IBM tape reel with white write ring in place, and an extra yellow ring.
From top to bottom: an unprotected Type I cassette, an unprotected Type II, an unprotected Type IV, and a protected Type IV.
A sheet of 5-1/4" floppy disk write protect tabs.
(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 inchmagnetic 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).
IomegaZip 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.
8 mm and digital video tape cartridges have a sliding tab on the rear edge.
Iomegaditto tape cartridges had a small sliding tab on the top left hand corner on the front face of the cartridge.
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. Download high resolution version (697x664, 139 KB)Write protect ring from early IBM magnetic tape. ... Download high resolution version (697x664, 139 KB)Write protect ring from early IBM magnetic tape. ... ImageMetadata File history File links Cassette_Write_Protect_IV.jpg Summary Cassette tapes, showing write protect tabs removed on bottom tape, type IV (metal). ... ImageMetadata File history File links Cassette_Write_Protect_IV.jpg Summary Cassette tapes, showing write protect tabs removed on bottom tape, type IV (metal). ... Image File history File links Floppy_tabs_3x2. ... Image File history File links Floppy_tabs_3x2. ... Data is the plural of datum. ... For other uses, see IBM (disambiguation). ... Mid-19th century tool for converting between different standards of the inch An inch is an Imperial and U.S. customary unit of length. ... Compact audio cassette Magnetic tape is a non-volatile storage medium consisting of a magnetic coating on a thin plastic strip. ... The 1950s were a decade that spanned the years 1950 through 1959, although some sources say from 1951 through 1960. ... For the meaning of cassette in genetics, see cassette (genetics). ... Top view VHS cassette with U.S. 25c coin for scale Bottom view of VHS cassette with magnetic tape exposed The Video Home System, better known by its abbreviation VHS or simply as Video, is a recording and playing standard for video cassette recorders (VCRs), developed by JVC (with some... A floppy disk is a data storage device that is composed of a ring of thin, flexible (i. ... The Iomega Corporation NYSE: IOM is a supplier of portable computer storage devices and media. ... The Zip drive is a medium-capacity Insert non-formatted text here removable disk storage system, introduced by Iomega in late 1994. ... SyQuest Technology, Inc. ... Digital video is a type of video recording system that works by using a digital, rather than analog, representation of the video signal. ... The Iomega Corporation NYSE: IOM is a supplier of portable computer storage devices and media. ... The Ditto Drive series was a proprietary tape-based storage medium released by Iomega during the 1990s. ... A USB keydrive, shown with a US quarter coin for scale. ... Solid state disk (SSD, also called solid state drive) is a data storage device that uses memory chips, such as SDRAMs, to store data, instead of the spinning platters found in conventional hard disk drives. ... In computer security, a computer virus is a self-replicating computer program that spreads by inserting copies of itself into other executable code or documents. ... Two rolls of adhesive tape. ... It has been suggested that this article or section be merged with Punchhole. ...
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. An operating system (OS) is an essential software program that manages the hardware and software resources of a computer. ...
Hardware protection can accomplish various things, including: writeprotection for hard disk drives, memory protection, monitoring and trapping unauthorized system calls, etc. Again, no single tool will be foolproof and the "stronger" hardware-based protection is, the more likely it will interfere with the "normal" operation of your computer.
Also, some existing hardware protection schemes can be easily bypassed, fooled, or disconnected, if the virus writer knows them well and designs a virus that is aware of the particular defense.
Therefore, making a hardware protection system for such a computer typically involves deciding on some (small) set of operations that are "valid but not normally performed except by viruses", and designing the system to prevent these operations.
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