DVD-RAM

Last updated

DVD-RAM
DVD-RAM Logo.svg
Data side of a DVD-RAM disc.png
Borders of the hard sectors are visible on the data side of a type 2 DVD-RAM disc
Media type Optical disc
Capacity
  • Version 1.0: 2.58 GB per side
  • Version 2.0: 4.7 GB per side
  • Version 2.1: 1.46 GB per side (8 cm; 3" discs)
Block size2 KiB
Read mechanism300–650 nm laser
Write mechanism650 nm laser
Dimensions12 cm (5"), 8 cm (3")
Extended from DVD
Released1996
Discontinued2019

DVD-RAM (DVD Random Access Memory) is a DVD-based disc specification presented in 1996 by the DVD Forum, which specifies rewritable DVD-RAM media and the appropriate DVD writers. DVD-RAM media have been used in computers as well as camcorders and personal video recorders since 1998. [1]

Contents

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.

The "RAM" in its name is not related to random-access memory (also named "system memory" or "computer memory") that computers use to store opened programs, a much different technology.

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. [3]

DVD-RAM uses concentric tracks each divided into hard (factory originated) sectors, in contrast to traditional spiral recording found in other DVD and CD formats. A 12 cm (5") 4.7 GB disc is divided into 35 zones of tracks, with each zone having more sectors per track compared to the previous zone. This makes its data structuring very similar to that of hard drives and floppy disks. This means that usually DVD-RAMs are suitable to be accessed by the OS without any special software [4]

Specification

DVD-RAM Detail Sectors.jpg
A DVD-RAM disc can be identified by many small rectangles distributed on the surface of the data carrier
Dvd-ram-closeup.jpg
These rectangles constitute the hard (factory originated) sectoring of the DVD-RAM

Recording speeds

Since the Internationale Funkausstellung Berlin 2003 the specification is being marketed by the RAM Promotion Group (RAMPRG), built by Hitachi, Toshiba, Maxell, LG Electronics, Matsushita/Panasonic, Samsung, Lite-On and Teac. The specification distinguishes between:

Speeds more than 2x are defined by Optional Specifications (Nx-speed DVD-RAM): [6] [8]

Diameters

DVD-RAM discs can have 12 or 8 cm in diameter, around 5 or 3 inches respectively. The latter variant is mainly intended for camcorders that use DVD as storage media and also exists 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).

Cartridge types

DVD-RAM cartridge types [9]
SizeBare discNon-removable cartridgeRemovable cartridgeEmpty cartridge/no disc
sidessingledoublesingledoublesingledoublesingledouble
12 cmyes (type 0)nonetype 1type 1type 2type 4type 3type 5
8 cmyes (type 0)nonenonenonetype 7type 6type 9type 8

Compatibility

A DVD-RAM Type 2 DVD-RAM FUJIFILM disc removable without cartridge locking pin.jpg
A DVD-RAM Type 2

Many operating systems like the classic Mac OS (from Mac OS 8.6 up), macOS, Linux, and Microsoft Windows XP can use DVD-RAM directly, while earlier versions of Windows require separate device drivers or the program InCD.

Windows XP can only write directly to FAT32 formatted DVD-RAM discs. For UDF formatted discs, which are considered faster,[ by whom? ] a third-party UDF file system driver capable of writing or software such as InCD or DLA are required. Windows Vista and later can natively access and write to both FAT32 and UDF formatted DVD-RAM discs using mastered burning method or packet writing. Even though it is possible to use any file system one likes, very few perform well on DVD-RAM. This is because some file systems frequently overwrite data on the disc and the table of contents is contained at the start of the disc. Windows Vista (and later) implement the CPRM data protection and thus discs formatted under Windows XP (or earlier) have compatibility issues with Vista onwards (and vice versa).

The classic Mac OS up to 9.2 can read and write HFS, HFS+, FAT, and UDF formatted DVD-RAM discs directly. In Mac OS X (versions 10.0.x through 10.4.x) UDF-formatting of DVD-RAM is no longer supported, instead formatting and writing DVD-RAM is done in HFS+ format. (UDF support was re-implemented in 10.5 Leopard) (HFS and UFS should also be supported on older versions of Mac OS X that retain support for these file systems.) [10] [11]

Many DVD standalone players and recorders do not work with DVD-RAM. However, within "RAMPRG" (the DVD-RAM Promotion Group consisting of Hitachi, Toshiba, Maxell, LG Electronics, Matsushita/Panasonic, Samsung, Lite-On, Teac) there were a number of well-known manufacturers of standalone players, recorders, and camcorders that could use DVD-RAM. Panasonic, for instance, had a range of players and recorders which made full use of the advantages of DVD-RAM.

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 half-height DVD Multi Recorder drives released between 2006 and 2010, including the TSSTcorp SH-S182/S183 (2006) and SH-S203/TS-H653B (2007) have officially adapted support for 12× DVD-RAM speeds, while more recent DVD writers such as the SH-224DB (2013) and Blu-ray writers such as the LG BE16NU50 (2016) have restricted the supported DVD-RAM writing speed to 5×. [17] [18]

Advantages

A DVD-RAM for DVD recorders Panasonic DVD-RAM001.JPG
A DVD-RAM for DVD recorders
A miniDVD-RAM with DVD round holder Mini-DVD-RAM with Holder.jpg
A miniDVD-RAM with DVD round holder
How to open a DVD-RAM cartridge (caddy) Dvdramopen2.gif
How to open a DVD-RAM cartridge (caddy)

Disadvantages

See also

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References

  1. ↑ "Understanding DVD - Physical, Logical and Application Specifications". www.osta.org. Optical Storage Technology Association . Retrieved 28 July 2020.
  2. ↑ "DVD-RAM Disc for Recording Completion of Production" (in Japanese). Panasonic Corporation. Retrieved 2019-05-22.
  3. ↑ "DVD Technical Guide - Printer Friendly version".
  4. ↑ "Data Tech Store".
  5. ↑ Taylor 2001, pp. 148, 228.
  6. 1 2 3 "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.
  7. ↑ "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.
  8. ↑ "DVD Book Construction" (PDF). DVD FLLC. Retrieved 2019-12-16.
  9. ↑ Taylor, Jim. "DVD FAQ - What are the DVD-RAM cartridge types?". DVD Demystified. Retrieved 2019-12-15.
  10. ↑ "Using DVD-RAM discs". support.apple.com. 2012-02-18. Retrieved 2014-02-05.
  11. ↑ "Mac OS X: "The disc 'Ram' could not be modified" Alert". support.apple.com. 2012-02-17. Retrieved 2014-02-05.
  12. ↑ "Usage Of 16 X DVD-RAM Disc (RAM2 Disc)". 2008-01-31. Archived from the original on 2008-01-31. Retrieved 2009-09-28.
  13. ↑ "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
  14. ↑ "Maxell DRM47D.1P Review" (in Japanese). 2008-03-10. Archived from the original on 2019-12-16. Retrieved 2019-12-16.
  15. ↑ 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.
  16. ↑ "HMC backup". Archived from the original on 2007-02-23. Retrieved 2009-09-28.
  17. ↑ "Archive of discontinued Hitachi-LG Data Storage optical drives". Archived from the original on 2020-07-11. Retrieved 2020-07-11.
  18. ↑ "Manual".
  19. ↑ "Fujifilm DVD-RAM Disc". Fujifilm. 2006-10-17. Archived from the original on 2006-10-17. Retrieved 2009-08-15.
  20. ↑ "Update: Phase Change WORM". West World Productions and Gale Group. Retrieved 2007-12-29.
  21. ↑ Mark L. Chambers (2004). CD and DVD Recording For Dummies. John Wiley & Sons. p. 54, Table 3-1. ISBN   978-0-7645-7073-5.
  22. ↑ Taylor 2001, p. 224, Table 5.3. Compatibility of Writable DVD Formats.
  23. ↑ Pioneer DVD-105S from 2000
  24. ↑ Technology Connextras (Technology Connections) (2019-01-11). DVD-RAMifications (experiments and other goodies relating to DVD-RAM). YouTube .

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