Optical data storage

from Wikipedia, the free encyclopedia

Exchangeable mass storage media are referred to as optical data storage media (also called optical disks ) and are read or written to by optical scanning (usually using a laser ).

The best-known optical storage media today are the CD-ROM (beginning of noteworthy distribution since around 1981) and its further developments DVD (since around 1996) and Blu-ray Disc (since around 2007). In addition, various other media and also the hybrid variant of the magneto-optical disc have been developed. However, these are of less importance in practice. Optical storage media that can only be written once are called WORM (from the English write once, read many , German write once, read multiple times ) and are used for archiving digital information.

history

The Foto-Mem company was founded in 1967 with the aim of developing mass storage devices for computers which, in contrast to the methods customary at the time, did not store data magnetically on drums, tapes or disks, but on optical media. In the early 1970s, Foto-Mem managed to sell one of its FM-360 systems to the New York Times, which wanted to use it to archive content from old issues. Eventually, Foto-Mem ran out of money and the company had to file for bankruptcy in 1973 without ever installing a fully functioning device.

Types

Table of the most common formats

There are many different formats of optical disks:

Surname Originally
for 		Capacity a
[GB] 		Not
writable 		one-time
writable 		re-
writable 		RAM version Larger version b
CD Audio 0.7 CD-DA (audio)
CD-ROM (data)		 CD-R CD-RW - -
DVD Video 4.7 DVD-Video
DVD-Audio
DVD-ROM 		DVD + R c
DVD-R 		DVD + RW c
DVD-RW		 DVD-RAM DL (8.5 GB)
DL Flipper (2 × 8.5 GB)
BD HD video 25th BD-ROM BD-R BD-RE - DL (50 GB)
BDXL (100–128 GB)
aThe actual capacities can vary by a few percent depending on the make. There are CD-Rs, for example. B. u. a. with 650 MB or 700 MB.
bThe larger versions are i. A. Both as ROM, write-once or rewritable version.
c The manufacturers could not agree on a format for the writable versions of the DVD, so there is a plus and a minus version.

Overview of optical data storage

Surname Capacity a Experimental b Period c
Laserdisc (LD) 300 MB 1971-2001
Compact Disc (CD) 650-900 MB since 1981
MiniDisc (MD) 140 MB since 1989
Magneto Optical Disc (MOD) 0.1-16.7 GB since 1990
Phasewriter Dual (PD) 600 MB 1995-1999
Digital Versatile Disc (DVD) 4.7-17 GB since 1995
Laser Intensity Modulation Direct OverWrite (Limdow-Disc) 2.6 GB 10 GB since 1996
GD-ROM 1.2 GB since 1997
Fluorescent multilayer disc 50-140 GB 1998-2003
Versatile multilayer disc (VMD) 5-20 GB 100 GB 1999-2010
Ultra Density Optical (UDO) 30-60 GB since 2000
HD-FVD (FVD) 5.4-15 GB since 2001
Enhanced Versatile Disc (EVD) DVD 2002-2004
HD DVD 15-51 GB 1 TB 2002-2008
Blu-ray Disc (BD) 25-100 GB 400 GB since 2002
Professional Disc for Data (PDD) 23 GB 2003-2006
Digital multilayer disk 22-32 GB 2004-2007
Multiplexed Optical Data Storage (MODS-Disc) 250 GB - 1 TB since 2004
Universal Media Disc (UMD) 900 MB - 1.8 GB since 2004
Holographic Versatile Disc (HVD) 3.9 TB since 2004
Protein-coated Disc (PCD) 50 TB since 2005
M-DISC 4.7 GB (DVD format), 25 GB (Blu-Ray format),

100 GB (Blu-ray - BD-R XL)

since 2009
aThe actual capacities can vary by a few percent depending on the make. There are CD-Rs, for example. B. u. a. with 650 MB or 700 MB.
b This includes prototypes and theoretical quantities.
c Information from the beginning of the development to the end of marketing or discontinuation of development.

advantages

  • Low wear due to contactless reading
  • Low media costs

disadvantage

  • Some writable and rewritable media - especially CD-R, CD-RW, DVD ± R and DVD ± RW - have a limited shelf life.
  • Improper storage can cause problems during the reading process.
  • Limited number of write cycles for rewritable media (DVD-RAM max. 1,000,000, other CD / DVD formats max. 1,000, in reality usually significantly less).

See also

Web links