<s>
A	O
port	B-Protocol
expander	I-Protocol
is	O
computer	B-Architecture
hardware	I-Architecture
that	O
allows	O
more	O
than	O
one	O
device	O
to	O
connect	O
to	O
a	O
single	O
port	B-Protocol
on	O
a	O
computer	O
.	O
</s>
<s>
The	O
VIC-20	B-Device
,	O
for	O
example	O
,	O
used	O
a	O
port	B-Protocol
expander	I-Protocol
to	O
allow	O
more	O
than	O
one	O
cartridge	B-Protocol
to	O
connect	O
to	O
the	O
single	O
ROM	B-Protocol
cartridge	I-Protocol
port	B-Protocol
.	O
</s>
<s>
A	O
port	B-Protocol
expander	I-Protocol
can	O
be	O
any	O
device	O
to	O
which	O
one	O
existing	O
or	O
onboard	O
port	B-Protocol
becomes	O
two	O
or	O
more	O
-	O
for	O
example	O
:	O
a	O
KVM	B-Device
switch	I-Device
or	O
a	O
USB	B-Protocol
hub	O
.	O
</s>
<s>
Such	O
expanders	O
offer	O
the	O
advantage	O
of	O
allowing	O
more	O
devices	O
of	O
a	O
particular	O
port	B-Protocol
type	O
to	O
be	O
utilized	O
at	O
the	O
same	O
time	O
.	O
</s>
<s>
A	O
major	O
downside	O
is	O
that	O
,	O
for	O
example	O
,	O
a	O
3Gbit/s	O
port	B-Protocol
might	O
have	O
a	O
hub	O
or	O
expander	O
installed	O
and	O
now	O
be	O
able	O
to	O
accommodate	O
6	O
devices	O
,	O
but	O
at	O
a	O
maximum	O
of	O
3Gbit/s	O
throughput	O
bandwidth	O
divided	O
by	O
the	O
said	O
6	O
devices	O
,	O
or	O
by	O
however	O
many	O
are	O
plugged	O
in	O
and	O
being	O
used	O
.	O
</s>
<s>
A	O
port	B-Protocol
expander	I-Protocol
is	O
a	O
device	O
that	O
allows	O
one	O
port	B-Protocol
on	O
a	O
computer	O
system	O
to	O
connect	O
to	O
multiple	O
devices	O
.	O
</s>
<s>
Two	O
basic	O
forms	O
of	O
port	B-Protocol
expander	I-Protocol
exist	O
:	O
internal	O
and	O
external	O
.	O
</s>
<s>
An	O
external	O
device	O
plugs	O
into	O
the	O
existing	O
port	B-Protocol
and	O
then	O
has	O
multiple	O
places	O
to	O
connect	O
.	O
</s>
<s>
Some	O
systems	O
may	O
even	O
use	O
an	O
A/B	B-Device
box	I-Device
,	O
a	O
device	O
that	O
connects	O
multiple	O
sets	O
of	O
devices	O
to	O
the	O
same	O
system	O
,	O
with	O
users	O
switching	O
between	O
them	O
by	O
flipping	O
between	O
the	O
A	O
or	O
B	O
mode	O
.	O
</s>
<s>
These	O
devices	O
all	O
perform	O
the	O
same	O
basic	O
job	O
that	O
a	O
port	B-Protocol
expander	I-Protocol
does	O
.	O
</s>
<s>
Manufacturers	O
have	O
produced	O
expanders	O
for	O
nearly	O
every	O
type	O
of	O
port	B-Protocol
,	O
but	O
the	O
most	O
common	O
household	O
versions	O
connect	O
to	O
universal	O
serial	O
bus	O
(	O
USB	B-Protocol
)	O
or	O
to	O
Ethernet	O
ports	O
.	O
</s>
