CD ROM
| Media type | Optical disc |
|---|---|
| Capacity | 194 MiB (8 cm), 650–900 MiB (12 cm) |
| Read mechanism | 150 KiB/s (1×), 10,800 KiB/s (72×) |
| Write mechanism | 150 KiB/s (1×), 8,400 KiB/s (56×) |
| Standard | ISO/IEC 10149 |
| Usage | Data storage |
A CD-ROM /ˌsiːˌdiːˈrɒm/ is a pre-pressed optical compact disc which contains data. The name is an acronym which stands for "Compact Disc Read-Only Memory". Computers can read CD-ROMs, but cannot write to CD-ROMs which are not writable or erasable.
From the mid-1990s until the mid-2000s, CD-ROMs were popularly used to distribute software for computers and video game consoles. Some CDs, called enhanced CDs, hold both computer data and audio with the latter capable of being played on a CD player, while data (such as software or digital video) is only usable on a computer (such as ISO 9660 format PC CD-ROMs).
An early CD-ROM format was developed by Sony and Denon, introduced at a Japanese computer show in 1984. It was an extension of Compact Disc Digital Audio, and adapted the format to hold any form of digital data, with a capacity of 540 MiB. The Yellow Book is the technical standard that defines the format of CD-ROMs. One of a set of color-bound books that contain the technical specifications for all CD formats, the Yellow Book, standardized by Sony and Philips in 1988, has a capacity of 650 MiB.
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