DVD-RAM
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Media type | Optical disc |
---|---|
Capacity |
|
Block size | 2 KiB |
Read mechanism | 300–650 nm laser |
Write mechanism | 650 nm laser |
Dimensions | 12cm, 8cm |
Extended from | DVD |
Released | 1996 |
Discontinued | 2019 |
Optical discs |
---|
DVD-RAM (DVD Random Access Memory) is a
In May 2019, Panasonic, the only remaining manufacturer of DVD-RAM discs, announced that it would end production of DVD-RAM media by the end of that month, citing shrinking demand as the primary motivation.[2] Panasonic made these discs under its own brand name and also under the Verbatim brand.
Cartridge types
Size | Bare disc | Non-removable cartridge | Removable cartridge | Empty cartridge/no disc | ||||
---|---|---|---|---|---|---|---|---|
sides | single | double | single | double | single | double | single | double |
12 cm | yes (type 0) | none | type 1 | type 1 | type 2 | type 4 | type 3 | type 5 |
8 cm | yes (type 0) | none | none | none | type 7 | type 6 | type 9 | type 8 |
Format
DVD-RAM works by means of phase change technology which was chosen instead of magneto-optical technology (an already existing rewritable solution at the time) because it doesn't require a magnetic head and therefore it represented reduced complexity and costs. Phase change technology uses laser light to heat the surface of a phase changing alloy and allows it to go from a crystalline to an amorphous state and vice versa, therefore altering its optical reflectivity index. To change the recording material from a crystalline to an amorphous state, and back again a high or medium power laser light is used to control the rate of cooling of the phase changing alloy therefore establishing the final state. Encoding is done by means of difference in reflectivity of the alloy, a laser is pointed at the surface and the returned intensity signifies either a 1 or a 0.[4]
DVD-RAM uses concentric
Specification
Since the Internationale Funkausstellung Berlin 2003 the specification is being marketed by the RAM Promotion Group (RAMPRG), built by
- DVD-RAM version 1.0 (1997), recording speed 1x
– Defines discs with capacity of 2.58 GB per side (24 track zones) (see also: DVD Capacity) - DVD-RAM version 2.0 (1999), recording speed 2x
– Defines discs with more common capacity of 4.7 GB per side (35 track zones) - DVD-RAM version 2.1 (2000)
– Introduces 8-cm discs with capacity of 1.46 GB per side (14 track zones)[6][7] - DVD-RAM version 2.2 (2004) divides drives and discs into two classes due to breaking compatibility:[7][8]
– Class 0, recording speed 2x/3x/5x
– Class 1, recording speed 6x/8x/12x/16x (DVD-RAM2)
Speeds more than 2x are defined by Optional Specifications (Nx-speed DVD-RAM):[7][9]
- Rev. 1.0 (2002) - 3x-speed
- Rev. 2.0 (2004) - 5x-speed
- Rev. 3.0 (2005) - 6x-speed
- Rev. 4.0 (2005) - 8x-speed
- Rev. 5.0 (2005) - 12x-speed
- Rev. 6.0 (2005) - 16x-speed (never released)
Physically smaller, 80 mm in diameter, DVD-RAM discs also exist with capacities of 1.46 GB for a single-sided disc, 2.8 GB for a double-sided disc, and 5.6 GB for a dual-layer double sided disc, however, they are relatively uncommon. DVD-RAMs were originally solely sold in disc caddy cartridges; recent DVD recorders can work with discs either with or without a cartridge, and many devices do not work with cartridges. Discs can be removed from cartridges for use with these drives (except with type 1 media, see table above).
Compatibility
Many operating systems like the
The
Many DVD standalone players and recorders do not work with DVD-RAM. However, within "RAMPRG" (the DVD-RAM Promotion Group consisting of
The last DVD-RAM Specification, DVD-RAM2 (also called RAM2 or Class 1), is not compatible with DVD drives that do not specifically allow reading DVD-RAM2 discs.[12] DVD-RAM2 medium was brought to the market in Japan,[13][14] but was not launched worldwide.[15]
Some high end products such as IBM System p mainframes require DVD-RAM instead of DVD-RW.[16]
Many
The Nintendo Wii U can use DVD-RAM for extended storage over USB.[19][20]
Advantages
- Long life — without physical damage, data is retained for an estimated 30 years. For this reason, it is used for archival storage of data.[21][22]
- Can be rewritten over 100,000 times for the lowest write speed discs (DVD±RW can be rewritten approx. 1,000 times). Faster DVD-RAMs allow fewer rewrites (3x speed: 100,000, 5x speed: 10,000) [DVD-RW. (These are theoretical numbers. In practice they could be smaller depending on the drive, the treatment of the disc and the file system.)
- Reliable writing of discs. Verification done in hardware by the drive, so post-write verification by software is unnecessary. Software verification is disabled in all current DVD Video Recorders.
- Disc defect management designed to safeguard data.
- DVD-burning software may not be required — discs can be used and accessed like a removable Mac OS (8.6 or later) uses DVD-RAM directly. Windows XP uses DVD-RAM directly for FAT32-formatted discs only. Windows Vistais able to write directly to both FAT32- and UDF-formatted DVD-RAM discs from within Windows Explorer. Device drivers or other software are needed for earlier versions of Windows.
- Very fast access of small files on the disc.
- Small 2 KB disc block size wastesless space when writing small files.
- Finalization not necessary. For video recording use, other media such as DVD+RW (when used in DVD+VR mode) do not require a separate finalisation either as finalisation is automatic. The table of contents can be overwritten in this latter media.
- Media available with or without protective cartridges; can be used in the cartridge by many devices.
- In some video recorders DVD-RAM can be written to and read at the same time, allowing one program to be recorded and a different one, or an earlier part of the same one (time slip recording), to be viewed at the same time. DVD+RW recorders can achieve the same thing, and more recently some DVD-RW recorders achieve it as well (though only at the slower recording speeds).
- Usable with some high-end security digital video recorders, such as the Tecton Darlex, as a secure and long-lasting export medium.
- Holds more data when using Double Sided discs than dual-layer DVD+RW and DVD-RW - 9.4GB for DVD-RAM vs 8.5GB for DVD+RW DL and DVD-RW DL.
- Has write-protect tabs to prevent accidental deletion when used in a cartridge.
Disadvantages
- High-speed media unavailability: Only 3x and 5x discs were readily available, with 12x RAM2 discs being among the rarest of optical media and never sold outside Japan.
- Higher media cost.[23]
- Less compatibility than DVD+RW and DVD-RW[24] on most DVD devices, despite predating both formats (as noted above).
- If random writes are performed with a constant linear velocity (CLV), which may be the only available speed mode on specific drives and/or media, the speed of the rotary engine needs to be re-adjusted each time the pickup system jumps to another position on the disc, significantly impeding transfer speeds.[25]
See also
- Chase Play
- MultiLevel Recording
- Phase-change Dual
- List of optical disc manufacturers
- Live File System
References
- ^ "Understanding DVD - Physical, Logical and Application Specifications". www.osta.org. Optical Storage Technology Association. Retrieved 28 July 2020.
- ^ "DVD-RAM Disc for Recording Completion of Production" (in Japanese). Panasonic Corporation. Retrieved 2019-05-22.
- ^ Taylor, Jim. "DVD FAQ - What are the DVD-RAM cartridge types?". DVD Demystified. Retrieved 2019-12-15.
- ^ "DVD Technical Guide - Printer Friendly version".
- ^ "Data Tech Store".
- ^ Taylor 2001, pp. 148, 228.
- ^ a b c "Supplementary Documents issued in the past for DVD-RAM(4.7G) Book" (PDF). DVD FLLC. June 2008. Archived (PDF) from the original on 2015-09-26. Retrieved 2019-12-17.
- ^ "Important Notice to the subscribers of the DVD-RAM Format Specifications Book Ver.2.2, regarding compatibility with legacy devices for Class 1 discs" (PDF). DVD Forum. Retrieved 2019-12-16.
- ^ "DVD Book Construction" (PDF). DVD FLLC. Retrieved 2019-12-16.
- ^ "Using DVD-RAM discs". support.apple.com. 2012-02-18. Retrieved 2014-02-05.
- ^ "Mac OS X: "The disc 'Ram' could not be modified" Alert". support.apple.com. 2012-02-17. Retrieved 2014-02-05.
- ^ "Usage Of 16 X DVD-RAM Disc (RAM2 Disc)". 2008-01-31. Archived from the original on 2008-01-31. Retrieved 2009-09-28.
- ^ "Maxell DRM47D.1P (RAM 12x 1-side) Price Comparison" (in Japanese). Archived from the original on 2007-10-27. Retrieved 2019-12-16.
Released on March 24, 2006
- ^ "Maxell DRM47D.1P Review" (in Japanese). 2008-03-10. Archived from the original on 2019-12-16. Retrieved 2019-12-16.
- ^ Gieselmann, Hartmut (2006-08-30). "No 12X DVD-RAM media for Europe". heise.de (in German). Archived from the original on 2019-05-30. Retrieved 2019-12-16.
- ^ "HMC backup". Archived from the original on 2007-02-23. Retrieved 2009-09-28.
- ^ "Archive of discontinued Hitachi-LG Data Storage optical drives". Archived from the original on 2020-07-11. Retrieved 2020-07-11.
- ^ "Manual".
- Nintendo Life. Hookshot Media. Retrieved 26 July 2022.
- ^ Friscia, John (17 May 2021). "Wii U can format DVDs and burn eShop games to them, it turns out". Destructoid. Archived from the original on 26 November 2022. Retrieved 26 July 2022.
- ^ "Fujifilm DVD-RAM Disc". Fujifilm. 2006-10-17. Archived from the original on 2006-10-17. Retrieved 2009-08-15.
- ^ "Update: Phase Change WORM". West World Productions and Gale Group. Retrieved 2007-12-29.
- ISBN 978-0-7645-7073-5.
- ^ Taylor 2001, p. 224, Table 5.3. Compatibility of Writable DVD Formats.
- ^ Technology Connextras (Technology Connections) (2019-01-11). "DVD-RAMifications (experiments and other goodies relating to DVD-RAM)". YouTube.
Books
- Taylor, Jim (2001). DVD Demystified (2nd ed.). ISBN 0-07-138944-X.