<s>
The	O
M9	B-Device
Gun	I-Device
Director	I-Device
was	O
an	O
electronic	O
director	O
developed	O
by	O
Bell	O
Labs	O
during	O
World	O
War	O
II	O
.	O
</s>
<s>
This	O
computer	O
continuously	O
calculated	O
trigonometric	O
firing	B-Application
solutions	I-Application
for	O
anti-aircraft	O
weapons	O
against	O
enemy	O
aircraft	O
.	O
</s>
<s>
The	O
SCR-268	O
'	O
s	O
longwave	B-Algorithm
did	O
not	O
provide	O
accurate	O
enough	O
data	O
for	O
the	O
pairing	O
to	O
be	O
an	O
effective	O
anti-aircraft	O
weapon	O
.	O
</s>
<s>
In	O
May	O
1940	O
,	O
an	O
engineer	O
at	O
Bell	O
named	O
David	O
Parkinson	O
had	O
a	O
dream	O
about	O
being	O
in	O
an	O
anti-aircraft	O
revetment	O
where	O
he	O
also	O
spotted	O
a	O
potentiometer	B-Device
.	O
</s>
<s>
He	O
spent	O
the	O
next	O
couple	O
of	O
weeks	O
working	O
with	O
his	O
boss	O
to	O
draft	O
up	O
specifications	O
for	O
an	O
analog	O
computer	O
that	O
provided	O
firing	B-Application
solutions	I-Application
for	O
anti-aircraft	O
guns	O
.	O
</s>
<s>
Their	O
proposed	O
director	O
would	O
calculate	O
course	O
and	O
speed	O
of	O
incoming	O
aircraft	O
,	O
shell	O
's	O
velocity	O
and	O
fuse	O
timing	O
,	O
powder	O
temperatures	O
,	O
shell	O
drift	O
,	O
and	O
air	O
density	O
and	O
wind	O
speed	O
to	O
provide	O
a	O
predicted	O
firing	B-Application
solution	I-Application
for	O
the	O
associated	O
gun	O
battery	O
.	O
</s>
<s>
A	O
prototype	O
,	O
designated	O
T-10	O
,	O
was	O
delivered	O
to	O
the	O
Army	O
only	O
a	O
few	O
days	O
after	O
the	O
attack	B-Application
on	I-Application
Pearl	I-Application
Harbor	I-Application
and	O
a	O
few	O
hundred	O
sets	O
were	O
ordered	O
immediately	O
.	O
</s>
<s>
90mm	O
anti-aircraft	O
guns	O
were	O
normally	O
operated	O
in	O
groups	O
of	O
four	O
,	O
utilizing	O
the	O
SCR-584	O
microwave	O
computer	O
and	O
being	O
controlled	O
by	O
the	O
M9	B-Device
Director	I-Device
.	O
</s>
<s>
Direction	O
and	O
range	O
information	O
was	O
sent	O
directly	O
to	O
the	O
M3	B-Device
Gun	I-Device
Data	I-Device
Computer	I-Device
,	O
and	O
M9	B-Device
Director	I-Device
,	O
which	O
directed	O
and	O
layed	O
the	O
guns	O
automatically	O
.	O
</s>
<s>
SCR-584s	O
with	O
the	O
associated	O
M9	B-Device
Gun	I-Device
Directors	I-Device
were	O
rushed	O
to	O
the	O
Anzio	O
beachhead	O
in	O
February	O
1944	O
to	O
assist	O
with	O
engaging	O
the	O
German/Italian	O
Air	O
Force	O
that	O
was	O
jamming	O
the	O
SCR-268s	O
and	O
bombing	O
the	O
beachhead	O
and	O
harbor	O
at	O
night	O
.	O
</s>
