Preamplifier circuit configurable to allow simultaneous read and write operations for self-servo writing a disk drive

A disk drive comprising:

• (a) a disk comprising a first radial location for storing first clock data including a plurality of magnetic transitions recorded at a predetermined interval and a second radial location for storing second clock data including a plurality of magnetic transitions recorded at a predetermined interval;
• (b) a head actuated radially over the disk, the head comprising a read element and a write element;
• (c) a preamp comprising:
• a data input for receiving write data from the control system;
• a read signal output for outputting an amplified read signal to the control system;
• a read signal input for receiving a read signal from the read element;
• a write signal output for supplying a write signal to the write element;
• a first amplifier circuit, responsive to the write data, for generating the write signal supplied to the write element via the write signal output;
• a second amplifier circuit for amplifying the read signal from the read element to generate the amplified read signal output to the control system via the read signal output;
• and
• a head control circuit, responsive to head select data received from the control system, for simultaneously enabling the first and second amplifier circuits to perform a simultaneous read and write operation;
• and
• (d) a control system for self-servo writing the disk by configuring the preamp circuit to enable the read element to read the first clock data from the first radial location and the write element to write the second clock data to the second radial location, wherein while the read element reads the magnetic transitions of the first clock data the write element simultaneously writes a DC erase signal between the magnetic transitions of the second clock data.