This page was last edited on 1 October , at Single-sided drives shipped in ,  and double sided in The diskette goes in only part of the way. Some errors are soft and can be resolved by automatically re-trying the read operation; other errors are permanent and the disk controller will signal a failure to the operating system if multiple attempts to read the data still fail.
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Census Record There are 3, census records available for the last name Kette. Search 's US census records for Kette. Passenger List There are immigration records available for the last name Kette. Both read and write operations require the media to be rotating and the head to contact the disk media, an action originally accomplished by a disk-load solenoid.
To write data, current is sent through a coil in the head as the media rotates. The head's magnetic field aligns the magnetization of the particles directly below the head on the media.
When the current is reversed the magnetization aligns in the opposite direction, encoding one bit of data. To read data, the magnetization of the particles in the media induce a tiny voltage in the head coil as they pass under it. This small signal is amplified and sent to the floppy disk controller , which converts the streams of pulses from the media into data, checks it for errors, and sends it to the host computer system. A blank unformatted diskette has a coating of magnetic oxide with no magnetic order to the particles.
During formatting, the magnetizations of the particles are aligned forming tracks, each broken up into sectors , enabling the controller to properly read and write data. The tracks are concentric rings around the center, with spaces between tracks where no data is written; gaps with padding bytes are provided between the sectors and at the end of the track to allow for slight speed variations in the disk drive, and to permit better interoperability with disk drives connected to other similar systems.
Each sector of data has a header that identifies the sector location on the disk. A cyclic redundancy check CRC is written into the sector headers and at the end of the user data so that the disk controller can detect potential errors. Some errors are soft and can be resolved by automatically re-trying the read operation; other errors are permanent and the disk controller will signal a failure to the operating system if multiple attempts to read the data still fail.
This enables a smaller concave area for the thumb and fingers to grasp the disk during removal. On Apple Macintosh computers with built-in floppy drives, the ejection button is replaced by software controlling an ejection motor which only does so when the operating system no longer needs to access the drive. The user could drag the image of the floppy drive to the trash can on the desktop to eject the disk.
In the case of a power failure or drive malfunction, a loaded disk can be removed manually by inserting a straightened paper clip into a small hole at the drive's front panel, just as one would do with a CD-ROM drive in a similar situation. Before a disk can be accessed, the drive needs to synchronize its head position with the disk tracks. In some drives, this is accomplished with a Track Zero Sensor, while for others it involves the drive head striking an immobile reference surface.
In either case, the head is moved so that it is approaching track zero position of the disk. When a drive with the sensor has reached track zero, the head stops moving immediately and is correctly aligned. For a drive without the sensor, the mechanism attempts to move the head the maximum possible number of positions needed to reach track zero, knowing that once this motion is complete, the head will be positioned over track zero.
Different sizes of floppy disks are mechanically incompatible, and disks can fit only one size of drive. In addition, there are many subtle, usually software-driven incompatibilities between the two. As computer platforms began to form, attempts were made at interchangeability. Alongside the common disk sizes were non-classical sizes for specialized systems.
The first floppy disk was 8 inches in diameter,  was protected by a flexible plastic jacket and was a read-only device used by IBM as a way of loading microcode. The family of 8-inch disks and drives increased over time and later versions could store up to 1. Single sided disks were coated on both sides, despite the availability of more expensive double sided disks. The reason usually given for the higher cost was that double sided disks were certified error-free on both sides of the media.
Double-sided disks could be used in some drives for single-sided disks, as long as an index signal was not needed. This was done one side at a time, by turning them over flippy disks ; more expensive dual-head drives which could read both sides without turning over were later produced, and eventually became used universally. In the early s, a number of manufacturers introduced smaller floppy drives and media in various formats. Micro diskette , Micro disk , or Micro floppy , similar to a Sony design but improved to support both single-sided and double-sided media, with formatted capacities generally of KB and KB respectively.
Single-sided drives shipped in ,  and double sided in What became the most common format, the double-sided, high-density HD 1. These were followed in by double-sided KB floppies. The higher capacity was achieved at the same recording density by varying the disk rotation speed with head position so that the linear speed of the disk was closer to constant.
Later Macs could also read and write 1. A sliding detented piece can be moved to block or reveal the part of the rectangular hole that is sensed by the drive. It is also possible to format a disk at a lower density than it was intended for, but only if the disk is first thoroughly demagnetized with a bulk eraser, as the high density format is magnetically stronger and will prevent the disk from working in lower density modes.
Writing at different densities than disks were intended for, sometimes by altering or drilling holes, was possible but deprecated.
Other, smaller, floppy sizes were proposed, especially for portable or pocket-sized devices that needed a smaller storage device. A 2-inch nominal size known as the Video Floppy was introduced by Sony for use with its Mavica still video camera. Floppy disk size is often referred to in inches, even in countries using metric and though the size is defined in metric. Other formats may get more or less capacity from the same drives and disks.
Data is generally written to floppy disks in sectors angular blocks and tracks concentric rings at a constant radius. On the IBM PC , MSX and most other microcomputer platforms, disks were written using a constant angular velocity CAV format,  with the disk spinning at a constant speed and the sectors holding the same amount of information on each track regardless of radial location. Because the sectors have constant angular size, the bytes in each sector are compressed more near the disk's center.
A more space-efficient technique would be to increase the number of sectors per track toward the outer edge of the disk, from 18 to 30 for instance, thereby keeping nearly constant the amount of physical disk space used for storing each sector; an example is zone bit recording.
Apple implemented this in early Macintosh computers by spinning the disk more slowly when the head was at the edge, while maintaining the data rate, allowing KB of storage per side and an extra 80 KB on a double-sided disk. Apple eventually reverted to constant angular velocity on HD floppy disks with their later machines, still unique to Apple as they supported the older variable-speed formats. Disk formatting is usually done by a utility program supplied by the computer OS manufacturer; generally, it sets up a file storage directory system on the disk, and initializes its sectors and tracks.
Areas of the disk unusable for storage due to flaws can be locked marked as "bad sectors" so that the operating system does not attempt to use them. This was time consuming so many environments had quick formatting which skipped the error checking process. When floppy disks were often used, disks pre-formatted for popular computers were sold. The unformatted capacity of a floppy disk does not include the sector and track headings of a formatted disk; the difference in storage between them depends on the drive's application.
It is implied that this should not be exceeded, since doing so will most likely result in performance problems. DMF was introduced permitting 1. Mixtures of decimal prefixes and binary sector sizes require care to properly calculate total capacity. Whereas semiconductor memory naturally favors powers of two size doubles each time an address pin is added to the integrated circuit , the capacity of a disk drive is the product of sector size, sectors per track, tracks per side and sides which in hard disk drives with multiple platters can be greater than 2.
Although other sector sizes have been known in the past, formatted sector sizes are now almost always set to powers of two bytes, bytes, etc. Hence, these disks hold 1. Usable data capacity is a function of the disk format used, which in turn is determined by the FDD controller and its settings. Differences between such formats can result in capacities ranging from approximately to KiB 1. The highest capacity techniques require much tighter matching of drive head geometry between drives, something not always possible and unreliable.
This represents the speed of raw data bits moving under the read head; however, the effective speed is somewhat less due to space used for headers, gaps and other format fields and can be even further reduced by delays to seek between tracks. From Wikipedia, the free encyclopedia. For other uses, see Floppy disambiguation. History of the floppy disk. Floppy disk format and List of floppy disk formats. List of floppy disk formats. Physics portal Electronics portal IT portal Apple portal.
The term was used f. The Designer's Guide to Disk Drives 1st ed. Reston Publishing Company, Inc. Floppy disk loads mainframe computer data". Archived from the original on Jarrett, Computer Technology Review, winter Jan , pp.
The McGraw-Hill Companies PC makers are still standing by floppy drives despite vanishing consumer demand". Report to Congressional Requesters. United States Government Accountability Office. New Delhi Television Limited. The Design of Everyday Things. Archived from the original PDF on Its single-sided SA micro-floppy drive offers K of unformatted storage. Shugart's Kevin Burr said the obvious next step is to put another K of storage on the other side of the diskette and that the firm will come out with a double-sided 1-megabyte micro-floppy drive soon.