Method of converting extended instructions based on an emulation flag and retirement of corresponding microinstructions, device and system using the same

An instruction conversion device, an instruction conversion method, an instruction conversion system, and a processor are provided. The instruction conversion device includes a monitor for determining whether a ready-for-execution instruction is an instruction that belongs to a new instruction set or an extended instruction set, wherein the new instruction set and the extended instruction set have the same type of the instruction set architecture as that of the processor. If the ready-for-execution instruction is determined as an extended instruction, this extended instruction is converted into a converted instruction sequence by means of the conversion system, this converted instruction sequence is then sent to the processor for executions, thereby extending the lifespans of the electronic devices embodied with old-version processors.