<s>
The	O
FX-501P	O
and	O
FX-502P	O
were	O
programmable	B-Application
calculators	I-Application
,	O
manufactured	O
by	O
Casio	O
from	O
1978/1979	O
.	O
</s>
<s>
They	O
were	O
the	O
predecessors	O
of	O
the	O
FX-601P	B-Device
and	O
FX-602P	B-Device
.	O
</s>
<s>
It	O
is	O
likely	O
that	O
the	O
FX-501P/502P	O
were	O
the	O
first	O
LCD	B-Device
programmable	B-Application
calculators	I-Application
to	O
be	O
produced	O
as	O
up	O
until	O
1979	O
(	O
and	O
the	O
introduction	O
of	O
the	O
HP-41C	O
)	O
no	O
manufacturer	O
had	O
introduced	O
such	O
a	O
device	O
.	O
</s>
<s>
The	O
FX-501P	O
and	O
FX-502P	O
featured	O
a	O
single	O
line	O
7-segment	B-General_Concept
liquid	B-Device
crystal	I-Device
display	I-Device
with	O
10	O
digits	O
as	O
main	O
display	O
.	O
</s>
<s>
An	O
additional	O
3	O
digits	O
7-segment	B-General_Concept
display	I-General_Concept
used	O
to	O
display	O
exponents	O
and	O
program	O
steps	O
when	O
entering	O
or	O
debugging	O
programs	O
and	O
10	O
status	O
indicators	O
.	O
</s>
<s>
The	O
FX-501P	O
and	O
FX-502P	O
supported	O
indirect	O
addressing	O
both	O
for	O
memory	O
access	O
and	O
jumps	O
and	O
therefore	O
the	O
programming	O
model	O
could	O
be	O
considered	O
Turing	B-Algorithm
complete	I-Algorithm
.	O
</s>
<s>
Since	O
the	O
FX-501P	O
and	O
FX-502P	O
only	O
employed	O
a	O
seven-segment	B-General_Concept
display	I-General_Concept
each	O
program	O
step	O
was	O
represented	O
by	O
a	O
special	O
2-digit	O
codes	O
made	O
up	O
of	O
the	O
digits	O
0	O
..	O
9	O
and	O
the	O
character	O
C	O
,	O
E	O
,	O
F	O
and	O
P	O
.	O
The	O
calculator	O
came	O
with	O
a	O
special	O
overlay	O
so	O
the	O
user	O
did	O
not	O
need	O
to	O
memorize	O
the	O
mapping	O
between	O
code	O
and	O
actual	O
command	O
.	O
</s>
<s>
The	O
FX-501P	O
and	O
FX-502P	O
used	O
the	O
FA-1	B-Device
to	O
store	O
program	O
and	O
data	O
to	O
Compact	B-Device
Cassette	I-Device
using	O
the	O
Kansas	B-Device
City	I-Device
standard	I-Device
.	O
</s>
<s>
The	O
FA-1	B-Device
also	O
enabled	O
the	O
calculators	O
to	O
generate	O
musical	O
notes	O
.	O
</s>
