A opcode prefix or prefix byte is a portion of an instruction that allows for a extended set of instructions to follow it by expanding an existing opcode with independent functions. Prefixed opcodes are those existing inside of the instruction subset created by the opcode prefix.
A opcode prefix or prefix byte is a portion of an instruction that allows for a extended set of instructions to follow it by expanding an existing opcode with independent functions. Prefixed opcodes are those existing inside of the instruction subset created by the opcode prefix.