A device (belt device) for fixing and securing a data processing device in a chassis includes a first bracket, a second bracket, and a buckle slidably connected to the second bracket. The first bracket is rotatable about the second bracket. The buckle can slide to and engage with the second bracket to connect the first bracket with the second bracket, the cavity defined by the first bracket and the second bracket of the belt device can receive and hold a data processor in place without tools being needed either for mounting or demounting the processing device.