<s>
A	O
human	B-General_Concept
interface	I-General_Concept
device	I-General_Concept
or	O
HID	O
is	O
a	O
type	O
of	O
computer	O
device	O
usually	O
used	O
by	O
humans	O
that	O
takes	O
input	B-Device
from	O
humans	O
and	O
gives	O
output	B-Device
to	O
humans	O
.	O
</s>
<s>
The	O
term	O
"	O
HID	O
"	O
most	O
commonly	O
refers	O
to	O
the	O
USB-HID	O
specification	O
.	O
</s>
<s>
The	O
term	O
was	O
coined	O
by	O
Mike	O
Van	O
Flandern	O
of	O
Microsoft	O
when	O
he	O
proposed	O
that	O
the	O
USB	B-Protocol
committee	O
create	O
a	O
Human	O
Input	B-Device
Device	I-Device
class	O
working	O
group	O
.	O
</s>
<s>
The	O
working	O
group	O
was	O
renamed	O
as	O
the	O
Human	B-General_Concept
Interface	I-General_Concept
Device	I-General_Concept
class	O
at	O
the	O
suggestion	O
of	O
Tom	O
Schmidt	O
of	O
DEC	O
because	O
the	O
proposed	O
standard	O
supported	O
bi-directional	O
communication	O
.	O
</s>
<s>
The	O
HID	O
standard	O
was	O
adopted	O
primarily	O
to	O
enable	O
innovation	O
in	O
PC	B-Device
input	B-Device
devices	I-Device
and	O
to	O
simplify	O
the	O
process	O
of	O
installing	O
such	O
devices	O
.	O
</s>
<s>
Prior	O
to	O
the	O
introduction	O
of	O
the	O
HID	O
concept	O
,	O
devices	O
usually	O
conformed	O
to	O
strictly	O
defined	O
protocols	O
for	O
mouse	B-Device
,	O
keyboards	B-Device
and	O
joysticks	B-Device
;	O
for	O
example	O
,	O
the	O
standard	O
mouse	B-Device
protocol	O
at	O
the	O
time	O
supported	O
relative	O
X	O
-	O
and	O
Y-axis	O
data	O
and	O
binary	O
input	B-Device
for	O
up	O
to	O
two	O
buttons	O
,	O
with	O
no	O
legacy	O
support	O
.	O
</s>
<s>
All	O
hardware	O
innovations	O
necessitated	O
either	O
overloading	O
the	O
use	O
of	O
data	O
in	O
an	O
existing	O
protocol	O
or	O
the	O
creation	O
of	O
custom	O
device	B-Application
drivers	I-Application
and	O
the	O
evangelization	O
of	O
a	O
new	O
protocol	O
to	O
developers	O
.	O
</s>
<s>
A	O
single	O
HID	O
driver	O
on	O
a	O
computer	O
parses	O
data	O
and	O
enables	O
dynamic	O
association	O
of	O
data	O
I/O	B-General_Concept
with	O
application	O
functionality	O
,	O
which	O
has	O
enabled	O
rapid	O
innovation	O
and	O
development	O
,	O
and	O
prolific	O
diversification	O
of	O
new	O
human-interface	O
devices	O
.	O
</s>
<s>
After	O
comparing	O
notes	O
at	O
a	O
Consumer	O
Game	O
Developer	O
Conference	O
,	O
Steve	O
and	O
Mike	O
agreed	O
to	O
collaborate	O
on	O
a	O
new	O
standard	O
for	O
the	O
emerging	O
Universal	B-Protocol
Serial	I-Protocol
Bus	I-Protocol
(	O
USB	B-Protocol
)	O
.	O
</s>
<s>
The	O
HID	O
protocol	O
has	O
its	O
limitations	O
,	O
but	O
all	O
modern	O
mainstream	O
operating	B-General_Concept
systems	I-General_Concept
will	O
recognize	O
standard	O
USB	B-Protocol
HID	B-General_Concept
devices	I-General_Concept
,	O
such	O
as	O
keyboards	B-Device
and	O
mice	O
,	O
without	O
needing	O
a	O
specialized	O
driver	O
.	O
</s>
<s>
In	O
comparison	O
,	O
this	O
message	O
does	O
not	O
usually	O
appear	O
for	O
devices	O
connected	O
via	O
the	O
PS/2	B-Protocol
6-pin	O
DIN	B-Architecture
connectors	I-Architecture
which	O
preceded	O
USB	B-Protocol
.	O
</s>
<s>
PS/2	B-Protocol
does	O
not	O
typically	O
support	O
plug-and-play	B-Device
,	O
which	O
means	O
that	O
connecting	O
a	O
PS/2	B-Protocol
keyboard	I-Protocol
or	O
mouse	B-Device
with	O
the	O
computer	O
powered	O
on	O
does	O
not	O
always	O
work	O
and	O
may	O
pose	O
a	O
hazard	O
to	O
the	O
computer	O
's	O
motherboard	O
.	O
</s>
<s>
Likewise	O
,	O
the	O
PS/2	B-Protocol
standard	O
does	O
not	O
support	O
the	O
HID	O
protocol	O
.	O
</s>
<s>
The	O
USB	B-Protocol
human	B-General_Concept
interface	I-General_Concept
device	I-General_Concept
class	O
describes	O
a	O
USB	B-Protocol
HID	O
.	O
</s>
<s>
The	O
device	O
is	O
the	O
entity	O
that	O
directly	O
interacts	O
with	O
a	O
human	O
,	O
such	O
as	O
a	O
keyboard	B-Device
or	O
mouse	B-Device
.	O
</s>
<s>
The	O
host	O
communicates	O
with	O
the	O
device	O
and	O
receives	O
input	B-General_Concept
data	I-General_Concept
from	O
the	O
device	O
on	O
actions	O
performed	O
by	O
the	O
human	O
.	O
</s>
<s>
Output	B-Device
data	O
flows	O
from	O
the	O
host	O
to	O
the	O
device	O
and	O
then	O
to	O
the	O
human	O
.	O
</s>
<s>
The	O
most	O
common	O
example	O
of	O
a	O
host	O
is	O
a	O
PC	B-Device
but	O
some	O
cell	O
phones	O
and	O
PDAs	B-Application
also	O
can	O
be	O
hosts	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
keyboard	B-Device
with	O
a	O
calculator	O
program	O
button	O
can	O
tell	O
the	O
host	O
that	O
the	O
button	O
's	O
pressed/released	O
state	O
is	O
stored	O
as	O
the	O
2nd	O
bit	O
in	O
the	O
6th	O
byte	O
in	O
data	O
packet	O
number	O
4	O
(	O
note	O
:	O
these	O
locations	O
are	O
only	O
illustrative	O
and	O
are	O
device-specific	O
)	O
.	O
</s>
<s>
Some	O
mouse	B-Device
and	O
keyboard	B-Device
hardware	O
in	O
the	O
market	O
today	O
is	O
implemented	O
using	O
only	O
an	O
8-bit	O
CPU	B-General_Concept
.	O
</s>
<s>
Multiple	O
operating	B-General_Concept
systems	I-General_Concept
are	O
known	O
to	O
have	O
shipped	O
bugs	O
in	O
the	O
device	B-Application
drivers	I-Application
responsible	O
for	O
parsing	O
the	O
HID	O
descriptors	O
years	O
after	O
the	O
device	B-Application
drivers	I-Application
were	O
originally	O
released	O
to	O
the	O
public	O
.	O
</s>
<s>
However	O
,	O
this	O
complexity	O
is	O
the	O
reason	O
why	O
rapid	O
innovation	O
with	O
HID	B-General_Concept
devices	I-General_Concept
is	O
possible	O
.	O
</s>
<s>
Keyboard	B-Device
–	O
Any	O
of	O
the	O
first	O
256	O
key	O
codes	O
(	O
"	O
Usages	O
"	O
)	O
defined	O
in	O
the	O
HID	O
Usage	O
Tables	O
,	O
Usage	O
Page	O
7	O
can	O
be	O
reported	O
by	O
a	O
keyboard	B-Device
using	O
the	O
boot	O
protocol	O
,	O
but	O
most	O
systems	O
only	O
handle	O
a	O
subset	O
of	O
these	O
keys	O
.	O
</s>
<s>
Most	O
systems	O
support	O
all	O
104	O
keys	O
on	O
the	O
IBM	B-Device
AT-101	I-Device
layout	O
,	O
plus	O
the	O
three	O
extra	O
keys	O
designed	O
for	O
Microsoft	B-Application
Windows	I-Application
95	I-Application
(	O
the	O
left	O
and	O
right	O
Windows	B-Device
key	I-Device
,	O
and	O
the	O
Menu	B-Device
key	I-Device
)	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
particular	O
US	O
keyboard	B-Device
's	O
QWERTY	O
keys	O
will	O
function	O
but	O
the	O
Calculator	O
and	O
Logoff	O
keys	O
will	O
not	O
because	O
they	O
are	O
defined	O
on	O
Usage	O
Page	O
12	O
and	O
cannot	O
be	O
reported	O
in	O
boot	O
protocol	O
.	O
</s>
<s>
Mouse	B-Device
–	O
Only	O
the	O
X-axis	O
,	O
Y-axis	O
,	O
and	O
the	O
first	O
3	O
buttons	O
will	O
be	O
available	O
.	O
</s>
<s>
Any	O
additional	O
features	O
on	O
the	O
mouse	B-Device
will	O
not	O
function	O
.	O
</s>
<s>
Directly	O
configuring	O
a	O
computer	O
's	O
BIOS	B-Operating_System
is	O
often	O
done	O
using	O
only	O
boot	O
mode	O
.	O
</s>
<s>
Since	O
HID	O
's	O
original	O
definition	O
over	O
USB	B-Protocol
,	O
HID	O
is	O
now	O
also	O
used	O
in	O
other	O
computer	B-General_Concept
communication	I-General_Concept
buses	I-General_Concept
.	O
</s>
<s>
This	O
enables	O
HID	B-General_Concept
devices	I-General_Concept
that	O
traditionally	O
were	O
only	O
found	O
on	O
USB	B-Protocol
to	O
also	O
be	O
used	O
on	O
alternative	O
buses	O
.	O
</s>
<s>
This	O
is	O
done	O
since	O
existing	O
support	O
for	O
USB	B-Protocol
HID	B-General_Concept
devices	I-General_Concept
can	O
typically	O
be	O
adapted	O
much	O
faster	O
than	O
having	O
to	O
invent	O
an	O
entirely	O
new	O
protocol	O
to	O
support	O
mouse	B-Device
,	O
touchpad	B-Application
,	O
keyboards	B-Device
,	O
and	O
the	O
like	O
.	O
</s>
<s>
Serial	O
HID	O
–	O
Used	O
in	O
Microsoft	O
's	O
Windows	B-Device
Media	I-Device
Center	I-Device
PC	B-Device
remote	O
control	O
receivers	O
.	O
</s>
<s>
Zigbee	B-Protocol
input	B-Device
device	I-Device
–	O
Zigbee	B-Protocol
(	O
RF4CE	B-Protocol
)	O
supports	O
HID	B-General_Concept
devices	I-General_Concept
through	O
the	O
Zigbee	B-Protocol
input	B-Device
device	I-Device
profile	O
.	O
</s>
