<s>
An	O
electronic	O
calculator	B-Application
is	O
typically	O
a	O
portable	O
electronic	O
device	O
used	O
to	O
perform	O
calculations	O
,	O
ranging	O
from	O
basic	O
arithmetic	O
to	O
complex	O
mathematics	O
.	O
</s>
<s>
The	O
first	O
solid-state	O
electronic	O
calculator	B-Application
was	O
created	O
in	O
the	O
early	O
1960s	O
.	O
</s>
<s>
Pocket-sized	O
devices	O
became	O
available	O
in	O
the	O
1970s	O
,	O
especially	O
after	O
the	O
Intel	B-General_Concept
4004	I-General_Concept
,	O
the	O
first	O
microprocessor	B-Architecture
,	O
was	O
developed	O
by	O
Intel	O
for	O
the	O
Japanese	O
calculator	B-Application
company	O
Busicom	O
.	O
</s>
<s>
Modern	O
electronic	O
calculators	B-Application
vary	O
from	O
cheap	O
,	O
give-away	O
,	O
credit-card-sized	O
models	O
to	O
sturdy	O
desktop	O
models	O
with	O
built-in	O
printers	O
.	O
</s>
<s>
By	O
the	O
end	O
of	O
that	O
decade	O
,	O
prices	O
had	O
dropped	O
to	O
the	O
point	O
where	O
a	O
basic	O
calculator	B-Application
was	O
affordable	O
to	O
most	O
and	O
they	O
became	O
common	O
in	O
schools	O
.	O
</s>
<s>
Computer	B-General_Concept
operating	I-General_Concept
systems	I-General_Concept
as	O
far	O
back	O
as	O
early	B-Operating_System
Unix	I-Operating_System
have	O
included	O
interactive	O
calculator	B-Application
programs	B-Application
such	O
as	O
dc	B-Application
and	O
hoc	B-Application
,	O
and	O
interactive	O
BASIC	O
could	O
be	O
used	O
to	O
do	O
calculations	O
on	O
most	O
1970s	O
and	O
1980s	O
home	O
computers	O
.	O
</s>
<s>
Calculator	B-Application
functions	O
are	O
included	O
in	O
most	O
smartphones	B-Application
,	O
tablets	B-Device
and	O
personal	B-Application
digital	I-Application
assistant	I-Application
(	O
PDA	B-Application
)	O
type	O
devices	O
.	O
</s>
<s>
In	O
addition	O
to	O
general	O
purpose	O
calculators	B-Application
,	O
there	O
are	O
those	O
designed	O
for	O
specific	O
markets	O
.	O
</s>
<s>
For	O
example	O
,	O
there	O
are	O
scientific	O
calculators	B-Application
which	O
include	O
trigonometric	O
and	O
statistical	O
calculations	O
.	O
</s>
<s>
Some	O
calculators	B-Application
even	O
have	O
the	O
ability	O
to	O
do	O
computer	B-Algorithm
algebra	I-Algorithm
.	O
</s>
<s>
Graphing	B-Application
calculators	I-Application
can	O
be	O
used	O
to	O
graph	O
functions	O
defined	O
on	O
the	O
real	O
line	O
,	O
or	O
higher-dimensional	O
Euclidean	O
space	O
.	O
</s>
<s>
,	O
basic	O
calculators	B-Application
cost	O
little	O
,	O
but	O
scientific	O
and	O
graphing	O
models	O
tend	O
to	O
cost	O
more	O
.	O
</s>
<s>
With	O
the	O
very	O
wide	O
availability	O
of	O
smartphones	B-Application
and	O
the	O
like	O
,	O
dedicated	O
hardware	O
calculators	B-Application
,	O
while	O
still	O
widely	O
used	O
,	O
are	O
less	O
common	O
than	O
they	O
once	O
were	O
.	O
</s>
<s>
In	O
1986	O
,	O
calculators	B-Application
still	O
represented	O
an	O
estimated	O
41%	O
of	O
the	O
world	O
's	O
general-purpose	O
hardware	O
capacity	O
to	O
compute	O
information	O
.	O
</s>
<s>
Electronic	O
calculators	B-Application
contain	O
a	O
keyboard	B-Device
with	O
buttons	O
for	O
digits	O
and	O
arithmetical	O
operations	O
;	O
some	O
even	O
contain	O
"	O
00	O
"	O
and	O
"	O
000	O
"	O
buttons	O
to	O
make	O
larger	O
or	O
smaller	O
numbers	O
easier	O
to	O
enter	O
.	O
</s>
<s>
Most	O
basic	O
calculators	B-Application
assign	O
only	O
one	O
digit	O
or	O
operation	O
on	O
each	O
button	O
;	O
however	O
,	O
in	O
more	O
specific	O
calculators	B-Application
,	O
a	O
button	O
can	O
perform	O
multi-function	O
working	O
with	O
key	O
combinations	O
.	O
</s>
<s>
Calculators	B-Application
usually	O
have	O
liquid-crystal	B-Device
displays	I-Device
(	O
LCD	B-Device
)	O
as	O
output	O
in	O
place	O
of	O
historical	O
light-emitting	O
diode	O
(	O
LED	O
)	O
displays	O
and	O
vacuum	B-General_Concept
fluorescent	I-General_Concept
displays	I-General_Concept
(	O
VFD	B-General_Concept
)	O
;	O
details	O
are	O
provided	O
in	O
the	O
section	O
Technical	O
improvements	O
.	O
</s>
<s>
Large-sized	O
figures	O
are	O
often	O
used	O
to	O
improve	O
readability	O
;	O
while	O
using	O
decimal	B-Application
separator	O
(	O
usually	O
a	O
point	O
rather	O
than	O
a	O
comma	O
)	O
instead	O
of	O
or	O
in	O
addition	O
to	O
vulgar	O
fractions	O
.	O
</s>
<s>
Various	O
symbols	O
for	O
function	B-Application
commands	I-Application
may	O
also	O
be	O
shown	O
on	O
the	O
display	O
.	O
</s>
<s>
Fractions	O
such	O
as	O
are	O
displayed	O
as	O
decimal	B-Application
approximations	O
,	O
for	O
example	O
rounded	O
to	O
.	O
</s>
<s>
Also	O
,	O
some	O
fractions	O
(	O
such	O
as	O
,	O
which	O
is	O
;	O
to	O
14	O
significant	B-Architecture
figures	I-Architecture
)	O
can	O
be	O
difficult	O
to	O
recognize	O
in	O
decimal	B-Application
form	O
;	O
as	O
a	O
result	O
,	O
many	O
scientific	O
calculators	B-Application
are	O
able	O
to	O
work	O
in	O
vulgar	O
fractions	O
or	O
mixed	O
numbers	O
.	O
</s>
<s>
Calculators	B-Application
also	O
have	O
the	O
ability	O
to	O
save	O
numbers	O
into	O
computer	B-General_Concept
memory	I-General_Concept
.	O
</s>
<s>
Basic	O
calculators	B-Application
usually	O
store	O
only	O
one	O
number	O
at	O
a	O
time	O
;	O
more	O
specific	O
types	O
are	O
able	O
to	O
store	O
many	O
numbers	O
represented	O
in	O
variables	O
.	O
</s>
<s>
Some	O
models	O
have	O
the	O
ability	O
to	O
extend	O
memory	B-General_Concept
capacity	O
to	O
store	O
more	O
numbers	O
;	O
the	O
extended	O
memory	B-General_Concept
address	I-General_Concept
is	O
termed	O
an	O
array	B-Data_Structure
index	O
.	O
</s>
<s>
Power	O
sources	O
of	O
calculators	B-Application
are	O
batteries	O
,	O
solar	O
cells	O
or	O
mains	O
electricity	O
(	O
for	O
old	O
models	O
)	O
,	O
turning	O
on	O
with	O
a	O
switch	O
or	O
button	O
.	O
</s>
<s>
Crank-powered	O
calculators	B-Application
were	O
also	O
common	O
in	O
the	O
early	O
computer	O
era	O
.	O
</s>
<s>
The	O
following	O
keys	O
are	O
common	O
to	O
most	O
pocket	O
calculators	B-Application
.	O
</s>
<s>
+	O
Usual	O
basic	O
pocket	O
calculator	B-Application
layout	O
MC	O
MR	O
M−	O
M+	O
C	O
±	O
%	O
√	O
7	O
8	O
9	O
÷	O
4	O
5	O
6	O
×	O
1	O
2	O
3	O
−	O
0	O
.	O
</s>
<s>
+	O
Calculator	B-Application
buttons	O
and	O
their	O
meanings	O
MC	O
or	O
CM	O
Memory	B-General_Concept
Clear	O
MR	O
,	O
RM	O
,	O
or	O
MRC	O
Memory	B-General_Concept
Recall	O
M−	O
Memory	B-General_Concept
Subtraction	O
M+	O
Memory	B-General_Concept
Addition	O
C	O
or	O
AC	O
All	O
Clear	O
CE	O
Clear	O
(	O
last	O
)	O
Entry	O
;	O
sometimes	O
called	O
CE/C	O
:	O
a	O
first	O
press	O
clears	O
the	O
last	O
entry	O
(	O
CE	O
)	O
,	O
a	O
second	O
press	O
clears	O
all	O
(	O
C	O
)	O
±	O
or	O
CHS	O
Toggle	O
positive/negative	O
number	O
aka	O
CHange	O
Sign	O
%	O
Percent	O
÷	O
Division	O
×	O
Multiplication	O
−	O
Subtraction	O
+	O
Addition	O
.	O
</s>
<s>
In	O
general	O
,	O
a	O
basic	O
electronic	O
calculator	B-Application
consists	O
of	O
the	O
following	O
components	O
:	O
</s>
<s>
Keypad	B-Device
(	O
input	O
device	O
)	O
–	O
consists	O
of	O
keys	O
used	O
to	O
input	O
numbers	O
and	O
function	B-Application
commands	I-Application
(	O
addition	O
,	O
multiplication	O
,	O
square-root	O
,	O
etc	O
.	O
)	O
</s>
<s>
Liquid-crystal	B-Device
displays	I-Device
(	O
LCDs	B-Device
)	O
,	O
vacuum	B-General_Concept
fluorescent	I-General_Concept
displays	I-General_Concept
(	O
VFDs	O
)	O
,	O
and	O
light-emitting	O
diode	O
(	O
LED	O
)	O
displays	O
use	O
seven	B-General_Concept
segments	I-General_Concept
to	O
represent	O
each	O
digit	O
in	O
a	O
basic	O
calculator	B-Application
.	O
</s>
<s>
Advanced	O
calculators	B-Application
may	O
use	O
dot	B-General_Concept
matrix	I-General_Concept
displays	O
.	O
</s>
<s>
A	O
printing	O
calculator	B-Application
,	O
in	O
addition	O
to	O
a	O
display	O
panel	O
,	O
has	O
a	O
printing	O
unit	O
that	O
prints	O
results	O
in	O
ink	O
onto	O
a	O
roll	O
of	O
paper	O
,	O
using	O
a	O
printing	O
mechanism	O
.	O
</s>
<s>
Processor	O
chip	B-Device
(	O
microprocessor	B-Architecture
or	O
central	B-General_Concept
processing	I-General_Concept
unit	I-General_Concept
)	O
.	O
</s>
<s>
+Processor	O
chip	B-Device
's	O
contentsUnit	O
Function	O
Scanning	O
(	O
Polling	B-General_Concept
)	O
unit	O
When	O
a	O
calculator	B-Application
is	O
powered	O
on	O
,	O
it	O
scans	O
the	O
keypad	B-Device
waiting	O
to	O
pick	O
up	O
an	O
electrical	O
signal	O
when	O
a	O
key	O
is	O
pressed.Encoder	O
unit	O
Converts	O
the	O
numbers	O
and	O
functions	O
into	O
binary	O
code	O
.	O
</s>
<s>
X	O
register	B-General_Concept
and	O
Y	O
register	B-General_Concept
They	O
are	O
number	O
stores	O
where	O
numbers	O
are	O
stored	O
temporarily	O
while	O
doing	O
calculations	O
.	O
</s>
<s>
All	O
numbers	O
go	O
into	O
the	O
X	O
register	B-General_Concept
first	O
;	O
the	O
number	O
in	O
the	O
X	O
register	B-General_Concept
is	O
shown	O
on	O
the	O
display	O
.	O
</s>
<s>
Flag	O
registerThe	O
function	O
for	O
the	O
calculation	O
is	O
stored	O
here	O
until	O
the	O
calculator	B-Application
needs	O
it	O
.	O
</s>
<s>
Permanent	B-General_Concept
memory	I-General_Concept
(	O
ROM	B-Device
)	O
The	O
instructions	O
for	O
in-built	O
functions	O
(	O
arithmetic	O
operations	O
,	O
square	O
roots	O
,	O
percentages	O
,	O
trigonometry	O
,	O
etc	O
.	O
)	O
</s>
<s>
These	O
instructions	O
are	O
programs	B-Application
,	O
stored	O
permanently	O
,	O
and	O
cannot	O
be	O
erased	O
.	O
</s>
<s>
User	O
memory	B-General_Concept
(	O
RAM	B-Architecture
)	O
The	O
store	O
where	O
numbers	O
can	O
be	O
stored	O
by	O
the	O
user	O
.	O
</s>
<s>
User	O
memory	B-General_Concept
contents	O
can	O
be	O
changed	O
or	O
erased	O
by	O
the	O
user	O
.	O
</s>
<s>
Arithmetic	B-General_Concept
logic	I-General_Concept
unit	I-General_Concept
(	O
ALU	B-General_Concept
)	O
The	O
ALU	B-General_Concept
executes	O
all	O
arithmetic	O
and	O
logic	O
instructions	O
,	O
and	O
provides	O
the	O
results	O
in	O
binary	O
coded	O
form	O
.	O
</s>
<s>
Binary	O
decoder	O
unit	O
Converts	O
binary	O
code	O
into	O
decimal	B-Application
numbers	O
which	O
can	O
be	O
displayed	O
on	O
the	O
display	O
unit	O
.	O
</s>
<s>
Clock	O
rate	O
of	O
a	O
processor	O
chip	B-Device
refers	O
to	O
the	O
frequency	O
at	O
which	O
the	O
central	B-General_Concept
processing	I-General_Concept
unit	I-General_Concept
(	O
CPU	O
)	O
is	O
running	O
.	O
</s>
<s>
For	O
basic	O
calculators	B-Application
,	O
the	O
speed	O
can	O
vary	O
from	O
a	O
few	O
hundred	O
hertz	O
to	O
the	O
kilohertz	O
range	O
.	O
</s>
<s>
A	O
basic	O
explanation	O
as	O
to	O
how	O
calculations	O
are	O
performed	O
in	O
a	O
simple	O
four-function	O
calculator	B-Application
:	O
</s>
<s>
To	O
perform	O
the	O
calculation	O
,	O
one	O
presses	O
keys	O
in	O
the	O
following	O
sequence	O
on	O
most	O
calculators	B-Application
:	O
.	O
</s>
<s>
When	O
is	O
entered	O
,	O
it	O
is	O
picked	O
up	O
by	O
the	O
scanning	O
unit	O
;	O
the	O
number	O
25	O
is	O
encoded	O
and	O
sent	O
to	O
the	O
X	O
register	B-General_Concept
;	O
</s>
<s>
Next	O
,	O
when	O
the	O
key	O
is	O
pressed	O
,	O
the	O
"	O
addition	O
"	O
instruction	O
is	O
also	O
encoded	O
and	O
sent	O
to	O
the	O
flag	O
or	O
the	O
status	B-General_Concept
register	I-General_Concept
;	O
</s>
<s>
The	O
second	O
number	O
is	O
encoded	O
and	O
sent	O
to	O
the	O
X	O
register	B-General_Concept
.	O
</s>
<s>
This	O
"	O
pushes	O
"	O
(	O
shifts	O
)	O
the	O
first	O
number	O
out	O
into	O
the	O
Y	O
register	B-General_Concept
;	O
</s>
<s>
When	O
the	O
key	O
is	O
pressed	O
,	O
a	O
"	O
message	O
"	O
(	O
signal	O
)	O
from	O
the	O
flag	O
or	O
status	B-General_Concept
register	I-General_Concept
tells	O
the	O
permanent	O
or	O
non-volatile	B-General_Concept
memory	I-General_Concept
that	O
the	O
operation	O
to	O
be	O
done	O
is	O
"	O
addition	O
"	O
;	O
</s>
<s>
The	O
numbers	O
in	O
the	O
X	O
and	O
Y	O
registers	O
are	O
then	O
loaded	O
into	O
the	O
ALU	B-General_Concept
and	O
the	O
calculation	O
is	O
carried	O
out	O
following	O
instructions	O
from	O
the	O
permanent	O
or	O
non-volatile	B-General_Concept
memory	I-General_Concept
;	O
</s>
<s>
The	O
answer	O
,	O
34	O
is	O
sent	O
(	O
shifted	O
)	O
back	O
to	O
the	O
X	O
register	B-General_Concept
.	O
</s>
<s>
From	O
there	O
,	O
it	O
is	O
converted	O
by	O
the	O
binary	O
decoder	O
unit	O
into	O
a	O
decimal	B-Application
number	O
(	O
usually	O
binary-coded	O
decimal	B-Application
)	O
,	O
and	O
then	O
shown	O
on	O
the	O
display	O
panel	O
.	O
</s>
<s>
Most	O
pocket	O
calculators	B-Application
do	O
all	O
their	O
calculations	O
in	O
binary-coded	O
decimal	B-Application
(	O
BCD	O
)	O
rather	O
than	O
binary	O
.	O
</s>
<s>
BCD	O
is	O
common	O
in	O
electronic	O
systems	O
where	O
a	O
numeric	B-Algorithm
value	O
is	O
to	O
be	O
displayed	O
,	O
especially	O
in	O
systems	O
consisting	O
solely	O
of	O
digital	O
logic	O
,	O
and	O
not	O
containing	O
a	O
microprocessor	B-Architecture
.	O
</s>
<s>
This	O
matches	O
much	O
more	O
closely	O
the	O
physical	O
reality	O
of	O
display	O
hardware	O
—	O
a	O
designer	O
might	O
choose	O
to	O
use	O
a	O
series	O
of	O
separate	O
identical	O
seven-segment	B-General_Concept
displays	I-General_Concept
to	O
build	O
a	O
metering	O
circuit	O
,	O
for	O
example	O
.	O
</s>
<s>
If	O
the	O
numeric	B-Algorithm
quantity	O
were	O
stored	O
and	O
manipulated	O
as	O
pure	O
binary	O
,	O
interfacing	O
to	O
such	O
a	O
display	O
would	O
require	O
complex	O
circuitry	O
.	O
</s>
<s>
(	O
For	O
example	O
,	O
CDs	B-Device
keep	O
the	O
track	O
number	O
in	O
BCD	O
,	O
limiting	O
them	O
to	O
99	O
tracks	O
.	O
)	O
</s>
<s>
Where	O
calculators	B-Application
have	O
added	O
functions	O
(	O
such	O
as	O
square	O
root	O
,	O
or	O
trigonometric	O
functions	O
)	O
,	O
software	O
algorithms	O
are	O
required	O
to	O
produce	O
high	O
precision	B-Architecture
results	O
.	O
</s>
<s>
Sometimes	O
significant	O
design	O
effort	O
is	O
needed	O
to	O
fit	O
all	O
the	O
desired	O
functions	O
in	O
the	O
limited	O
memory	B-General_Concept
space	O
available	O
in	O
the	O
calculator	B-Application
chip	B-Device
,	O
with	O
acceptable	O
calculation	O
time	O
.	O
</s>
<s>
The	O
fundamental	O
difference	O
between	O
a	O
calculator	B-Application
and	O
computer	O
is	O
that	O
a	O
computer	O
can	O
be	O
programmed	B-General_Concept
in	O
a	O
way	O
that	O
allows	O
the	O
program	B-Application
to	O
take	O
different	O
branches	B-General_Concept
according	I-General_Concept
to	I-General_Concept
intermediate	I-General_Concept
results	I-General_Concept
,	O
while	O
calculators	B-Application
are	O
pre-designed	O
with	O
specific	O
functions	O
(	O
such	O
as	O
addition	O
,	O
multiplication	O
,	O
and	O
logarithms	O
)	O
built	O
in	O
.	O
</s>
<s>
The	O
distinction	O
is	O
not	O
clear-cut	O
:	O
some	O
devices	O
classed	O
as	O
programmable	B-Application
calculators	I-Application
have	O
programming	B-General_Concept
functions	O
,	O
sometimes	O
with	O
support	O
for	O
programming	B-General_Concept
languages	O
(	O
such	O
as	O
RPL	B-Device
or	O
TI-BASIC	B-Language
)	O
.	O
</s>
<s>
For	O
instance	O
,	O
instead	O
of	O
a	O
hardware	O
multiplier	O
,	O
a	O
calculator	B-Application
might	O
implement	O
floating	B-Algorithm
point	I-Algorithm
mathematics	O
with	O
code	O
in	O
read-only	B-Device
memory	I-Device
(	O
ROM	B-Device
)	O
,	O
and	O
compute	O
trigonometric	O
functions	O
with	O
the	O
CORDIC	B-Algorithm
algorithm	I-Algorithm
because	O
CORDIC	B-Algorithm
does	O
not	O
require	O
much	O
multiplication	O
.	O
</s>
<s>
Bit	B-Protocol
serial	I-Protocol
logic	O
designs	O
are	O
more	O
common	O
in	O
calculators	B-Application
whereas	O
bit	O
parallel	O
designs	O
dominate	O
general-purpose	O
computers	O
,	O
because	O
a	O
bit	B-Protocol
serial	I-Protocol
design	O
minimizes	O
chip	B-Device
complexity	O
,	O
but	O
takes	O
many	O
more	O
clock	O
cycles	O
.	O
</s>
<s>
This	O
distinction	O
blurs	O
with	O
high-end	O
calculators	B-Application
,	O
which	O
use	O
processor	O
chips	O
associated	O
with	O
computer	O
and	O
embedded	O
systems	O
design	O
,	O
more	O
so	O
the	O
Z80	B-General_Concept
,	O
MC68000	B-Device
,	O
and	O
ARM	B-Architecture
architectures	I-Architecture
,	O
and	O
some	O
custom	O
designs	O
specialized	O
for	O
the	O
calculator	B-Application
market	O
.	O
</s>
<s>
The	O
first	O
known	O
tools	O
used	O
to	O
aid	O
arithmetic	O
calculations	O
were	O
:	O
bones	O
(	O
used	O
to	O
tally	O
items	O
)	O
,	O
pebbles	O
,	O
and	O
counting	O
boards	O
,	O
and	O
the	O
abacus	B-Application
,	O
known	O
to	O
have	O
been	O
used	O
by	O
Sumerians	O
and	O
Egyptians	O
before	O
2000BC	O
.	O
</s>
<s>
In	O
1642	O
,	O
the	O
Renaissance	B-Application
saw	O
the	O
invention	O
of	O
the	O
mechanical	O
calculator	B-Application
(	O
by	O
Wilhelm	O
Schickard	O
and	O
several	O
decades	O
later	O
Blaise	O
Pascal	O
)	O
,	O
a	O
device	O
that	O
was	O
at	O
times	O
somewhat	O
over-promoted	O
as	O
being	O
able	O
to	O
perform	O
all	O
four	O
arithmetic	O
operations	O
with	O
minimal	O
human	O
intervention	O
.	O
</s>
<s>
Pascal	O
's	O
calculator	B-Application
could	O
add	O
and	O
subtract	O
two	O
numbers	O
directly	O
and	O
thus	O
,	O
if	O
the	O
tedium	O
could	O
be	O
borne	O
,	O
multiply	O
and	O
divide	O
by	O
repetition	O
.	O
</s>
<s>
Schickard	O
and	O
Pascal	O
were	O
followed	O
by	O
Gottfried	O
Leibniz	O
who	O
spent	O
forty	O
years	O
designing	O
a	O
four-operation	O
mechanical	O
calculator	B-Application
,	O
the	O
stepped	O
reckoner	O
,	O
inventing	O
in	O
the	O
process	O
his	O
leibniz	O
wheel	O
,	O
but	O
who	O
could	O
n't	O
design	O
a	O
fully	O
operational	O
machine	O
.	O
</s>
<s>
The	O
Arithmometer	O
,	O
invented	O
in	O
1820	O
as	O
a	O
four-operation	O
mechanical	O
calculator	B-Application
,	O
was	O
released	O
to	O
production	O
in	O
1851	O
as	O
an	O
adding	O
machine	O
and	O
became	O
the	O
first	O
commercially	O
successful	O
unit	O
;	O
forty	O
years	O
later	O
,	O
by	O
1890	O
,	O
about	O
2,500	O
arithmometers	O
had	O
been	O
sold	O
plus	O
a	O
few	O
hundreds	O
more	O
from	O
two	O
arithmometer	O
clone	O
makers	O
(	O
Burkhardt	O
,	O
Germany	O
,	O
1878	O
and	O
Layton	O
,	O
UK	O
,	O
1883	O
)	O
and	O
Felt	O
and	O
Tarrant	O
,	O
the	O
only	O
other	O
competitor	O
in	O
true	O
commercial	O
production	O
,	O
had	O
sold	O
100	O
comptometers	O
.	O
</s>
<s>
In	O
1921	O
,	O
Edith	O
Clarke	O
invented	O
the	O
"	O
Clarke	O
calculator	B-Application
"	O
,	O
a	O
simple	O
graph-based	O
calculator	B-Application
for	O
solving	O
line	O
equations	O
involving	O
hyperbolic	O
functions	O
.	O
</s>
<s>
The	O
Curta	O
calculator	B-Application
was	O
developed	O
in	O
1948	O
and	O
,	O
although	O
costly	O
,	O
became	O
popular	O
for	O
its	O
portability	O
.	O
</s>
<s>
This	O
purely	O
mechanical	O
hand-held	B-Application
device	I-Application
could	O
do	O
addition	O
,	O
subtraction	O
,	O
multiplication	O
and	O
division	O
.	O
</s>
<s>
By	O
the	O
early	O
1970s	O
electronic	O
pocket	O
calculators	B-Application
ended	O
manufacture	O
of	O
mechanical	O
calculators	B-Application
,	O
although	O
the	O
Curta	O
remains	O
a	O
popular	O
collectable	O
item	O
.	O
</s>
<s>
The	O
first	O
mainframe	B-Architecture
computers	I-Architecture
,	O
using	O
firstly	O
vacuum	O
tubes	O
and	O
later	O
transistors	B-Application
in	O
the	O
logic	O
circuits	O
,	O
appeared	O
in	O
the	O
1940s	O
and	O
1950s	O
.	O
</s>
<s>
This	O
technology	O
was	O
to	O
provide	O
a	O
stepping	O
stone	O
to	O
the	O
development	O
of	O
electronic	O
calculators	B-Application
.	O
</s>
<s>
The	O
Casio	O
Computer	O
Company	O
,	O
in	O
Japan	O
,	O
released	O
the	O
Model	O
14-A	O
calculator	B-Application
in	O
1957	O
,	O
which	O
was	O
the	O
world	O
's	O
first	O
all-electric	O
(	O
relatively	O
)	O
compact	O
calculator	B-Application
.	O
</s>
<s>
In	O
October	O
1961	O
,	O
the	O
world	O
's	O
first	O
all-electronic	O
desktop	O
calculator	B-Application
,	O
the	O
British	O
Bell	O
Punch/Sumlock	O
Comptometer	O
ANITA	B-Device
(	O
A	O
New	O
Inspiration	O
To	O
Arithmetic/Accounting	O
)	O
was	O
announced	O
.	O
</s>
<s>
This	O
machine	O
used	O
vacuum	O
tubes	O
,	O
cold-cathode	O
tubes	O
and	O
Dekatrons	B-General_Concept
in	O
its	O
circuits	O
,	O
with	O
12	O
cold-cathode	O
"	B-Application
Nixie	I-Application
"	I-Application
tubes	O
for	O
its	O
display	O
.	O
</s>
<s>
The	O
ANITA	B-Device
had	O
a	O
full	O
keyboard	B-Device
,	O
similar	O
to	O
mechanical	O
comptometers	O
of	O
the	O
time	O
,	O
a	O
feature	O
that	O
was	O
unique	O
to	O
it	O
and	O
the	O
later	O
Sharp	O
CS-10A	O
among	O
electronic	O
calculators	B-Application
.	O
</s>
<s>
The	O
ANITA	B-Device
weighed	O
roughly	O
due	O
to	O
its	O
large	O
tube	O
system	O
.	O
</s>
<s>
Bell	O
Punch	O
had	O
been	O
producing	O
key-driven	O
mechanical	O
calculators	B-Application
of	O
the	O
comptometer	O
type	O
under	O
the	O
names	O
"	O
Plus	O
"	O
and	O
"	O
Sumlock	O
"	O
,	O
and	O
had	O
realised	O
in	O
the	O
mid-1950s	O
that	O
the	O
future	O
of	O
calculators	B-Application
lay	O
in	O
electronics	O
.	O
</s>
<s>
They	O
employed	O
the	O
young	O
graduate	O
Norbert	O
Kitz	O
,	O
who	O
had	O
worked	O
on	O
the	O
early	O
British	O
Pilot	B-Device
ACE	I-Device
computer	O
project	O
,	O
to	O
lead	O
the	O
development	O
.	O
</s>
<s>
The	O
ANITA	B-Device
sold	O
well	O
since	O
it	O
was	O
the	O
only	O
electronic	O
desktop	O
calculator	B-Application
available	O
,	O
and	O
was	O
silent	O
and	O
quick	O
.	O
</s>
<s>
The	O
tube	O
technology	O
of	O
the	O
ANITA	B-Device
was	O
superseded	O
in	O
June	O
1963	O
by	O
the	O
U.S.	O
manufactured	O
Friden	O
EC-130	O
,	O
which	O
had	O
an	O
all-transistor	O
design	O
,	O
a	O
stack	O
of	O
four	O
13-digit	O
numbers	O
displayed	O
on	O
a	O
cathode	B-Device
ray	I-Device
tube	I-Device
(	O
CRT	B-Device
)	O
,	O
and	O
introduced	O
Reverse	O
Polish	O
Notation	O
(	O
RPN	O
)	O
to	O
the	O
calculator	B-Application
market	O
for	O
a	O
price	O
of	O
$2200	O
,	O
which	O
was	O
about	O
three	O
times	O
the	O
cost	O
of	O
an	O
electromechanical	O
calculator	B-Application
of	O
the	O
time	O
.	O
</s>
<s>
Like	O
Bell	O
Punch	O
,	O
Friden	O
was	O
a	O
manufacturer	O
of	O
mechanical	O
calculators	B-Application
that	O
had	O
decided	O
that	O
the	O
future	O
lay	O
in	O
electronics	O
.	O
</s>
<s>
In	O
1964	O
more	O
all-transistor	O
electronic	O
calculators	B-Application
were	O
introduced	O
:	O
Sharp	O
introduced	O
the	O
CS-10A	O
,	O
which	O
weighed	O
and	O
cost	O
500,000	O
yen	O
( $	O
)	O
,	O
and	O
Industria	O
Macchine	O
Elettroniche	O
of	O
Italy	O
introduced	O
the	O
IME	O
84	O
,	O
to	O
which	O
several	O
extra	O
keyboard	B-Device
and	O
display	O
units	O
could	O
be	O
connected	O
so	O
that	O
several	O
people	O
could	O
make	O
use	O
of	O
it	O
(	O
but	O
apparently	O
not	O
at	O
the	O
same	O
time	O
)	O
.	O
</s>
<s>
The	O
Victor	B-Device
3900	I-Device
was	O
the	O
first	O
to	O
use	O
integrated	O
circuits	O
in	O
place	O
of	O
individual	O
transistors	B-Application
,	O
but	O
production	O
problems	O
delayed	O
sales	O
until	O
1966	O
.	O
</s>
<s>
There	O
followed	O
a	O
series	O
of	O
electronic	O
calculator	B-Application
models	O
from	O
these	O
and	O
other	O
manufacturers	O
,	O
including	O
Canon	O
,	O
Mathatronics	O
,	O
Olivetti	O
,	O
SCM	O
(	O
Smith-Corona-Marchant	O
)	O
,	O
Sony	O
,	O
Toshiba	O
,	O
and	O
Wang	O
.	O
</s>
<s>
The	O
early	O
calculators	B-Application
used	O
hundreds	O
of	O
germanium	O
transistors	B-Application
,	O
which	O
were	O
cheaper	O
than	O
silicon	O
transistors	B-Application
,	O
on	O
multiple	O
circuit	O
boards	O
.	O
</s>
<s>
Display	O
types	O
used	O
were	O
CRT	B-Device
,	O
cold-cathode	O
Nixie	B-Application
tubes	I-Application
,	O
and	O
filament	O
lamps	O
.	O
</s>
<s>
Memory	B-General_Concept
technology	O
was	O
usually	O
based	O
on	O
the	O
delay-line	O
memory	B-General_Concept
or	O
the	O
magnetic-core	O
memory	B-General_Concept
,	O
though	O
the	O
Toshiba	O
"	O
Toscal	O
"	O
BC-1411	O
appears	O
to	O
have	O
used	O
an	O
early	O
form	O
of	O
dynamic	O
RAM	B-Architecture
built	O
from	O
discrete	O
components	O
.	O
</s>
<s>
It	O
is	O
the	O
first	O
calculator	B-Application
in	O
the	O
world	O
which	O
includes	O
the	O
square	O
root	O
function	O
.	O
</s>
<s>
Later	O
that	O
same	O
year	O
were	O
released	O
the	O
ELKA	B-Device
22	I-Device
(	O
with	O
a	O
luminescent	O
display	O
)	O
and	O
the	O
ELKA	O
25	O
,	O
with	O
an	O
in-built	O
printer	O
.	O
</s>
<s>
Retrieved	O
Oct	O
2013.	O
<	O
/ref	O
>ELKA	O
101	O
description	O
,	O
Vintage	O
Calculators	B-Application
.	O
</s>
<s>
The	O
first	O
desktop	O
programmable	B-Application
calculators	I-Application
were	O
produced	O
in	O
the	O
mid-1960s	O
.	O
</s>
<s>
They	O
included	O
the	O
Mathatronics	O
Mathatron	O
(	O
1964	O
)	O
and	O
the	O
Olivetti	B-Device
Programma	I-Device
101	I-Device
(	O
late	O
1965	O
)	O
which	O
were	O
solid-state	O
,	O
desktop	O
,	O
printing	O
,	O
floating	B-Algorithm
point	I-Algorithm
,	O
algebraic	O
entry	O
,	O
programmable	O
,	O
stored-program	O
electronic	O
calculators	B-Application
.	O
</s>
<s>
Both	O
could	O
be	O
programmed	B-General_Concept
by	O
the	O
end	O
user	O
and	O
print	O
out	O
their	O
results	O
.	O
</s>
<s>
The	O
Programma	B-Device
101	I-Device
saw	O
much	O
wider	O
distribution	O
and	O
had	O
the	O
added	O
feature	O
of	O
offline	O
storage	O
of	O
programs	B-Application
via	O
magnetic	O
cards	O
.	O
</s>
<s>
Another	O
early	O
programmable	O
desktop	O
calculator	B-Application
(	O
and	O
maybe	O
the	O
first	O
Japanese	O
one	O
)	O
was	O
the	O
Casio	O
(	O
AL-1000	O
)	O
produced	O
in	O
1967	O
.	O
</s>
<s>
It	O
featured	O
a	O
nixie	B-Application
tubes	I-Application
display	O
and	O
had	O
transistor	B-Application
electronics	O
and	O
ferrite	O
core	O
memory	B-General_Concept
.	O
</s>
<s>
The	O
Monroe	B-Device
Epic	I-Device
programmable	B-Application
calculator	I-Application
came	O
on	O
the	O
market	O
in	O
1967	O
.	O
</s>
<s>
A	O
large	O
,	O
printing	O
,	O
desk-top	O
unit	O
,	O
with	O
an	O
attached	O
floor-standing	O
logic	O
tower	O
,	O
it	O
could	O
be	O
programmed	B-General_Concept
to	O
perform	O
many	O
computer-like	O
functions	O
.	O
</s>
<s>
However	O
,	O
the	O
only	O
branch	B-General_Concept
instruction	I-General_Concept
was	O
an	O
implied	O
unconditional	B-General_Concept
branch	I-General_Concept
(	O
GOTO	O
)	O
at	O
the	O
end	O
of	O
the	O
operation	O
stack	O
,	O
returning	O
the	O
program	B-Application
to	O
its	O
starting	O
instruction	O
.	O
</s>
<s>
Thus	O
,	O
it	O
was	O
not	O
possible	O
to	O
include	O
any	O
conditional	B-General_Concept
branch	I-General_Concept
(	O
IF-THEN-ELSE	O
)	O
logic	O
.	O
</s>
<s>
During	O
this	O
era	O
,	O
the	O
absence	O
of	O
the	O
conditional	B-General_Concept
branch	I-General_Concept
was	O
sometimes	O
used	O
to	O
distinguish	O
a	O
programmable	B-Application
calculator	I-Application
from	O
a	O
computer	O
.	O
</s>
<s>
The	O
first	O
Soviet	O
programmable	O
desktop	O
calculator	B-Application
ISKRA	O
123	O
,	O
powered	O
by	O
the	O
power	O
grid	O
,	O
was	O
released	O
at	O
the	O
start	O
of	O
the	O
1970s	O
.	O
</s>
<s>
The	O
electronic	O
calculators	B-Application
of	O
the	O
mid-1960s	O
were	O
large	O
and	O
heavy	O
desktop	O
machines	O
due	O
to	O
their	O
use	O
of	O
hundreds	O
of	O
transistors	B-Application
on	O
several	O
circuit	O
boards	O
with	O
a	O
large	O
power	O
consumption	O
that	O
required	O
an	O
AC	O
power	O
supply	O
.	O
</s>
<s>
There	O
were	O
great	O
efforts	O
to	O
put	O
the	O
logic	O
required	O
for	O
a	O
calculator	B-Application
into	O
fewer	O
and	O
fewer	O
integrated	O
circuits	O
(	O
chips	O
)	O
and	O
calculator	B-Application
electronics	O
was	O
one	O
of	O
the	O
leading	O
edges	O
of	O
semiconductor	O
development	O
.	O
</s>
<s>
This	O
led	O
to	O
alliances	O
between	O
Japanese	O
calculator	B-Application
manufacturers	O
and	O
U.S.	O
semiconductor	O
companies	O
:	O
Canon	O
Inc	O
.	O
with	O
Texas	O
Instruments	O
,	O
Hayakawa	O
Electric	O
(	O
later	O
renamed	O
Sharp	O
Corporation	O
)	O
with	O
North-American	O
Rockwell	O
Microelectronics	O
(	O
later	O
renamed	O
Rockwell	O
International	O
)	O
,	O
Busicom	O
with	O
Mostek	O
and	O
Intel	O
,	O
and	O
General	O
Instrument	O
with	O
Sanyo	O
.	O
</s>
<s>
By	O
1970	O
,	O
a	O
calculator	B-Application
could	O
be	O
made	O
using	O
just	O
a	O
few	O
chips	O
of	O
low	O
power	O
consumption	O
,	O
allowing	O
portable	O
models	O
powered	O
from	O
rechargeable	O
batteries	O
.	O
</s>
<s>
The	O
first	O
handheld	B-Application
calculator	B-Application
was	O
a	O
1967	O
prototype	O
called	O
Cal	O
Tech	O
,	O
whose	O
development	O
was	O
led	O
by	O
Jack	O
Kilby	O
at	O
Texas	O
Instruments	O
in	O
a	O
research	O
project	O
to	O
produce	O
a	O
portable	O
calculator	B-Application
.	O
</s>
<s>
It	O
could	O
add	O
,	O
multiply	O
,	O
subtract	O
,	O
and	O
divide	O
,	O
and	O
its	O
output	O
device	O
was	O
a	O
paper	O
tape.Texas	O
Instruments	O
Celebrates	O
the	O
35th	O
Anniversary	O
of	O
Its	O
Invention	O
of	O
the	O
Calculator	B-Application
Texas	O
Instruments	O
press	O
release	O
,	O
15	O
August	O
2002.Electronic	O
Calculator	B-Application
Invented	O
40	O
Years	O
Ago	O
All	O
Things	O
Considered	O
,	O
NPR	O
,	O
30	O
September	O
2007	O
.	O
</s>
<s>
As	O
a	O
result	O
of	O
the	O
"	O
Cal-Tech	O
"	O
project	O
,	O
Texas	O
Instruments	O
was	O
granted	O
master	O
patents	O
on	O
portable	O
calculators	B-Application
.	O
</s>
<s>
The	O
first	O
commercially	O
produced	O
portable	O
calculators	B-Application
appeared	O
in	O
Japan	O
in	O
1970	O
,	O
and	O
were	O
soon	O
marketed	O
around	O
the	O
world	O
.	O
</s>
<s>
These	O
included	O
the	O
Sanyo	O
ICC-0081	O
"	O
Mini	O
Calculator	B-Application
"	O
,	O
the	O
Canon	O
Pocketronic	O
,	O
and	O
the	O
Sharp	B-Device
QT-8B	I-Device
"	O
micro	O
Compet	O
"	O
.	O
</s>
<s>
Sharp	O
put	O
in	O
great	O
efforts	O
in	O
size	O
and	O
power	O
reduction	O
and	O
introduced	O
in	O
January	O
1971	O
the	O
Sharp	B-Device
EL-8	I-Device
,	O
also	O
marketed	O
as	O
the	O
Facit	B-Device
1111	I-Device
,	O
which	O
was	O
close	O
to	O
being	O
a	O
pocket	O
calculator	B-Application
.	O
</s>
<s>
It	O
weighed	O
1.59	O
pounds	O
(	O
721	O
grams	O
)	O
,	O
had	O
a	O
vacuum	B-General_Concept
fluorescent	I-General_Concept
display	I-General_Concept
,	O
rechargeable	O
NiCad	O
batteries	O
,	O
and	O
initially	O
sold	O
for	O
US$395	O
.	O
</s>
<s>
However	O
,	O
integrated	O
circuit	O
development	O
efforts	O
culminated	O
in	O
early	O
1971	O
with	O
the	O
introduction	O
of	O
the	O
first	O
"	O
calculator	B-Application
on	O
a	O
chip	B-Device
"	O
,	O
the	O
MK6010	O
by	O
Mostek	O
,	O
"	O
Single	O
Chip	B-Device
Calculator	B-Application
Hits	O
the	O
Finish	O
Line	O
"	O
,	O
Electronics	O
,	O
February	O
1	O
,	O
1971	O
,	O
p19	O
followed	O
by	O
Texas	O
Instruments	O
later	O
in	O
the	O
year	O
.	O
</s>
<s>
Although	O
these	O
early	O
hand-held	B-Application
calculators	B-Application
were	O
very	O
costly	O
,	O
these	O
advances	O
in	O
electronics	O
,	O
together	O
with	O
developments	O
in	O
display	O
technology	O
(	O
such	O
as	O
the	O
vacuum	B-General_Concept
fluorescent	I-General_Concept
display	I-General_Concept
,	O
LED	O
,	O
and	O
LCD	B-Device
)	O
,	O
led	O
within	O
a	O
few	O
years	O
to	O
the	O
cheap	O
pocket	O
calculator	B-Application
available	O
to	O
all	O
.	O
</s>
<s>
In	O
1971	O
,	O
Pico	O
Electronics	O
and	O
General	O
Instrument	O
also	O
introduced	O
their	O
first	O
collaboration	O
in	O
ICs	O
,	O
a	O
full	O
single	O
chip	B-Device
calculator	B-Application
IC	O
for	O
the	O
Monroe	O
Royal	O
Digital	O
III	O
calculator	B-Application
.	O
</s>
<s>
Pico	O
was	O
a	O
spinout	O
by	O
five	O
GI	O
design	O
engineers	O
whose	O
vision	O
was	O
to	O
create	O
single	O
chip	B-Device
calculator	B-Application
ICs	O
.	O
</s>
<s>
Pico	O
and	O
GI	O
went	O
on	O
to	O
have	O
significant	O
success	O
in	O
the	O
burgeoning	O
handheld	B-Application
calculator	B-Application
market	O
.	O
</s>
<s>
The	O
first	O
truly	O
pocket-sized	O
electronic	O
calculator	B-Application
was	O
the	O
Busicom	O
LE-120A	O
"	O
HANDY	O
"	O
,	O
which	O
was	O
marketed	O
early	O
in	O
1971	O
.	O
</s>
<s>
"	O
The	O
one-chip	O
calculator	B-Application
is	O
here	O
,	O
and	O
it	O
's	O
only	O
the	O
beginning	O
"	O
,	O
Electronic	O
Design	O
,	O
February	O
18	O
,	O
1971	O
,	O
p34	O
.	O
</s>
<s>
Made	O
in	O
Japan	O
,	O
this	O
was	O
also	O
the	O
first	O
calculator	B-Application
to	O
use	O
an	O
LED	O
display	O
,	O
the	O
first	O
hand-held	B-Application
calculator	B-Application
to	O
use	O
a	O
single	O
integrated	O
circuit	O
(	O
then	O
proclaimed	O
as	O
a	O
"	O
calculator	B-Application
on	O
a	O
chip	B-Device
"	O
)	O
,	O
the	O
Mostek	O
MK6010	O
,	O
and	O
the	O
first	O
electronic	O
calculator	B-Application
to	O
run	O
off	O
replaceable	O
batteries	O
.	O
</s>
<s>
The	O
first	O
European-made	O
pocket-sized	O
calculator	B-Application
,	O
DB	O
800	O
was	O
made	O
in	O
May	O
1971	O
by	O
Digitron	B-Application
in	O
Buje	O
,	O
Croatia	O
(	O
former	O
Yugoslavia	O
)	O
with	O
four	O
functions	O
and	O
an	O
eight-digit	O
display	O
and	O
special	O
characters	O
for	O
a	O
negative	O
number	O
and	O
a	O
warning	O
that	O
the	O
calculation	O
has	O
too	O
many	O
digits	O
to	O
display	O
.	O
</s>
<s>
The	O
first	O
American-made	O
pocket-sized	O
calculator	B-Application
,	O
the	O
Bowmar	O
901B	O
(	O
popularly	O
termed	O
The	O
Bowmar	O
Brain	O
)	O
,	O
measuring	O
,	O
came	O
out	O
in	O
the	O
Autumn	O
of	O
1971	O
,	O
with	O
four	O
functions	O
and	O
an	O
eight-digit	O
red	O
LED	O
display	O
,	O
for	O
,	O
while	O
in	O
August	O
1972	O
the	O
four-function	O
Sinclair	B-Device
Executive	I-Device
became	O
the	O
first	O
slimline	O
pocket	O
calculator	B-Application
measuring	O
and	O
weighing	O
.	O
</s>
<s>
By	O
the	O
end	O
of	O
the	O
decade	O
,	O
similar	O
calculators	B-Application
were	O
priced	O
less	O
than	O
£5	O
( $	O
)	O
.	O
</s>
<s>
Following	O
protracted	O
development	O
over	O
the	O
course	O
of	O
two	O
years	O
including	O
a	O
botched	O
partnership	O
with	O
Texas	O
Instruments	O
,	O
Eldorado	O
Electrodata	O
released	O
five	O
pocket	O
calculators	B-Application
in	O
1972	O
.	O
</s>
<s>
The	O
first	O
Soviet	O
Union	O
made	O
pocket-sized	O
calculator	B-Application
,	O
the	O
Elektronika	O
B3-04	O
was	O
developed	O
by	O
the	O
end	O
of	O
1973	O
and	O
sold	O
at	O
the	O
start	O
of	O
1974	O
.	O
</s>
<s>
One	O
of	O
the	O
first	O
low-cost	O
calculators	B-Application
was	O
the	O
Sinclair	B-Device
Cambridge	I-Device
,	O
launched	O
in	O
August	O
1973	O
.	O
</s>
<s>
The	O
Sinclair	O
calculators	B-Application
were	O
successful	O
because	O
they	O
were	O
far	O
cheaper	O
than	O
the	O
competition	O
;	O
however	O
,	O
their	O
design	O
led	O
to	O
slow	O
and	O
inaccurate	O
computations	O
of	O
transcendental	O
functions.Reversing	O
Sinclair	O
's	O
amazing	O
1974	O
calculator	B-Application
hack	O
–	O
half	O
the	O
ROM	B-Device
of	O
the	O
HP-35	B-Device
,	O
Ken	O
Shirriff	O
,	O
2013	O
.	O
</s>
<s>
Meanwhile	O
,	O
Hewlett-Packard	O
(	O
HP	O
)	O
had	O
been	O
developing	O
a	O
pocket	O
calculator	B-Application
.	O
</s>
<s>
Launched	O
in	O
early	O
1972	O
,	O
it	O
was	O
unlike	O
the	O
other	O
basic	O
four-function	O
pocket	O
calculators	B-Application
then	O
available	O
in	O
that	O
it	O
was	O
the	O
first	O
pocket	O
calculator	B-Application
with	O
scientific	O
functions	O
that	O
could	O
replace	O
a	O
slide	O
rule	O
.	O
</s>
<s>
The	O
$395	O
HP-35	B-Device
,	O
along	O
with	O
nearly	O
all	O
later	O
HP	O
engineering	O
calculators	B-Application
,	O
uses	O
reverse	O
Polish	O
notation	O
(	O
RPN	O
)	O
,	O
also	O
called	O
postfix	O
notation	O
.	O
</s>
<s>
It	O
had	O
35	O
buttons	O
and	O
was	O
based	O
on	O
Mostek	O
Mk6020	O
chip	B-Device
.	O
</s>
<s>
The	O
first	O
Soviet	O
scientific	O
pocket-sized	O
calculator	B-Application
the	O
"	O
B3-18	O
"	O
was	O
completed	O
by	O
the	O
end	O
of	O
1975	O
.	O
</s>
<s>
In	O
1973	O
,	O
Texas	O
Instruments	O
(	O
TI	O
)	O
introduced	O
the	O
SR-10	O
,	O
(	O
SR	O
signifying	O
slide	O
rule	O
)	O
an	O
algebraic	O
entry	O
pocket	O
calculator	B-Application
using	O
scientific	O
notation	O
for	O
$150	O
.	O
</s>
<s>
It	O
was	O
followed	O
the	O
next	O
year	O
by	O
the	O
SR-50	B-Device
which	O
added	O
log	O
and	O
trig	O
functions	O
to	O
compete	O
with	O
the	O
HP-35	B-Device
,	O
and	O
in	O
1977	O
the	O
mass-marketed	O
TI-30	B-Device
line	O
which	O
is	O
still	O
produced	O
.	O
</s>
<s>
Their	O
first	O
calculator	B-Application
,	O
the	O
Loan	O
Arranger	O
(	O
1978	O
)	O
was	O
a	O
pocket	O
calculator	B-Application
marketed	O
to	O
the	O
Real	O
Estate	O
industry	O
with	O
preprogrammed	O
functions	O
to	O
simplify	O
the	O
process	O
of	O
calculating	O
payments	O
and	O
future	O
values	O
.	O
</s>
<s>
In	O
1985	O
,	O
CI	O
launched	O
a	O
calculator	B-Application
for	O
the	O
construction	O
industry	O
called	O
the	O
Construction	O
Master	O
which	O
came	O
preprogrammed	O
with	O
common	O
construction	O
calculations	O
(	O
such	O
as	O
angles	O
,	O
stairs	O
,	O
roofing	O
math	O
,	O
pitch	O
,	O
rise	O
,	O
run	O
,	O
and	O
feet-inch	O
fraction	O
conversions	O
)	O
.	O
</s>
<s>
This	O
would	O
be	O
the	O
first	O
in	O
a	O
line	O
of	O
construction	O
related	O
calculators	B-Application
.	O
</s>
<s>
The	O
first	O
programmable	O
pocket	O
calculator	B-Application
was	O
the	O
HP-65	B-Device
,	O
in	O
1974	O
;	O
it	O
had	O
a	O
capacity	O
of	O
100	O
instructions	O
,	O
and	O
could	O
store	O
and	O
retrieve	O
programs	B-Application
with	O
a	O
built-in	O
magnetic	O
card	O
reader	O
.	O
</s>
<s>
Two	O
years	O
later	O
the	O
HP-25C	B-Device
introduced	O
continuous	B-Device
memory	I-Device
,	O
i.e.	O
,	O
programs	B-Application
and	O
data	O
were	O
retained	O
in	O
CMOS	B-Device
memory	I-Device
during	O
power-off	O
.	O
</s>
<s>
In	O
1979	O
,	O
HP	O
released	O
the	O
first	O
alphanumeric	O
,	O
programmable	O
,	O
expandable	O
calculator	B-Application
,	O
the	O
HP-41C	B-Device
.	O
</s>
<s>
It	O
could	O
be	O
expanded	O
with	O
random-access	B-Architecture
memory	I-Architecture
(	O
RAM	B-Architecture
,	O
for	O
memory	B-General_Concept
)	O
and	O
read-only	B-Device
memory	I-Device
(	O
ROM	B-Device
,	O
for	O
software	O
)	O
modules	O
,	O
and	O
peripherals	O
like	O
bar	O
code	O
readers	O
,	O
microcassette	O
and	O
floppy	B-Device
disk	I-Device
drives	I-Device
,	O
paper-roll	O
thermal	O
printers	O
,	O
and	O
miscellaneous	O
communication	O
interfaces	O
(	O
RS-232	O
,	O
HP-IL	B-Architecture
,	O
HP-IB	O
)	O
.	O
</s>
<s>
The	O
first	O
Soviet	O
pocket	O
battery-powered	O
programmable	B-Application
calculator	I-Application
,	O
Elektronika	B-Device
B3-21	I-Device
,	O
was	O
developed	O
by	O
the	O
end	O
of	O
1976	O
and	O
released	O
at	O
the	O
start	O
of	O
1977	O
.	O
</s>
<s>
The	O
successor	O
of	O
B3-21	B-Device
,	O
the	O
Elektronika	B-Device
B3-34	I-Device
was	O
n't	O
backward	O
compatible	O
with	O
B3-21	B-Device
,	O
even	O
if	O
it	O
kept	O
the	O
reverse	O
Polish	O
notation	O
(	O
RPN	O
)	O
.	O
</s>
<s>
Thus	O
B3-34	B-Device
defined	O
a	O
new	O
command	O
set	O
,	O
which	O
later	O
was	O
used	O
in	O
a	O
series	O
of	O
later	O
programmable	O
Soviet	O
calculators	B-Application
.	O
</s>
<s>
Despite	O
very	O
limited	O
abilities	O
(	O
98	O
bytes	O
of	O
instruction	O
memory	B-General_Concept
and	O
about	O
19	O
stack	O
and	O
addressable	O
registers	O
)	O
,	O
people	O
managed	O
to	O
write	O
all	O
kinds	O
of	O
programs	B-Application
for	O
them	O
,	O
including	O
adventure	O
games	O
and	O
libraries	O
of	O
calculus-related	O
functions	O
for	O
engineers	O
.	O
</s>
<s>
Hundreds	O
,	O
perhaps	O
thousands	O
,	O
of	O
programs	B-Application
were	O
written	O
for	O
these	O
machines	O
,	O
from	O
practical	O
scientific	O
and	O
business	O
software	O
,	O
which	O
were	O
used	O
in	O
real-life	O
offices	O
and	O
labs	O
,	O
to	O
fun	O
games	O
for	O
children	O
.	O
</s>
<s>
The	O
Elektronika	B-Device
MK-52	I-Device
calculator	B-Application
(	O
using	O
the	O
extended	O
B3-34	B-Device
command	O
set	O
,	O
and	O
featuring	O
internal	O
EEPROM	B-General_Concept
memory	B-General_Concept
for	O
storing	O
programs	B-Application
and	O
external	O
interface	O
for	O
EEPROM	B-General_Concept
cards	O
and	O
other	O
periphery	O
)	O
was	O
used	O
in	O
Soviet	O
spacecraft	O
program	B-Application
(	O
for	O
Soyuz	O
TM-7	O
flight	O
)	O
as	O
a	O
backup	O
of	O
the	O
board	O
computer	O
.	O
</s>
<s>
This	O
series	O
of	O
calculators	B-Application
was	O
also	O
noted	O
for	O
a	O
large	O
number	O
of	O
highly	O
counter-intuitive	O
mysterious	O
undocumented	O
features	O
,	O
somewhat	O
similar	O
to	O
"	O
synthetic	B-Device
programming	I-Device
"	O
of	O
the	O
American	O
HP-41	B-Device
,	O
which	O
were	O
exploited	O
by	O
applying	O
normal	O
arithmetic	O
operations	O
to	O
error	O
messages	O
,	O
jumping	O
to	O
nonexistent	O
addresses	O
and	O
other	O
methods	O
.	O
</s>
<s>
A	O
number	O
of	O
respected	O
monthly	O
publications	O
,	O
including	O
the	O
popular	O
science	O
magazine	O
Nauka	O
i	O
Zhizn	O
( Наука	O
и	O
жизнь	O
,	O
Science	O
and	O
Life	O
)	O
,	O
featured	O
special	O
columns	O
,	O
dedicated	O
to	O
optimization	O
methods	O
for	O
calculator	B-Application
programmers	O
and	O
updates	O
on	O
undocumented	O
features	O
for	O
hackers	O
,	O
which	O
grew	O
into	O
a	O
whole	O
esoteric	O
science	O
with	O
many	O
branches	O
,	O
named	O
"	O
yeggogology	B-Device
"	O
("еггогология"	O
)	O
.	O
</s>
<s>
The	O
error	O
messages	O
on	O
those	O
calculators	B-Application
appear	O
as	O
a	O
Russian	O
word	O
"	O
YEGGOG	O
"	O
("ЕГГОГ"	O
)	O
which	O
,	O
unsurprisingly	O
,	O
is	O
translated	O
to	O
"	O
Error	O
"	O
.	O
</s>
<s>
A	O
similar	O
hacker	O
culture	O
in	O
the	O
USA	O
revolved	O
around	O
the	O
HP-41	B-Device
,	O
which	O
was	O
also	O
noted	O
for	O
a	O
large	O
number	O
of	O
undocumented	O
features	O
and	O
was	O
much	O
more	O
powerful	O
than	O
B3-34	B-Device
.	O
</s>
<s>
Through	O
the	O
1970s	O
the	O
hand-held	B-Application
electronic	O
calculator	B-Application
underwent	O
rapid	O
development	O
.	O
</s>
<s>
The	O
red	O
LED	O
and	O
blue/green	O
vacuum	B-General_Concept
fluorescent	I-General_Concept
displays	I-General_Concept
consumed	O
a	O
lot	O
of	O
power	O
and	O
the	O
calculators	B-Application
either	O
had	O
a	O
short	O
battery	O
life	O
(	O
often	O
measured	O
in	O
hours	O
,	O
so	O
rechargeable	O
nickel-cadmium	O
batteries	O
were	O
common	O
)	O
or	O
were	O
large	O
so	O
that	O
they	O
could	O
take	O
larger	O
,	O
higher	O
capacity	O
batteries	O
.	O
</s>
<s>
In	O
the	O
early	O
1970s	O
liquid-crystal	B-Device
displays	I-Device
(	O
LCDs	B-Device
)	O
were	O
in	O
their	O
infancy	O
and	O
there	O
was	O
a	O
great	O
deal	O
of	O
concern	O
that	O
they	O
only	O
had	O
a	O
short	O
operating	O
lifetime	O
.	O
</s>
<s>
Busicom	O
introduced	O
the	O
Busicom	O
LE-120A	O
"	O
HANDY	O
"	O
calculator	B-Application
,	O
the	O
first	O
pocket-sized	O
calculator	B-Application
and	O
the	O
first	O
with	O
an	O
LED	O
display	O
,	O
and	O
announced	O
the	O
Busicom	O
LC	O
with	O
LCD	B-Device
.	O
</s>
<s>
However	O
,	O
there	O
were	O
problems	O
with	O
this	O
display	O
and	O
the	O
calculator	B-Application
never	O
went	O
on	O
sale	O
.	O
</s>
<s>
The	O
first	O
successful	O
calculators	B-Application
with	O
LCDs	B-Device
were	O
manufactured	O
by	O
Rockwell	O
International	O
and	O
sold	O
from	O
1972	O
by	O
other	O
companies	O
under	O
such	O
names	O
as	O
:	O
Dataking	O
LC-800	O
,	O
Harden	O
DT/12	O
,	O
Ibico	O
086	O
,	O
Lloyds	O
40	O
,	O
Lloyds	O
100	O
,	O
Prismatic	O
500	O
(	O
a.k.a.	O
</s>
<s>
The	O
LCDs	B-Device
were	O
an	O
early	O
form	O
using	O
the	O
Dynamic	O
Scattering	O
Mode	O
DSM	O
with	O
the	O
numbers	O
appearing	O
as	O
bright	O
against	O
a	O
dark	O
background	O
.	O
</s>
<s>
To	O
present	O
a	O
high-contrast	O
display	O
these	O
models	O
illuminated	O
the	O
LCD	B-Device
using	O
a	O
filament	O
lamp	O
and	O
solid	O
plastic	O
light	O
guide	O
,	O
which	O
negated	O
the	O
low	O
power	O
consumption	O
of	O
the	O
display	O
.	O
</s>
<s>
A	O
more	O
successful	O
series	O
of	O
calculators	B-Application
using	O
a	O
reflective	O
DSM-LCD	O
was	O
launched	O
in	O
1972	O
by	O
Sharp	O
Inc	O
with	O
the	O
Sharp	O
EL-805	O
,	O
which	O
was	O
a	O
slim	O
pocket	O
calculator	B-Application
.	O
</s>
<s>
This	O
,	O
and	O
another	O
few	O
similar	O
models	O
,	O
used	O
Sharp	O
's	O
Calculator	B-Application
On	O
Substrate	O
(	O
COS	O
)	O
technology	O
.	O
</s>
<s>
An	O
extension	O
of	O
one	O
glass	O
plate	O
needed	O
for	O
the	O
liquid	B-Device
crystal	I-Device
display	I-Device
was	O
used	O
as	O
a	O
substrate	O
to	O
mount	O
the	O
needed	O
chips	O
based	O
on	O
a	O
new	O
hybrid	O
technology	O
.	O
</s>
<s>
In	O
the	O
mid-1970s	O
the	O
first	O
calculators	B-Application
appeared	O
with	O
field-effect	O
,	O
twisted	O
nematic	O
(	O
TN	O
)	O
LCDs	B-Device
with	O
dark	O
numerals	O
against	O
a	O
grey	O
background	O
,	O
though	O
the	O
early	O
ones	O
often	O
had	O
a	O
yellow	O
filter	O
over	O
them	O
to	O
cut	O
out	O
damaging	O
ultraviolet	B-Application
rays	O
.	O
</s>
<s>
The	O
advantage	O
of	O
LCDs	B-Device
is	O
that	O
they	O
are	O
passive	O
light	O
modulators	O
reflecting	O
light	O
,	O
which	O
require	O
much	O
less	O
power	O
than	O
light-emitting	O
displays	O
such	O
as	O
LEDs	O
or	O
VFDs	O
.	O
</s>
<s>
This	O
led	O
the	O
way	O
to	O
the	O
first	O
credit-card-sized	O
calculators	B-Application
,	O
such	O
as	O
the	O
Casio	O
Mini	O
Card	O
LC-78	O
of	O
1978	O
,	O
which	O
could	O
run	O
for	O
months	O
of	O
normal	O
use	O
on	O
button	O
cells	O
.	O
</s>
<s>
There	O
were	O
also	O
improvements	O
to	O
the	O
electronics	O
inside	O
the	O
calculators	B-Application
.	O
</s>
<s>
All	O
of	O
the	O
logic	O
functions	O
of	O
a	O
calculator	B-Application
had	O
been	O
squeezed	O
into	O
the	O
first	O
"	O
calculator	B-Application
on	O
a	O
chip	B-Device
"	O
integrated	O
circuits	O
(	O
ICs	O
)	O
in	O
1971	O
,	O
but	O
this	O
was	O
leading	O
edge	O
technology	O
of	O
the	O
time	O
and	O
yields	O
were	O
low	O
and	O
costs	O
were	O
high	O
.	O
</s>
<s>
Many	O
calculators	B-Application
continued	O
to	O
use	O
two	O
or	O
more	O
ICs	O
,	O
especially	O
the	O
scientific	O
and	O
the	O
programmable	O
ones	O
,	O
into	O
the	O
late	O
1970s	O
.	O
</s>
<s>
The	O
power	O
consumption	O
of	O
the	O
integrated	O
circuits	O
was	O
also	O
reduced	O
,	O
especially	O
with	O
the	O
introduction	O
of	O
CMOS	B-Device
technology	O
.	O
</s>
<s>
Appearing	O
in	O
the	O
Sharp	O
"	O
EL-801	O
"	O
in	O
1972	O
,	O
the	O
transistors	B-Application
in	O
the	O
logic	O
cells	O
of	O
CMOS	B-Device
ICs	O
only	O
used	O
any	O
appreciable	O
power	O
when	O
they	O
changed	O
state	O
.	O
</s>
<s>
The	O
LED	O
and	O
VFD	B-General_Concept
displays	O
often	O
required	O
added	O
driver	O
transistors	B-Application
or	O
ICs	O
,	O
whereas	O
the	O
LCDs	B-Device
were	O
more	O
amenable	O
to	O
being	O
driven	O
directly	O
by	O
the	O
calculator	B-Application
IC	O
itself	O
.	O
</s>
<s>
With	O
this	O
low	O
power	O
consumption	O
came	O
the	O
possibility	O
of	O
using	O
solar	O
cells	O
as	O
the	O
power	O
source	O
,	O
realised	O
around	O
1978	O
by	O
calculators	B-Application
such	O
as	O
the	O
Royal	O
Solar	O
1	O
,	O
Sharp	O
EL-8026	O
,	O
and	O
Teal	O
Photon	O
.	O
</s>
<s>
At	O
the	O
start	O
of	O
the	O
1970s	O
,	O
hand-held	B-Application
electronic	O
calculators	B-Application
were	O
very	O
costly	O
,	O
at	O
two	O
or	O
three	O
weeks	O
 '	O
wages	O
,	O
and	O
so	O
were	O
a	O
luxury	O
item	O
.	O
</s>
<s>
Many	O
firms	O
saw	O
that	O
there	O
were	O
good	O
profits	O
to	O
be	O
made	O
in	O
the	O
calculator	B-Application
business	O
with	O
the	O
margin	O
on	O
such	O
high	O
prices	O
.	O
</s>
<s>
However	O
,	O
the	O
cost	O
of	O
calculators	B-Application
fell	O
as	O
components	O
and	O
their	O
production	O
methods	O
improved	O
,	O
and	O
the	O
effect	O
of	O
economies	O
of	O
scale	O
was	O
felt	O
.	O
</s>
<s>
By	O
1976	O
,	O
the	O
cost	O
of	O
the	O
cheapest	O
four-function	O
pocket	O
calculator	B-Application
had	O
dropped	O
to	O
a	O
few	O
dollars	O
,	O
about	O
1/20	O
of	O
the	O
cost	O
five	O
years	O
before	O
.	O
</s>
<s>
The	O
results	O
of	O
this	O
were	O
that	O
the	O
pocket	O
calculator	B-Application
was	O
affordable	O
,	O
and	O
that	O
it	O
was	O
now	O
difficult	O
for	O
the	O
manufacturers	O
to	O
make	O
a	O
profit	O
from	O
calculators	B-Application
,	O
leading	O
to	O
many	O
firms	O
dropping	O
out	O
of	O
the	O
business	O
or	O
closing	O
.	O
</s>
<s>
The	O
firms	O
that	O
survived	O
making	O
calculators	B-Application
tended	O
to	O
be	O
those	O
with	O
high	O
outputs	O
of	O
higher	O
quality	O
calculators	B-Application
,	O
or	O
producing	O
high-specification	O
scientific	O
and	O
programmable	B-Application
calculators	I-Application
.	O
</s>
<s>
The	O
first	O
calculator	B-Application
capable	O
of	O
symbolic	B-Algorithm
computing	I-Algorithm
was	O
the	O
HP-28C	B-Device
,	O
released	O
in	O
1987	O
.	O
</s>
<s>
The	O
first	O
graphing	B-Application
calculator	I-Application
was	O
the	O
Casio	B-Device
fx-7000G	I-Device
released	O
in	O
1985	O
.	O
</s>
<s>
The	O
two	O
leading	O
manufacturers	O
,	O
HP	O
and	O
TI	O
,	O
released	O
increasingly	O
feature-laden	O
calculators	B-Application
during	O
the	O
1980s	O
and	O
1990s	O
.	O
</s>
<s>
At	O
the	O
turn	O
of	O
the	O
millennium	O
,	O
the	O
line	O
between	O
a	O
graphing	B-Application
calculator	I-Application
and	O
a	O
handheld	B-Application
computer	I-Application
was	O
not	O
always	O
clear	O
,	O
as	O
some	O
very	O
advanced	O
calculators	B-Application
such	O
as	O
the	O
TI-89	B-Device
,	O
the	O
Voyage	B-Device
200	I-Device
and	O
HP-49G	O
could	O
differentiate	B-Algorithm
and	O
integrate	O
functions	O
,	O
solve	O
differential	O
equations	O
,	O
run	O
word	B-General_Concept
processing	I-General_Concept
and	O
PIM	B-Application
software	O
,	O
and	O
connect	O
by	O
wire	O
or	O
IR	O
to	O
other	O
calculators/computers	O
.	O
</s>
<s>
The	O
HP	B-Device
12c	I-Device
financial	O
calculator	B-Application
is	O
still	O
produced	O
.	O
</s>
<s>
The	O
HP	B-Device
12c	I-Device
featured	O
the	O
reverse	O
Polish	O
notation	O
mode	O
of	O
data	O
entry	O
.	O
</s>
<s>
In	O
2003	O
several	O
new	O
models	O
were	O
released	O
,	O
including	O
an	O
improved	O
version	O
of	O
the	O
HP	B-Device
12c	I-Device
,	O
the	O
"	O
HP	B-Device
12c	I-Device
platinum	O
edition	O
"	O
which	O
added	O
more	O
memory	B-General_Concept
,	O
more	O
built-in	O
functions	O
,	O
and	O
the	O
addition	O
of	O
the	O
algebraic	O
mode	O
of	O
data	O
entry	O
.	O
</s>
<s>
Calculated	O
Industries	O
competed	O
with	O
the	O
HP	B-Device
12c	I-Device
in	O
the	O
mortgage	O
and	O
real	O
estate	O
markets	O
by	O
differentiating	O
the	O
key	O
labeling	O
;	O
changing	O
the	O
"	O
I	O
"	O
,	O
"	O
PV	O
"	O
,	O
"	O
FV	O
"	O
to	O
easier	O
labeling	O
terms	O
such	O
as	O
"	O
Int	O
"	O
,	O
"	O
Term	O
"	O
,	O
"	O
Pmt	O
"	O
,	O
and	O
not	O
using	O
the	O
reverse	O
Polish	O
notation	O
.	O
</s>
<s>
However	O
,	O
CI	O
's	O
more	O
successful	O
calculators	B-Application
involved	O
a	O
line	O
of	O
construction	O
calculators	B-Application
,	O
which	O
evolved	O
and	O
expanded	O
in	O
the	O
1990s	O
to	O
present	O
.	O
</s>
<s>
According	O
to	O
Mark	O
Bollman	O
,	O
a	O
mathematics	O
and	O
calculator	B-Application
historian	O
and	O
associate	O
professor	O
of	O
mathematics	O
at	O
Albion	O
College	O
,	O
the	O
"	O
Construction	O
Master	O
is	O
the	O
first	O
in	O
a	O
long	O
and	O
profitable	O
line	O
of	O
CI	O
construction	O
calculators	B-Application
"	O
which	O
carried	O
them	O
through	O
the	O
1980s	O
,	O
1990s	O
,	O
and	O
to	O
the	O
present	O
.	O
</s>
<s>
Personal	O
computers	O
often	O
come	O
with	O
a	O
calculator	B-Application
utility	O
program	B-Application
that	O
emulates	O
the	O
appearance	O
and	O
functions	O
of	O
a	O
calculator	B-Application
,	O
using	O
the	O
graphical	B-Application
user	I-Application
interface	I-Application
to	O
portray	O
a	O
calculator	B-Application
.	O
</s>
<s>
One	O
such	O
example	O
is	O
Windows	B-Application
Calculator	I-Application
.	O
</s>
<s>
Most	O
personal	B-Application
data	I-Application
assistants	I-Application
(	O
PDAs	B-Application
)	O
and	O
smartphones	B-Application
also	O
have	O
such	O
a	O
feature	O
.	O
</s>
<s>
In	O
most	O
countries	O
,	O
students	O
use	O
calculators	B-Application
for	O
schoolwork	O
.	O
</s>
<s>
There	O
remains	O
disagreement	O
about	O
the	O
importance	O
of	O
the	O
ability	O
to	O
perform	O
calculations	O
in	O
the	O
head	O
,	O
with	O
some	O
curricula	O
restricting	O
calculator	B-Application
use	O
until	O
a	O
certain	O
level	O
of	O
proficiency	O
has	O
been	O
obtained	O
,	O
while	O
others	O
concentrate	O
more	O
on	O
teaching	O
estimation	O
methods	O
and	O
problem-solving	O
.	O
</s>
<s>
Others	O
have	O
argued	O
that	O
calculator	B-Application
use	O
can	O
even	O
cause	O
core	O
mathematical	O
skills	O
to	O
atrophy	O
,	O
or	O
that	O
such	O
use	O
can	O
prevent	O
understanding	O
of	O
advanced	O
algebraic	O
concepts	O
.	O
</s>
<s>
In	O
December	O
2011	O
the	O
UK	O
's	O
Minister	O
of	O
State	O
for	O
Schools	O
,	O
Nick	O
Gibb	O
,	O
voiced	O
concern	O
that	O
children	O
can	O
become	O
"	O
too	O
dependent	O
"	O
on	O
the	O
use	O
of	O
calculators	B-Application
.	O
</s>
<s>
As	O
a	O
result	O
,	O
the	O
use	O
of	O
calculators	B-Application
is	O
to	O
be	O
included	O
as	O
part	O
of	O
a	O
review	O
of	O
the	O
Curriculum	O
.	O
</s>
<s>
In	O
the	O
United	O
States	O
,	O
many	O
math	O
educators	O
and	O
boards	O
of	O
education	O
have	O
enthusiastically	O
endorsed	O
the	O
National	O
Council	O
of	O
Teachers	O
of	O
Mathematics	O
(	O
NCTM	O
)	O
standards	O
and	O
actively	O
promoted	O
the	O
use	O
of	O
classroom	O
calculators	B-Application
from	O
kindergarten	O
through	O
high	O
school	O
.	O
</s>
<s>
The	O
Japanese	O
Patent	O
Office	O
granted	O
a	O
patent	O
in	O
June	O
1978	O
to	O
Texas	O
Instruments	O
(	O
TI	O
)	O
based	O
on	O
US	O
patent	O
3819921	O
,	O
notwithstanding	O
objections	O
from	O
12	O
Japanese	O
calculator	B-Application
manufacturers	O
.	O
</s>
<s>
–	O
Floating	B-Algorithm
Point	I-Algorithm
Calculator	B-Application
With	O
RAM	B-Architecture
Shift	O
Register	B-General_Concept
–	O
1977	O
(	O
originally	O
filed	O
GB	O
March	O
1971	O
,	O
US	O
July	O
1971	O
)	O
,	O
very	O
early	O
single	O
chip	B-Device
calculator	B-Application
claim	O
.	O
</s>
<s>
–	O
Extended	O
Numerical	O
Keyboard	B-Device
with	O
Structured	O
Data-Entry	O
Capability	O
–	O
J	O
.	O
H	O
.	O
Redin	O
,	O
1997	O
(	O
originally	O
filed	O
1996	O
)	O
,	O
Usage	O
of	O
Verbal	O
Numerals	O
as	O
a	O
way	O
to	O
enter	O
a	O
number	O
.	O
</s>
<s>
Collectors	O
Guide	O
to	O
Pocket	O
Calculators''	O
.	O
</s>
<s>
by	O
Guy	O
Ball	O
and	O
Bruce	O
Flamm	O
,	O
1997	O
,	O
–	O
includes	O
an	O
extensive	O
history	O
of	O
early	O
pocket	O
calculators	B-Application
and	O
highlights	O
over	O
1,500	O
different	O
models	O
from	O
the	O
early	O
1970s	O
.	O
</s>
