PHOTO: Timothy Archibald

Eric Hahn, a geeky 12-year-old in middle school in East Hampton, N.Y., wanted a computer in the worst way. It was the early 1970s, and computers were owned by corporations and schools, not by kids, but Hahn had to try to get one. He wrote a letter to C. Gordon Bell, then the brash vice president of research and development for the mighty Digital Equipment Corp., at the time the world's largest maker of minicomputers.

The object of Hahn's desire was a Digital PDP-8/a minicomputer. It may be hard to remember what it was like to get excited about a computer the size of a microwave oven with 4 kilobytes of main memory and a 12-bit word length. But this was at a time when men's sideburns were big, women's shoes were high, and Donny Osmond and the Carpenters ruled the airwaves.

Hahn didn't want charity—just a price break. A PDP-8/a, then two years past its introduction, could be had for around US $1000—in quantities of 100. All Hahn wanted from Bell was the 100-quantity price. He'd already saved up close to $1000 by soldering circuit boards for his father, who had a small electronics company that did one-off projects.

Bell, already a minor legend for having led the design of the time-shared PDP-6, knew a publicity opportunity when he saw it. So a few months later Hahn and Bell met in an office in DEC's Maynard, Mass., headquarters, Bell in a dress shirt, Hahn in a sweater, and posed over the computer gear [see photo, “At the Keyboard”]. Hahn gave his $1000 to Bell, and Bell handed over a PDP-8/m, a much faster and more expensive machine than Hahn had sought. “It was a no-brainer to get him a computer at a price he could afford,” Bell says, “and it turned out to be one of the better investments Digital ever made!”

And then, Hahn recalls, came “one of the high points of my young life. I spent two or three hours debating with Gordon Bell, who had personally designed the instruction set used on the PDP-8, about the foibles of programming the machine.”

Hahn carried his new computer home and began writing code for it. Within four years—at age 16—his work on the PDP-8/m became the basis of his first successful software company, Amide Software, which sold an emulation program that enabled Intel 8080-based personal computers to run PDP-8 software.

Touch a child's life, they say, and you never know what other lives might be touched in turn. But in Hahn's case, you can make a darn good guess. He has helped start about a dozen companies, including the e-mail and collaborative software company Collabra, which was acquired by Netscape in 1995. He ran technical initiatives at Bolt, Beranek & Newman (now BBN Technologies), Convergent Technologies, Lotus (now IBM Lotus Software), and Netscape. Along the way he became a millionaire.

Nine years ago he started the Inventures Group, a tiny, early-stage investment business in Palo Alto, Calif., that is similar in some respects to a venture capital firm but invests mainly Hahn's money. It has stakes in some highly touted start-ups, including Linux pioneer Red Hat and Opsware (formerly Loudcloud), purchased by Hewlett-Packard in July for $1.6 billion.

But what has Hahn really excited these days is Zimbra, a San Mateo, Calif., company that is replacing traditional low-function e-mail software with much more versatile software that uses the power of the browser. Hahn calls Zimbra his quintessential project. He invested in it in 2004 and, shortly thereafter, joined its board of directors. “I eat, drink, and sleep Zimbra these days,” he says. Zimbra's key technical insight was that the browser itself could be used to deliver fully functional e-mail to users without installing any software. People knew about Web e-mail, but they had never seen a system like this. Zimbra was one of the first browser-based e-mail systems to have more functionality and a better user experience than traditional desktop packages.

After Hahn took Zimbra under his wing, his first step was a product architecture review. During weeks of intense meetings, Hahn grilled the key developers. “Why is this in a single database table? What happens if there is a corruption?” Hundreds of such questions were hashed out in the next few weeks. “I've made many, many product mistakes over the years,” Hahn says. “I should at least help make sure we make new mistakes this time around!”

Hahn got hooked on software early. Hobbyist computers running on the Intel 8080 microprocessor came out in 1975. A friend, Howard Cannon, got an Imsai. The boys, in high school, quickly discovered that while lots of free software was available from user groups for Hahn's PDP-8, little software existed for the Imsai. So the two wrote a program that let the 8080 emulate a PDP-8, thereby opening up the PDP-8's vast software library for the 8080. They distributed the program on paper tape, selling it by mail for $35 a copy.

“We sold hundreds of copies,” Hahn recalls. “It was a significant amount of money.” The boys wanted to spend the cash on computer gear; their parents insisted they save it for college.

Cannon studied artificial intelligence at MIT and went on to become a key contributor at newly founded Symbolics, in Cambridge, Mass. Hahn, rejected by MIT, went to Worcester Polytechnic Institute. WPI had close ties with DEC, so given Hahn's passion for PDPs and his connection with Gordon Bell, it was an easy choice. He blasted through in less than three years and graduated at age 19.