<s>
Apple	B-Device
II	I-Device
system	I-Device
clocks	I-Device
,	O
also	O
known	O
as	O
real-time	O
clocks	O
,	O
were	O
devices	O
in	O
the	O
early	O
years	O
of	O
microcomputing	O
.	O
</s>
<s>
A	O
clock/calendar	O
did	O
not	O
become	O
standard	O
in	O
the	O
Apple	B-Device
II	I-Device
line	O
of	O
computers	O
until	O
1986	O
with	O
the	O
introduction	O
of	O
the	O
Apple	B-Device
IIGS	I-Device
.	O
</s>
<s>
Although	O
many	O
productivity	O
programs	O
as	O
well	O
as	O
the	O
ProDOS	B-Operating_System
operating	O
system	O
implemented	O
time	O
and	O
date	O
functions	O
,	O
users	O
would	O
have	O
to	O
manually	O
enter	O
this	O
information	O
every	O
time	O
they	O
turned	O
the	O
computer	O
on	O
.	O
</s>
<s>
Power	O
users	O
often	O
had	O
their	O
Apple	B-Device
II	I-Device
's	O
peripheral	O
slots	O
completely	O
filled	O
with	O
expansion	O
cards	O
,	O
so	O
third	O
party	O
vendors	O
came	O
up	O
with	O
alternative	O
approaches	O
with	O
products	O
like	O
the	O
Serial	O
Pro	O
and	O
No-Slot	O
Clock	O
.	O
</s>
<s>
The	O
No-Slot	O
Clock	O
,	O
also	O
known	O
as	O
the	O
Dallas	O
Smartwatch	O
(	O
DS1216E	O
)	O
http://datasheets.maximintegrated.com/en/ds/DS1216-DS1216H.pdf	O
,	O
was	O
a	O
28-pin	O
chip-like	O
device	O
that	O
could	O
be	O
used	O
directly	O
in	O
any	O
Apple	B-Device
II	I-Device
or	O
Apple	B-Device
II	I-Device
compatible	O
with	O
a	O
28-pin	O
ROM	B-Device
.	O
</s>
<s>
In	O
an	O
Apple	B-Device
II	I-Device
,	O
the	O
No-Slot	O
Clock	O
resided	O
under	O
any	O
28-pin	O
ROM	B-Device
chip	I-Device
,	O
including	O
one	O
on	O
a	O
peripheral	O
card	O
.	O
</s>
<s>
A	O
user	O
had	O
to	O
remove	O
the	O
ROM	B-Device
from	O
its	O
socket	O
,	O
insert	O
the	O
No-Slot	O
Clock	O
,	O
and	O
then	O
reinsert	O
the	O
ROM	B-Device
chip	I-Device
into	O
the	O
top	O
of	O
the	O
No-Slot	O
Clock	O
.	O
</s>
<s>
The	O
No-Slot	O
Clock	O
was	O
both	O
ProDOS	B-Operating_System
and	O
Dos	B-Operating_System
3.3	I-Operating_System
compatible	O
,	O
however	O
a	O
software	B-Application
driver	I-Application
had	O
to	O
be	O
patched	O
into	O
ProDOS	B-Operating_System
or	O
integrated	O
into	O
the	O
applicable	O
DOS	B-Operating_System
3.3	I-Operating_System
program	O
.	O
</s>
<s>
The	O
card	O
was	O
capable	O
of	O
a	O
12‑	O
and	O
24‑hour	O
clock	O
format	O
,	O
was	O
both	O
ProDOS	B-Operating_System
and	O
DOS	B-Operating_System
3.3	I-Operating_System
compatible	O
,	O
and	O
had	O
on-screen	O
time	O
and	O
date	O
setting	O
built	O
into	O
its	O
ROM	B-Device
,	O
eliminating	O
the	O
need	O
to	O
run	O
a	O
program	O
in	O
order	O
to	O
set	O
the	O
time	O
.	O
</s>
<s>
For	O
more	O
on	O
the	O
Serial	O
Pro	O
's	O
communication	O
capabilities	O
,	O
see	O
its	O
entry	O
in	O
Apple	B-Device
II	I-Device
serial	O
cards	O
.	O
</s>
<s>
When	O
the	O
Thunderware	O
Thunderclock	O
Plus	O
was	O
released	O
in	O
1980	O
,	O
it	O
quickly	O
became	O
the	O
de	O
facto	O
standard	O
for	O
an	O
Apple	B-Device
II	I-Device
system	O
clock	O
.	O
</s>
<s>
When	O
Apple	O
Computer	O
released	O
its	O
new	O
ProDOS	B-Operating_System
operating	O
system	O
in	O
1984	O
,	O
a	O
Thunderclock	O
software	B-Application
driver	I-Application
came	O
built-in	O
.	O
</s>
<s>
From	O
that	O
point	O
on	O
,	O
all	O
new	O
Apple	B-Device
II	I-Device
system	I-Device
clocks	I-Device
strived	O
to	O
emulate	O
the	O
Thunderclock	O
.	O
</s>
<s>
The	O
card	O
itself	O
was	O
more	O
compact	O
than	O
the	O
earlier	O
"	O
The	O
Clock	O
"	O
from	O
Mountain	O
Computers	O
and	O
contained	O
two	O
battery	O
holders	O
for	O
off	O
the	O
shelf	O
alkaline	B-Algorithm
batteries	I-Algorithm
which	O
were	O
easily	O
replaceable	O
.	O
</s>
<s>
clock	O
card	O
from	O
Applied	O
Engineering	O
was	O
possibly	O
the	O
most	O
advanced	O
system	O
clock	O
ever	O
designed	O
for	O
any	O
Apple	B-Device
II	I-Device
.	O
</s>
<s>
It	O
also	O
maintained	O
an	O
internal	O
calendar	O
,	O
separate	O
of	O
the	O
7‑year	O
cycle	O
which	O
ProDOS	B-Operating_System
mapped	O
.	O
</s>
<s>
was	O
100%	O
ProDOS	B-Operating_System
and	O
DOS	B-Operating_System
3.3	I-Operating_System
compatible	O
.	O
</s>
