Writing process

A writing process is a process for writing data on a data carrier .

Logical writing method

In the case of data carriers, a logical writing process is the type of coding that is carried out before the physical writing to the data carrier. Common writing methods for magnetic data storage devices today are:

• Partial Response / Maximum Likelihood ( PRML ) and increased
• Extended Partial Response / Maximum Likelihood ( EPRML )

There used to be procedures like:

• digital frequency modulation (FM), (also known as Miller code)
• Modified Frequency Modulation (MFM),
• Group Coded Recording (GCR) and
• Run Length Limited (RLL) common.

Today only MFM is used for diskettes . Other writing methods are used for optical data carriers , such as:

• Eight-to-fourteen modulation (EFM) applied.

Physical writing technique

The physical writing technique is the actual physical process of modifying a data carrier in such a way that (the same) data can be retrieved from it later.

This includes:

• Perpendicular Recording (vertical recording)
• Longitudinal Recording (Longitudinal recording)
• Patterned media process (storage in isolated magnetic islands)
• Heat-assisted magnetic recording (HAMR)