"Radiohead ZX Spectrum program from OK Computer OKNOTOK 1997-2017" https://www.youtube.com/watch?v=JDM5YBS6KMc
At the end of tape from Radiohead's OK Computer OKNOTOK 1997-2017 bonus material there is a ZX Spectrum program. Also, inside the code there's a hidden, black text on a black background: "congratulations….you've found the secret message syd lives hmmmm. We should get out more"
If you would like to repeat this yourself note that you need to filter the audio with 3.5kHz low pass filter.
"How to run secret ZX Spectrum message from Radiohead’s OKNOTOK C90 tape" https://medium.com/@maciejkorsan/how-to-run-secret-zx-spectrum-message-from-radioheads-oknotok-c90-tape-795bfd429ba1
"Radiohead album hides an app that only runs on an '80s computer" (News Source: Engadget) https://www.engadget.com/2017/07/13/radiohead-album-hides-an-app-that-only-runs-on-an-80s-computer/
They’ve really out niched themselves this time.