What Is a Write-Protect Switch on an SD Memory Card?by Ralph Horton
For several decades, photographers and video operators were limited by the capacity of their film. However, many 21st-century consumers prefer digital cameras and video recorders, which write data to high-capacity memory cards. The Secure Digital card is a standard among device manufacturers.
As digital cameras started appearing on the market, Panasonic, SanDisk and Toshiba united in January 2000 to form the SD Card Association. The organization developed, produced and promoted SD cards for use among manufacturers and consumers, and SD card technology gradually gained acceptance within the marketplace.
Full-size SD cards are universally rectangular in shape. When held facing the front side of an SD card, the top right corner appears tapered to allow for simple installation in consumer devices. SD cards measure 32 mm tall by 24 mm wide, or only slightly larger than the average postage stamp, and just 2.1 mm thick.
Most, but not all, SD cards have a small write-protection switch. This switch is visible along the top left edge of the card when held facing forward. If moved to the "Lock" position (down), this switch prevents any device from erasing or writing to the memory card. For example, if you place a locked SD card inside a digital camera, you are limited to merely viewing the images or video on the card. However, if the write-protect switch is in the unlock position (up), you can take new pictures, delete pictures, view your pictures and format the card.
- photo_camera film can and sd card image by dwags from Fotolia.com