<s>
In	O
computing	O
,	O
multiple	B-Operating_System
instruction	I-Operating_System
,	I-Operating_System
single	I-Operating_System
data	I-Operating_System
(	O
MISD	O
)	O
is	O
a	O
type	O
of	O
parallel	B-Operating_System
computing	I-Operating_System
architecture	B-General_Concept
where	O
many	O
functional	O
units	O
perform	O
different	O
operations	O
on	O
the	O
same	O
data	O
.	O
</s>
<s>
Pipeline	B-General_Concept
architectures	I-General_Concept
belong	O
to	O
this	O
type	O
,	O
though	O
a	O
purist	O
might	O
say	O
that	O
the	O
data	O
is	O
different	O
after	O
processing	O
by	O
each	O
stage	O
in	O
the	O
pipeline	B-General_Concept
.	O
</s>
<s>
Fault	B-General_Concept
tolerance	I-General_Concept
executing	O
the	O
same	O
instructions	O
redundantly	O
in	O
order	O
to	O
detect	O
and	O
mask	O
errors	O
,	O
in	O
a	O
manner	O
known	O
as	O
task	B-Architecture
replication	I-Architecture
,	O
may	O
be	O
considered	O
to	O
belong	O
to	O
this	O
type	O
.	O
</s>
<s>
Applications	O
for	O
this	O
architecture	B-General_Concept
are	O
much	O
less	O
common	O
than	O
MIMD	B-Operating_System
and	O
SIMD	B-Device
,	O
as	O
the	O
latter	O
two	O
are	O
often	O
more	O
appropriate	O
for	O
common	O
data	O
parallel	B-Operating_System
techniques	O
.	O
</s>
<s>
Systolic	B-Architecture
arrays	I-Architecture
(	O
<	O
wavefront	O
processors	O
)	O
,	O
first	O
described	O
by	O
H	O
.	O
T	O
.	O
Kung	O
and	O
Charles	O
E	O
.	O
Leiserson	O
are	O
an	O
example	O
of	O
MISD	O
architecture	B-General_Concept
.	O
</s>
<s>
In	O
a	O
typical	O
systolic	B-Architecture
array	I-Architecture
,	O
parallel	B-Operating_System
input	B-General_Concept
data	O
flows	O
through	O
a	O
network	O
of	O
hard-wired	O
processor	B-Architecture
nodes	O
,	O
resembling	O
the	O
human	O
brain	O
which	O
combine	O
,	O
process	O
,	O
merge	B-Algorithm
or	O
sort	B-Algorithm
the	O
input	B-General_Concept
data	O
into	O
a	O
derived	O
result	O
.	O
</s>
<s>
Systolic	B-Architecture
arrays	I-Architecture
are	O
often	O
hard-wired	O
for	O
a	O
specific	O
operation	O
,	O
such	O
as	O
"	O
multiply	O
and	O
accumulate	O
"	O
,	O
to	O
perform	O
massively	O
parallel	B-Operating_System
integration	O
,	O
convolution	B-Language
,	O
correlation	O
,	O
matrix	O
multiplication	O
or	O
data	O
sorting	B-Algorithm
tasks	O
.	O
</s>
<s>
A	O
systolic	B-Architecture
array	I-Architecture
typically	O
consists	O
of	O
a	O
large	O
monolithic	O
network	O
of	O
primitive	O
computing	O
nodes	O
,	O
which	O
can	O
be	O
hardwired	O
or	O
software-configured	O
for	O
a	O
specific	O
application	O
.	O
</s>
<s>
More	O
general	O
wavefront	O
processors	O
,	O
by	O
contrast	O
,	O
employ	O
sophisticated	O
and	O
individually	O
programmable	O
nodes	O
which	O
may	O
or	O
may	O
not	O
be	O
monolithic	O
,	O
depending	O
on	O
the	O
array	B-Data_Structure
size	O
and	O
design	O
parameters	O
.	O
</s>
<s>
Because	O
the	O
wave-like	O
propagation	O
of	O
data	O
through	O
a	O
systolic	B-Architecture
array	I-Architecture
resembles	O
the	O
pulse	O
of	O
the	O
human	O
circulatory	O
system	O
,	O
the	O
name	O
systolic	O
was	O
coined	O
from	O
medical	O
terminology	O
.	O
</s>
<s>
A	O
significant	O
benefit	O
of	O
systolic	B-Architecture
arrays	I-Architecture
is	O
that	O
all	O
operand	O
data	O
and	O
partial	O
results	O
are	O
contained	O
within	O
(	O
passing	O
through	O
)	O
the	O
processor	B-Architecture
array	B-Data_Structure
.	O
</s>
<s>
The	O
sequential	O
limits	O
on	O
parallel	B-Operating_System
performance	O
dictated	O
by	O
Amdahl	B-Operating_System
's	I-Operating_System
law	I-Operating_System
also	O
do	O
not	O
apply	O
in	O
the	O
same	O
way	O
because	O
data	O
dependencies	O
are	O
implicitly	O
handled	O
by	O
the	O
programmable	O
node	B-Data_Structure
interconnect	O
.	O
</s>
<s>
Therefore	O
,	O
systolic	B-Architecture
arrays	I-Architecture
are	O
extremely	O
good	O
at	O
artificial	O
intelligence	O
,	O
image	O
processing	O
,	O
pattern	O
recognition	O
,	O
computer	O
vision	O
,	O
and	O
other	O
tasks	O
that	O
animal	O
brains	O
do	O
exceptionally	O
well	O
.	O
</s>
<s>
While	O
systolic	B-Architecture
arrays	I-Architecture
are	O
officially	O
classified	O
as	O
MISD	O
,	O
their	O
classification	O
is	O
somewhat	O
problematic	O
.	O
</s>
<s>
Because	O
the	O
input	B-General_Concept
is	O
typically	O
a	O
vector	O
of	O
independent	O
values	O
,	O
the	O
systolic	B-Architecture
array	I-Architecture
is	O
not	O
SISD	B-Operating_System
.	O
</s>
<s>
Since	O
these	O
input	B-General_Concept
values	O
are	O
merged	O
and	O
combined	O
into	O
the	O
result(s )	O
and	O
do	O
not	O
maintain	O
their	O
independence	O
as	O
they	O
would	O
in	O
a	O
SIMD	B-Device
vector	O
processing	O
unit	O
,	O
the	O
array	B-Data_Structure
cannot	O
be	O
classified	O
as	O
such	O
.	O
</s>
<s>
Consequently	O
,	O
the	O
array	B-Data_Structure
cannot	O
be	O
classified	O
as	O
a	O
MIMD	B-Operating_System
either	O
,	O
since	O
MIMD	B-Operating_System
can	O
be	O
viewed	O
as	O
a	O
mere	O
collection	O
of	O
smaller	O
SISD	B-Operating_System
and	O
SIMD	B-Device
machines	O
.	O
</s>
<s>
Finally	O
,	O
because	O
the	O
data	O
swarm	B-Application
is	O
transformed	O
as	O
it	O
passes	O
through	O
the	O
array	B-Data_Structure
from	O
node	B-Data_Structure
to	O
node	B-Data_Structure
,	O
the	O
multiple	O
nodes	O
are	O
not	O
operating	O
on	O
the	O
same	O
data	O
,	O
which	O
makes	O
the	O
MISD	O
classification	O
a	O
misnomer	O
.	O
</s>
<s>
The	O
other	O
reason	O
why	O
a	O
systolic	B-Architecture
array	I-Architecture
should	O
not	O
qualify	O
as	O
a	O
MISD	O
is	O
the	O
same	O
as	O
the	O
one	O
which	O
disqualifies	O
it	O
from	O
the	O
SISD	B-Operating_System
category	O
:	O
The	O
input	B-General_Concept
data	O
is	O
typically	O
a	O
vector	O
,	O
not	O
a	O
single	O
data	O
value	O
,	O
although	O
one	O
could	O
argue	O
that	O
any	O
given	O
input	B-General_Concept
vector	O
is	O
a	O
single	O
dataset	O
.	O
</s>
<s>
The	O
above	O
notwithstanding	O
,	O
systolic	B-Architecture
arrays	I-Architecture
are	O
often	O
offered	O
as	O
a	O
classic	O
example	O
of	O
MISD	O
architecture	B-General_Concept
in	O
textbooks	O
on	O
parallel	B-Operating_System
computing	I-Operating_System
and	O
in	O
the	O
engineering	O
class	O
.	O
</s>
<s>
If	O
the	O
array	B-Data_Structure
is	O
viewed	O
from	O
the	O
outside	O
as	O
atomic	B-General_Concept
it	O
should	O
perhaps	O
be	O
classified	O
as	O
SFMuDMeR	O
=	O
single	O
function	O
,	O
multiple	O
data	O
,	O
merged	O
result(s )	O
.	O
</s>
