Technical information

8.2 Hard Disk Preparation Steps

Before a hard disk can be used to store data it must be “prepared”. This is done in three steps:

 The first step is called low-level formatting (often referred as formatting in Atari world):

It is used to create the actual structures on the surface of the media that are used to hold the data.

The magnetic medium on the surfaces must be divided into tracks that contain numbered sectors

that the controller can find. Once the disk has been formatted, the locations of the tracks and

sectors on the disk are fixed in place.

 Note: With modern SCSI / IDE drives and with host adapter using SD card this operation is not

required anymore since many years and therefore is not described in this document. You should

never do this unless you understand exactly what you are doing.

 The second step is called partitioning: Hard drives can be divided into smaller logical drive units

called partitions. In this way a single hard drive can appear to be two or more drives to the

computer. Besides simply keeping drive sizes under the file system limits, dividing a drive also

allows partitions to be used for specific purposes, keeping the drive organized. The maximum size

of a partition depends on the OS, the Hard Disk Drivers, and the Host Adapter. The partition

information is stored in the first physical sector of the disk called the Root Sector for the TOS file

system and the Master Boot Record for the DOS/FAT file system.

 The third step is called high-level formatting (often referred as Formatting in the PC world and

Initialization in the Atari world): This is the process of creating the basic disk's logical structures: In

order for the OS to use a disk it has to know about the number of tracks, the number of sectors per

tracks, the size of the sectors and the number of heads. This information is defined in the Boot

Sector. Beyond that it is necessary for the OS to find information (e.g. location of all the sectors

belonging to this file, attributes ...) about any files stored on the diskette as well as global

information (e.g. the space still available on the diskette). This information is kept in the File

Allocation Tables (FATs) and the in the Root Directory structure.