http://www.c-jump.com/CIS77/CIS77syllabus.htm
Encoding x86 Instructions It is time to take a look that the actual machine instruction format of the x86 CPU family.
They don't call the x86 CPU a Complex Instruction Set Computer (CISC) for nothing!
Although more complex instruction encodings exist, no one is going to challenge that the x86 has a complex instruction encoding! 1. x86 Instructions Overview x86 Instruction Encoding:
The prefix bytes are not the opcode expansion prefix discussed earlier - they are special bytes to modify the behavior of existing instructions.
2. x86 Instruction Format Reference
Another view of the x86 instruction format:
3. x86 Opcode Sizes
standard one-byte opcode two-byte opcode consisting of a 0Fh opcode expansion prefix byte.
The second byte then specifies the actual instruction.
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