Simulation of Magnetic Disk Defects by Off-Track Writing and Reading
Original Publication Date: 1987-Jul-01
Included in the Prior Art Database: 2005-Feb-01
The manufacture of high-performance magnetic disk storage devices requires careful testing of the disk surfaces for defects that could result in readback errors. A tester used for testing the disk surface writes different patterns on the disk and looks for distortions in the readback signal. Checking the function of this tester normally involves feeding in externally synthesized waveforms which simulate a disk surface with various types of defects. A method is described here which eliminates the need for external equipment to synthesize the test waveforms. This method uses off-track writing to generate amplitude- modulated patterns on the disk. The disk tester has the following inherent capabilities. It can move the read/write heads to any track and can move them off the center of the track in small increments.