Identifying the Beginning Sector of a Track

The two main methods of identifying the beginning sector of a track are

• Hard Sectored Floppy

In hard sectored, the start of each sector is identified by a physical hole. A light is shone through the hole and picked up on the other side by a detector. As the disk rotates, this causes a sequence of pulses to occur as the sector ID holes allow the light to pass through to the detector. The holes are called index holes. This method was used in the Apple II computer.

• Soft Sectored Floppy

In soft sectored, only one index hole is used, and each sector is preceded with data bytes which identify the sector number. This format is used in IBM-PC compatible computers.



Fig 5.6: Floppy Drive

Cleaning Kit The image on the TOP shows a floppy diskette cleaning system. It consists of a floppy disk containing a cleaning disk and some cleaning fluid. The fluid is placed on the floppy disk and then the disk is inserted. Any foriegn material on the read/write heads are transferred to the disk. The cleaning disk can only be used a limited number of times.