January is claimed to be the day that HAL, the intelligent computer, "became operational" in the film/book 2001, A Space Odyssey.

I have watched the film again. About 1 hour 40 minutes into the film, while his higher functions are being cut, HAL is heard to say: "Good afternoon, gentlemen. I am a HAL 9000 computer. I became operational at the HAL plant in Urbana, Illinois, on 12 January 1992" - not 1997.

The story underwent numerous rewrites, and the plot varies between the film and the book. Small wonder HAL became psychotic - the first uncertainty it had to deal with was its age.

COLVILLE CROOKS

Wokingham, Berkshire