Having delivered hundreds, perhaps thousands, of live product demonstrations during his career at Microsoft Corp., Bill Gates has experienced his share of on-stage gaffes.But the memory of his first demo, when he was still a teenaged high school student in Seattle and a budding entrepreneur, probably still stings, a little. According to an excerpt from an upcoming book, Showing Up for Life, written by his father, William H. Gates Sr., and excerpted in Fortune magazine Thursday, the first demo by the young Bill Gates, who was called "Trey" by his family, took place in 1972, when he was a 17-year-old prep schooler developing a hardware gadget with future Microsoft co-founder Paul Allen and a third partner, Paul Gilbert. The mini-computer was called the "Traf-o-Data" and it was meant to automate the processing of data collected by traffic counters, those black hoses we drive over on roads, according to the Startup Web site about Microsoft and Gates created by the New Mexico Museum of Natural History and Science (Microsoft early on was based in Albuquerque for several years in the mid-1970s). "After many successful kitchen-table practice sessions, my son persuaded some employees of the city of Seattle to come to the house for a demonstration," wrote Gates Sr. "Well, things that day at the Gates home didn't go according to plan. The Traf-O-Data did not perform." "How did Trey react when the first live demonstration of his system failed?" continued Gates Sr., who called his son Trey. "He went running into the kitchen, shouting on the way, 'Mom! Mom! Come and tell them that it worked!'" The trio eventually got the device to work, according to Startup, though only one was ever sold. But Gates and Allen were already turning their attention to Microsoft, which Gates helped start after dropping out of Harvard in 1975. Gates' product demonstrations have since improved, and he has even starred in a number of tongue-in-cheek videos shown at Microsoft technical conferences (we'll ignore the baffling TV commercials with Jerry Seinfeld last year).