<s>
In	O
parallel	B-Operating_System
computing	I-Operating_System
,	O
the	O
Geometric	B-General_Concept
Arithmetic	I-General_Concept
Parallel	I-General_Concept
Processor	I-General_Concept
(	O
GAPP	O
)	O
,	O
invented	O
by	O
Polish	O
mathematician	O
Włodzimierz	O
Holsztyński	O
in	O
1981	O
,	O
was	O
patented	O
by	O
Martin	O
Marietta	O
and	O
is	O
now	O
owned	O
by	O
Silicon	O
Optix	O
,	O
Inc	O
.	O
</s>
<s>
The	O
GAPP	O
's	O
network	B-Architecture
topology	I-Architecture
is	O
a	O
mesh-connected	O
array	O
of	O
single-bit	O
SIMD	B-Device
processing	O
elements	O
(	O
PEs	O
)	O
,	O
where	O
each	O
PE	O
can	O
communicate	O
with	O
its	O
neighbor	O
to	O
the	O
north	O
,	O
east	O
,	O
south	O
,	O
and	O
west	O
.	O
</s>
<s>
Characteristically	O
,	O
the	O
cell	O
's	O
arithmetic	B-General_Concept
logic	I-General_Concept
unit	I-General_Concept
(	O
ALU	O
)	O
(	O
that	O
is	O
,	O
its	O
PE	O
)	O
in	O
the	O
early	O
versions	O
of	O
GAPP	O
was	O
nothing	O
but	O
a	O
1-bit	O
full-adder/subtractor	O
,	O
which	O
efficiently	O
served	O
both	O
the	O
complex	O
arithmetic	O
as	O
well	O
as	O
logical	O
functions	O
,	O
and	O
with	O
the	O
help	O
of	O
shifts	O
it	O
served	O
also	O
the	O
geometric	O
transformations	O
—	O
in	O
short	O
,	O
it	O
was	O
doing	O
all	O
three	O
types	O
of	O
the	O
tasks	O
(	O
while	O
other	O
designs	O
used	O
three	O
separate	O
hardware	O
special-purpose	O
units	O
instead	O
)	O
.	O
</s>
