Cyrix - Legal Troubles

Legal Troubles

Unlike AMD, Cyrix had never manufactured or sold Intel designs under a negotiated license. Cyrix's designs were the result of meticulous in-house reverse engineering. Thus, while AMD's 386s and even 486s had some Intel-written microcode software, Cyrix's designs were completely independent. Focused on removing potential competitors, Intel spent many years in legal battles with Cyrix, consuming Cyrix financial resources, claiming that the Cyrix 486 violated Intel's patents, when in reality the design was proven independent.

Intel largely lost the Cyrix case. But the final settlement was out of court: Intel agreed that Cyrix had the right to produce their own x86 designs in any foundry that happened to already hold an Intel license. Both firms gained out of this: Cyrix could carry on having their CPUs made by Texas Instruments, SGS Thomson, or IBM, all holders of Intel cross-licenses; Intel avoided a potentially embarrassing loss.

The follow-on 1997 Cyrix-Intel litigation was the reverse: instead of Intel claiming that Cyrix 486 chips violated their patents, now Cyrix claimed that Intel's Pentium Pro and Pentium II violated Cyrix patents—in particular, power management and register renaming techniques. The case was expected to drag on for years but was settled quite promptly, by another mutual cross-license agreement. Intel and Cyrix now had full and free access to each other's patents. The settlement didn't say whether the Pentium Pro violated Cyrix patents or not; it simply allowed Intel to carry on making them either way—exactly as the previous settlement sidestepped Intel's claim that the Cyrix 486 violated Intel patents.