<s>
One	O
meaning	O
of	O
system	B-Device
console	I-Device
,	O
computer	O
console	O
,	O
root	B-Device
console	I-Device
,	O
operator	O
's	O
console	O
,	O
or	O
simply	O
console	O
is	O
the	O
text	O
entry	O
and	O
display	O
device	O
for	O
system	O
administration	O
messages	O
,	O
particularly	O
those	O
from	O
the	O
BIOS	B-Operating_System
or	O
boot	B-Application
loader	I-Application
,	O
the	O
kernel	B-Operating_System
,	O
from	O
the	O
init	B-Operating_System
system	O
and	O
from	O
the	O
system	B-Protocol
logger	I-Protocol
.	O
</s>
<s>
It	O
is	O
a	O
physical	O
device	O
consisting	O
of	O
a	O
keyboard	B-Device
and	O
a	O
screen	O
,	O
and	O
traditionally	O
is	O
a	O
text	O
terminal	B-General_Concept
,	O
but	O
may	O
also	O
be	O
a	O
graphical	B-Application
terminal	I-Application
.	O
</s>
<s>
System	B-Device
consoles	I-Device
are	O
generalized	O
to	O
computer	B-General_Concept
terminals	I-General_Concept
,	O
which	O
are	O
abstracted	O
respectively	O
by	O
virtual	B-Application
consoles	I-Application
and	O
terminal	B-Application
emulators	I-Application
.	O
</s>
<s>
Today	O
communication	O
with	O
system	B-Device
consoles	I-Device
is	O
generally	O
done	O
abstractly	O
,	O
via	O
the	O
standard	B-Operating_System
streams	I-Operating_System
(	O
stdin	O
,	O
stdout	O
,	O
and	O
stderr	O
)	O
,	O
but	O
there	O
may	O
be	O
system-specific	O
interfaces	O
,	O
for	O
example	O
those	O
used	O
by	O
the	O
system	O
kernel	B-Operating_System
.	O
</s>
<s>
Another	O
,	O
older	O
,	O
meaning	O
of	O
system	B-Device
console	I-Device
,	O
computer	O
console	O
,	O
hardware	O
console	O
,	O
operator	O
's	O
console	O
or	O
simply	O
console	O
is	O
a	O
hardware	O
component	O
used	O
by	O
an	O
operator	O
to	O
control	O
the	O
hardware	O
,	O
typically	O
some	O
combination	O
of	O
front	B-Device
panel	I-Device
,	O
keyboard/printer	O
and	O
keyboard/display	O
.	O
</s>
<s>
Prior	O
to	O
the	O
development	O
of	O
alphanumeric	O
CRT	B-Device
system	B-Device
consoles	I-Device
,	O
some	O
computers	O
such	O
as	O
the	O
IBM	B-Device
1620	I-Device
had	O
console	O
typewriters	O
and	O
front	B-Device
panels	I-Device
while	O
the	O
very	O
first	O
programmable	O
computer	O
,	O
the	O
Manchester	B-Device
Baby	I-Device
,	O
used	O
a	O
combination	O
of	O
electromechanical	O
switches	O
and	O
a	O
CRT	B-Device
to	O
provide	O
console	O
functions	O
—	O
the	O
CRT	B-Device
displaying	O
memory	O
contents	O
in	O
binary	O
by	O
mirroring	O
the	O
machine	O
's	O
Williams-Kilburn	B-General_Concept
tube	I-General_Concept
CRT-based	O
RAM	O
.	O
</s>
<s>
Some	O
early	O
operating	B-General_Concept
systems	I-General_Concept
supported	O
either	O
a	O
single	O
keyboard/print	O
or	O
keyboard/display	O
device	O
for	O
controlling	O
the	O
OS	O
.	O
</s>
<s>
Some	O
also	O
supported	O
a	O
single	O
alternate	O
console	O
,	O
and	O
some	O
supported	O
a	O
hardcopy	B-General_Concept
console	O
for	O
retaining	O
a	O
record	O
of	O
commands	O
,	O
responses	O
and	O
other	O
console	O
messages	O
.	O
</s>
<s>
However	O
,	O
in	O
the	O
late	O
1960s	O
it	O
became	O
common	O
for	O
operating	B-General_Concept
systems	I-General_Concept
to	O
support	O
many	O
more	O
consoles	O
than	O
3	O
,	O
and	O
operating	B-General_Concept
systems	I-General_Concept
began	O
appearing	O
in	O
which	O
the	O
console	O
was	O
simply	O
any	O
terminal	B-General_Concept
with	O
a	O
privileged	O
user	O
logged	O
on	O
.	O
</s>
<s>
On	O
early	O
minicomputers	B-Architecture
,	O
the	O
console	O
was	O
a	O
serial	B-Device
console	I-Device
,	O
an	O
RS-232	O
serial	O
link	O
to	O
a	O
terminal	B-General_Concept
such	O
as	O
a	O
ASR-33	B-Application
or	O
later	O
a	O
DECWriter	B-Application
or	O
DEC	B-Device
VT100	I-Device
.	O
</s>
<s>
This	O
terminal	B-General_Concept
was	O
usually	O
kept	O
in	O
a	O
secured	O
room	O
since	O
it	O
could	O
be	O
used	O
for	O
certain	O
privileged	O
functions	O
such	O
as	O
halting	O
the	O
system	O
or	O
selecting	O
which	O
media	O
to	O
boot	O
from	O
.	O
</s>
<s>
Large	O
midrange	B-Device
systems	I-Device
,	O
e.g.	O
</s>
<s>
those	O
from	O
Sun	O
Microsystems	O
,	O
Hewlett-Packard	O
and	O
IBM	O
,	O
still	O
use	O
serial	B-Device
consoles	I-Device
.	O
</s>
<s>
In	O
larger	O
installations	O
,	O
the	O
console	O
ports	O
are	O
attached	O
to	O
multiplexers	O
or	O
network-connected	O
multiport	O
serial	O
servers	O
that	O
let	O
an	O
operator	O
connect	O
a	O
terminal	B-General_Concept
to	O
any	O
of	O
the	O
attached	O
servers	O
.	O
</s>
<s>
Today	O
,	O
serial	B-Device
consoles	I-Device
are	O
often	O
used	O
for	O
accessing	O
headless	B-Application
systems	I-Application
,	O
usually	O
with	O
a	O
terminal	B-Application
emulator	I-Application
running	O
on	O
a	O
laptop	B-Device
.	O
</s>
<s>
Also	O
,	O
routers	O
,	O
enterprise	O
network	B-Protocol
switches	I-Protocol
and	O
other	O
telecommunication	O
equipment	O
have	O
RS-232	O
serial	B-Device
console	I-Device
ports	O
.	O
</s>
<s>
On	O
PCs	B-Device
and	O
workstations	B-Device
,	O
the	O
computer	O
's	O
attached	O
keyboard	B-Device
and	O
monitor	B-Device
have	O
the	O
equivalent	O
function	O
.	O
</s>
<s>
Since	O
the	O
monitor	B-Device
cable	O
carries	O
video	O
signals	O
,	O
it	O
cannot	O
be	O
extended	O
very	O
far	O
.	O
</s>
<s>
Often	O
,	O
installations	O
with	O
many	O
servers	O
therefore	O
use	O
keyboard/video	O
multiplexers	O
(	O
KVM	B-Device
switches	I-Device
)	O
and	O
possibly	O
video	O
amplifiers	O
to	O
centralize	O
console	O
access	O
.	O
</s>
<s>
In	O
recent	O
years	O
,	O
KVM/IP	B-Device
devices	O
have	O
become	O
available	O
that	O
allow	O
a	O
remote	O
computer	O
to	O
view	O
the	O
video	O
output	O
and	O
send	O
keyboard	B-Device
input	O
via	O
any	O
TCP/IP	O
network	O
and	O
therefore	O
the	O
Internet	O
.	O
</s>
<s>
Some	O
PC	B-Device
BIOSes	O
,	O
especially	O
in	O
servers	O
,	O
also	O
support	O
serial	B-Device
consoles	I-Device
,	O
giving	O
access	O
to	O
the	O
BIOS	B-Operating_System
through	O
a	O
serial	O
port	O
so	O
that	O
the	O
simpler	O
and	O
cheaper	O
serial	B-Device
console	I-Device
infrastructure	O
can	O
be	O
used	O
.	O
</s>
<s>
Even	O
where	O
BIOS	B-Operating_System
support	O
is	O
lacking	O
,	O
some	O
operating	B-General_Concept
systems	I-General_Concept
,	O
e.g.	O
</s>
<s>
FreeBSD	B-Operating_System
and	O
Linux	B-Application
,	O
can	O
be	O
configured	O
for	O
serial	B-Device
console	I-Device
operation	O
either	O
during	O
bootup	O
,	O
or	O
after	O
startup	O
.	O
</s>
<s>
Starting	O
with	O
the	O
IBM	O
9672	O
,	O
IBM	O
large	O
systems	O
have	O
used	O
a	O
Hardware	B-Device
Management	I-Device
Console	I-Device
(	O
HMC	O
)	O
,	O
consisting	O
of	O
a	O
PC	B-Device
and	O
a	O
specialized	O
application	O
,	O
instead	O
of	O
a	O
3270	O
or	O
serial	O
link	O
.	O
</s>
<s>
Other	O
IBM	O
product	O
lines	O
also	O
use	O
an	O
HMC	O
,	O
e.g.	O
,	O
System	B-Device
p	I-Device
.	O
</s>
<s>
Depending	O
on	O
configuration	O
,	O
the	O
operating	B-General_Concept
system	I-General_Concept
may	O
treat	O
a	O
login	O
session	O
from	O
the	O
console	O
as	O
being	O
more	O
trustworthy	O
than	O
a	O
login	O
session	O
from	O
other	O
sources	O
.	O
</s>
