What's inside your computer


The DVD-RAM

DVD-RAM (DVD–Random Access Memory) is
a disc specification presented in 1996 by theAdvantages  of  DVD-RAM
DVD Forum, which specifies rewritable DVD-RAM
media and the appropriate DVD writers.Long life — without physical damage,
DVD-RAM media have been used in computers asdata  is  retained  for  30  years  minimum.
well as camcorders and personal video
recorders  since  1998.Can be rewritten over 100,000 times
(DVD±RW can be rewritten approx. 1,000
Currently there are three competingtimes). Faster DVD-RAMs support fewer
technologies for rewritable DVDs: DVD-RAM,rewrites (3x speed: 100,000, 5x speed:
DVD+RW and DVD-RW. DVD-RAM is considered a10,000), but still more than DVD±RW.
highly reliable format, as the discs have(Remember, these are theoretical numbers. In
built-in error control and a defectpractice they could be smaller depending on
management system. Therefore, DVD-RAM isthe drive, the treatment of the disc and the
perceived to be better than the other DVDfile  system.)
technologies for traditional computer usage
tasks such as general data storage, backupReliable writing of discs. Verification done
and archival, though the Mt. Rainier standardin hardware by the drive, so post-write
for DVD+RW lessens this somewhat. Curiously,verification  by  software  is  unnecessary.
DVD-RAM has a larger presence in camcorders
and set-top boxes than in computers, althoughDisc  defect  management  safeguards  data.
the DVD-RAM's popularity in these devices can
be explained by the fact that it is veryWrite speed twice as fast (when verification
easily written to and erased, which fornot enabled) as DVD±RW. (Note: 12x DVD-RAM
example  allows  extensive in-camera editing.spec = 16 DVD±RW spec. As of 7/24/06,
DVD±RW write speed was at 8x (DVD±RW
The on-disc structure of DVD-RAMs is closelyspecifications) while DVD-RAM is at 12x
related to hard disk and floppy disk(DVD-RAM  speed  specification).)
technology, as it stores data in concentric
tracks. DVD-RAMs can be accessed just like aDVD-burning software may not be required
hard or floppy disk and usually without any— discs can be used and accessed like
special software. DVD-RWs and DVD+RWs, on thea removable hard disk. Mac OS (8.6 or later)
other hand, store data in one long spiralsupports DVD-RAM directly. Windows XP
track and require special packet readingsupports DVD-RAM directly only for
writing software to read and write dataFAT32-formatted discs. Device drivers or
discs. It is a common misconception thatother software are needed for earlier
DVD-RAM uses magneto-optical (MO)versions of Windows or if one wants to use
technologies: DVD-RAM is a pure phase changethe decidedly better UDF format rather than
medium,  similar  to  CD-RW  or  DVD-RWFAT32.
Many operating systems like Mac OS (Mac OSEasier  to  use  than  other DVD technology.
8.6 or later), Linux and Microsoft Windows XP
support DVD-RAM operation directly, whileVery fast access of smaller files on the
earlier versions of Windows require devicedisc.
drivers or the program InCD. The optical
drives shipped with most Apple Macintosh2 KB disc block size wastes less space when
computers do not support DVD-RAM operation,writing  small  files.
but a third party DVD-RAM-compatible drive
can be connected and used directly with MacFinalization  not  necessary.
OS.
Media available with or without protective
Windows XP can only write directly to FAT32cartridges.
formatted DVD-RAM discs. For UDF formatted
discs, which are considered faster,In video recorders, DVD-RAM can be written to
compatible device drivers or software such asand watched (even separate programs) at the
InCD or DLA are required. Windows Vista cansame  time,  much  like  TiVo.
natively access and write to UDF formatted
DVD-RAM discs. This is a non-issue with LinuxSupports time slip recording and recording
however, which allows the use of virtuallywithout  border  in/out  writing.
any file system of the multitude that ship
with the operating system, including UDF. MacDisadvantages  of  DVD-RAM
OS can read and write HFS, HFS Plus, FAT and
UDF formatted DVD-RAM discs directly. It isLess compatibility than DVD+RW and DVD-RW (as
even possible to use the ext3 file system onnoted  above).
a DVD-RAM disc. So while it is possible to
use any filesystem one likes, only very few12x media is not readily available in the USA
perform well on DVD-RAM. This is because someand will not be available in the US and
file systems frequently over-write data onEurope in the near future due to low market
the disc and the table of contents isdemand. 16x media may not be available
contained  at  the  start  of  the  disc.anywhere except manufacturers' R&D
laboratories.
Many DVD standalone players and recorders do
not support DVD-RAM, especially older orDVD-RAM media is more expensive than other
cheaper versions. However, within theDVD types. 12x media is expected to cost
"RAMPRO" (DVD RAM promotion) group are aalmost $9 per disc, at least initially, but
number of well-known manufacturers ofthis price will fall as production ramps up.
standalone players and recorders that DO
support DVD-RAM. Panasonic for instance haveDVD-RAM writing will be slower than DVD+RW
a range of players and recorders which makeand DVD-RW until 12x DVD-RAM media becomes
full use of the advantages of DVD-RAM. Thereavailable. If write verification is enabled,
are also a number of video cameras that usethe writing speed is decreased by about half.
DVD-RAM  as  the  recording  media.Using FAT32 instead of UDF may also slow
DVD-RAM performance.
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