Thread: Floppy Disk Geometry

Before using a disk it must be formatted, which prepares it to accept data. Many 3.5" disks are formatted by the manufacturer. If not, the disk must be formatted before it is used in a computer. To format a disk and make it bootable in a DOS/Windows-based computer, go to the command prompt and type. FORMAT A: IS. A prompt appears on the screen to insert a disk. Insert the disk and press Enter.

To format a disk and make it bootable in a Windows 9x-based computer, double-click on the My Computer desktop icon., Right dick on the 3-1/2" (A icon. Select Format from the drop-down menu. Click to enable the Copy system files option. Click the Start button to begin the format process. When a disk is formatted, whether by the manufacturer, the user, or the technician, concentric circles called tracks are drawn on that disk. The 360KB disk has 40 tracks. The 1.2MB, nOKB, 1.44MB, and 2:SSMB disks all have 80 tracks.



The track numbering starts at the outermost ring beginning with the number 0 (zero). These eighty tracks on a 1.44MB high- density disk number from o to 79. The tracks are further subdivided into pie¬shaped wedges. The section defined between a track and an intersecting line is a sector that holds 512 bytes of information. Each sector is identified by a track number and a sector number.

When you save a file, the data is stored in two sectors on the floppy disk. If the file is larger than two sectors, two additional sectors are allocated for the file. The minimum amount of space one file occupies is defined as a cluster. On a floppy disk, a cluster is 1,024 bytes or two sectors. As a file grows in size, it uses more clusters.