Prove Yourself Lyrics

Lyric discussion by x_Heather_x 

Cover art for Prove Yourself lyrics by Radiohead

What does the line "hooked back up to the cathode ray" mean? I did something about the cathode thingy in chemistry =p lol and from what i can remember i think it woz the negative bit of a battery. But i cant make sense of that line at all. Any help?

cathode ray = tv (before we had plasma's, lcds..)

@x_Heather_x its what old monitors were made from E.G. crt (cathode ray tube)