Inventor of audio cassettes Lou Ottens, who also engineered the concept of magnetic tape players and the computer discs (CDs) died on Sunday aged 94. According to Hindustan Times, the Dutch founder of the reel to reel tapes cassettes breath his last in Duizel, the Netherlands, Dutch newspaper NRC Handelsblad reported, without citing the cause of his death. Ottens founded the cassettes in1960s when he was employed with tech giant Philips. He unveiled what went on to be called a cassette at a radio Berlin exhibition, which led to the invention of the first reel-to-reel walkman in 1963.

A structural engineer who trained at the prestigious Technical University in Delft, he joined Philips in 1952 and was head of the Dutch company’s product development department when he began work on an alternative for existing tape recorders with their cumbersome large spools of tape. His goal was simple. Make tapes and their players far more portable and easier to use.

Also Read: Your Weekly Tech Guide to the Coolest Gadgets and Accessories

“During the development of the cassette tape, in the early 1960s, he had a wooden block made that fit exactly in his coat pocket,” said Olga Coolen, director of the Philips Museum in the southern city of Eindhoven. “This was how big the first Compact Cassette was to be, making it a lot handier than the bulky tape recorders in use at the time.”

The late engineer also struck a deal between Sony and Philips to manufacture cassettes feasible for the portable tape recorders, according to the newspaper, which prompted Japanese electronic companies to produce the iterations of similar-looking models with varying sizes. Ottens, however, managed to sell approximately 100 billion units worldwide and also reached a deal to patent the model of the audio cassettes that were widely selling in the market.

Also Read: Carvaan 2.0: Nostalgia And Technology Combined In The Best Way