Write protection

From Free net encyclopedia

Image:Write protect ring.agr.jpg Image:Cassette Write Protect IV.jpg

Write protection, (also known as record protection) is any physical mechanism that prevents modification or erasure of valuable data on a device. Most commercial software, audio and video is sold pre-protected.

• IBM 1/2 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.
• Audio cassettes and VHS tapes have tabs on the top/rear edge that can be broken off (uncovered = protected).
• 8 and 5-1/4 inch floppies can have a notch on the right side (covered/not present = protected).
• 3-1/2 inch floppy disks have a sliding tab in a window on the right side (open = protected).
• 8 mm and digital video tape cartridges have a sliding tab on the rear edge.
• USB keys generally have a small switch.

These mechanisms are only intended to prevent accidental data loss or attacks by computer viruses. A determined user can easily circumvent them either by covering a notch with adhesive tape, or creating one with a punch, as appropriate.

Write-protection is typically enforced by the hardware. In the case of computer devices, attempting to violate it will return an error to the operating system, while some tape recorders physically lock the record button when a write-protected cassette is present.