Write protection

Write protection, also known as read-only memory, is a data protection feature used to prevent users from accidentally overwriting important data in a computer system or program. It is common in computers, disk controllers, diskettes, and flash memory. It can be used as a form of security against malicious software, or to protect important files from accidental damage.

The feature is usually implemented in two ways: physical enforcement or logic enforcement. Physical enforcement utilizes hardware devices to deny access to the storage mechanism and to protect written data from damage. Logic enforcement works within the operating system or application and prevents the user from performing certain write operations.

Physical enforcement locks the device or media in order to make it impossible to write any data to it, regardless of the user’s permissions or rights. This form of write protection is common in disk controllers as well as in the media device in which media is stored. It is also found on some removable disks such as floppy disks, Zip drives, and USB flash drives.

Logic enforcement works by denying permission for certain user groups to write to the device or folder. This type of write protection is managed within the application or operating system’s security settings. Many applications, for example, allow only administrators to write to certain files or folders.

In addition, some forms of storage media supports write protection through software features, allowing users to set read-only permissions on a file or folder. On the other hand, some programs–such as the Mac OS X Finder–can be set to ignore the read-only flag, making data on the device or media vulnerable to accidental overwrites.

Write protection is an important feature for data safety. While it is not a foolproof security measure, it can help prevent accidental damage to valuable data. For this reason, it is important for users of certain types of data storage devices to be aware of the write protection settings of their devices or media.