record method

Record methods are procedures for recording data on storage media. The methods aim to store as much data as possible on an existing storage medium, i.e. to achieve the highest possible recording density, and also to ensure error-free reading of the data.

All recording methods attempt to store and read out a storage element, which corresponds to one bit, in as small a time window as possible. Such a storage element is defined by a voltage change.

Depending on the type of storage medium, a distinction is made between recording methods for rotating magnetic storage media such as diskettes or hard disks, for rotating optical storage media and for magnetic tapes.

1. Recording methods for rotating storage media such as hard disks and floppy disks include the FM method (Frequency Modulation), Modified Frequency Modulation ( MFM), Modified Modified Frequency Modulation ( MMFM), Run Length Limited ( RLL), its further development Advanced Run Length Limited( ARLL) and the manufacturer-specific Partial Response Maximum Likelihood ( PRML). In addition, the procedures with which the storage capacities are better utilized. These include Variable Track Capacity Recording(VTCR) and the Zone Bit Recording(ZBR) variant.
2. For optical media such as compact discs(CDs) and DVDs, Constant Angular Velocity ( CAV) and Constant Linear Velocity( CLV) as well as Track-at-Once ( TAO) and Disk-at-Once ( DAO) have become established recording methods.
3. For tape drives, the recording method is the way in which the magnetic tape is magnetized. A distinction is made here between the cross- track method, the longitudinal track method and the helical-scan method. These recording methods can work with normal or with high recording density, High Density Digital Recording (HDDR).