In 1981 Kramer filed for a UK patent. UK patent 2115996 was issued in 1985, and U.S. Patent 4,667,088 was issued in 1987. In 1988 Kramer's failure to raise the £60,000 required to renew the patent resulted in the patent entering the public domain, but he is still the owner of the designs.
IXI was around the size of a credit card and had a LCD screen and navigation and volume buttons. Four prototype models were built and a pre-production model went on sale at the APRS exhibition at Earls Court in London, in October 1986.
- "Kane Kramer - The Inventor of the Digital Audio Player". www.kanekramer.com. Retrieved 9 June 2017.
- "Portable data processing and storage system". Retrieved 9 June 2017.
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