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WORM drives preceded the invention of the CD-R, DVD-R and BD-R.An example was the IBM 3363. [1] These drives typically used either a 5.1 in (13 cm) or a 12 in (30 cm) disc in a cartridge, with an ablative optical layer that could be written to only once, and were often used in places like libraries that needed to store large amounts of data.
This often increases the speed of image write operations by several times, at the cost of losing the simple sequential read/write semantics of normal memory. Additional bits which are provided on some computer architectures , such as AMD64 , allow the shadowing of ROM contents in memory (shadow ROM), and the configuration of memory-mapped I/O .
These mechanisms are intended to prevent only accidental data loss or attacks by computer viruses. A determined user can easily circumvent them either by covering a notch with adhesive tape or by creating one with a punch as appropriate, or sometimes by physically altering the media transport to ignore the write-protect mechanism.
A reference to a memory location includes a value that identifies a segment and an offset within that segment. A segment descriptor may limit access rights, e.g., read only, only from certain rings. The x86 architecture has multiple segmentation features, which are helpful for using protected memory on this architecture. [1]
In addition to its literal meaning, the term may be applied to a situation when the data written by one circuit can be read only by other circuitry. The most common occurrence of the latter situation is when a processor writes data to a write-only register of hardware the processor is controlling. The hardware can read the instruction but the ...
An RW lock allows concurrent access for read-only operations, whereas write operations require exclusive access. This means that multiple threads can read the data in parallel but an exclusive lock is needed for writing or modifying data. When a writer is writing the data, all other writers and readers will be blocked until the writer is ...
In computer technology, read-only can refer to: Read-only memory (ROM), a type of storage media; Read-only access to memory using memory protection; Read-only access to files or directories in file system permissions; Read-only access for database administrators in database system permissions
As the file format is a group of XML files within a ZIP; unzipping, editing, and replacing the workbook.xml file (and/or the individual worksheet XML files) with identical copies in which the unknown key and salt are replaced with a known pair or removed altogether allows the sheets to be edited. [citation needed]