Optinai diskai
Kompaktiniai diskai:
Compact disc (CD) is a digital optical disc data storage format. The format was originally developed to store
and play only sound recordings but was later adapted for storage of data (CD-ROM). Several other formats
were further derived from these, including write-once audio and data storage (CD-R), rewritable media (CDRW), Video Compact Disc (VCD), Super Video Compact Disc (SVCD), Photo CD, PictureCD, CD-i, and
Enhanced Music CD. Audio CDs and audio CD players have been commercially available since October 1982.
Diagram of CD layers.
A. A polycarbonate disc layer has the data encoded by using bumps.
B. A shiny layer reflects the laser.
C. A layer of lacquer protects the shiny layer.
D. Artwork is screen printed on the top of the disc.
E. A laser beam reads the CD and is reflected back to a sensor, which converts it into electronic data
http://en.wikipedia.org/wiki/Compact_disc
First-generation
Initially, optical discs were used to store music and computer software. The Laserdisc format
stored analog video signals for the distribution of home video, but commercially lost to
the VHS videocassette format, due mainly to its high cost and non-re-recordability; other firstgeneration disc formats were designed only to store digital data and were not initially capable of
use as a digital video medium.
Second-generation
Second-generation optical discs were for storing great amounts of data, including broadcast-quality
digital video. Such discs usually are read with a visible-light laser (usually red); the shorter
wavelength and greater numerical aperture[12] allow a narrower light beam, permitting smaller pits
and lands in the disc. In the DVD format, this allows 4.7 GB storage on a standard 12 cm, single-
sided, single-layer disc; alternatively, smaller media, such as the DataPlay format, can have
capacity comparable to that of the larger, standard compact 12 cm disc.[13]
Third-generation
Third-generation optical discs are in development, meant for distributing high-definition video and
support greater data storage capacities, accomplished with short-wavelength visible-light lasers
and greater numerical apertures. Blu-ray Disc and HD DVD uses blue-violet lasers and focusing
optics of greater aperture, for use with discs with smaller pits and lands, thereby greater data
storage capacity per layer.[12] In practice, the effective multimedia presentation capacity is
improved with enhanced video data compressioncodecs such as H.264/MPEG-4 AVC and VC-1.
Overview of optical types
Experimental1
Years2
Name
Capacity
Laserdisc (LD)
0.3GB
19712001
Compact Disc (CD)
0.7-0.9GB
1981today
MiniDisc (MD)
0.14GB
1989today
Magneto Optical Disc (MOD)
0.116.7GB
1990today
Digital Versatile Disc (DVD)
4.7-17GB
1995today
Laser Intensity Modulation Direct
OverWrite (Limdow-Disc)
2.6GB
10GB
1996today
GD-ROM
1997today
1.2GB
Fluorescent Multilayer Disc
50-140GB
19982003
100GB
19992010
Versatile Multilayer Disc (VMD)
5-20GB
Ultra Density Optical (UDO)
30-60GB
2000today
FVD (FVD)
5.4-15GB
2001today
Enhanced Versatile Disc (EVD)
DVD
20022004
HD DVD
15-51GB
Blu-ray Disc (BD)
25-128GB 400GB
2002today
Professional Disc for Data (PDD)
23GB
20032006
1TB
20022008
Digital Multilayer Disk
22-32GB
20042007
Multiplexed Optical Data Storage (MODS-Disc)
250GB-1TB
2004today
Universal Media Disc (UMD)
20042014
0.9-1.8GB
Holographic Versatile Disc (HVD)
6.0TB
2004today
Protein-coated Disc (PCD)
50TB
2005today
M-DISC
4,7 GB (DVD format), 25 GB (Bluray format)
2009today
1)Prototypes and theoretical Values.
2)Years from (known) start of development till end of sales or development.
http://en.wikipedia.org/wiki/Optical_disc
Magnetines laikmenos
Magnetic storage (or magnetic recording) is the storage of data on a magnetized medium. Magnetic
storage uses different patterns of magnetization in a magnetizable material to store data and is a form of
non-volatile memory. The information is accessed using one or more read/write heads.
As of 2013, magnetic storage media, primarily hard disks, are widely used to store computer data as
well as audio and video signals. In the field of computing, the term magnetic storage is preferred and in
the field of audio and video production, the term magnetic recording is more commonly used. The
distinction is less technical and more a matter of preference. Other examples of magnetic storage
media include floppy disks, magnetic recording tape, and magnetic stripes on credit cards.
Longitudinal recording and perpendicular recording, two types of writing heads on a hard disk.
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Wire (1898)
Tape (1928)
Drum (1932)
Ferrite core (1949)
Hard disk (1956)
Stripe card (1956)
MICR (1956)
Thin film (1962)
CRAM (1962)
Twistor (~1968)
Floppy disk (1969)
Bubble (~1970)
MRAM (1995)
Racetrack (2008)
http://en.wikipedia.org/wiki/Magnetic_storage
Hard drive
Alternatively referred to as a hard disk drive and abbreviated as HD or HDD, thehard drive is
the computer's main storage media device that permanently stores all data on the computer. The hard
drive was first introduced on September 13, 1956and consists of one or more hard drive platters (hard
disks) inside of an air sealed casing. Most computer hard drives are in an internal drive bay at the front of
the computer and connect to the motherboard using either an ATA, SCSI, or SATA cable and power cable.
Below is a picture of what the inside of a hard drive looks like for a desktop and laptop hard drive.
As can be seen in the above picture, the desktop hard drive consists of the following components: the head
actuator, read/write actuator arm, read/write head, spindle, andplatter. On the back of a hard drive is a
circuit board called the disk controller.
http://www.computerhope.com/jargon/h/harddriv.htm
Stacionarūs diskas(SSD)
A solid-state drive (SSD) (also known as a solid-state disk[1][2][3] or electronic disk,[4] though it contains no
actual disk, nor a drive motor to spin a disk) is a data storage device that uses integrated circuit assemblies
as memory to store data persistently. SSD technology uses electronic interfaces compatible with traditional
block input/output (I/O) hard disk drives, thus permitting simple replacement in common applications.[5]
Additionally, new I/O interfaces, like SATA Express, have been designed to address specific requirements of
the SSD technology.
SDs have no moving (mechanical) components. This distinguishes them from
traditional electromechanical magnetic disks such as hard disk drives (HDDs) or floppy disks, which
contain spinning disks and movable read/write heads.[6] Compared with electromechanical disks, SSDs
are typically more resistant to physical shock, run silently, have lower access time, and
less latency.[7] However, while the price of SSDs has continued to decline over time,[8] SSDs are still
roughly seven to eight times more expensive per unit of storage than HDDs.