Early in the episode, we hear Peppermint Patty singing the 1892 song "Daisy" (full title of which is "Daisy Bell (Bicycle Built for Two)"). This song was used in the movie "2001: A Space Oddysey", at the moment HAL begs for his life. The use in 2001 is significant because it was the first song ever performed by a computer, specifically, the IBM 704, at Bell Labs in 1962. On a surface level, this moment functions as an homage to the early days of artificial intelligence, but it also poses an important question about sentiency and humanity.
HAL's scheming and logic fade to simplicity as the computer regresses by 40 years, back to a time when computers were programmed to bring joy to those around them. The song takes HAL back to its childhood, and emphasizes that Dave is killing that child just as much as he is dismantling a malfunctioning computer system. Adding to the overall themes and interpretations of 2001: A Space Odyssey, HAL's callback to an earlier system command suggests that evolution may be just as possible for computers as it is for humans, given a sufficient level of sentience.
