<s>
The	O
power	B-Device
key	I-Device
,	O
or	O
power	O
button	O
,	O
is	O
a	O
key	O
found	O
on	O
many	O
computer	B-Device
keyboards	I-Device
during	O
the	O
1980s	O
and	O
into	O
the	O
early	O
2000s	O
.	O
</s>
<s>
They	O
were	O
introduced	O
on	O
the	O
first	O
Apple	B-Device
Desktop	I-Device
Bus	I-Device
keyboards	B-Device
in	O
the	O
1980s	O
and	O
have	O
been	O
a	O
standard	O
feature	O
of	O
many	O
Macintosh	B-Device
keyboards	B-Device
since	O
then	O
.	O
</s>
<s>
They	O
are	O
also	O
found	O
on	O
an	O
increasing	O
number	O
of	O
Microsoft	B-Application
Windows	I-Application
keyboards	B-Device
,	O
sometimes	O
supplanted	O
with	O
additional	O
keys	O
for	O
sleep	O
.	O
</s>
<s>
The	O
power	B-Device
key	I-Device
is	O
becoming	O
increasingly	O
rare	O
,	O
as	O
most	O
modern	O
personal	B-Device
computers	I-Device
using	O
USB	B-Protocol
allow	O
the	O
system	O
to	O
be	O
started	O
up	O
by	O
pressing	O
any	O
key	O
on	O
the	O
keyboard	B-Device
.	O
</s>
<s>
The	O
Apple	B-Device
Desktop	I-Device
Bus	I-Device
(	O
ADB	O
)	O
was	O
introduced	O
on	O
the	O
Apple	B-Device
IIGS	I-Device
in	O
1986	O
.	O
</s>
<s>
This	O
peripheral	B-Architecture
bus	I-Architecture
was	O
intended	O
to	O
connect	O
low-speed	O
input	O
devices	O
like	O
keyboards	B-Device
and	O
computer	B-Device
mice	I-Device
.	O
</s>
<s>
Looking	O
for	O
a	O
low-cost	O
connector	O
,	O
the	O
design	O
team	O
selected	O
the	O
4-pin	O
mini-DIN	B-Protocol
connector	I-Protocol
,	O
which	O
is	O
also	O
used	O
for	O
S-Video	O
.	O
</s>
<s>
A	O
separate	O
connection	O
was	O
required	O
as	O
the	O
keyboard	B-Device
controller	O
of	O
machines	O
of	O
this	O
era	O
was	O
not	O
powered	O
when	O
the	O
machine	O
was	O
powered	O
down	O
.	O
</s>
<s>
Introduced	O
along	O
with	O
the	O
IIGS	B-Device
was	O
the	O
Apple	O
Keyboard	B-Device
,	O
which	O
featured	O
a	O
rather	O
large	O
power	B-Device
key	I-Device
roughly	O
centered	O
above	O
the	O
main	O
part	O
of	O
the	O
keyboard	B-Device
.	O
</s>
<s>
A	O
power	B-Device
key	I-Device
became	O
a	O
standard	O
feature	O
of	O
all	O
ADB	O
keyboards	B-Device
,	O
notably	O
the	O
lauded	O
Apple	B-Device
Extended	I-Device
Keyboard	I-Device
and	O
its	O
follow-ons	O
.	O
</s>
<s>
It	O
began	O
to	O
become	O
less	O
common	O
on	O
later	O
USB-based	O
keyboards	B-Device
as	O
these	O
machines	O
keep	O
the	O
keyboard	B-Device
powered	O
when	O
the	O
machine	O
is	O
sleeping	O
,	O
so	O
any	O
key	O
can	O
act	O
as	O
a	O
power	B-Device
key	I-Device
.	O
</s>
<s>
Power	B-Device
keys	I-Device
remain	O
on	O
some	O
modern	O
Macs	O
,	O
including	O
the	O
MacBook	B-Device
Air	I-Device
,	O
but	O
most	O
others	O
have	O
replaced	O
it	O
with	O
an	O
"	O
eject	O
"	O
key	O
,	O
formerly	O
used	O
to	O
open	O
the	O
now-non-existent	O
CD	O
drive	O
.	O
</s>
<s>
Early	O
Windows	B-Application
PCs	I-Application
generally	O
lacked	O
the	O
ability	O
to	O
control	O
power	O
through	O
software	O
,	O
and	O
power	B-Device
keys	I-Device
were	O
not	O
physically	O
possible	O
.	O
</s>
<s>
The	O
increasing	O
use	O
of	O
USB	B-Protocol
connections	O
allowed	O
these	O
,	O
but	O
the	O
ability	O
to	O
use	O
any	O
key	O
for	O
"	O
power	O
on	O
"	O
generally	O
negated	O
their	O
need	O
in	O
most	O
cases	O
.	O
</s>
<s>
Power	B-Device
keys	I-Device
did	O
become	O
relatively	O
common	O
on	O
some	O
multimedia	O
keyboards	B-Device
,	O
where	O
they	O
were	O
known	O
as	O
power	B-Device
management	I-Device
keys	I-Device
.	O
</s>
<s>
These	O
are	O
supported	O
in	O
Microsoft	B-Application
Windows	I-Application
and	O
various	O
Unix-like	B-Operating_System
systems	I-Operating_System
.	O
</s>
