PC Hardware A Beginner’s Guide

(^200) PC Hardware: A Beginner’s Guide
per inch (tpi), to the extra-high density specification for 3.5-inch disks that have just
under 35,000 bpi and 135 tpi. The higher the density standard of the disk, the more data it
will hold, and the more it will cost. Most disks proudly display their density and their
storage abilities on their packaging.

Formatting

Afloppydisk,regardlessofitssizeordensity,mustbeformattedbeforeitcanreceiveand

store data.Formattingperforms two tasks, in two separate steps of the same process:

 Low-level formatting This level of formatting creates the organization

structures on the disk, including the tracks and the beginning points for

each sector on the track.

 High-level formatting This format level adds the logical structures,

including the file allocation table (FAT) and the disk’s root directory.

You can pay a little more and buy preformatted disks just about anywhere, including

the supermarket. However, not all PCs will work with these diskettes and you may need

to reformat them on your PC.

The low-level and high-level formatting processes together create the storage charac-

teristics of the floppy disk, which summarizes the overall storage structure for the disk.

Table 9-5 lists the characteristics for the two most popular diskette sizes in use.

Disk Size Capacity Tracks Sectors/Track Total Sectors/Disk Bytes/Sector

5.25” 1.2MB 80 15 2,400 512

3.5” 1.44MB 80 18 2,880 512

Table 9-5. Typical Diskette Storage Characteristics