<s>
A	O
hardware	B-Operating_System
reset	I-Operating_System
or	O
hard	B-Operating_System
reset	I-Operating_System
of	O
a	O
computer	O
system	O
is	O
a	O
hardware	O
operation	O
that	O
re-initializes	O
the	O
core	O
hardware	O
components	O
of	O
the	O
system	O
,	O
thus	O
ending	O
all	O
current	O
software	O
operations	O
in	O
the	O
system	O
.	O
</s>
<s>
This	O
is	O
typically	O
,	O
but	O
not	O
always	O
,	O
followed	O
by	O
booting	B-Operating_System
of	O
the	O
system	O
into	O
firmware	B-Application
that	O
re-initializes	O
the	O
rest	O
of	O
the	O
system	O
,	O
and	O
restarts	O
the	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
Hardware	B-Operating_System
resets	I-Operating_System
are	O
an	O
essential	O
part	O
of	O
the	O
power-on	B-Device
process	I-Device
,	O
but	O
may	O
also	O
be	O
triggered	O
without	O
power	O
cycling	O
the	O
system	O
by	O
direct	O
user	O
intervention	O
via	O
a	O
physical	O
reset	B-Application
button	I-Application
,	O
watchdog	B-Application
timers	I-Application
,	O
or	O
by	O
software	O
intervention	O
that	O
,	O
as	O
its	O
last	O
action	O
,	O
activates	O
the	O
hardware	B-Operating_System
reset	I-Operating_System
line	O
(	O
e.g	O
,	O
in	O
a	O
fatal	O
error	O
where	O
the	O
computer	O
crashes	O
)	O
.	O
</s>
<s>
User	O
initiated	O
hard	B-Operating_System
resets	I-Operating_System
can	O
be	O
used	O
to	O
reset	O
the	O
device	O
if	O
the	O
software	O
hangs	O
,	O
crashes	O
,	O
or	O
is	O
otherwise	O
unresponsive	O
.	O
</s>
<s>
Generally	O
,	O
a	O
hard	B-Operating_System
reset	I-Operating_System
is	O
initiated	O
by	O
pressing	O
a	O
dedicated	O
reset	B-Application
button	I-Application
,	O
or	O
holding	O
a	O
combination	O
of	O
buttons	O
on	O
some	O
mobile	O
devices	O
.	O
</s>
<s>
Devices	O
may	O
not	O
have	O
a	O
dedicated	O
Reset	B-Application
button	I-Application
,	O
but	O
have	O
the	O
user	O
hold	O
the	O
power	O
button	O
to	O
cut	O
power	O
,	O
which	O
the	O
user	O
can	O
then	O
turn	O
the	O
computer	O
back	O
on	O
.	O
</s>
<s>
On	O
some	O
systems	O
(	O
e.g	O
,	O
the	O
PlayStation	B-Device
2	I-Device
video	O
game	O
console	O
)	O
,	O
pressing	O
and	O
releasing	O
the	O
power	O
button	O
initiates	O
a	O
hard	B-Operating_System
reset	I-Operating_System
,	O
and	O
holding	O
the	O
button	O
turns	O
the	O
system	O
off	O
.	O
</s>
<s>
The	O
8086	B-General_Concept
microprocessors	I-General_Concept
provide	O
RESET	O
pin	O
that	O
is	O
used	O
to	O
do	O
the	O
hardware	B-Operating_System
reset	I-Operating_System
.	O
</s>
<s>
When	O
a	O
HIGH	O
is	O
applied	O
to	O
the	O
pin	O
,	O
the	O
CPU	O
immediately	O
stops	O
,	O
and	O
sets	O
the	O
major	O
registers	B-General_Concept
to	O
these	O
values	O
:	O
</s>
<s>
The	O
CPU	O
uses	O
the	O
values	O
of	O
CS	O
and	O
IP	O
registers	B-General_Concept
to	O
find	O
the	O
location	O
of	O
the	O
next	B-General_Concept
instruction	I-General_Concept
to	O
execute	O
.	O
</s>
<s>
Location	O
of	O
next	B-General_Concept
instruction	I-General_Concept
is	O
calculated	O
using	O
this	O
simple	O
equation	O
:	O
</s>
<s>
This	O
implies	O
that	O
after	O
the	O
hardware	B-Operating_System
reset	I-Operating_System
,	O
the	O
CPU	O
will	O
start	O
execution	O
at	O
the	O
physical	O
address	O
0xFFFF0	O
.	O
</s>
<s>
In	O
IBM	O
PC	O
compatible	O
computers	O
,	O
This	O
address	O
maps	O
to	O
BIOS	B-Operating_System
ROM	I-Operating_System
.	O
</s>
<s>
The	O
memory	O
word	O
at	O
0xFFFF0	O
usually	O
contains	O
a	O
JMP	B-Device
instruction	O
that	O
redirects	O
the	O
CPU	O
to	O
execute	O
the	O
initialization	O
code	O
of	O
BIOS	B-Operating_System
.	O
</s>
<s>
This	O
JMP	B-Device
instruction	O
is	O
absolutely	O
the	O
first	O
instruction	O
executed	O
after	O
the	O
reset	O
.	O
</s>
<s>
Later	O
x86	O
processors	O
reset	O
the	O
CS	O
and	O
IP	O
registers	B-General_Concept
similarly	O
,	O
refer	O
to	O
Reset	B-General_Concept
vector	I-General_Concept
.	O
</s>
