I am going through the following series of lectures on OS development .
In the fourth tutorial , I came across the term " OEM" parameter block that stores the windows MBR and the Boot-record information whose soul purpose is to describe the file system on the disk .
And then on moving to the following tutorial ,by taking the authors promise to explain about it at a later opportune point , I came across the term "FAT" file system . And I could see that there were few terms in the parameter block like "bpbNumberofFATS" and "bpbsectorsperFAT" . "FAT" stands for "File Allocation Table" and it is a again a "filesystem" .
This got me confused as "OEM" parameter block is used to describe the filesystem on a disk . And if "FAT" itself is a file system , then that means and surely there are other file systems ,which could have been on that disk . Why will the "OEM" block predefine the file system in terms of "FAT".
On reading a bit about other file systems , I came across statements like "FAT was written by .." . And it further piqued me to ask , what does it mean to write a filesystem ?
So , basically I am confused about :
What exactly is a filesystem ? (Is it a kind of coordinate system to provide information about the storage of the contents of the file ?)
How is a file system written ?
- There are a lots of other file systems , OEM is used to describe the file system on a disk , so why OEM has parameters concerned about FAT's ? And who sets the filesystem of a disk and how ?