or host usb device 35 one could choose to proceed with an improved usb bus mode through improved usb bus 29 or a standard usb bus mode through standard usb bus 39 according to the practical needs thus the dual mode structure could be formed in either client usb device 31 or host usb device 35 this setting differs from the single mode design in the previously said preferred embodiment between the client usb controller 312 and the improved usb bus 29 is placed with a communicating tool adjuster 314 which is used to facilitate data transmission the client usb controller 312 could act the same function as conventional client usb controller 312 by adding the design of the adjuster 314 nevertheless the function of the adjuster 314 could also get executed right within the client usb controller 312 therefore the client usb controller 312 and the adjuster 314 could also get further integrated to form a client controller 313 furthermore by taking the practical circuits design into consideration the improved usb bus 29 could have options in ways of connecting to the cpu 251 firstly it could be directly connected to the cpu 251 by means of a first connecting circuit 351 secondly it could be connected to cpu 251 through a second connecting circuit 352 and the local cpu bus 252 thirdly it could be connected to.