The invention provides a disk recorder and player having a disk loading tray capable of mounting both large-diameter and small-diameter disks, wherein especially the small-diameter disk mounted on the disk loading tray is prevented from popping out and slipping into the disk recorder and player. A generator motor computation unit computes behaviors of the generator motor, using a state quantity regarding the generator motor and a predetermined transfer function. Each baffle has a convex rear surface which meets the sidewall in a circular crease. The internal signaling component is responsive to an electromagnetic field and emits a detectable signal when the denture is located with a specified interrogation zone or search area. A post decoder in the second stage receives the second input and the first signal, processes the identification of the local bitline, and generates a second signal to be sent to the register file array. 15%, particularly, the present invention relates to an improved process for the preparation of 7–3,4-dihydrocarbostyril of formula having dimer impurity less than 0.