. An inner rack of a mobile rack in a computer, comprising:
a rack chamber disposed at a central area thereof;
a signal conversion circuit board disposed at a rear side thereof, having a jut out inner signal connector at an outer side thereof, providing a control IC for converting a USB interface signal into an IDE interface signal, and having a power outlet separating from an IDE interface connector at an inner side thereof;
whereby, once an IDE interface storage device is placed in and located at the rack chamber and the inner rack is inserted into an outer rack of the mobile rack, the inner signal connector engages with an outer signal connector suitable for IDE and USB interface signals to connect an USB signal of the inner signal connector to an USB signal of the outer signal connector; and the IDE interface storage device can provide functions of hot swap and plug and play via a switch control of power on/off.