Fans who pre-ordered the OK Computer box set were offered a 78-minute digital download, featuring old demo tracks and discarded audio. The last few minutes contain audio which, after processing through a low-pass filter, becomes a small Spectrum program. It took a fair amount of determination by Reddit user Maciej Korsan to get it working, and here are the results:
Additionally, the program's code contains a giant REM (remark) statement, blacked out. When revealed, it reads "congratulations....you've found the secret message syd lives hmmmm. We should get out more".
Want some more Radiohead coding fun? You're welcome.