Getty Images Radio Shack's TRS-80 Model I microcomputer, complete with Expansion Interface, floppy-disk drive and printer

Quick — name the most important personal computer of the late 1970s and early 1980s.

Those of you who mentioned the legendary Apple II–that’s fine. I respect your decision. Forced to think objectively in 2012, I may even agree. But if you just named Radio Shack’s TRS-80, you made me smile.

Your choice is entirely defensible. And back in the TRS-80’s heyday, I not only would have agreed with it but would have vehemently opposed any other candidate.

(MORE: 25 Years of IBM’s OS/2: The Strange Days and Surprising Afterlife of a Legendary Operating System)

Gadget-retailing giant Radio Shack unveiled the TRS-80 Model I at a press conference at New York’s Warwick Hotel 35 years ago today, on August 3, 1977. (The company didn’t call it the Model I at the time: Like Apple’s Apple I, it only became the I after a II was introduced.)

It wasn’t the city’s biggest news story that day. That would be the bombings of two office buildings by Puerto Rican terrorist group FALN, which killed one man and prompted the evacuation of 100,000 people from other buildings, including the Empire State Building and both towers of the World Trade Center. But it was a big moment in the burgeoning microcomputer industry: The TRS-80, which began shipping in September, was one of 1977’s trinity of early consumer PCs, along with the Apple II and Commodore’s PET 2001.

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I wasn’t paying attention at the time, but my father was. In the spring of 1978, as I was wrapping up junior high, he brought a TRS-80 home. The moment I saw it could do graphics and animation, I was transfixed.

That fall, I entered a high school whose rudimentary computer lab was outfitted with TRS-80s. I rarely left the lab except when I was supposed to go to class, and sometimes not even then. The fact that I was a TRS-80 user was a defining aspect of my identity until 1982, when I bought an Atari 400. And the TRS-80 helped to define things about the PC industry that persist to this day.

The project had been instigated by Don French, a Radio Shack executive and computer hobbyist. In 1976, he convinced the company’s president, Lew Kornfeld, and vice president, John Roach, that it should look into the PC market. They were initially skeptical about the idea, but French’s timing was fortuitous: The market for CB radios, which had been extraordinarily good to Radio Shack, was on the verge of faltering. The company needed something new to pick up the slack.

Forced with the challenge of creating a PC in Radio Shack’s headquarters of Fort Worth, Texas — nowhere near the epicenter of the PC revolution in Silicon Valley — Radio Shack did a sensible thing: It imported a computer nerd from the Valley.

That nerd was Steve Leininger, an employee of chipmaker National Semiconductor. Like Apple’s Steve Jobs and Steve Wozniak, he was a member of the Homebrew Computer Club, whose members designed their own PCs for fun. He’d also been an employee of Paul Terrell’s Byte Shop, the pioneering computer store where the first Apple machines were sold. Working to French’s specifications, Leininger did most of the heavy lifting of designing the TRS-80.

The computer’s name sounded a bit retro even in the 1970s. The “TRS” stood for “Tandy Radio Shack” and the “80” referenced the machine’s microprocessor, the Z-80. Radio Shack kept the branding even on later models which used different chips.

Radio Shack parent company Tandy Corporation–which started out as a maker of products for leather handicrafters–was run by Charles Tandy. His main role in the TRS-80 project seems to have been not preventing it from proceeding, which is often the most important contribution a CEO makes to a groundbreaking effort. In November of 1978, he died of a heart attack — a little over a year after the TRS-80 shipped, and before it and its competitors and successors really started making a dent in the universe.

At first, Radio Shack envisioned the TRS-80 as a solder-it-yourself kit which it wanted to sell for $199. Leininger convinced the company to build a fully-assembled, plug-and-play computer. It ended up starting at an economical-sounding $399.95, but that assumed that you supplied your own monitor, a configuration I don’t recall ever seeing in the wild. $599.95 got you a system with Radio Shack’s 12″ black-and-white display, 4KB of memory and a cassette-tape deck which let you save and load programs (albeit very slowly and very unreliably).

What you really wanted, though, was a TRS-80 with 16KB of memory, the powerful Level II BASIC programming language (provided by a company called Microsoft), and a floppy-disk drive that could store up to 49KB of data. In 1979, that cost $1,647–about what you’d pay for a 16KB Apple II without a display or disk drive.

At first, Radio Shack kept its hopes for the TRS-80 in check. Legend has it that it originally planned to build just 3,500 units, figuring that if the product was a flop, the company could just use the machines for book-keeping purposes in its 3,500 company-owned stores. But it soon found that the computer was shattering its expectations, and just kept doing better and better.

According to one analysis, the TRS-80 was the best-selling PC from its introduction through 1982. The Apple II steadily gained on it, but even as late as 1980, Radio Shack’s machine may have outsold the pricier Apple II by more than five-to-one.

That isn’t surprising given the huge advantage the TRS-80 had on the retail front. The Apple II and other microcomputers were initially sold mostly in funky little mom-and-pop computer stores. But Radio Shack had 5,000 company-owned locations and franchisees in 1977, many of which were located in malls. The TRS-80 was therefore the first computer widely sold in stores frequented by typical consumers, not just geeks.

Radio Shack

The richest ecosystem of the era sprung up around the TRS-80. You could buy TRS-80 hard drives and networking gear and kits to give the system lower-case letters. (Radio Shack had initially left out lower case to save $1.97 per TRS-80 sold.) There was a TRS-80 voice synthesizer, and joysticks and a box which added color graphics capability. You could buy an add-on that gave the system the ability to play sound, although some enterprising users discovered that you could place a radio nearby and write BASIC programs that would cause the radio to buzz in a manner that approximated music.

There were even TRS-80 clones, such as Australia’s Dick Smith System 80, perhaps the most wonderfully-named computer of all time.

TRS-80 software was just as important as TRS-80 hardware, and at first, it had a wider selection than any other microcomputer. Conventional wisdom has long held that Dan Bricklin and Bob Frankston’s VisiCalc spreadsheet for the Apple II was the first killer app–a program so useful that people bought a computer to run it. But even before Apple got VisiCalc, the TRS-80 had the Electric Pencil, the first microcomputer word processor. At the very least, it was a proto-killer app.

A bevy of games were available, too, despite the fact that the computer did only black-and-white graphics at 128-by-48, which was bare-bones even back then. For some of us, the name “Scott Adams” will always bring to mind not Dilbert but the author of the plain-text adventure games which started on the TRS-80 before migrating to other platforms.

And a genius schoolteacher named Leo Christopherson was the Disney of TRS-80 graphics, creating masterworks such as Dancing Demon, which let you play choreographer for a tap-dancing gremlin:

[youtube=http://www.youtube.com/watch?v=6CCJFQ_bP0E]

Many of these products were advertised in the first slick computer magazine devoted to a specific PC, Wayne Green’s 80 Microcomputing. Wildly successful later publications such as PC Magazine, Macworld and my former employer, PC World, all followed its template.