Êtes-vous un étudiant de l'EPFL à la recherche d'un projet de semestre?
Travaillez avec nous sur des projets en science des données et en visualisation, et déployez votre projet sous forme d'application sur Graph Search.
Concept
Write protection
Résumé
Write protection is any physical mechanism that prevents writing, modifying, or erasing data on a device. Most commercial software, audio and video on writeable media is write-protected when distributed.
IBM -inch magnetic tape reels, introduced in the 1950s, had a circular groove on one side of the reel, into which a soft plastic ring had to be placed in order to write on the tape. ("No ring, no write.")
Audio cassettes and VHS videocassettes have tabs on the top/rear edge that can be broken off (uncovered = protected).
8 and -inch floppies can have, respectively, write-protect and write-enable notches on the right side (8-inch punched = protected; -inch covered/notch not present = protected). A common practice with single-sided floppies was to punch a second notch on the opposite side of the disk to enable use of both sides of the media, creating a flippy disk, so called because one originally had to flip the disk over to use the other side.
inch floppy disks have a sliding tab in a window on the right side (open = protected).
Iomega Zip disks were write-protected using the IomegaWare software.
Syquest EZ-drive (135 & 250 MB) disks were write-protected using a small metal switch on the rear of the disk at the bottom.
VHS-C, Video8, Hi8, and DV videocassettes have a sliding tab on the rear edge.
Iomega ditto tape cartridges had a small sliding tab on the top left hand corner on the front face of the cartridge.
USB flash drives sometimes have a small switch, though this has become uncommon. An example of a USB flash drive that supported write protection via a switch is the Transcend JetFlash series.
Secure Digital (SD) cards have a write-protect tab on the left side.
Extensively, media that, by means of design, can't operate outside from this mode: CD-R, DVD-R, Vinyl records, etc.
These mechanisms are intended to prevent only accidental data loss or attacks by computer viruses. A determined user can easily circumvent them either by covering a notch with adhesive tape or by creating one with a punch as appropriate, or sometimes by physically altering the media transport to ignore the write-protect mechanism.
Source officielle
À propos de ce résultat
Cette page est générée automatiquement et peut contenir des informations qui ne sont pas correctes, complètes, à jour ou pertinentes par rapport à votre recherche. Il en va de même pour toutes les autres pages de ce site. Veillez à vérifier les informations auprès des sources officielles de l'EPFL.