<s>
The	O
IBM	B-Device
1360	I-Device
Photo-Digital	O
Storage	O
System	O
,	O
or	O
PDSS	O
,	O
was	O
an	O
online	O
archival	O
storage	O
system	O
for	O
large	O
data	O
centers	O
.	O
</s>
<s>
Kalvar	O
was	O
developed	O
to	O
make	O
copies	O
of	O
existing	O
microfilm	O
stock	O
,	O
simply	O
by	O
placing	O
the	O
Kalvar	O
and	O
original	O
together	O
,	O
exposing	O
them	O
to	O
ultraviolet	B-Application
light	O
,	O
and	O
then	O
heating	O
the	O
Kalvar	O
to	O
develop	O
it	O
.	O
</s>
<s>
Kalvar	O
is	O
based	O
on	O
a	O
diazo	B-Application
film	I-Application
and	O
Kuehler	O
was	O
able	O
to	O
identify	O
a	O
similar	O
film	O
that	O
would	O
provide	O
the	O
reliability	O
required	O
,	O
although	O
at	O
the	O
price	O
of	O
needing	O
to	O
be	O
developed	O
in	O
a	O
wet	O
lab	O
process	O
.	O
</s>
<s>
He	O
proposed	O
a	O
new	O
version	O
of	O
Walnut	O
that	O
replaced	O
the	O
Kalvar	O
developer	O
with	O
an	O
automated	O
diazo	B-Application
film	I-Application
developer	O
system	O
that	O
developed	O
the	O
film	O
in	O
a	O
few	O
minutes	O
.	O
</s>
<s>
Users	O
would	O
look	O
up	O
keywords	O
stored	O
on	O
an	O
IBM	B-Device
1405	I-Device
hard	B-Device
disk	I-Device
system	O
,	O
identifying	O
individual	O
documents	O
to	O
be	O
retrieved	O
.	O
</s>
<s>
The	O
machine	O
produced	O
punched	B-Architecture
cards	I-Architecture
that	O
were	O
inserted	O
into	O
the	O
Walnut	O
.	O
</s>
<s>
The	O
Walnut	O
system	O
retrieved	O
the	O
documents	O
,	O
copied	O
them	O
onto	O
a	O
film	O
strip	O
and	O
developed	O
it	O
,	O
and	O
then	O
inserted	O
four	O
such	O
images	O
into	O
an	O
aperture	B-Application
card	I-Application
.	O
</s>
<s>
Both	O
systems	O
used	O
the	O
same	O
photographic	O
cards	O
and	O
automated	O
film	O
development	O
system	O
originally	O
developed	O
for	O
Walnut	O
,	O
but	O
replaced	O
the	O
diazo	B-Application
film	I-Application
with	O
longer-lasting	O
conventional	O
silver	O
halide	O
films	O
.	O
</s>
<s>
At	O
about	O
the	O
same	O
time	O
,	O
the	O
Atomic	O
Energy	O
Commission	O
started	O
looking	O
for	O
a	O
system	O
able	O
to	O
store	O
1	O
terabit	O
for	O
online	O
access	O
by	O
supercomputers	B-Architecture
running	O
simulations	O
.	O
</s>
<s>
IBM	O
's	O
Thomas	O
J	O
.	O
Watson	O
Research	O
Center	O
proposed	O
a	O
new	O
version	O
of	O
the	O
10	O
inch	O
optical	O
disk	O
they	O
had	O
developed	O
for	O
the	O
AN/GSQ	B-General_Concept
-16	I-General_Concept
(	O
Mark	O
II	O
)	O
Russian-to-English	O
machine	B-Application
translation	I-Application
system	I-Application
.	O
</s>
<s>
By	O
the	O
time	O
they	O
were	O
in	O
place	O
,	O
IBM	O
had	O
developed	O
a	O
number	O
of	O
other	O
storage	O
systems	O
of	O
similar	O
size	O
,	O
and	O
started	O
suggesting	O
the	O
IBM	B-Device
3850	I-Device
in	O
favor	O
of	O
the	O
1360	O
.	O
</s>
<s>
Each	O
frame	O
contained	O
492	O
lines	O
of	O
about	O
420	O
bits	O
each	O
,	O
0s	O
written	O
as	O
a	O
black-clear	O
pattern	O
,	O
and	O
1s	O
as	O
a	O
clear-black	O
(	O
using	O
Manchester	B-Protocol
encoding	I-Protocol
)	O
.	O
</s>
<s>
Flaws	O
on	O
the	O
film	O
,	O
impossible	O
to	O
avoid	O
,	O
were	O
addressed	O
to	O
some	O
degree	O
through	O
the	O
use	O
of	O
complex	O
error	B-Error_Name
correction	I-Error_Name
codes	O
,	O
which	O
used	O
up	O
about	O
30%	O
of	O
the	O
overall	O
storage	O
capacity	O
thus	O
in	O
each	O
line	O
in	O
a	O
frame	O
only	O
300	O
bits	O
were	O
user	O
data	O
,	O
the	O
remainder	O
being	O
used	O
for	O
data	O
redundancy	O
.	O
</s>
<s>
Error	B-Error_Name
correction	I-Error_Name
could	O
correct	O
for	O
minor	O
imperfections	O
,	O
but	O
not	O
for	O
larger	O
problems	O
or	O
bad	O
developing	O
,	O
so	O
after	O
developing	O
the	O
chips	O
were	O
immediately	O
passed	O
to	O
the	O
1364	O
Photo-Digital	O
Reader	O
to	O
ensure	O
they	O
worked	O
.	O
</s>
