On June 22, 1979, Sony invited a group of journalists to Yoyogi Park in Tokyo and handed each of them a small blue and silver device attached to headphones. After they pressed play, an audio presentation informed them that the international electronics conglomerate was releasing a portable cassette player called the Walkman. As they listened, models on roller skates, skateboards, and tandem bicycles circled through the park with Walkmans on their waistbands and new lightweight earphones atop their heads.

Less than two weeks later, on July 1, 1979, the Walkman hit store shelves in Japan. It would popularize the compact cassette developed 15 years earlier by Dutch manufacturer Philips, help define the ’80s, and usher in a new era of device-enabled disconnection. The Walkman and the company behind it are profiled in John Nathan's book Sony; here are a few things you might not have known about the device.

1. IT WAS INSPIRED BY A SONY CO-FOUNDER’S DESIRE TO LISTEN TO OPERA ON LONG FLIGHTS.

Sony cofounder Masaru Ibuka officially retired in 1976, but he continued to advise the company after his departure. In February 1979, he made a personal request of executives: an easy-to-carry device that would allow him to listen to operas on cassettes during international flights. It turned out to be a pretty simple request to fulfill: Kozo Ohsone, general manager of the tape recorder division, adapted a Pressman—a recording device that Sony marketed to journalists—by replacing the recording mechanism with a stereo amplifier and circuitry.

2. SONY HOPED THE WALKMAN WOULD MAKE UP FOR THE FAILURE OF BETAMAX.

In the ’70s, Sony introduced its Betamax tapes, video cameras, and players. Though popular with film production companies for their sound and picture quality, Betamax products were knocked out of the consumer market by the VHS tape, a product of JVC (the Victor Company of Japan). By 1980, VHS had more than half of the market share, and Betamax kept losing ground until it represented less than 10 percent of the market in 1986. VHS tapes could hold 120 minutes, compared to the 60 minutes of the original Betamax tapes, and JVC entered into savvy licensing agreements with American, European, and Asian electronics companies to create VHS-compatible products. Sony never successfully licensed Betamax technology, and its failure was a humiliating blow to the company.

Sony’s chairman and other cofounder, Akio Morita, received a Walkman prototype soon after Ibuka got his, in the spring of 1979; he used it while golfing and was amazed by the quality of the sound. He thought the device could redeem Sony and rushed it into production for release that summer. This meant there wasn’t much difference between the first Walkmans on the shelves and the prototype made for Ibuka.

3. IT WAS MARKETED TO TEENAGERS.

Morita wanted the new device to be marketed to teenagers; he had seen teens lug radios and boomboxes to beaches and up mountains. This meant offering it at a price much lower than that of the Pressman—which retailed in the U.S. for $400 (in 1979 dollars)—even though it contained mostly the same technology. Morita’s imagined retail price for the Walkman was the equivalent of $125 in Japanese Yen. At that price, Sony needed to produce and sell 30,000 Walkmans to turn a profit—a hefty first order for a new product, especially at a time when compact cassettes were a fraction of the prerecorded music market and seen mostly as a professional tool to record speech.

The teen angle also meant that Sony had to produce new, more stylish and lightweight headphones, improving on the earmuff-like ones available at the time.

The initial ad campaigns emphasized youth and sportiness: young people on roller skates and bicycles, earphones on their ears and Walkmans on their belts. One advertisement said it all: a young, pretty girl with a Walkman wearing futuristic earphones walking past an elderly monk wearing a clunky, old ’60s-style headset.

4. ITS ENTRY INTO FOREIGN MARKETS WAS DELAYED, MAKING IT ONLY MORE DESIRABLE.

Two months after the July 1 rollout, Sony sold out of the initial production in Japan. The company intended to introduce the Walkman to foreign markets in September 1979, but scrapped that plan in order to dedicate production to meet Japanese demand. This only made the Walkman more desired in other countries. Tourists and airline crews searched them out and brought them home. Whenever Sony executives went abroad, colleagues badgered them about obtaining Walkmans.

5. THE WALKMAN HELPED THE CASSETTE OVERTAKE VINYL AS THE BEST-SELLING MUSIC FORMAT.

In 1979, the year of the Walkman’s release in Japan, recorded music sales were about $4 billion in the U.S., half of which went to vinyl, a quarter to compact cassettes, and a quarter to 8-tracks, according to Mark Coleman's book Playback. The Walkman made its U.S. debut in June 1980, and just three years later, in 1983, cassettes overtook vinyl as the top format. By the time Sony stopped manufacturing the Walkman portable cassette players in 2010, the company had sold around 385 million units.

6. THERE’S A SOCIOLOGICAL TERM CALLED "THE WALKMAN EFFECT."

In an essay that may seem either quaint or prophetic in the age of smartphones, Japanese professor Shuhei Hosokawa accused the Walkman of altering the urban landscape, from one in which experiences were shared and spontaneous into one where individuals were preoccupied and autonomous in thought and mood. In a 1984 article for the journal Popular Music, entitled "The Walkman Effect," Hosokawa, of the inter-university International Research Center for Japanese Studies, wrote that the “listener seems to cut the auditory contact with the outer world where he really lives: seeking the perfection of his ‘individual’ zone of listening.”

7. IT HELPED PEOPLE EXERCISE.

The Walkman coincided with the exercise craze of the ’80s, which saw the Western middle class, newly confined to office jobs, take to the gym and fitness classes. “[A]lmost immediately, it became common to see people exercising with the new device,” Richard James Burgess wrote in The History of Music Production. “Appropriate personalized music eases the boredom and pain of repetitive exercise.”

8. IT RULED THE PORTABLE TAPE PLAYER MARKET.

Nearly every consumer electronics company released a portable tape player in the ’80s, most of which undercut the Walkman in price. Yet because of brand power, the Walkman was unbeatable. A decade after its launch, it retained 50 percent of the market share in the U.S. and 46 percent in Japan despite costing about $20 more than the average personal tape player.

9. BY 1990, THERE HAD BEEN 80 WALKMAN MODELS.

For a decade, Sony created new redesigned and specialized Walkmans, including water-resistant, solar-powered, and double-cassette-deck models. By 1990, 80 varieties had gone to market.

10. THE BRAND NAME WAS SCRAPPED FOR CD DEVICES BUT REINSTATED FOR LATER TECHNOLOGY.

In 1979, the year the Walkman quickly went from prototype to cultural sensation, Sony president Norio Ohga commissioned a joint task force with Philips to create a commercially viable digital audio disc, which became the compact disc. Ohga championed the CD and was sideswiped by the company cofounders’ enthusiasm for the Walkman, its instant success, and the resultant surge in the cassette market.

But Sony slowly rolled out the compact disc in the ’80s, and by the end of the decade, CDs had overtaken cassettes as the most popular format. Because the Walkman brand had become so associated with tapes, Sony used the term Discman for most of its portable CD players.

Meanwhile, Sony continued manufacturing Walkmans, at a reduced capacity, until 2010, when it manufactured and shipped the last order of cassette players under the name. (The company still licenses the name to Chinese manufacturers of tape players, though.) The company has used the Walkman name for some of its MP3 players and cell phones to date.