[ The PC Guide | Systems and Components Reference Guide | Hard Disk Drives | Construction and Operation of the Hard Disk | Hard Disk Logic Board ]

Sense, Amplification and Conversion Circuits

Since the signals read from the hard disk on a modern drive are very weak, special circuits are required to read the low-voltage signals coming from the drive heads, amplify them and interpret them, to decide if each signal read is a one or a zero. As hard disks have their data packed more tightly the signals get weaker, and this job becomes more complex. The new PRML read methods used in modern hard disks involve using complicated digital signal processing techniques to allow the use of even weaker signals, making this job more complex.

During the write process the opposite conversion is necessary. The logic board must translate the "1"s and "0"s of the data stream into appropriate commands and signals for the read/write heads, using the drive's encoding method.

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