A clock synchronizer for generating a local clock signal synchronized to a received clock signal. Thus, the present invention provides a needle threading machine, in which a thread is stably hooked on a hook, thereby reducing a defective needle threading work and enhancing productivity. The method includes, loading a bus functional module in an ASIC simulator; determining configuration of devices supported by a host emulation system; and mapping configuration information to the host emulation system, wherein a virtual interface driver maps the configuration information to the host emulation system. At least one carrier has at least two storage spaces for tools. Thus, the drive member can be detached from the connector to facilitate a user replace the drive member. Otherwise, the modification is discarded.