Every time a software program locks up and you want to start over, every time you need to change your password or log on or off your computer, you can thank David J. Bradley.

That's the same David Bradley who was the "answer" to Final Jeopardy on an episode of that show's special college edition last fall.

It's the same David Bradley who saved Bill Gates' derriere before the Windows operating system became the monster it is today.

Bradley is the man who gave the world "control-alt-delete."

"It was not a memorable event," said Bradley, a longtime IBM employee, speaking of that day in 1980 or '81 when he discovered control-alt-delete.

"It wasn't intended as something we were going to tell the customers about," he says. "Then it turned out that this reset was a problem-solver for people who were writing the programs and writing the instruction manuals."

He's much too modest. Would Alexander Fleming have said, "It wasn't a memorable event," when he discovered penicillin?

Would Albert Einstein have said, "I really can't recall when I discovered E=MC squared?"

The original idea was simply to reset early PCs without turning them off. Microsoft adopted control-alt-delete to help ensure people powered down correctly, then to handle "administrative functions" such as the vital "end task" feature for computer software that crashes or otherwise gets stuck.

Bradley chose the control and alt keys because he needed two shift keys to make the operation work, and he chose the delete key because it was on the opposite side of the keyboard. He didn't want people to hit control-alt-delete by accident.

It's more complicated than that, of course, but most people don't have a Ph.D. in electrical engineering from Purdue University, as Bradley does.

Bradley, who speaks at universities on IBM's behalf, is on a mission — to encourage more students to go into science and technology. He's aware that much of the growth in college attendance in recent decades is in the humanities.

"I actually have a real job, but I enjoy doing this," Bradley says. "I'm as close as you get to a rock star within IBM."

Bradley says the "strength of the country" is at stake because relatively few students go into science or technology. Further, he says, ordinary citizens need to understand science and technology better to make informed choices in the voting booth.