1. Origins (1970s)
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Intel 8086 (1978) – The beginning of the x86 instruction set architecture (ISA).
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The name "x86" comes from the last digits of its successors (8086, 80186, 80286, etc.).
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Intel owned the ISA design as intellectual property, but the CPU market soon became more complex due to licensing.
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Early Licensing
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In the late 1970s and 1980s, Intel licensed x86 designs to other companies to ensure supply for IBM PCs.
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IBM insisted on multiple suppliers for CPUs, which forced Intel to share rights.
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2. The Second Source Era (1980s)
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AMD, NEC, Siemens, Fujitsu, Harris, IBM – became “second-source” manufacturers of Intel x86 processors.
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AMD was the most significant: it gained rights to manufacture Intel’s 8086, 80186, and 80286 under cross-license deals.
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These licenses gave AMD deep knowledge of x86 internals and set the stage for future competition.
3. Legal Battles and Divergence (1980s–1990s)
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80386 Era (1985) – Intel refused to share 386 designs with AMD, claiming the license didn’t extend that far.
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AMD sued, leading to a decade-long legal battle over x86 IP.
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Result:
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AMD won rights to design x86-compatible chips (Am386, Am486, K5, K6).
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Intel maintained ownership of the x86 ISA definition, but courts ruled that AMD could implement compatible CPUs.
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4. Cross-Licensing and Exclusivity (1990s–2000s)
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Intel vs. AMD cross-license agreements (renewed periodically):
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AMD had rights to use x86 ISA, but only to make its own designs.
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Intel kept the right to manufacture but agreed not to block AMD from ISA compatibility.
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These agreements typically renewed every 10 years.
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Cyrix, VIA, Transmeta – also built x86-compatible CPUs via clean-room reverse engineering.
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They did not have the same legal depth as AMD, which limited their market longevity.
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VIA eventually acquired Cyrix and Centaur, securing its own limited x86 IP rights.
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5. 64-bit Extensions and IP Leadership (2000s)
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AMD64 (2003) – AMD introduced 64-bit extensions to x86 (later called x86-64).
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Intel initially resisted, pushing IA-64 (Itanium), but it failed commercially.
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Intel eventually adopted AMD’s extensions (calling it Intel 64).
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IP note: AMD originated x86-64, but Intel licensed and implemented it, creating shared control.
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6. Modern Era (2010s–2020s)
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Intel–AMD Cross-License Renewal – still active, covering use of x86 ISA.
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AMD cannot sublicense x86 to others.
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VIA remains the only other company with legitimate x86 rights.
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Chinese x86 Projects:
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Zhaoxin (joint venture between VIA and Shanghai city government) has legal x86 rights via VIA’s IP.
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Hygon (AMD + Chinese partnership) briefly licensed Zen cores for China, but restrictions tightened under U.S. trade controls.
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IP Restrictions:
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Today, only Intel, AMD, and VIA (Zhaoxin) have full legal rights to design and sell x86 CPUs.
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No new entrants can gain access because Intel no longer grants new ISA licenses.
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7. Summary of x86 IP Control
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Intel: Original creator, still primary owner of the ISA.
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AMD: Gained x86 IP rights through lawsuits and cross-licensing; created x86-64.
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VIA/Zhaoxin: Survived via acquisitions and licenses, primarily in niche and Chinese markets.
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Others (Cyrix, Transmeta, NEC, etc.): Defunct or absorbed.
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