<s>
The	O
Symbolic	B-Application
Optimal	I-Application
Assembly	I-Application
Program	I-Application
(	O
SOAP	O
)	O
is	O
an	O
assembler	B-Application
for	O
the	O
IBM	B-Device
650	I-Device
Magnetic	B-General_Concept
Drum	I-General_Concept
Data-Processing	O
Machine	O
,	O
an	O
early	O
computer	O
first	O
used	O
in	O
1954	O
.	O
</s>
<s>
SOAP	O
is	O
called	O
Optimal	O
(	O
or	O
Optimum	O
)	O
because	O
it	O
attempts	O
to	O
store	O
generated	O
instructions	O
on	O
the	O
storage	B-General_Concept
drum	I-General_Concept
to	O
minimize	O
the	O
access	B-General_Concept
time	I-General_Concept
from	O
one	O
instruction	O
to	O
the	O
next	O
.	O
</s>
<s>
SOAP	O
is	O
a	O
multi-pass	B-Application
assembler	B-Application
,	O
that	O
is	O
,	O
it	O
processes	O
the	O
source	O
program	O
more	O
than	O
once	O
in	O
order	O
to	O
generate	O
the	O
object	B-Application
program	I-Application
.	O
</s>
<s>
The	O
first	O
version	O
of	O
SOAP	O
was	O
succeeded	O
by	O
SOAP	O
II	O
in	O
1957	O
,	O
which	O
supported	O
additional	O
hardware	O
features	O
such	O
as	O
index	B-General_Concept
registers	I-General_Concept
and	O
magnetic	O
core	O
memory	O
,	O
SOAP	O
IIA	O
in	O
1958	O
,	O
SOAP	O
2L	O
,	O
SOAP	O
2L	O
Tape	O
,	O
SOAP	O
4000	O
,	O
and	O
SOAP	O
42	O
in	O
1961	O
.	O
</s>
<s>
SOAP	O
was	O
used	O
as	O
a	O
backend	O
to	O
the	O
FOR	B-Language
TRANSIT	I-Language
compiler	O
in	O
1957	O
.	O
</s>
<s>
The	O
IBM	B-Device
650	I-Device
uses	O
a	O
magnetic	B-General_Concept
drum	I-General_Concept
as	O
main	O
storage	O
.	O
</s>
<s>
The	O
drum	O
holds	O
up	O
to	O
4,000	O
words	O
and	O
rotates	O
at	O
12,500	O
revolutions	O
per	O
minute	O
(	O
RPM	O
)	O
,	O
4.8msec	O
per	O
rotation	O
,	O
or	O
average	O
access	B-General_Concept
time	I-General_Concept
of	O
2.4	O
msec	O
.	O
</s>
