<s>
The	O
STD	B-Architecture
Bus	I-Architecture
is	O
a	O
computer	B-General_Concept
bus	I-General_Concept
that	O
was	O
used	O
primarily	O
for	O
industrial	O
control	O
systems	O
,	O
but	O
has	O
also	O
found	O
applications	O
in	O
computing	O
.	O
</s>
<s>
The	O
STD	B-Architecture
Bus	I-Architecture
has	O
also	O
been	O
designated	O
as	O
STD-80	B-Architecture
,	O
referring	O
to	O
its	O
relation	O
to	O
the	O
Zilog	B-General_Concept
Z80	I-General_Concept
series	O
microprocessors	B-Architecture
.	O
</s>
<s>
The	O
STD	B-Architecture
Bus	I-Architecture
uses	O
6.5	O
"	O
by	O
4.5	O
"	O
expansion	B-Device
card	I-Device
with	O
an	O
edge	O
connector	O
with	O
56	O
pins	O
.	O
</s>
<s>
Many	O
different	O
types	O
of	O
cards	O
have	O
been	O
available	O
for	O
the	O
STD	B-Architecture
Bus	I-Architecture
,	O
from	O
processing	O
cards	O
,	O
RAM	B-Architecture
cards	O
,	O
I/O	B-Device
cards	I-Device
,	O
and	O
specialized	O
cards	O
for	O
various	O
applications	O
.	O
</s>
<s>
The	O
use	O
of	O
the	O
STD	B-Architecture
bus	I-Architecture
has	O
declined	O
.	O
</s>
<s>
The	O
STD	B-Architecture
Bus	I-Architecture
has	O
a	O
card	O
edge	O
connector	O
with	O
56	O
contacts	O
.	O
</s>
<s>
Flow	O
is	O
relative	O
using	O
a	O
STD	B-Architecture
Bus	I-Architecture
Processor	O
Card	O
.	O
</s>
<s>
A	O
focus	O
of	O
the	O
STD	B-Architecture
bus	I-Architecture
was	O
its	O
ability	O
to	O
build	O
a	O
system	O
using	O
the	O
exact	O
bus	O
cards	O
required	O
for	O
an	O
application	O
.	O
</s>
<s>
The	O
compact	O
size	O
of	O
a	O
card	O
made	O
the	O
STD	B-Architecture
bus	I-Architecture
system	O
more	O
adaptable	O
to	O
various	O
applications	O
than	O
the	O
contemporary	O
computer	B-General_Concept
buses	I-General_Concept
of	O
the	O
mid-1980s	O
such	O
as	O
the	O
S-100	O
and	O
the	O
SS-50	O
,	O
because	O
it	O
could	O
use	O
servo	B-Algorithm
control	I-Algorithm
cards	O
along	O
with	O
a	O
fully	O
programmable	B-General_Concept
computer	I-General_Concept
for	O
mathematical	O
operations	O
.	O
</s>
<s>
In	O
applications	O
for	O
running	O
an	O
astronomical	O
observatory	O
,	O
the	O
large	O
industrial	O
base	O
of	O
cards	O
,	O
and	O
the	O
system	O
's	O
expandability	O
,	O
made	O
the	O
system	O
desirable	O
for	O
use	O
in	O
a	O
photometry	O
lab	O
to	O
control	O
the	O
telescope	O
as	O
well	O
as	O
do	O
the	O
data	B-General_Concept
logging	O
and	O
computations	O
required	O
.	O
</s>
<s>
In	O
typical	O
university	O
laboratory	O
settings	O
of	O
the	O
mid	O
-	O
late	O
80	O
's	O
,	O
STD	B-Architecture
bus	I-Architecture
data	B-General_Concept
acquisition	O
systems	O
were	O
commonplace	O
using	O
Z80	B-General_Concept
or	O
similar	O
processor	O
cards	O
for	O
the	O
data	B-General_Concept
capture	O
,	O
processing	O
and	O
control	O
,	O
parallel	O
I/O	B-Device
cards	I-Device
for	O
experiment	O
control	O
as	O
well	O
as	O
analogue	O
to	O
digital	O
conversion	O
cards	O
for	O
reading	O
experiment	O
analogue	O
parameters	O
.	O
</s>
<s>
This	O
allows	O
with	O
the	O
proper	O
STD-32	O
backplane	B-Architecture
the	O
ability	O
to	O
run	O
legacy	B-Device
cards	O
used	O
for	O
specific	O
applications	O
on	O
the	O
same	O
bus	O
without	O
having	O
to	O
upgrade	O
the	O
complete	O
system	O
.	O
</s>
