CTRL-ALT-DEL ++++++++++++ The man who spent five minutes writing the computer code that would bail out the world's PC users for decades is retiring Friday. David Bradley programmed one of the most well-known key combinations around: Ctrl-Alt-Delete. It forces obstinate computers to restart when they no longer follow other commands. Bradley, 55, is leaving IBM Corp. after 28 1/2 years. By 1980, Bradley was one of 12 people working to create the IBM PC. The engineers knew they had to design a simple way to restart the computer should it fail. Bradley wrote the code to make it work. "I didn't know it was going to be a cultural icon," Bradley said. "I did a lot of other things than Ctrl-Alt-Delete, but I'm famous for that one." His fame depends on the failures of others. At a 20-year celebration for the IBM PC, Bradley was on a panel with Microsoft Corp. founder Bill Gates and other tech icons. The discussion turned to the keys. "I may have invented it, but Bill made it famous," Bradley said. Gates didn't laugh. The key combination also is used when Microsoft's Windows operating system fails. Bradley will continue teaching at North Carolina State University after retirement.