<s>
The	O
flying-spot	B-General_Concept
store	I-General_Concept
was	O
an	O
optical	O
digital	O
memory	O
used	O
in	O
early	O
stored	B-Device
program	I-Device
control	I-Device
components	O
of	O
electronic	B-Device
switching	I-Device
systems	I-Device
.	O
</s>
<s>
The	O
flying-spot	B-General_Concept
store	I-General_Concept
used	O
a	O
photographic	B-Algorithm
plate	I-Algorithm
as	O
the	O
store	O
of	O
binary	O
data	O
.	O
</s>
<s>
The	O
optical	O
system	O
consisted	O
of	O
a	O
cathode	B-Device
ray	I-Device
tube	I-Device
that	O
functioned	O
as	O
a	O
flying-spot	B-Algorithm
scanner	I-Algorithm
,	O
the	O
source	O
of	O
light	O
beams	O
produced	O
on	O
its	O
face	O
and	O
focused	O
onto	O
the	O
photographic	B-Algorithm
plates	I-Algorithm
with	O
a	O
system	O
of	O
lenses	O
.	O
</s>
<s>
A	O
flying-spot	B-General_Concept
store	I-General_Concept
was	O
the	O
main	O
permanent	O
program	O
and	O
data	O
memory	O
for	O
the	O
first	O
electronic	O
central	O
office	O
installed	O
on	O
a	O
trial	O
basis	O
in	O
Morris	O
,	O
Illinois	O
in	O
1960	O
.	O
</s>
<s>
The	O
memory	O
was	O
organized	O
as	O
a	O
set	O
of	O
nine	O
photographic	B-Algorithm
plates	I-Algorithm
and	O
permitted	O
reading	O
two	O
spots	O
per	O
memory	O
address	O
,	O
yielding	O
a	O
word	O
size	O
of	O
18	O
bits	O
.	O
</s>
<s>
For	O
temporary	O
data	O
,	O
the	O
system	O
used	O
a	O
barrier-grid	O
electrostatic	O
storage	B-General_Concept
tube	I-General_Concept
.	O
</s>
