DVD-RAM (DVD Random Access Memory) is a

DVD The DVD (common abbreviation for Digital Video Disc or Digital Versatile Disc) is a digital optical disc data storage format. It was invented and developed in 1995 and first released on November 1, 1996, in Japan. The medium can store any kin ...

-based disc specification presented in 1996 by the

DVD Forum The DVD Forum is an international organization composed of hardware, software, media and production companies that use and develop the DVD and formerly HD DVD formats. It was initially known as the DVD Consortium when it was founded in 1995. H ...

, which specifies rewritable DVD-RAM media and the appropriate

DVD writer A DVD recorder is an optical disc recorder that uses optical disc recording technologies to digitally record analog or digital signals onto blank writable DVD media. Such devices are available as either installable drives for computers o ...

s. DVD-RAM media have been used in computers as well as

camcorder A camcorder is a self-contained portable electronic device with video camera, video and recording as its primary function. It is typically equipped with an articulating screen mounted on the left side, a belt to facilitate holding on the right s ...

s and

personal video recorder A digital video recorder (DVR) is an electronic device that records video in a digital format to a disk drive, USB flash drive, SD memory card, SSD or other local or networked mass storage device. The term includes set-top boxes with direct to ...

s since 1998. In May 2019,

Panasonic formerly between 1935 and 2008 and the first incarnation of between 2008 and 2022, is a major Japanese multinational conglomerate corporation, headquartered in Kadoma, Osaka. It was founded by Kōnosuke Matsushita in 1918 as a lightbulb ...

, 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. Panasonic made its discs under its own brand name and also under the Verbatim brand.

Cartridge types

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. DVD-RAM uses concentric tracks each divided into hard (factory originated)

sectors Sector may refer to: Places * Sector, West Virginia, U.S. Geometry * Circular sector, the portion of a disc enclosed by two radii and a circular arc * Hyperbolic sector, a region enclosed by two radii and a hyperbolic arc * Spherical sector, a ...

, in contrast to traditional spiral recording found in other DVD and CD formats. A 12 cm 4.7 GB disc is divided into 35

zones Zone or The Zone may refer to: Places Climate and altitude zones * Death zone (originally the lethal zone), altitudes above a certain point where the amount of oxygen is insufficient to sustain human life for an extended time span * Frigid zone, ...

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 drive A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating platters coated with magne ...

s and

floppy disk A floppy disk or floppy diskette (casually referred to as a floppy, or a diskette) is an obsolescent type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined ...

s. This means that usually DVD-RAMs are suitable to be accessed by the OS without any special software

Specification

Since the Internationale Funkausstellung Berlin 2003 the specification is being marketed by the ''RAM Promotion Group'' (RAMPRG), built by

Hitachi () is a Japanese multinational corporation, multinational Conglomerate (company), conglomerate corporation headquartered in Chiyoda, Tokyo, Japan. It is the parent company of the Hitachi Group (''Hitachi Gurūpu'') and had formed part of the Ni ...

Toshiba , commonly known as Toshiba and stylized as TOSHIBA, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan. Its diversified products and services include power, industrial and social infrastructure systems ...

Maxell , commonly known as Maxell, is a Japanese company that manufactures consumer electronics. The company's name is a contraction of "Maximum capacity dry cell". Its main products are batteries, wireless charging products, storage devices, LCD/lase ...

LG Electronics LG Electronics Inc. () is a South Korean multinational electronics company headquartered in Yeouido-dong, Seoul, South Korea. LG Electronics is a part of LG Corporation, the fourth largest ''chaebol'' in South Korea, and often considered ...

, Matsushita/Panasonic,

Samsung The Samsung Group (or simply Samsung) ( ko, 삼성 ) is a South Korean multinational manufacturing conglomerate headquartered in Samsung Town, Seoul, South Korea. It comprises numerous affiliated businesses, most of them united under the ...

Lite-On Lite-On (also known as LiteOn and LiteON) is a Taiwanese company that primarily manufactures consumer electronics, including LEDs, semiconductors, computer chassis, monitors, motherboards, optical disc drives, and other electronic components. ...

and

Teac TEAC may refer to: * TEAC Corporation, a Japanese electronics company * TEAC Oval, a sports stadium in Port Melbourne, Australia * Tetraethylammonium chloride, a chemical compound * Trolox equivalent antioxidant capacity, a measure of antioxidan ...

. The specification distinguishes between: * 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) * DVD-RAM version 2.2 (2004) divides drives and discs into two classes due to breaking compatibility:
– 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): * 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 a capacity of 1.46 GB for a single-sided disc and 2.8 GB for a double-sided disc, but they are uncommon. DVD-RAMs were originally solely sold in

cartridge Cartridge may refer to: Objects * Cartridge (firearms), a type of modern ammunition * ROM cartridge, a removable component in an electronic device * Cartridge (respirator), a type of filter used in respirators Other uses * Cartridge (surname), a ...

s; 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

classic Mac OS Mac OS (originally System Software; retronym: Classic Mac OS) is the series of operating systems developed for the Macintosh family of personal computers by Apple Computer from 1984 to 2001, starting with System 1 and ending with Mac OS 9. Th ...

(from

Mac OS 8.6 Mac OS 8 is an operating system that was released by Apple Computer on July 26, 1997. It includes the largest overhaul of the classic Mac OS experience since the release of System 7, approximately six years before. It places a greater emphasis on ...

up),

macOS macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac (computer), Mac computers. Within the market of ...

Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, which i ...

, and

Microsoft Windows XP Windows XP is a major release of Microsoft's Windows NT operating system. It was released to manufacturing on August 24, 2001, and later to retail on October 25, 2001. It is a direct upgrade to its predecessors, Windows 2000 for high-end and ...

can use DVD-RAM directly, while earlier versions of Windows require separate device drivers or the program

InCD InCD is
a

Windows XP Windows XP is a major release of Microsoft's Windows NT operating system. It was release to manufacturing, released to manufacturing on August 24, 2001, and later to retail on October 25, 2001. It is a direct upgrade to its predecessors, Wind ...

Home and Professional can only write directly to

FAT32 File Allocation Table (FAT) is a file system developed for personal computers. Originally developed in 1977 for use on floppy disks, it was adapted for use on hard disks and other devices. It is often supported for compatibility reasons by ...

formatted DVD-RAM discs. For UDF formatted discs, which are considered faster, a third-party UDF file system driver capable of writing or software such as

InCD InCD is
a

DLA DLA may refer to: Entities and organizations * DLA Piper, an international law firm * DLA (TV), a Latin American television provider * Defense Logistics Agency, United States * Democratic Left Alliance, a Polish political party * Dental Laborat ...

are required.

Windows Vista Windows Vista is a major release of the Windows NT operating system developed by Microsoft. It was the direct successor to Windows XP, which was released five years before, at the time being the longest time span between successive releases of ...

and later can natively access and write to both FAT32 and UDF formatted DVD-RAM discs using mastered burning method or

packet writing Packet writing (or incremental packet writing, IPW) is an optical disc recording technology used to allow write-once and rewritable CD and DVD media to be used in a similar manner to a floppy disk from within the operating system. Details ...

. 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 Content Protection for Recordable Media and Pre-Recorded Media (CPRM / CPPM) is a mechanism for controlling the copying, moving, and deletion of digital media on a host device, such as a personal computer, or other player. It is a form of digit ...

data protection and thus discs formatted under Windows XP (or earlier) have compatibility issues with Vista onwards (and vice versa). The

up to 9.2 can read and write

HFS HFS may refer to: Computing * Hardware functionality scan, a security mechanism used in Microsoft Windows operating systems * Hierarchical File System, a file system used by Apple Macintosh computers * Hierarchical File System (IBM MVS), used MV ...

HFS+ HFS Plus or HFS+ (also known as Mac OS Extended or HFS Extended) is a journaling file system developed by Apple Inc. It replaced the Hierarchical File System (HFS) as the primary file system of Apple computers with the 1998 release of Mac OS 8. ...

FAT In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food. The term often refers specifically to triglycerides (triple es ...

, and UDF formatted DVD-RAM discs directly. In

Mac OS X macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop and lapt ...

(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 UFS may refer to: Computers *Universal Flash Storage *Unix File System *Unsupervised Forward Selection, a data reduction algorithm Other

* UFS (trade union), former trade union in the United Kingdom * United Family Services * United Feature Sy ...

should also be supported on older versions of Mac OS X that retain support for these file systems.) Many DVD standalone players and recorders do not work with DVD-RAM. However, within "RAMPRG" (the DVD-RAM Promotion Group consisting of

, Matsushita/

) there were a number of well-known manufacturers of standalone players, recorders, and camcorders that ''could'' use DVD-RAM.

, 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. DVD-RAM2 medium was brought to the market in Japan, but was not launched worldwide. Some high end products such as

IBM System p The IBM System p is a high-end line of RISC ( Power)/UNIX-based servers. It was the successor of the RS/6000 line, and predecessor of the IBM Power Systems server series. History The previous RS/6000 line was originally a line of workstations ...

mainframes require DVD-RAM instead of DVD-RW. Many

half-height A drive bay is a standard-sized area for adding hardware to a computer. Most drive bays are fixed to the inside of a case, but some can be removed. Over the years since the introduction of the IBM PC, it and its compatibles have had many form f ...

DVD Multi Recorder The DVD (common abbreviation for Digital Video Disc or Digital Versatile Disc) is a digital optical disc data storage format. It was invented and developed in 1995 and first released on November 1, 1996, in Japan. The medium can store any kind ...

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×.Archive of TSSTcorp optical drive manuals
/ref> The Nintendo Wii U can use DVD-RAM for extended storage over USB.

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. * 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) , but still more than

DVD+RW DVD recordable and DVD rewritable are optical disc recording technologies. Both terms describe DVD optical discs that can be written to by a DVD recorder, whereas only 'rewritable' discs are able to erase and rewrite data. Data is written ('burne ...

DVD-RW DVD recordable and DVD rewritable are optical disc recording technologies. Both terms describe DVD optical discs that can be written to by a DVD recorder, whereas only 'rewritable' discs are able to erase and rewrite data. Data is written ('b ...

. (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

hard disk A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating platters coated with mag ...

Mac OS Two major famlies of Mac operating systems were developed by Apple Inc. In 1984, Apple debuted the operating system that is now known as the "Classic" Mac OS with its release of the original Macintosh System Software. The system, rebranded " ...

(8.6 or later) uses DVD-RAM directly.

uses DVD-RAM directly for FAT32-formatted discs only.

is 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

wastes Waste (or wastes) are unwanted or unusable materials. Waste is any substance discarded after primary use, or is worthless, defective and of no use. A by-product, by contrast is a joint product of relatively minor Value (economics), economic v ...

less space when writing small files. * Finalization not necessary. For video recording use, other media such as DVD+RW (when used in

DVD+VR The DVD (common abbreviation for Digital Video Disc or Digital Versatile Disc) is a digital optical disc data storage format. It was invented and developed in 1995 and first released on November 1, 1996, in Japan. The medium can store any kin ...

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. * Less compatibility than DVD+RW and DVD-RW on most DVD devices, despite predating both formats (as noted above). * If random writes are performed with a

constant linear velocity In optical storage, constant linear velocity (CLV) is a qualifier for the rated speed of an optical disc drive, and may also be applied to the writing speed of recordable discs. CLV implies that the angular velocity (i.e. rpm) varies during an ...

(CLV), which may be the only available speed mode on specific drives and/or media, the speed of the

rotary engine The rotary engine is an early type of internal combustion engine, usually designed with an odd number of cylinders per row in a radial configuration. The engine's crankshaft remained stationary in operation, while the entire crankcase and i ...

needs to be re-adjusted each time the pickup system jumps to another position on the disc, significantly impeding transfer speeds.

References

Books

External links

RAM Promotion Group (RAMPRG)

ISO/IEC 17592:2004
- publicly available standard

* ttps://web.archive.org/web/20080131133310/http://www.fujitsu.com/ph/services/computing/pc/support/drivers/usage_dvdram.html Fujitsu DVD-RAM2 compatibility note
Understanding Recordable & Rewritable DVD
{{DEFAULTSORT:Dvd-Ram DVD Audio storage Video storage Optical computer storage