Category:Optical computer storage media
This category has the following 2 subcategories, out of 2 total.
This category has the following 2 subcategories, out of 2 total.
1. CD-ROM – 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, some CDs, called enhanced CDs, hold both computer data and audio with the latter capable of being played on a CD player, while data is only usable on a computer. An early CD-ROM format was developed by Sony and Denon, introduced at a Japanese computer show in 1984 and 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 standard that defines the format of CD-ROMs. One of a set of books that contain the technical specifications for all CD formats. CD-ROMs are identical in appearance to audio CDs, and data are stored and retrieved in a similar manner. Discs are made from a 1.2 mm thick disc of polycarbonate plastic, data is stored on the disc as a series of microscopic indentations. A laser is shone onto the surface of the disc to read the pattern of pits. This pattern of changing intensity of the beam is converted into binary data. Several formats are used for data stored on discs, known as the Rainbow Books. The Yellow Book, published in 1988, defines the specifications for CD-ROMs, the CD-ROM standard builds on top of the original Red Book CD-DA standard for CD audio. Other standards, such as the White Book for Video CDs, the Yellow Book itself is not freely available, but the standards with the corresponding content can be downloaded for free from ISO or ECMA. There are several standards that define how to structure data files on a CD-ROM, ISO9660 defines the standard file system for a CD-ROM. ISO13490 is an improvement on this standard which adds support for non-sequential write-once and re-writeable discs such as CD-R and CD-RW, as well as multiple sessions. The ISO13346 standard was designed to address most of the shortcomings of ISO9660, and a subset of it evolved into the UDF format, which was adopted for DVDs. The bootable CD specification was issued in January 1995, to make a CD emulate a hard disk or floppy disk, is called El Torito, data stored on CD-ROMs follows the standard CD data encoding techniques described in the Red Book specification. This includes cross-interleaved Reed–Solomon coding, eight-to-fourteen modulation, and the use of pits, the structures used to group data on a CD-ROM are also derived from the Red Book
2. Optical disc – The encoding material sits atop a thicker substrate which makes up the bulk of the disc and forms a dust defocusing layer. The encoding pattern follows a continuous, spiral path covering the disc surface. Most optical discs exhibit a characteristic iridescence as a result of the diffraction grating formed by its grooves and this side of the disc contains the actual data and is typically coated with a transparent material, usually lacquer. The reverse side of a disc usually has a printed label, sometimes made of paper. Optical discs are usually between 7.6 and 30 cm in diameter, with 12 cm being the most common size, a typical disc is about 1.2 mm thick, while the track pitch ranges from 1.6 µm to 320 nm. An optical disc is designed to support one of three recording types, read-only, recordable, or re-recordable, write-once optical discs commonly have an organic dye recording layer between the substrate and the reflective layer. Rewritable discs typically contain an alloy recording layer composed of a phase change material, most often AgInSbTe, an alloy of silver, indium, antimony, Optical discs are most commonly used for storing music, video, or data and programs for personal computers. The Optical Storage Technology Association promotes standardized optical storage formats, although optical discs are more durable than earlier audio-visual and data storage formats, they are susceptible to environmental and daily-use damage. Libraries and archives enact optical media preservation procedures to ensure continued usability in the optical disc drive or corresponding disc player. For computer data backup and physical data transfer, optical discs such as CDs and DVDs are gradually being replaced with faster, smaller solid-state devices and this trend is expected to continue as USB flash drives continue to increase in capacity and drop in price. Additionally, music purchased or shared over the Internet has significantly reduced the number of audio CDs sold annually. The first recorded use of an optical disc was in the 1884 when Alexander Graham Bell, Chichester Bell. An early optical disc system existed in 1935, named Lichttonorgel, an early analog optical disc used for video recording was invented by David Paul Gregg in 1958 and patented in the US in 1961 and 1969. This form of optical disc was an early form of the DVD. It is of special interest that U. S, patent 4,893,297, filed 1989, issued 1990, generated royalty income for Pioneer Corporations DVA until 2007 —then encompassing the CD, DVD, and Blu-ray systems. In the early 1960s, the Music Corporation of America bought Greggs patents and his company, american inventor James T. Russell has been credited with inventing the first system to record a digital signal on an optical transparent foil which is lit from behind by a high-power halogen lamp. Russells patent application was first filed in 1966 and he was granted a patent in 1970, following litigation, Sony and Philips licensed Russells patents in the 1980s. Both Greggs and Russells disc are floppy media read in transparent mode, in the Netherlands in 1969, Philips Research physicist, Pieter Kramer invented an optical videodisc in reflective mode with a protective layer read by a focused laser beam U. S
3. Optical Disc Archive – Optical Disc Archive is a media and hardware technology that was introduced by the Sony Corporation. The technology was announced on 16 April 2012 during the NAB Show with the first units shipping in February 2013. Generation 2 of the Optical Disc Archive technology is scheduled for mid-2016, generation 2 will increase the cartridge capacity to 3. 6TB, the read speed to 2Gbps and the write speed to 1Gbps. Sony Corporation and Panasonic Corporation on announced on 10 March 2014 their cooperation in producing a new media trademarked as Archival disc, the Archival disc media will be used in future Optical Disc Archive Media to achieve at least 6TB of storage
4. Optical tape – Optical tape is a medium for optical storage generally consisting of a long and narrow strip of plastic onto which patterns can be written and from which the patterns can be read back. It shares some technologies with film stock and optical discs. In the 1990s, it was projected that optical tape would be a used, high-capacity. At least one working system and several prototypes were developed, but as of 2007, the primary motivation behind developing this technology was the possibility of far greater storage capacities than either magnetic tape or optical discs. It was also considered more durable than magnetic tape, since it is not vulnerable to magnetic fields and is read by lasers instead of contact with a magnetic head. Creo — Former manufacturer of Optical tape recorders, now a part of Kodak, TRAAMS — An optical tape technology developed by a consortium led by Terabank, Inc. LOTS — Another optical tape technology developed by LOTS Technology, Inc
5. Professional Disc – Professional Disc is a digital recording optical disc format introduced by Sony in 2003 primarily for XDCAM, its new tapeless camcorder system. PFD uses a 405 nm wavelength and an aperture of 0. After the 23GB disc was released, a dual-layer 50 GB was developed and released and this format is sometimes confused with the Blu-ray Disc format, another optical disc format using blue-violet lasers and supported by Sony. Even the PFDs caddy and Blu-rays bk prototype caddy looked very similar, capabilities differ, single-layer PFD discs have a capacity of 23 GB whereas Blu-rays can store 25 GB. However, Blu-ray Discs currently allows a 2x data transfer rate of 72 Mbit/s – lower than PFD and this is because PFD discs use much higher quality media and drives use higher quality components, making them prohibitively expensive for the consumer segment to which Blu-ray is aimed. The PFD format is used as the medium in Sonys XDCAM professional video devices. Professional Disc for DATA was a general-use recording media variant of PFD, aimed primarily at small and medium-sized enterprise for data archival, PDD drives and media became available in mid-2004. The BW-RS101 external SCSI-3 drive originally retailed in the UK at £2,344 directly from Sony, two other drives – the BW-F101/A internal SCSI drive and the BW-RU101 external USB2.0 drive also became available around the same time. On March 31,2007, Professional Disc for DATA reached their end of life, PFD are still being manufactured and used in Sony XDCAM devices. Sony states that PDD and PFD media are not compatible, Sonys PDW-U1 Professional Disc drive is an external drive that connects via USB2.0 to Windows or Mac OS X computers using the included free software from Sony. In a firmware and software upgrade in late July 2009, Sony added the ability for users to store any computer files on the Professional Disc into the dedicated User Data folder. Blu-ray Disc HD DVD Ultra Density Optical Optical disc Sony Global - Professional Disc for DATA Sony Storage Solutions - ProData Sony b2b - Professional Disk