Help wanted: business application archaeologists… Teaching mainframe skills is out of vogue at many universities with the advent of newer approaches to solving the biggest computing challenges. At the same time, many of the engineers capable of tinkering with the refrigerator-sized machines are nearing retirement. The average age of mainframe workers is 55 to 60, according to Dayton Semerjian, a senior vice-president at CA Technologies (CA), the second-largest maker of software for mainframe computers after IBM. "The big challenge with the mainframe is that the group that has worked on it—the Baby Boomers—is retiring," Semerjian says. "The demographics are inescapable....