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Illegal opcode

In computer science, an illegal opcode, also called an unimplemented operation, unintended opcode or undocumented instruction, is an instruction to a CPU that is not mentioned in any official documentation released by the CPU's designer or manufacturer, which nevertheless has an effect. Illegal opcodes were common on older CPUs designed during the 1970s…

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Illegal opcode

Nodes35
Edges34
Triples37
Avg. degree1.94
Density0.057143
Components1

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Illegal opcode

Top relations

related to Further reading · 28
Illegal opcode → Adam, Alex, Archived, Brown, Extra Instructions Of The, Harald Feldmann, How MOS, Illegal, Illegal Opcodes, Interrupt List, LST, Michael, NB, OPCODES, Potemkin, Ralf, Ralf Brown's Interrupt List's, Retrieved, Sean, Series CPU
related to overview · 8
Illegal opcode → Another, Apple II, Apple IIc, CPU, For, Here, Such, While

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Important terminology

instructions opcodes illegal cpu undocumented also instruction official older processors archived operation manufacturer 6502 z80 x86 original retrieved common usually

Entity relationships Subject–Predicate–Object triples

SubjectPredicateObjectConfidenceSrc
fuzzing uncovered a vast number of undocumented instructions in x86 processors as late as 2018instance ofresearch using techniques0.80text
Illegal opcoderelated to Further readingVardy0.60section
Illegal opcoderelated to Further readingAdam0.60section
Illegal opcoderelated to Further readingExtra Instructions Of The0.60section
Illegal opcoderelated to Further readingSeries CPU0.60section
Illegal opcoderelated to Further readingArchived0.60section
Illegal opcoderelated to Further readingRetrieved0.60section
Illegal opcoderelated to Further readingNB0.60section
Illegal opcoderelated to Further readingIllegal0.60section
Illegal opcoderelated to Further readingSteil0.60section
Illegal opcoderelated to Further readingMichael0.60section
Illegal opcoderelated to Further readingHow MOS0.60section

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