<s>
A	O
RAID	B-General_Concept
processing	I-General_Concept
unit	I-General_Concept
(	O
RPU	O
)	O
is	O
an	O
integrated	O
circuit	O
that	O
performs	O
specialized	O
calculations	O
in	O
a	O
RAID	B-Architecture
host	B-Architecture
adapter	I-Architecture
.	O
</s>
<s>
XOR	B-Application
calculations	O
,	O
for	O
example	O
,	O
are	O
necessary	O
for	O
calculating	O
parity	O
data	O
,	O
and	O
for	O
maintaining	O
data	O
integrity	O
when	O
writing	O
to	O
a	O
disk	B-General_Concept
array	I-General_Concept
that	O
uses	O
a	O
parity	B-General_Concept
drive	I-General_Concept
or	O
data	B-General_Concept
striping	I-General_Concept
.	O
</s>
<s>
An	O
RPU	O
may	O
perform	O
these	O
calculations	O
more	O
efficiently	O
than	O
the	O
computer	O
's	O
central	B-General_Concept
processing	I-General_Concept
unit	I-General_Concept
(	O
CPU	O
)	O
.	O
</s>
