<s>
The	O
TI-59	B-Device
is	O
an	O
early	O
programmable	B-Application
calculator	I-Application
,	O
that	O
was	O
manufactured	O
by	O
Texas	O
Instruments	O
from	O
1977	O
.	O
</s>
<s>
It	O
is	O
the	O
successor	O
to	O
the	O
TI	O
SR-52	O
,	O
quadrupling	O
the	O
number	O
of	O
"	O
program	O
steps	O
"	O
of	O
storage	O
,	O
and	O
adding	O
"	O
ROM	B-Device
Program	B-Architecture
Modules	I-Architecture
"	O
(	O
an	O
insertable	O
ROM	B-Device
chip	I-Device
,	O
capable	O
of	O
holding	O
5000	O
program	O
steps	O
)	O
.	O
</s>
<s>
One	O
quarter	O
of	O
the	O
memory	B-General_Concept
is	O
stored	O
on	O
each	O
side	O
of	O
one	O
card	O
.	O
</s>
<s>
The	O
TI-58	B-Device
(	O
May	O
1977	O
)	O
,	O
and	O
later	O
TI-58C	B-Device
(	O
1979	O
)	O
,	O
are	O
cut-down	O
versions	O
of	O
the	O
TI-59	B-Device
,	O
lacking	O
the	O
magnetic	O
card	O
reader	O
and	O
having	O
half	O
the	O
memory	B-General_Concept
,	O
but	O
otherwise	O
identical	O
.	O
</s>
<s>
Although	O
the	O
TI-58C	B-Device
uses	O
a	O
different	O
chip	O
than	O
the	O
TI-58	B-Device
,	O
the	O
technical	O
data	O
remain	O
identical	O
.	O
</s>
<s>
The	O
"	O
C	O
"	O
in	O
a	O
TI	O
(	O
or	O
Hewlett-Packard	O
)	O
model	O
name	O
indicates	O
that	O
the	O
calculator	O
has	O
a	O
constant	O
memory	B-General_Concept
(	O
or	O
continuous	B-Device
memory	I-Device
,	O
respectively	O
)	O
allowing	O
retention	O
of	O
programs	O
and	O
data	O
when	O
turned	O
off	O
.	O
</s>
<s>
The	O
calculator	O
can	O
be	O
powered	O
from	O
an	O
external	O
adapter	B-Device
or	O
from	O
internal	O
NiCd	O
rechargeable	O
battery	O
pack	O
(	O
although	O
the	O
battery	O
has	O
to	O
remain	O
present	O
when	O
using	O
the	O
external	O
AC	O
adapter	B-Device
to	O
avoid	O
damage	O
to	O
the	O
calculator	O
circuitry	O
)	O
.	O
</s>
<s>
Programming	O
simple	O
problems	O
with	O
the	O
TI-59	B-Device
or	O
TI-58	B-Device
is	O
a	O
very	O
straightforward	O
process	O
.	O
</s>
<s>
In	O
programming	O
mode	O
,	O
the	O
TI-59	B-Device
simply	O
records	O
key	O
presses	O
.	O
</s>
<s>
It	O
is	O
also	O
possible	O
to	O
activate	O
any	O
of	O
the	O
programs	O
in	O
the	O
pre-programmed	O
memory	B-General_Concept
module	B-Architecture
,	O
and	O
run	O
one	O
like	O
any	O
user-written	O
program	O
.	O
</s>
<s>
Programs	O
written	O
by	O
the	O
user	O
can	O
also	O
use	O
programs	O
in	O
the	O
module	B-Architecture
as	O
subroutines	O
.	O
</s>
<s>
The	O
module	B-Architecture
's	O
programs	O
run	O
directly	O
from	O
ROM	B-Device
,	O
so	O
they	O
leave	O
the	O
calculator	O
's	O
memory	B-General_Concept
free	O
for	O
the	O
user	O
.	O
</s>
<s>
However	O
,	O
exploiting	O
the	O
computer-like	O
capabilities	O
of	O
the	O
TI-59	B-Device
is	O
a	O
different	O
matter	O
.	O
</s>
<s>
Although	O
the	O
TI-59	B-Device
is	O
Turing-complete	B-Algorithm
,	O
supporting	O
straight-line	O
programming	O
,	O
conditions	O
,	O
loops	O
,	O
and	O
indirect	O
access	O
to	O
memory	B-General_Concept
registers	O
,	O
and	O
although	O
it	O
supports	O
limited	O
alphanumeric	O
output	O
on	O
the	O
printer	O
only	O
,	O
writing	O
sophisticated	O
routines	O
is	O
essentially	O
a	O
matter	O
of	O
planning	O
machine	O
language	O
and	O
using	O
a	O
coding	O
pad	O
.	O
</s>
<s>
A	O
large	O
degree	O
of	O
sharing	O
occurred	O
in	O
the	O
TI-59	B-Device
and	O
TI-58	B-Device
community	O
.	O
</s>
<s>
Unlike	O
the	O
SR-52	O
,	O
the	O
TI-58	B-Device
and	O
TI-59	B-Device
do	O
not	O
have	O
the	O
factorial	O
function	O
built-in	O
,	O
but	O
do	O
support	O
it	O
through	O
the	O
software	O
module	B-Architecture
which	O
was	O
delivered	O
with	O
the	O
calculator	O
.	O
</s>
<s>
In	O
comparison	O
to	O
its	O
contemporary	O
main	O
competitor	O
,	O
Hewlett-Packard	O
HP-67	B-Device
,	O
the	O
TI-59	B-Device
has	O
about	O
twice	O
the	O
memory	B-General_Concept
.	O
</s>
<s>
The	O
TI-59	B-Device
was	O
the	O
first	O
programmable	B-Application
pocket	O
calculator	O
where	O
the	O
manufacturer	O
provided	O
a	O
system	O
for	O
sharing	O
memory	B-General_Concept
between	O
data	O
registers	O
and	O
program	O
storage	O
.	O
</s>
<s>
The	O
memory	B-General_Concept
is	O
only	O
about	O
twice	O
as	O
large	O
as	O
in	O
the	O
SR-52	O
,	O
but	O
more	O
flexible	O
,	O
and	O
thus	O
the	O
possible	O
number	O
of	O
program	O
steps	O
was	O
four	O
times	O
as	O
high	O
.	O
</s>
<s>
Contents	O
of	O
this	O
memory	B-General_Concept
are	O
lost	O
when	O
the	O
calculator	O
is	O
turned	O
off	O
.	O
</s>
<s>
The	O
TI-58	B-Device
has	O
half	O
the	O
memory	B-General_Concept
of	O
the	O
TI-59	B-Device
and	O
supports	O
up	O
to	O
480	O
program	O
steps	O
or	O
60	O
memories	O
.	O
</s>
<s>
It	O
competed	O
with	O
the	O
HP-34C	B-Device
.	O
</s>
<s>
The	O
TI-58	B-Device
and	O
TI-59	B-Device
calculators	O
have	O
variable-length	O
instructions	O
.	O
</s>
<s>
The	O
HP-67	B-Device
always	O
stores	O
one	O
instruction	O
in	O
one	O
programming	O
step	O
,	O
which	O
is	O
efficient	O
for	O
some	O
frequently	O
used	O
instructions	O
but	O
also	O
limits	O
the	O
number	O
of	O
possible	O
instructions	O
.	O
</s>
<s>
The	O
TI-59	B-Device
can	O
store	O
programs	O
and	O
data	O
on	O
small	O
magnetic	O
cards	O
when	O
the	O
calculator	O
is	O
turned	O
off	O
and	O
quickly	O
reloaded	O
when	O
needed	O
.	O
</s>
<s>
The	O
TI-58	B-Device
does	O
not	O
have	O
a	O
magnetic	O
card	O
reader	O
.	O
</s>
<s>
The	O
TI-59	B-Device
and	O
TI-58	B-Device
were	O
the	O
first	O
hand-held	O
calculators	O
to	O
utilize	O
removable	O
ROM	B-Device
program	B-Architecture
modules	I-Architecture
.	O
</s>
<s>
The	O
Master	O
Library	O
Module	B-Architecture
ROM	B-Device
was	O
included	O
with	O
the	O
TI-59	B-Device
and	O
TI-58	B-Device
,	O
and	O
contains	O
several	O
useful	O
pre-programmed	O
routines	O
and	O
even	O
a	O
game	O
.	O
</s>
<s>
Additional	O
modules	B-Architecture
-	O
for	O
such	O
applications	O
as	O
real	O
estate	O
,	O
investment	O
,	O
statistics	O
,	O
surveying	O
and	O
aviation	O
-	O
were	O
sold	O
separately	O
.	O
</s>
<s>
The	O
programs	O
in	O
the	O
modules	B-Architecture
used	O
the	O
user-defined	O
keys	O
heavily	O
.	O
</s>
<s>
Also	O
available	O
for	O
the	O
TI-59	B-Device
and	O
TI-58	B-Device
was	O
a	O
thermal	O
printer	O
(	O
the	O
PC-100A	O
,	O
B	O
,	O
and	O
C	O
models	O
)	O
;	O
the	O
calculator	O
was	O
mounted	O
on	O
top	O
of	O
the	O
printer	O
and	O
locked	O
in	O
place	O
with	O
a	O
key	O
.	O
</s>
<s>
In	O
the	O
early	O
model	O
PC-100A	O
,	O
a	O
switch	O
inside	O
the	O
battery	O
charger	O
compartment	O
allows	O
use	O
with	O
the	O
earlier	O
SR-52	O
and	O
SR-56	O
calculators	O
as	O
well	O
as	O
the	O
TI-58/59	O
series	O
.	O
</s>
<s>
In	O
addition	O
,	O
it	O
also	O
works	O
with	O
non-programmable	O
TI	O
machines	O
of	O
the	O
era	O
such	O
as	O
the	O
SR-50A	B-Device
.	O
</s>
