Background: In September 2007, during a lawsuit with patent holding company Burst.com, Apple drew attention to a patent for a similar device that was developed in 1979. Kane Kramer applied for a UK patent for his design of a "plastic music box" in 1981, which he called the IXI. He was unable to secure funding to renew the US$120,000 worldwide patent, so it lapsed and Kramer never profited from his idea.
Question: What was the name of the previously-patented music player from 1981?
Answer:<extra_id_0>.
<extra_id_0> IXI<extra_id_1>