One electronics manufacturer, for example, used his crew to test-market new packaging for a portable CD player.

CNN: ASIANOW - TIME Asia

In 1984 Sony did it again with the D-50 portable CD player, offering near-audiophile fidelity on a much more durable medium.

FORBES: TRACKING THE EVOLUTION OF TAKE-OUT TUNES

Sony invented the Walkman and the portable CD player, but was never more than a third-fiddle player in the digital audio world.

FORBES: These Are The Six Reasons Companies Drop The Ball

You can even use an old-fashioned wire to hook them up to less-portable devices a desktop computer or CD player, for example.

WSJ: Big Sound, Wire-Free: Audyssey Bluetooth Speakers | Geek Chic

We realised that if you had digital music, music that was digitised that is, then you could store it on flash memory or a hard drive and thus create a music player that could store many more songs that the Sony Walkmans or portable CD players that were the rage at the time.

FORBES: iPod is Ten Years Old: I Invented it 20 Years Ago