<s>
Centralized	B-General_Concept
computing	I-General_Concept
is	O
computing	O
done	O
at	O
a	O
central	O
location	O
,	O
using	O
terminals	B-General_Concept
that	O
are	O
attached	O
to	O
a	O
central	O
computer	O
.	O
</s>
<s>
The	O
computer	O
itself	O
may	O
control	O
all	O
the	O
peripherals	O
directly	O
(	O
if	O
they	O
are	O
physically	O
connected	O
to	O
the	O
central	O
computer	O
)	O
,	O
or	O
they	O
may	O
be	O
attached	O
via	O
a	O
terminal	B-Device
server	I-Device
.	O
</s>
<s>
Alternatively	O
,	O
if	O
the	O
terminals	B-General_Concept
have	O
the	O
capability	O
,	O
they	O
may	O
be	O
able	O
to	O
connect	O
to	O
the	O
central	O
computer	O
over	O
the	O
network	O
.	O
</s>
<s>
The	O
terminals	B-General_Concept
may	O
be	O
text	O
terminals	B-General_Concept
or	O
thin	B-Device
clients	I-Device
,	O
for	O
example	O
.	O
</s>
<s>
It	O
offers	O
greater	O
security	O
over	O
decentralized	B-Operating_System
systems	I-Operating_System
because	O
all	O
of	O
the	O
processing	B-Operating_System
is	O
controlled	O
in	O
a	O
central	O
location	O
.	O
</s>
<s>
Depending	O
on	O
the	O
system	O
,	O
they	O
may	O
even	O
be	O
able	O
to	O
resume	O
their	O
session	B-Protocol
from	O
the	O
point	O
they	O
were	O
at	O
before	O
,	O
as	O
if	O
nothing	O
had	O
happened	O
.	O
</s>
<s>
The	O
central	O
computer	O
performs	O
the	O
computing	O
functions	O
and	O
controls	O
the	O
remote	O
terminals	B-General_Concept
.	O
</s>
<s>
Should	O
the	O
central	O
computer	B-General_Concept
crash	I-General_Concept
,	O
the	O
entire	O
system	O
will	O
"	O
go	O
down	O
"	O
(	O
i.e.	O
</s>
<s>
The	O
reverse	O
situation	O
,	O
however	O
,	O
(	O
i.e.	O
,	O
a	O
system	O
supported	O
better	O
than	O
your	O
needs	O
)	O
is	O
one	O
of	O
the	O
key	O
advantages	O
to	O
centralized	B-General_Concept
computing	I-General_Concept
.	O
</s>
<s>
The	O
very	O
first	O
computers	O
did	O
not	O
have	O
separate	O
terminals	B-General_Concept
as	O
such	O
;	O
their	O
primitive	O
input/output	O
devices	O
were	O
built	O
in	O
.	O
</s>
<s>
The	O
idea	O
of	O
centralized	B-General_Concept
computing	I-General_Concept
was	O
born	O
.	O
</s>
<s>
Early	O
text	O
terminals	B-General_Concept
used	O
electro-mechanical	O
teletypewriters	O
,	O
but	O
these	O
were	O
replaced	O
by	O
cathode	B-Device
ray	I-Device
tube	I-Device
displays	I-Device
(	O
as	O
found	O
in	O
20th	O
century	O
televisions	O
and	O
computers	O
)	O
.	O
</s>
<s>
The	O
text	O
terminal	O
model	O
dominated	O
computing	O
from	O
the	O
1960s	O
,	O
until	O
the	O
rise	O
to	O
dominance	O
of	O
home	O
computers	O
and	O
personal	B-Device
computers	I-Device
in	O
the	O
1980s	O
.	O
</s>
<s>
As	O
of	O
2007	O
,	O
centralized	B-General_Concept
computing	I-General_Concept
is	O
now	O
coming	O
back	O
into	O
fashion	O
–	O
to	O
a	O
certain	O
extent	O
.	O
</s>
<s>
Cloud	O
computing	O
has	O
had	O
an	O
important	O
role	O
in	O
the	O
return	O
of	O
centralized	B-General_Concept
computing	I-General_Concept
.	O
</s>
<s>
Thin	B-Device
clients	I-Device
have	O
been	O
used	O
for	O
many	O
years	O
by	O
businesses	O
to	O
reduce	O
total	O
cost	O
of	O
ownership	O
,	O
while	O
web	B-Application
applications	I-Application
are	O
becoming	O
more	O
popular	O
because	O
they	O
can	O
potentially	O
be	O
used	O
on	O
many	O
types	O
of	O
computing	O
device	O
without	O
any	O
need	O
for	O
software	O
installation	O
.	O
</s>
<s>
Already	O
,	O
however	O
,	O
there	O
are	O
signs	O
that	O
the	O
pendulum	O
is	O
swinging	O
back	O
again	O
,	O
away	O
from	O
pure	O
centralization	O
,	O
as	O
thin	B-Device
client	I-Device
devices	O
become	O
more	O
like	O
diskless	B-Device
workstations	I-Device
due	O
to	O
increased	O
computing	O
power	O
,	O
and	O
web	B-Application
applications	I-Application
start	O
to	O
do	O
more	O
processing	B-Operating_System
on	O
the	O
client	O
side	O
,	O
with	O
technologies	O
such	O
as	O
AJAX	B-Device
and	O
rich	B-Protocol
clients	I-Protocol
.	O
</s>
<s>
In	O
addition	O
,	O
mainframes	B-Architecture
are	O
still	O
being	O
used	O
for	O
some	O
mission-critical	O
applications	O
,	O
such	O
as	O
payroll	O
,	O
or	O
for	O
processing	B-Operating_System
day-to-day	O
account	O
transactions	O
in	O
banks	O
.	O
</s>
<s>
These	O
mainframes	B-Architecture
will	O
typically	O
be	O
accessed	O
either	O
using	O
terminal	B-Application
emulators	I-Application
(	O
real	O
terminal	O
devices	O
are	O
not	O
used	O
much	O
any	O
more	O
)	O
or	O
via	O
modern	O
front-ends	O
such	O
as	O
web	B-Application
applications	I-Application
–	O
or	O
(	O
in	O
the	O
case	O
of	O
automated	O
access	O
)	O
protocols	O
such	O
as	O
web	O
services	O
protocols	O
.	O
</s>
<s>
Some	O
organizations	O
use	O
a	O
diskless	B-Device
node	I-Device
model	O
partway	O
between	O
centralized	B-General_Concept
computing	I-General_Concept
and	O
conventional	O
desktop	B-Device
computing	I-Device
,	O
in	O
which	O
some	O
applications	O
(	O
such	O
as	O
web	B-Application
browsers	I-Application
)	O
are	O
run	O
locally	O
,	O
while	O
other	O
applications	O
(	O
such	O
as	O
critical	O
business	O
systems	O
)	O
are	O
run	O
on	O
the	O
terminal	B-Device
server	I-Device
.	O
</s>
<s>
One	O
way	O
to	O
implement	O
this	O
is	O
simply	O
by	O
running	O
remote	B-Protocol
desktop	I-Protocol
software	I-Protocol
on	O
a	O
standard	O
desktop	B-Device
computer	I-Device
.	O
</s>
<s>
A	O
relatively	O
new	O
method	O
of	O
centralized	B-General_Concept
computing	I-General_Concept
,	O
hosted	O
computing	O
,	O
solves	O
many	O
of	O
the	O
problems	O
associated	O
with	O
traditional	O
distributed	O
computing	O
systems	O
.	O
</s>
<s>
By	O
centralizing	O
processing	B-Operating_System
and	O
storage	O
on	O
powerful	O
server	O
hardware	O
located	O
in	O
a	O
data	O
center	O
,	O
rather	O
than	O
in	O
a	O
local	O
office	O
,	O
it	O
relieves	O
organizations	O
of	O
the	O
many	O
responsibilities	O
in	O
owning	O
and	O
maintaining	O
an	O
information	O
technology	O
system	O
.	O
</s>
