About FloppyDisk

A small motor in the drive rotates the diskette at a regulated speed, while a second motor-operated mechanism moves the magnetic read–write head, (or heads, if a double-sided drive) along the surface of the disk. Both read and write operations require physically contacting the read–write head to the disk media, an action accomplished by a "disk load" solenoid.[3] To write data onto the disk, current is sent through a coil in the head. The magnetic field of the coil magnetizes spots on the disk as it rotates; the change in magnetization encodes the digital data. To read data, the tiny voltages induced in the head coil by the magnetization on the disk are detected, amplified by the disk drive electronics, and sent to the Floppy disk controller. The controller separates the data from the stream of pulses coming from the drive, decodes the data, tests for errors, and sends the data on to the host computer system.
A blank diskette has a uniform featureless coating of magnetic oxide on it. A pattern of magnetized tracks, each broken up into sectors, is initially written to the diskette so that the diskette controller can find data on the disk. The tracks are concentric rings around the diskette, with spaces between the tracks where no data is written. Gaps, where no user data is written, are provided between the sectors and at the end of the track to allow for slight speed variations in the disk drive. These gaps are filled with padding bytes that are discarded by the diskette controller. Each sector of data has a header that identifies the sector location on disk. An error checking cyclic redundancy check is written into the sector headers and at the end of the user data so that the diskette controller can detect errors when reading the data. Some errors (soft errors) can be handled by re-trying the read operation. Other errors are permanent and the disk controller will signal failure to the operating system if multiple tries cannot recover the data.

Formatting a blank diskette is usually done by a utility program supplied by the computer operating system manufacturer. Generally the disk formatting utility will also set up an empty file storage directory system on the diskette, as well as initializing the sectors and tracks on a blank diskette. Areas of the diskette that can't be used for storage due to some flaw can be locked out so that the operating system does not attempt to use the "bad sectors". This could be quite time consuming, so many environments had an option to "quick format" which would skip the error checking process. During the heyday of diskette usage, diskettes pre-formatted for popular computers were sold.
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