Computer centers were intimidating places in 1969. Machines were huge, locked in air-conditioned rooms, and fed with punched cards. Time on them did not come cheaply and was tightly rationed. And the computer room in Boelter Hall at the University of California, Los Angeles (UCLA), was no exception.

In one corner of the room sat a state-of-the-art Scientific Data Systems Sigma 7 computer. Off limits to the countless engineering students, it was reserved for a small group of researchers funded by the Defense Advanced Research Projects Agency (Darpa) and busy inventing the technology that would evolve into the Internet.

Among those researchers was Vinton Cerf, now senior vice president of Internet architecture and technology at Worldcom Inc., Ashburn, Va. One evening, he was sitting next to the Sigma 7 doing some programming when a scruffy 12-year-old with a piping voice interrupted him with a question, then asked another, and another. The kid was Steve Kirsch--or little Stevie, as he came to be known around UCLA.

"He must have grabbed the door when someone walked out of the room," Cerf said. The door was usually locked. "I didn't want to be bothered at first."

But something about Kirsch reminded Cerf of himself at that age. "A part of me said, 'Be nice to the kid, you can't buy enthusiasm'." So Cerf and his colleagues set up Kirsch with a computer account.

Kirsch was thrilled, his parents less so, since he took to sneaking out of the house at 4 a.m. to bike over to UCLA. (Computer terminals were more likely to be available in the wee hours.) Eventually the boy was handed a real job--write a program to send and receive electronic mail.

At the time, some of the mainframe computers being linked into the so-called Arpanet had internal messaging programs, a precursor to e-mail; but there was no easy way to send messages from one machine to another. A messaging standard began to evolve, but that standard had to be implemented at each local system.

"We were a small group at UCLA," recalled Charles Kline, another of the researchers there. "Additional help was great. So Stevie wrote that first e-mail program for the Sigma 7."

During his junior high and high school years, Kirsch also worked on operating systems for the group and wrote a status monitoring program, so users could tell who else was on the system.

From the UCLA computer room, Kirsch went on to invent the optical mouse, patent the method of tracking advertising impressions on the Internet by click-counting, and start and profitably sell three companies. His Mouse Systems Corp. marketed the mouse; his Frame Technology Corp. developed publishing software that could handle equations and tables; and his Infoseek Corp. developed a pioneering search engine. He is now launching his fourth venture: Propel Corp., which intends to make operating systems and provide other tools for e-commerce. Along the way, he has made several hundred million dollars and launched a charitable foundation that gives over US $5 million in grants annually.

A programmable calculator

But at 12 years of age, how did he know enough about computers to get Cerf's attention? It started with a calculator.

Earlier, when Kirsch was already in sixth grade, a teacher brought in a programmable calculator and showed the students how it worked. Intrigued, Kirsch took a class on computers at a nearby museum.

"I thought it was really neat, the power one person could have using a machine," he told IEEE Spectrum.

Then he tried to sign up for classes at the local Computer Learning Center. Although he passed the entrance exam, he was refused admittance by the instructor out of concern that the pre-teen would discomfit the adult students in the class. Instead, he offered Kirsch some weekend computer time, and the boy began teaching himself to program an IBM 360 mainframe. A year or so later, he discovered the UCLA computer.

When not in school or in the UCLA computer lab, Kirsch was to be found at the local arcade--not pumping quarters into pinball machines, but making $30 an hour fixing them, having taught himself on an old machine his father had at home.

At Cerf's suggestion, Kirsch applied to the Massachusetts Institute of Technology (MIT), in Cambridge, staying through his master's degree. Summers, he worked for Bell Laboratories, in Murray Hill and Holmdel, N.J., where he also became involved in optics. His master's thesis was on integrated optical isolators, which pass laser light through in one direction, but not the other.

What ended up having the biggest impact, however, was a side project he pulled together at MIT in three intense weeks--and later patented, manufactured, and sold in the hundreds of thousands. That was the optical mouse.

A man and a mouse

At MIT, Kirsch often worked with high-end computers programmed in Lisp, for which mechanical mice were one of the input devices.

"They were very unreliable," Kirsch remembered. "They'd track one way and not the other way, they would skip. And I thought this was stupid--a Lisp machine costing a hundred grand being brought down by a device made up of $30 worth of components."

Deciding he could do better, he came up with two basic designs. The first used a single optical sensor that had four quadrants, creating, in effect, a two-by-two sensor array. This mouse ran over a checkerboard pad and detected speed and direction from the pattern of changing black and white squares.

His second design used the same sensor, but instead of a checkerboard pad, this mouse ran over a grid of lines, blue ink in one direction, infrared ink in the other. Along with the sensor were a red and an infrared light-emitting diode (LED), which alternated turning on and off. Since the blue ink was transparent when the infrared light was on, and the infrared ink was transparent when the red light was on, the sensor got only one type of information--vertical or horizontal motion--at a time.

Using only one sensor saved money, but Kirsch later changed the second mouse design to incorporate two sensors, one for each direction, each with a four-by-one array. The LEDs had no need to blink and were turned on continuously. This approach was more reliable, because the position of the mouse could be determined through the use of differential signals from the detector, rather than calibrating an absolute signal threshold, as had been required in the first red-infrared approach.

"What I learned at MIT," Kirsch said, "is that when you have a really hard problem you don't know how to solve, you break it into smaller problems you can solve. Calculating motion in one direction is trivial, so, using different colors of light, I broke the hard problem into two trivial problems."

After sketching out his designs, he immediately contacted Steve Jobs at Apple Computer Inc., Cupertino, Calif., and asked to show him his invention during spring break, three weeks away. He was given an appointment, and spent those three weeks constructing a prototype, using the first version of the red-infrared mouse.

Jobs met with Kirsch, but decided against marketing the optical mouse, choosing to stick with the more established mechanical device. Kirsch applied for, and was awarded, a U.S. patent on the technology, then licensed it to Summagraphics, Danbury, Conn., and forgot about it for a while.