Intel had introduced the first x86 microprocessors in 1978.[50] In 1981, IBM created its PC, and wanted Intel's x86 processors, but only under the condition that Intel also provide a second-source manufacturer for its patented x86 microprocessors.[11] Intel and AMD entered into a 10-year technology exchange agreement, first signed in October 1981[45][51] and formally executed in February 1982.[34]
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In 1986, Intel broke an agreement it had with AMD to allow them to produce Intel's micro-chips for IBM; AMD filed for arbitration in 1987 and the arbitrator decided in AMD's favor in 1992. Intel disputed this, and the case ended up in the Supreme Court of California. In 1994, that court upheld the arbitrator's decision and awarded damages for breach of contract.

https://en.wikipedia.org/wiki/Advanced_Micro_Devices#History