- What happens if you give the Intel 8086 processor an instruction that doesn’t exist? A modern microprocessor (80186 and later) will generate an exception, indicating that an illegal instruction was executed. However, early microprocessors didn’t include the circuitry to detect illegal instructions, since the chips didn’t have transistors to spare. Instead these processors would do something, but the results weren’t specified.
Then all the elders of Israel gathered themselves together, and came to Samuel unto Ramah,
1 Samuel 8:4 KJV
undocumented instructions of