Disk

Storage medium
90-mm-(3,5")-Diskette
general
name disk
type magnetically
origin
invention year of 1971
inventors Alan Shugart (IBM)
storage capacity 80 KiB
data (3.5 " - disks)
size 3.5 " (90.0 mm × 94.0 mm × 3.3 mm)
storage capacity 1440 KiB (see also diskette format)
life span approx. 5 years
130-mm (5.25 ") - disk
of parts 3.5 " - disk:
1. Writing protection
2. Turning camp
3. Protection screen
4. Housing from plastic
5. Ring of paper
6. Magnet disk
7. Disk sector
3,5"-Diskette Vorder- und Rückseite, sowie Innenseite
3.5 " - disk front and back, as well as inside

a disk is a magnetic data medium, which is used for the data storage.It consists of a flexible plastic disk (therefore it the name, often also „floppy ones “of English floppy disk), which is coated with a magnetizable material (usually ferric oxide). To the protection this disk is usually in a plastic housing packed, depending upon kindeither likewise flexibly or rigidly.

In contrast to non removable disks the write/read head sharpens directly with disks on the coated magnetizable surface, which leads with the time to clear abrasion and which durable usefulness of disks limits strongly.

Table of contents

characteristics

of the diameters of disks usually in tariff (“) one indicates, common sizes are or were:

  • 200 mm (approx. 8 ") with 180 KB - thatoriginal diskette format of IBM as replacement for the unmanageable piles of punch cards
  • 130 mm (approx. 5.25 ") with 80 KiB to 1200 KiB (160 KiB with the first IBM PCs)
  • 90 mm (approx. 3,5 ") with 720 KiB to 3520 KiB ≈ 3,4Beyond that MT (OD disks with 44 sectors formatted

) became still different sizes of (among other things 80 mm (approx. 3 tariff) (cutter CPC), 3.25 tariff and 50 mm (approx. 2 tariff)) developed, which could not become generally accepted however.

The standardsfor 3,5 " - disks are ISO/CInternational Electronical Commission 8860-1: 1987 (doubled density), ISO/CInternational Electronical Commission 9529-1: 1989 (high density) and ISO/CInternational Electronical Commission 10994-1: 1992 (specially-high density); all data take place in metric units. These standards clarify the measurements, which result in 90.0 mm × 94.0 mm × 3.3 mm. The magnetic diskon the inside has a diameter of exactly 86.0 mm. One differentiates between

With hardsectorized disks there is on the plastic disk an index hole per sector, with soft-sectored only one. This index hole specifies the starting point of a trace, if it ofDrive assembly is not ignored (soft synchronization: Recognize the beginning of trace by a synchronization bit sequence).

To the exact specification still further data belong to a disk:

  • the number of magnetic tracks („TRACKs “) (typically 40 or 80)
  • the number of sectors (of blocks per trace) (for example 18)
  • the block size(in former times 128, 256 or 512 byte, today usually only 512 byte)
  • the recording method (initially FM, later usually MFM; with Apple and Commodore also the GCR became - procedure assigned)

it is technically possible, depending upon trace a differentTo accommodate number of sectors, particularly since more place is theoretical on the outside traces; since the relative speed of the head is also higher however there, this encountered difficulties. Some manufacturers varied therefore either the rotational speed (Apple) or the data rate (Commodore)dependent on the head position, which permitted to store more on the disk, this however incompatible drive assemblies of other manufacturers made.

A trick to increase the Zugriffsgeschwindkeit existed in the so-called Interleave, whereby the sectors not numerically ascending, but in other oneSequence on a trace were noted. Thus could e.g. the technically necessary rework of a reading take place, and after it arranged logically next sector shifts directly to be read in. The ideal Interleave rate depended often on the used hardware.

Was similarly storedthe idea, that logically first sector of a trace somewhat shifts in relation to the neighbouring traces to arrange, so that after a track switching ideally e.g. to be equivalent further read could.

Disks have a writing protection, which itself with 3,5 " - disks by onesmall slidegate valve in the back on the top right on and/or. to switch off leaves. With 5,25 " - and 8 " - disks a lateral writing protection recess with a sticker must be sealed to the writing protection.

A disk keeps the data approx. five years. If it is accordingly shielded against magnetism, are also longer storage times problem-free possible. By the earth liking nestism it is advisable however the data after 1 - on the disk to tape 2 years again, in order to prevent an overrun with security.

floppy disk drives

3.5 " - floppy disk drive
Anschlusskabel für Diskettenlaufwerke in IBM-Kompatiblen PCs
lead for floppy disk drivesin IBM-compatible PCs

a floppy disk drive serves the disk for reading and writing the data. There are internal, which are integrated into a computer housing, and external drive assemblies, which are attached their own housing to have and over cables to the computer. ThoseDesigns correspond to those of the disks: 200 mm (8 "), 130 mm (5.25 ") and 90 mm (3.5 ").

During 8 " - drive assemblies after turning on to usually run nonstop and with nonusage the read-write heads from the disk be taken off, the engine becomes with the smaller variantsonly if necessary turned on; the heads can always remain therefore on the disk surface, without these to overloads.

history

the first disk (200 mm, 8 tariff) with the drive assembly belonging to it becomes of IBM 1971 on the marketbrought. The invention is generally attributed to Alan Shugart. This creates 1973 its own company (Shugart Associates) and develops 1976 the 5.25 " - disk. 1978 presented first 5.25 " - the floppy disk drive of the world to TEAC; for the then new microcomputers the new format becomes immediatelytaken up, for large computers only somewhat later.1981 place Sony the 90-mm (3.5 ") - disk in the rigid housing with first 720 · 1024 byte = 720 KiB ≈ 737 KB (9 sectors), later 1440 · 1024 byte = 1440 KiB = 1   474   560 byte ≈1.40625 MT (18 sectors, unformated) (falsely with 1,44 MT designates). The wrong designation with „1.44 MT “agitates by the fact that with disks 1 MT with 1000 · 1024 byte (!) one computed. She is used in the IBM-PC andbecomes thereby the standard.

Many other systems used the same disks, however with different recording formats and file systems. Thus about one seizes with FFS formatted 3.5 " - disk of an Amiga - computer 1.76 MT. Still so-called OD disks with 2880 appear later · 1024 byte =2880 KiB (36 sectors) (falsely with 2,88 MT designates). The latters found particularly with computers of NEXT one and IBM the PS/2s use, beyond that however hardly reached spreading. „The 1,44-MB “- disk remained through many years the usual standard, until the diskby the increasing cross-linking of the computers and the new, substantially more data lost seizing, recordable optical media (CD-R and DVD-R) at spreading and use. Since approx. 2000 is sold completely ever more new computers without floppy disk drive.

alternatives

  • Occasionally in IBM-PC and also Apple - computers Zip - were blocked drive assemblies (100 MT) than floppy disk drive replacement. These could not become generally accepted however durably, since they were displaced by the recordable optical media.
  • A very short appearance as replacement had superdisk Drive assemblies (LS120). Beside special storage media here also Standard-3,5 is " - disks with a capacity of 1440 KiB and/or. 720 KiB usable.
  • Sony tried 1998 with a HiFD - floppy disk drive with 200MB capacity and to 1,44 the MT disk compatibly thoseusual drive assemblies to replace should.

All these improved versions of the original 3,5-Zoll-Diskettenlaufwerkes could attain however no broader spreading; meanwhile (2006) also they are outdated regarding storage capacity and speed.

Usually no inserted floppy disk drives have newer PC more since the year 2004/2005. Insteadone can attach external floppy disk drives to the USB - interface, which are not contained in the scope of supply however with new equipment. Often the diskette CONTROLLER is nevertheless present on the Main board, so that one then can later insert a floppy disk drive.

Since 2002/2003 becomeincreasingly USB stick (Flashspeicher) as well as other external USB and FireWire mass storages such as non removable disks and DVDs than data media uses, however the necessary abilities for complete substitution of the disk on this basis, above all the boat ability , are only with newerx86-PC motherboards given.

diskette formats

Größenvergleich zwischen einer 8"- und einer 3,5"-Diskette
size comparison between 8 " - and 3.5 " - a disk
Historical list after appearance of the diskette formats, including the last everywhere existing format, 3 ½ - inch of hp.
Format feature year capacity in KiB
(if differently not indicated)
of it deviating inTrade indicated capacity
8-inch (READ only) 1971 80
8-inch 1973 256 ,256 KB
8-inch 1974 800
8-inch binary sided 1975 1000
5 ¼ - inch of 1976 110
5 ¼ - inch of dd 1978 360 ,360 KB
5 ¼ - inch of hp 1984 1200
3-inch 1982? 360
3-inch dd 1984? 720
3 ½ - inch of dd 1984 720
2-inch 1985? 720?
3 ½ - inch of hp 1987 1440 1.44 MT
3 ½ - inch of OD 1991 2880 2.88 MT
3 ½ - inch of LS-120 1996 120.375 MIB 120 MT
3 ½ - inch of LS-240 1997 240.75 MIB 240 MT
3 ½ - inch of HiFD 1998/99 150/200 MIB? 150/200 MT
abbreviations: Dd = double Density; QD = Quad Density; Hp = High Density OD = Extended Density; LS = laser servo; HiFD = High capacity floppy disk
also ?characterized data are unknown quantity origin andmust be examined by vouchers. The other listed storage capacities refer up:
  • For 8-inch: Standard IBM - formats, like it of the System/370 - large computers and newer systems to be used
  • for 5 ¼ - and 3 ½ - inch: Standard PC formats, the indicated capacities are the total volume of allThe storage capacity attainable with the same drive assemblies and disks can vary sectors

of the disk, including the storage location with other formats, used for boat sector and file system.

see also

Wiktionary: Disk - word origin, synonyms and translations

Web on the left of

Commons: Disk - pictures, videos and/or audio files
 

  > German to English > de.wikipedia.org (Machine translated into English)