<s>
The	O
Sharp	B-Device
QT-8B	I-Device
Micro	O
Compet	O
,	O
a	O
portable	O
electronic	O
desktop	O
calculator	B-Application
,	O
was	O
the	O
first	O
mass-produced	O
calculator	B-Application
to	O
be	O
battery-powered	O
.	O
</s>
<s>
Introduced	O
in	O
mid-1970	O
,	O
it	O
was	O
based	O
on	O
its	O
immediate	O
predecessor	O
,	O
the	O
QT-8D	B-Device
introduced	O
in	O
late	O
1969	O
,	O
but	O
it	O
replaced	O
the	O
QT-8D	B-Device
'	O
s	O
integrated	O
power	O
supply	O
with	O
a	O
rechargeable	B-Architecture
battery	I-Architecture
pack	O
.	O
</s>
<s>
It	O
has	O
the	O
same	O
calculating	O
integrated	O
circuits	O
as	O
the	O
QT-8D	B-Device
and	O
is	O
of	O
similar	O
appearance	O
and	O
dimensions	O
;	O
the	O
power	O
supply	O
is	O
the	O
only	O
major	O
difference	O
.	O
</s>
<s>
These	O
prices	O
were	O
somewhat	O
higher	O
than	O
those	O
for	O
the	O
preceding	O
QT-8D	B-Device
.	O
</s>
<s>
The	O
QT-8B	O
'	O
s	O
battery	B-Algorithm
pack	I-Algorithm
contains	O
six	O
nickel-cadmium	O
C	B-Algorithm
batteries	I-Algorithm
connected	O
in	O
series	O
,	O
giving	O
a	O
total	O
voltage	O
of	O
7.5	O
volts	O
and	O
,	O
with	O
the	O
original	O
batteries	O
,	O
a	O
total	O
capacity	O
of	O
1200	O
milliampere-hours	O
.	O
</s>
<s>
(	O
Modern	O
nickel-cadmium	O
C	B-Algorithm
batteries	I-Algorithm
have	O
much	O
greater	O
capacity	O
.	O
)	O
</s>
<s>
For	O
recharging	O
,	O
the	O
calculator	B-Application
accepts	O
12-volt	O
DC	O
external	O
power	O
,	O
with	O
an	O
input	O
power	O
rating	O
of	O
6.5	O
watts	O
.	O
</s>
<s>
Normally	O
the	O
calculator	B-Application
is	O
recharged	O
from	O
AC	O
power	O
by	O
plugging	O
it	O
into	O
an	O
external	O
charging	O
station	O
(	O
model	O
QTA-2	O
)	O
which	O
is	O
a	O
little	O
longer	O
than	O
the	O
calculator	B-Application
and	O
has	O
a	O
plug	O
that	O
fits	O
into	O
the	O
calculator	B-Application
's	O
charging	O
socket	O
.	O
</s>
<s>
The	O
calculator	B-Application
sits	O
on	O
top	O
of	O
the	O
base	O
of	O
this	O
charging	O
station	O
and	O
can	O
be	O
used	O
while	O
charging	O
;	O
it	O
can	O
also	O
be	O
locked	O
into	O
the	O
station	O
for	O
extra	O
stability	O
.	O
</s>
<s>
The	O
display	O
used	O
is	O
vacuum	O
fluorescent	O
display.There	O
is	O
a	O
slight	O
difference	O
between	O
the	O
QT-8D	B-Device
and	O
the	O
QT-8B	O
in	O
the	O
operation	O
of	O
the	O
right-hand	O
display	O
tube	O
,	O
which	O
contains	O
both	O
a	O
minus-sign	O
indicator	O
and	O
a	O
large	O
dot	O
.	O
</s>
<s>
On	O
the	O
QT-8D	B-Device
,	O
this	O
dot	O
is	O
used	O
as	O
an	O
overflow	O
error	O
indicator	O
.	O
</s>
<s>
Sharp	O
made	O
an	O
OEM	O
version	O
of	O
the	O
QT-8B	O
for	O
Burroughs	O
,	O
the	O
Burroughs	B-Device
C3146	I-Device
,	O
which	O
has	O
some	O
significant	O
differences	O
from	O
Sharp	O
's	O
own	O
version	O
.	O
</s>
<s>
Since	O
the	O
C3146	O
has	O
both	O
a	O
battery	B-Algorithm
pack	I-Algorithm
and	O
an	O
AC	O
power	O
supply	O
,	O
it	O
also	O
has	O
a	O
larger	O
case	O
to	O
accommodate	O
them	O
.	O
</s>
