Write 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 videocassettes 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). 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.3-1/2 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 & 250MB) disks were write protected using a small metal switch on the rear of the disk at the bottom.
8mm,
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 and most other forms of
solid state storage often have a small switch.
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