<s>
In	O
computer	B-Architecture
hardware	I-Architecture
,	O
a	O
port	O
serves	O
as	O
an	O
interface	O
between	O
the	O
computer	O
and	O
other	O
computers	O
or	O
peripheral	B-Device
devices	I-Device
.	O
</s>
<s>
In	O
computer	O
terms	O
,	O
a	O
port	O
generally	O
refers	O
to	O
the	O
part	O
of	O
a	O
computing	O
device	O
available	O
for	O
connection	O
to	O
peripherals	B-Device
such	O
as	O
input	O
and	O
output	O
devices	O
.	O
</s>
<s>
Computer	B-Protocol
ports	I-Protocol
have	O
many	O
uses	O
,	O
to	O
connect	O
a	O
monitor	B-Device
,	O
webcam	B-Protocol
,	O
speakers	B-Device
,	O
or	O
other	O
peripheral	B-Device
devices	I-Device
.	O
</s>
<s>
On	O
the	O
physical	B-Application
layer	I-Application
,	O
a	O
computer	B-Protocol
port	I-Protocol
is	O
a	O
specialized	O
outlet	O
on	O
a	O
piece	O
of	O
equipment	O
to	O
which	O
a	O
plug	B-Protocol
or	O
cable	O
connects	O
.	O
</s>
<s>
Computer	B-Protocol
ports	I-Protocol
in	O
common	O
use	O
cover	O
a	O
wide	O
variety	O
of	O
shapes	O
such	O
as	O
round	O
(	O
PS/2	B-Protocol
,	O
etc	O
.	O
</s>
<s>
)	O
,	O
rectangular	O
(	O
FireWire	B-Protocol
,	O
etc	O
.	O
</s>
<s>
)	O
,	O
square	O
(	O
Telephone	B-Protocol
plug	I-Protocol
)	O
,	O
trapezoidal	O
(	O
D-Sub	B-Protocol
—	O
the	O
old	O
printer	B-Device
port	I-Device
was	O
a	O
DB-25	B-Protocol
)	O
,	O
etc	O
.	O
</s>
<s>
For	O
instance	O
,	O
most	O
computers	O
have	O
a	O
keyboard	B-Device
port	O
(	O
currently	O
a	O
Universal	B-Protocol
Serial	I-Protocol
Bus	I-Protocol
USB-like	O
outlet	O
referred	O
to	O
as	O
USB	B-Protocol
Port	I-Protocol
)	O
,	O
into	O
which	O
the	O
keyboard	B-Device
is	O
connected	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
9-pin	O
D-subminiature	B-Protocol
connector	I-Protocol
on	O
the	O
original	O
IBM	B-Device
PC	I-Device
could	O
have	O
been	O
used	O
for	O
monochrome	O
video	O
,	O
color	O
analog	O
video	O
(	O
in	O
two	O
incompatible	O
standards	O
)	O
,	O
a	O
joystick	O
interface	O
,	O
or	O
a	O
MIDI	O
musical	O
instrument	O
digital	O
control	O
interface	O
.	O
</s>
<s>
The	O
original	O
IBM	B-Device
PC	I-Device
also	O
had	O
two	O
identical	O
5	O
pin	O
DIN	O
connectors	O
,	O
one	O
used	O
for	O
the	O
keyboard	B-Device
,	O
the	O
second	O
for	O
a	O
cassette	O
recorder	O
interface	O
;	O
the	O
two	O
were	O
not	O
interchangeable	O
.	O
</s>
<s>
The	O
smaller	O
mini-DIN	O
connector	O
has	O
been	O
variously	O
used	O
for	O
the	O
keyboard	B-Device
and	O
two	O
different	O
kinds	O
of	O
mouse	O
;	O
older	O
Macintosh	B-Device
family	O
computers	O
used	O
the	O
mini-DIN	O
for	O
a	O
serial	B-Protocol
port	I-Protocol
or	O
for	O
a	O
keyboard	B-Device
connector	O
with	O
different	O
standards	O
than	O
the	O
IBM-descended	O
systems	O
.	O
</s>
<s>
Electronically	O
,	O
hardware	B-Architecture
ports	O
can	O
almost	O
always	O
be	O
divided	O
into	O
two	O
groups	O
based	O
on	O
the	O
signal	O
transfer	O
:	O
</s>
<s>
Parallel	B-Device
ports	I-Device
send	O
multiple	O
bits	O
at	O
the	O
same	O
time	O
over	O
several	O
sets	O
of	O
wires	O
.	O
</s>
<s>
Serial	B-Protocol
ports	I-Protocol
send	O
and	O
receive	O
one	O
bit	O
at	O
a	O
time	O
via	O
a	O
single	O
wire	O
pair	O
(	O
Ground	O
and	O
+	O
/	O
-	O
)	O
.	O
</s>
<s>
After	O
ports	O
are	O
connected	O
,	O
they	O
typically	O
require	O
handshaking	B-Protocol
,	O
where	O
transfer	O
type	O
,	O
transfer	O
rate	O
,	O
and	O
other	O
necessary	O
information	O
is	O
shared	O
before	O
data	O
is	O
sent	O
.	O
</s>
<s>
Plug-and-play	B-Device
ports	O
are	O
designed	O
so	O
that	O
the	O
connected	O
devices	O
automatically	O
start	O
handshaking	B-Protocol
as	O
soon	O
as	O
the	O
hot-swapping	O
is	O
done	O
.	O
</s>
<s>
USB	B-Protocol
ports	I-Protocol
and	O
FireWire	B-Protocol
ports	I-Protocol
are	O
plug-and-play	B-Device
.	O
</s>
<s>
Auto-detect	O
or	O
auto-detection	O
ports	O
are	O
usually	O
plug-and-play	B-Device
,	O
but	O
they	O
offer	O
another	O
type	O
of	O
convenience	O
.	O
</s>
<s>
For	O
example	O
,	O
some	O
sound	B-Device
cards	I-Device
allow	O
plugging	O
in	O
several	O
different	O
types	O
of	O
audio	B-Device
speakers	I-Device
;	O
then	O
a	O
dialogue	O
box	O
pops	O
up	O
on	O
the	O
computer	B-Device
screen	I-Device
asking	O
whether	O
the	O
speaker	O
is	O
left	O
,	O
right	O
,	O
front	O
,	O
or	O
rear	O
for	O
surround	O
sound	O
installations	O
.	O
</s>
<s>
The	O
user	O
's	O
response	O
determines	O
the	O
purpose	O
of	O
the	O
port	O
,	O
which	O
is	O
physically	O
a	O
1/8	B-Device
"	I-Device
tip-ring-sleeve	I-Device
mini	I-Device
jack	I-Device
.	O
</s>
<s>
FireWire	B-Protocol
ports	I-Protocol
used	O
with	O
video	O
equipment	O
(	O
among	O
other	O
devices	O
)	O
can	O
be	O
either	O
4-pin	O
or	O
6-pin	O
.	O
</s>
<s>
This	O
is	O
also	O
why	O
laptop	O
computers	O
usually	O
have	O
only	O
4-pin	O
FireWire	B-Protocol
ports	I-Protocol
,	O
as	O
they	O
cannot	O
provide	O
enough	O
power	O
to	O
meet	O
requirements	O
for	O
devices	O
needing	O
the	O
power	O
provided	O
by	O
6-pin	O
connections	O
.	O
</s>
<s>
Hardware	B-Architecture
port	B-Architecture
trunking	I-Architecture
(	O
HPT	O
)	O
is	O
a	O
technology	O
that	O
allows	O
multiple	O
hardware	B-Architecture
ports	O
to	O
be	O
combined	O
into	O
a	O
single	O
group	O
,	O
effectively	O
creating	O
a	O
single	O
connection	O
with	O
a	O
higher	O
Bandwidth	O
sometimes	O
referred	O
to	O
as	O
a	O
double-barrel	O
approach	O
.	O
</s>
<s>
This	O
technology	O
also	O
provides	O
a	O
higher	O
degree	O
of	O
fault	B-General_Concept
tolerance	I-General_Concept
because	O
a	O
failure	O
on	O
one	O
port	O
may	O
just	O
mean	O
a	O
slow-down	O
rather	O
than	O
a	O
dropout	O
.	O
</s>
<s>
By	O
contrast	O
,	O
in	O
software	O
port	B-Architecture
trunking	I-Architecture
(	O
SPT	O
)	O
,	O
two	O
agents	O
(	O
websites	O
,	O
channels	O
,	O
etc	O
.	O
)	O
</s>
<s>
are	O
bonded	O
into	O
one	O
with	O
the	O
same	O
effectiveness	O
;	O
i.e.	O
,	O
ISDN	B-Protocol
B1	O
(	O
64K	O
)	O
plus	O
B2	O
(	O
64K	O
)	O
equals	O
data	O
throughput	O
of	O
128K	O
.	O
</s>
