A tale of pointlessness: retro 5″ black and white TV as a computer monitor

When my brother's old 1980s 5"^3 black and white TV was recently discovered during a "I wonder what's under here?" exercise and amazingly seemed to still be working my first thought was, of course, "Nice!! 3rd monitor for my PC". I knew that wouldn't be exactly simple as the TV only appeared to have a 3.5mm "EXT. ANT" socket. "I can't do anything but applaud this.