theodp writes "Thirty years after the partial nuclear core meltdown at Three Mile Island, Robert Cringely describes the terrible TMI user interface, blaming a confluence of bad design decisions — some made by Congress — for making the accident vastly worse. While computers could be used to monitor the reactor, U.S. law prohibited using computers to directly control nuclear power plants — men would do that. So when the (one) computer noticed a problem, it would set off audible and visual alarms, and send a problem description to a line printer. Simple, except the computer noticed 700 things wrong in the first few minutes of the TMI accident, causing the one audible alarm to ring continuously until it was shut off as useless. The one visual alarm blinked for days, indicating nothing useful. And the print queue was quickly flooded with 700 error reports followed by thousands of updates and corrections, making it almost instantly hours behind. So the operators had to guess at what the problem was. 'Not good,' says Cringely."