Think back to 1974, if you're old enough. Vietnam was still a raw wound. Richard Nixon had ended the Watergate crisis by resigning from office. Inflation was rampant, oil was running out and the Japanese would soon seem to be taking over everything. Surely the years ahead would be a humbling time of irreversible national decline.

In the middle of all this, an Albuquerque, N.M., entrepreneur named Ed Roberts had a scheme to produce a personal computer kit that would sell for under $500. The task was considered impossible - there really were no personal computers, after all - and Roberts was broke, but Popular Electronics, a big deal in those days, had promised him the cover if only he could deliver.

Somehow, Roberts and his band created a prototype, but the shipping company supposedly lost it en route to New York, so all parties held their noses and a mock-up was slapped together for the photo shoot. Then the magazine made like Gabriel: "Project Breakthrough!" trumpeted the January 1975 cover of PE. "World's First Minicomputer Kit to Rival Commercial Models ... Altair 8800."

Beneath that innocuous-looking machine, the earth shook. Small computers in those days were the size of a stove, but this one was the size of - well, what people now think of as a computer. And it sold for $397, an unheard-of price.

It wasn't perfect, of course. There was no display and no real storage. Input was via a series of switches (a program might require thousands of error-free toggles), and output was in the form of flashing lights, something like the computers on old TV shows. (Altair was where the Enterprise (ETP) was headed one night on Star Trek.) The machine didn't even come assembled.

Nonetheless, the kit was an overnight sensation. Unfortunately, Altair's makers were selling a product they couldn't immediately deliver or support. When the marketplace rejected the Altair's uniformly defective memory boards, Roberts forced them on his customers by bundling boards with the machine's crucial Basic software - created, incidentally, by a couple of brash young fellows named Bill Gates and Paul Allen. They had naturally pitched the software to Roberts before it even existed.

Reading Paul Freiberger and Michael Swaine's Fire in the Valley: The Making of the Personal Computer, it's hard not to conclude that maybe the computer business hasn't changed as much as we think it has, the original Altair's 256 bytes of memory notwithstanding.

First published in 1984 and out of print for years, Fire in the Valley has now been updated and reissued, complete with what surely must be bar mitzvah pictures of Gates, Steve Jobs and others looking younger, skinnier and hairier than any human could possibly be. Although the book takes a stab at comprehensiveness, these gawky youngsters are really the focus of the story, and the authors tell their tale with surprising human as well as technological insight. Of course, Freiberger and Swaine are blessed with a remarkable tale to tell; if you don't already think so, you'll probably be bored at times by the comings and goings of so many nerds so badly in need of shampoo. But even nongeeks need to understand what happened here, because it subverts the funereal narrative of recent American history that both liberals and conservatives seem so readily to embrace.

Fire in the Valley proves that old-fashioned American ingenuity wasn't dead; it had just moved out West. Nor were the 1960s and '70s merely a time of self-indulgence and license, as some conservatives have contended. Aside from such gains as civil rights, the era's hallmark openness and sense of play - the preference for tie-dye over gray flannel, so to speak - has paid big dividends. The computer revolution "had its genetic coding in the '60s," observes Jim Warren, an industry pioneer and self-described "chair-being" of an early industry computer fair - "antiestablishment, antiwar, profreedom, antidiscipline attitudes."

At the same time, the industry that these crazies founded is a powerful rebuff to the strange cult of pessimism and nostalgia that characterizes recent liberal economic cant. It turns out that growth isn't over, and there are even signs that our huge investment in computer technology is showing tangible results now that the machines finally work and people have some idea what to do with them.

More mundanely, Fire in the Valley offers comfort to the parents of smart but difficult boys everywhere. (I myself have stopped shopping for an exorcist for one of my sons; we'll give him an old laptop instead.) It gives comfort but also pause, because nowadays such boys are often medicated, the rough spots of childhood and adolescence smoothed out by Ritalin until the kids get old enough for Prozac.

Back in the 1970s, though, it was still possible to be young, male and different without being slapped with a prescription. Consider Steve Wozniak, the early technical genius behind Apple (AOIXQ). A whiz all through his Silicon Valley childhood, in high school he planted an electronic metronome in a friend's locker, taped to some unlabeled battery cylinders and wired with a switch that accelerated the ticking when the locker door was opened. Upon discovering the device, the authors report, "the principal bravely snatched the metronome from the locker and ran out of the building with it."

A book like this really is kind of a boys' story; its heroes, virtually all men, inspired Robert X. Cringely in his book Accidental Empires to attribute the computer industry to mass sublimation by a collection of nerds who couldn't get laid. With its star-studded cast of unwashed, unwed brainiacs, Fire in the Valley offers unwitting support for that thesis. Of his own nerdity, for example, Bill Gates says: "I tried to be normal, the best I could."

The personal computer revolution was driven by these brilliant and individualistic misfits, and their legacy - who could have foreseen it? - is a revitalized U.S. economy in which no one talks enviously anymore of Japanese firms that have 100-year plans and put their employees in what look like Jiffy Lube uniforms.

Fire in the Valley offers many nerd pleasures, not the least of which is a stroll down memory lane, back to a sunny time of youth and innocence and endlessly whirring floppy drives. All the highlights are covered. You'll read about the earliest BBS, the rise of the Phoenix BIOS, the creation of computer magazines, and the unhappy life and death of poor Gary Kildall, creator of CP/M. Remember Adam Osborne? Peachtree Software? Wordstar? It's all here, enough to give any aging computer freak a lump in his throat.

Here too is the incomparable Doug Englebart, who in 1968 took the stage at the Fall Joint Computer Conference in San Francisco to give what the authors say was by all accounts "one of the most impressive technology demonstrations since the atomic bomb test at Alamogordo." He showed off hyperlinked text, remote video conferencing (including live document sharing), cursor control via mouse (he made the first one of wood) and the mixing of text, graphics and video.

"Englebart is justly credited with the invention of the computer mouse, hypermedia, multiple-window screens, groupware, online publishing and electronic mail," the authors write. Another high-tech visionary, Alan Kay, wasn't kidding when he said, "I don't know what Silicon Valley will do when it runs out of Doug's ideas."

One of the strengths of this fine book is that it isn't tendentious about its subject matter. If Fire in the Valley has any thesis, it's that, like Englebart, the very earliest players weren't much motivated by money. Some were simply visionaries. Others just loved computers. Others still couldn't fit in anywhere else.

The plutocrats are here too, of course, but most of them come later and get relatively short shrift. So do the chip engineers, who are mentioned only at the beginning. Like indulgent gods, Freiberger and Swaine seem to love all of Silicon Valley's children, but their hearts are clearly with the hobbyists and hackers, gifted weirdos and insanely curious oddballs, the ones they show us most clearly.

The classic examples may be Alan Cooper and Keith Parsons (dossier), who created a bookkeeping program and actually sold a copy for $995. The, uh, corporate culture at their impressively named Structured Systems Group differed somewhat from the average business organization.

"The atmosphere was giddy," the authors write. "Parsons paced the office shirtless, while Cooper, hair down to midback, guzzled coffee that would dissolve steel. The two of them, wired on caffeine and the excitement of the $995 check, wrangled about potential markets and dealer terms. Parsons' girlfriend made phone sales while sunbathing nude in the backyard."

Cooper, by the way, had a ready explanation for why he started a software company: "My unemployment had run out."

Daniel Akstis a writer teaching this semester at UC Berkeley's Graduate School of Journalism.