<s>
In	O
computing	B-General_Concept
,	O
external	B-Device
storage	I-Device
refers	O
to	O
non-volatile	B-General_Concept
(	O
secondary	O
)	O
data	B-General_Concept
storage	I-General_Concept
outside	O
a	O
computer	O
's	O
own	O
internal	O
hardware	B-Architecture
,	O
and	O
thus	O
can	O
be	O
readily	O
disconnected	O
and	O
accessed	O
elsewhere	O
.	O
</s>
<s>
Such	O
storage	B-General_Concept
devices	O
may	O
refer	O
to	O
removable	B-Device
media	I-Device
(	O
e.g.	O
</s>
<s>
punched	B-General_Concept
paper	I-General_Concept
,	O
magnetic	B-Architecture
tape	I-Architecture
,	O
floppy	B-Device
disk	I-Device
and	O
optical	B-Device
disc	I-Device
)	O
,	O
compact	B-Device
flash	I-Device
drives	O
(	O
USB	O
flash	B-Device
drive	I-Device
and	O
memory	B-Device
card	I-Device
)	O
,	O
portable	B-Device
storage	I-Device
devices	I-Device
(	O
external	O
solid	B-Device
state	I-Device
drive	I-Device
and	O
enclosured	O
hard	B-Device
disk	I-Device
drive	I-Device
)	O
,	O
or	O
network-attached	B-Application
storage	I-Application
.	O
</s>
<s>
Web-based	O
cloud	O
storage	B-General_Concept
is	O
the	O
latest	O
technology	O
for	O
external	B-Device
storage	I-Device
.	O
</s>
<s>
Today	O
the	O
term	O
external	B-Device
storage	I-Device
most	O
commonly	O
applies	O
to	O
those	O
storage	B-General_Concept
devices	O
external	O
to	O
a	O
personal	O
computer	O
.	O
</s>
<s>
The	O
terms	O
refer	O
to	O
any	O
storage	B-General_Concept
external	O
to	O
the	O
computer	O
.	O
</s>
<s>
Storage	B-General_Concept
as	O
distinct	O
from	O
memory	O
in	O
the	O
early	O
days	O
of	O
computing	B-General_Concept
was	O
always	O
external	O
to	O
the	O
computer	O
as	O
for	O
example	O
in	O
the	O
punched	B-Architecture
card	I-Architecture
devices	O
and	O
media	O
.	O
</s>
<s>
Today	O
storage	B-General_Concept
devices	O
may	O
be	O
internal	O
or	O
external	O
to	O
a	O
computer	O
system	O
.	O
</s>
<s>
In	O
the	O
1950s	O
,	O
introduction	O
of	O
magnetic	O
tapes	O
and	O
hard	B-Device
disk	I-Device
drives	I-Device
allowed	O
for	O
mass	O
external	B-Device
storage	I-Device
of	O
information	O
,	O
which	O
played	O
the	O
key	O
part	O
of	O
the	O
computer	O
revolution	O
.	O
</s>
<s>
Initially	O
all	O
external	B-Device
storage	I-Device
,	O
tape	O
and	O
hard	B-Device
disk	I-Device
drives	I-Device
are	O
today	O
available	O
as	O
both	O
internal	O
and	O
external	B-Device
storage	I-Device
.	O
</s>
<s>
In	O
the	O
1964	O
removable	B-Device
disk	I-Device
media	O
was	O
introduced	O
by	O
the	O
IBM	B-Device
2310	I-Device
disk	B-Device
drive	I-Device
with	O
its	O
2315	O
cartridge	O
used	O
in	O
IBM	B-Device
1800	I-Device
and	O
IBM	B-Device
1130	I-Device
computers	O
.	O
</s>
<s>
Magnetic	O
disk	B-Device
media	O
is	O
today	O
not	O
removable	O
;	O
however	O
disk	B-Device
devices	O
and	O
media	O
such	O
as	O
optical	B-Device
disc	I-Device
drives	O
and	O
optical	B-Device
discs	I-Device
are	O
available	O
both	O
as	O
internal	O
storage	B-General_Concept
and	O
external	B-Device
storage	I-Device
.	O
</s>
<s>
As	O
a	O
consequence	O
of	O
rapid	O
development	O
of	O
electronic	O
computers	O
,	O
capability	O
for	O
integration	O
of	O
existing	O
input	O
,	O
output	O
,	O
and	O
storage	B-General_Concept
devices	O
was	O
a	O
determinant	O
factor	O
in	O
their	O
adoption	O
.	O
</s>
<s>
IBM	B-Device
650	I-Device
was	O
a	O
first	O
mass-produced	O
electronic	O
computer	O
that	O
encompassed	O
wide	O
range	O
of	O
existing	O
in	O
technologies	O
for	O
input-output	O
and	O
memory	O
devices	O
,	O
and	O
it	O
also	O
included	O
tape-to-card	O
and	O
card-to-tape	O
conversion	O
units	O
.	O
</s>
<s>
Earlier	O
"	O
transportable	O
personal	O
storage	B-General_Concept
"	O
was	O
introduced	O
by	O
IBM	O
's	O
2315	O
disk	B-Device
cartridges	O
,	O
which	O
were	O
used	O
in	O
IBM	B-Device
1800	I-Device
and	O
IBM	B-Device
1130	I-Device
computers	O
.	O
</s>
<s>
Operating	O
systems	O
of	O
the	O
earlier	O
1960s	O
provided	O
a	O
general-purpose	O
file	B-Application
system	I-Application
for	O
external	B-Device
storage	I-Device
,	O
which	O
included	O
hierarchical	O
directories	O
,	O
symbolic	B-Application
links	I-Application
,	O
and	O
access	O
control	O
to	O
time-sharing	B-General_Concept
mainframe	B-Architecture
computers	I-Architecture
.	O
</s>
<s>
Some	O
of	O
such	O
earlier	O
examples	O
include	O
UNIVAC	O
,	O
MULTICS	B-Application
,	O
and	O
UNIX	B-Application
.	O
</s>
<s>
Optical	O
storage	B-General_Concept
devices	O
have	O
media	O
that	O
use	O
laser	O
light	O
technology	O
for	O
data	B-General_Concept
storage	I-General_Concept
and	O
retrieval	O
.	O
</s>
<s>
CD-ROM	B-Device
:	O
(	O
Compact	O
Disc	B-Device
Read	O
Only	O
Memory	O
)	O
It	O
can	O
only	O
be	O
read	O
through	O
the	O
drive	O
.	O
</s>
<s>
CD-R	O
:	O
(	O
Compact	O
Disc	B-Device
Recordable	O
)	O
was	O
invented	O
in	O
the	O
1990s	O
.	O
</s>
<s>
Using	O
CD-R	O
,	O
it	O
is	O
possible	O
to	O
write	O
data	O
once	O
on	O
a	O
disc	B-Device
at	O
home	O
without	O
the	O
stamping	O
equipment	O
required	O
for	O
CD-ROMs	B-Device
.	O
</s>
<s>
These	O
are	O
considered	O
write	O
once	O
,	O
read	O
many	O
disks	B-Device
.	O
</s>
<s>
CD-RW	O
:	O
(	O
Compact	O
Disc	B-Device
Re-Writable	O
)	O
same	O
as	O
the	O
CD-R	O
but	O
can	O
be	O
erased	O
and	O
reused	O
.	O
</s>
<s>
CD-RW	O
drives	O
are	O
compatible	O
with	O
CD-ROM	B-Device
and	O
CD-R	O
.	O
</s>
<s>
DVD	O
stands	O
for	O
Digital	O
Versatile	O
Disc	B-Device
.	O
</s>
<s>
Its	O
speed	O
is	O
much	O
faster	O
than	O
CD	O
but	O
not	O
as	O
fast	O
as	O
hard	B-Device
disk	I-Device
.	O
</s>
<s>
The	O
standard	O
DVD-5	O
technology	O
has	O
a	O
storage	B-General_Concept
capacity	I-General_Concept
of	O
4.7GB	O
per	O
layer	O
;	O
most	O
DVDs	O
have	O
a	O
single	O
layer	O
but	O
up	O
to	O
four	O
layers	O
are	O
specified	O
.	O
</s>
<s>
Also	O
DVD	O
storage	B-General_Concept
capacity	I-General_Concept
changes	O
with	O
recording	O
format	O
.	O
</s>
<s>
Blu-ray	O
storage	B-General_Concept
capacity	I-General_Concept
is	O
up	O
to	O
50	O
gigabytes	O
(	O
or	O
even	O
100GB	O
)	O
of	O
data	O
.	O
</s>
<s>
The	O
Blu-ray	O
Disc	B-Device
(	O
BD	O
)	O
is	O
a	O
digital	O
optical	B-Device
disc	I-Device
format	O
.	O
</s>
<s>
It	O
was	O
originally	O
created	O
to	O
take	O
the	O
place	O
of	O
the	O
DVD	O
format	O
due	O
to	O
its	O
expanded	O
storage	B-General_Concept
capacity	I-General_Concept
.	O
</s>
<s>
The	O
name	O
"	O
Blu-ray	O
"	O
is	O
derived	O
from	O
the	O
use	O
of	O
a	O
blue	O
laser	O
that	O
is	O
used	O
to	O
read	O
the	O
disc	B-Device
.	O
</s>
<s>
M-Discs	B-Device
are	O
available	O
as	O
DVD	O
or	O
Blu-ray	O
discs	O
.	O
</s>
<s>
Memory	B-Device
cards	I-Device
are	O
flash	O
memory	O
storage	B-General_Concept
media	O
used	O
to	O
store	O
digital	O
information	O
in	O
many	O
electronics	O
products	O
.	O
</s>
<s>
The	O
types	O
of	O
memory	B-Device
cards	I-Device
include	O
:	O
CompactFlash	B-Device
,	O
PCMCIA	B-Architecture
,	O
secure	B-Device
digital	I-Device
card	I-Device
,	O
multimedia	O
card	O
,	O
memory	O
stick	O
,	O
etc	O
.	O
</s>
<s>
Memory	O
stick	O
is	O
an	O
integrated	O
circuit	O
designed	O
to	O
serve	O
as	O
a	O
storage	B-General_Concept
and	O
transfer	O
medium	O
for	O
digital	O
data	O
.	O
</s>
<s>
Memory	O
sticks	O
are	O
available	O
in	O
various	O
storage	B-General_Concept
sizes	O
ranging	O
from	O
4GB	O
to	O
64GB	O
.	O
</s>
<s>
A	O
USB	O
flash	B-Device
drive	I-Device
,	O
also	O
variously	O
known	O
as	O
a	O
,	O
thumb	O
drive	O
,	O
pen	O
drive	O
,	O
jump	O
drive	O
,	O
disk	B-Device
key	O
,	O
disk	B-Device
on	O
key	O
,	O
flash-drive	O
,	O
memory	O
stick	O
or	O
USB	O
memory	O
,	O
is	O
a	O
data	B-General_Concept
storage	I-General_Concept
device	O
that	O
includes	O
flash	O
memory	O
with	O
an	O
integrated	O
USB	O
interface	O
.	O
</s>
<s>
Portable	O
solid-state	B-Device
drive	I-Device
(	O
SSD	B-Device
)	O
is	O
a	O
common	O
solid-state	B-Device
storage	I-Device
device	I-Device
that	O
uses	O
semiconductor	O
cells	O
on	O
integrated	O
circuit	O
assemblies	O
for	O
mass	B-Device
storage	I-Device
.	O
</s>
<s>
Compared	O
to	O
hard	B-Device
disk	I-Device
drives	I-Device
and	O
similar	O
electromechanical	O
disk	B-Device
storage	I-Device
that	O
use	O
moving	O
physical	O
parts	O
to	O
spin	O
a	O
platter	B-Device
or	O
disc	B-Device
,	O
SSDs	B-Device
are	O
typically	O
more	O
compact	O
,	O
quieter	O
,	O
more	O
resistant	O
to	O
physical	O
shock	O
,	O
and	O
have	O
higher	O
input/output	O
rates	O
,	O
lower	O
latency	O
and	O
less	O
power	O
consumption	O
.	O
</s>
