What's inside your computer


The DVD-RAM

DVD-RAM (DVD–Random Access Memory) iswell-known manufacturers of standalone
a disc specification presented in 1996players and recorders that DO support
by the DVD Forum, which specifiesDVD-RAM. Panasonic for instance have a
rewritable DVD-RAM media and therange of players and recorders which
appropriate DVD writers. DVD-RAM mediamake full use of the advantages of
have been used in computers as well asDVD-RAM. There are also a number of
camcorders and personal video recordersvideo cameras that use DVD-RAM as the
since 1998.recording media.
Currently there are three competingEvaluation
technologies for rewritable DVDs:Advantages of DVD-RAM
DVD-RAM, DVD+RW and DVD-RW. DVD-RAM isLong life — without physical damage,
considered a highly reliable format, asdata is retained for 30 years minimum.
the discs have built-in error controlCan be rewritten over 100,000 times
and a defect management system.(DVD±RW can be rewritten approx. 1,000
Therefore, DVD-RAM is perceived to betimes). Faster DVD-RAMs support fewer
better than the other DVD technologiesrewrites (3x speed: 100,000, 5x speed:
for traditional computer usage tasks10,000), but still more than DVD±RW.
such as general data storage, backup and(Remember, these are theoretical
archival, though the Mt. Rainiernumbers. In practice they could be
standard for DVD+RW lessens thissmaller depending on the drive, the
somewhat. Curiously, DVD-RAM has atreatment of the disc and the file
larger presence in camcorders andsystem.)
set-top boxes than in computers,Reliable writing of discs. Verification
although the DVD-RAM's popularity indone in hardware by the drive, so
these devices can be explained by thepost-write verification by software is
fact that it is very easily written tounnecessary.
and erased, which for example allowsDisc defect management safeguards data.
extensive in-camera editing.Write speed twice as fast (when
The on-disc structure of DVD-RAMs isverification not enabled) as DVD±RW.
closely related to hard disk and floppy(Note: 12x DVD-RAM spec = 16 DVD±RW
disk technology, as it stores data inspec. As of 7/24/06, DVD±RW write speed
concentric tracks. DVD-RAMs can bewas at 8x (DVD±RW specifications) while
accessed just like a hard or floppy diskDVD-RAM is at 12x (DVD-RAM speed
and usually without any specialspecification).)
software. DVD-RWs and DVD+RWs, on theDVD-burning software may not be required
other hand, store data in one long— discs can be used and accessed like
spiral track and require special packeta removable hard disk. Mac OS (8.6 or
reading/writing software to read andlater) supports DVD-RAM directly.
write data discs. It is a commonWindows XP supports DVD-RAM directly
misconception that DVD-RAM usesonly for FAT32-formatted discs. Device
magneto-optical (MO) technologies:drivers or other software are needed for
DVD-RAM is a pure phase change medium,earlier versions of Windows or if one
similar to CD-RW or DVD-RWwants to use the decidedly better UDF
Many operating systems like Mac OS (Macformat rather than FAT32.
OS 8.6 or later), Linux and MicrosoftEasier to use than other DVD technology.
Windows XP support DVD-RAM operation
directly, while earlier versions ofVery fast access of smaller files on the
Windows require device drivers or thedisc.
program InCD. The optical drives shipped2 KB disc block size wastes less space
with most Apple Macintosh computers dowhen writing small files.
not support DVD-RAM operation, but aFinalization not necessary.
third party DVD-RAM-compatible drive canMedia available with or without
be connected and used directly with Macprotective cartridges.
OS.In video recorders, DVD-RAM can be
Windows XP can only write directly towritten to and watched (even separate
FAT32 formatted DVD-RAM discs. For UDFprograms) at the same time, much like
formatted discs, which are consideredTiVo.
faster, compatible device drivers orSupports time slip recording and
software such as InCD or DLA arerecording without border in/out writing.
required. Windows Vista can natively
access and write to UDF formattedDisadvantages of DVD-RAM
DVD-RAM discs. This is a non-issue withLess compatibility than DVD+RW and
Linux however, which allows the use ofDVD-RW (as noted above).
virtually any file system of the12x media is not readily available in
multitude that ship with the operatingthe USA and will not be available in the
system, including UDF. Mac OS can readUS and Europe in the near future due to
and write HFS, HFS Plus, FAT and UDFlow market demand. 16x media may not be
formatted DVD-RAM discs directly. It isavailable anywhere except manufacturers'
even possible to use the ext3 fileR&D laboratories.
system on a DVD-RAM disc. So while it isDVD-RAM media is more expensive than
possible to use any filesystem oneother DVD types. 12x media is expected
likes, only very few perform well onto cost almost $9 per disc, at least
DVD-RAM. This is because some fileinitially, but this price will fall as
systems frequently over-write data onproduction ramps up.
the disc and the table of contents isDVD-RAM writing will be slower than
contained at the start of the disc.DVD+RW and DVD-RW until 12x DVD-RAM
Many DVD standalone players andmedia becomes available. If write
recorders do not support DVD-RAM,verification is enabled, the writing
especially older or cheaper versions.speed is decreased by about half. Using
However, within the "RAMPRO" (DVD RAMFAT32 instead of UDF may also slow
promotion) group are a number ofDVD-RAM performance.



1 A B C 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105