<s>
Open	B-Architecture
architecture	I-Architecture
is	O
a	O
type	O
of	O
computer	B-General_Concept
architecture	I-General_Concept
or	O
software	B-Architecture
architecture	I-Architecture
intended	O
to	O
make	O
adding	O
,	O
upgrading	O
,	O
and	O
swapping	O
components	O
with	O
other	O
computers	O
easy	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
IBM	B-Device
PC	I-Device
,	O
Amiga	B-Device
500	I-Device
and	O
Apple	B-Device
IIe	I-Device
have	O
an	O
open	B-Architecture
architecture	I-Architecture
supporting	O
plug-in	O
cards	O
,	O
whereas	O
the	O
Apple	O
IIc	O
computer	O
has	O
a	O
closed	B-Architecture
architecture	I-Architecture
.	O
</s>
<s>
Open	B-Architecture
architecture	I-Architecture
systems	O
may	O
use	O
a	O
standardized	O
system	B-Architecture
bus	I-Architecture
such	O
as	O
S-100	B-Architecture
,	O
PCI	B-Protocol
or	O
ISA	B-Architecture
or	O
they	O
may	O
incorporate	O
a	O
proprietary	O
bus	O
standard	O
such	O
as	O
that	O
used	O
on	O
the	O
Apple	B-Device
II	I-Device
,	O
with	O
up	O
to	O
a	O
dozen	O
slots	O
that	O
allow	O
multiple	O
hardware	O
manufacturers	O
to	O
produce	O
add-ons	O
,	O
and	O
for	O
the	O
user	O
to	O
freely	O
install	O
them	O
.	O
</s>
<s>
By	O
contrast	O
,	O
closed	B-Architecture
architectures	I-Architecture
,	O
if	O
they	O
are	O
expandable	O
at	O
all	O
,	O
have	O
one	O
or	O
two	O
"	O
expansion	O
ports	O
"	O
using	O
a	O
proprietary	O
connector	O
design	O
that	O
may	O
require	O
a	O
license	O
fee	O
from	O
the	O
manufacturer	O
,	O
or	O
enhancements	O
may	O
only	O
be	O
installable	O
by	O
technicians	O
with	O
specialized	O
tools	O
or	O
training	O
.	O
</s>
<s>
Computer	B-Device
platforms	I-Device
may	O
include	O
systems	O
with	O
both	O
open	O
and	O
closed	B-Architecture
architectures	I-Architecture
.	O
</s>
<s>
The	O
Mac	B-Device
mini	I-Device
and	O
Compact	O
Macintosh	O
are	O
closed	O
;	O
the	O
Macintosh	B-Device
II	I-Device
and	O
Power	B-Device
Macintosh	I-Device
G5	I-Device
are	O
open	O
.	O
</s>
<s>
Most	O
desktop	B-Device
PCs	I-Device
are	O
open	B-Architecture
architecture	I-Architecture
.	O
</s>
<s>
Similarly	O
,	O
an	O
open	B-Application
software	I-Application
architecture	O
is	O
one	O
in	O
which	O
additional	O
software	O
modules	O
can	O
be	O
added	O
to	O
the	O
basic	O
framework	O
provided	O
by	O
the	O
architecture	O
.	O
</s>
<s>
The	O
Google	B-Application
APIs	I-Application
are	O
examples	O
.	O
</s>
<s>
A	O
second	O
type	O
of	O
open	B-Application
software	I-Application
architecture	O
consists	O
of	O
the	O
messages	O
that	O
can	O
flow	O
between	O
computer	O
systems	O
.	O
</s>
<s>
An	O
example	O
is	O
IBM	O
's	O
Distributed	B-Operating_System
Data	I-Operating_System
Management	I-Operating_System
Architecture	I-Operating_System
.	O
</s>
<s>
Open	B-Architecture
architecture	I-Architecture
allows	O
potential	O
users	O
to	O
see	O
inside	O
all	O
or	O
parts	O
of	O
the	O
architecture	O
without	O
any	O
proprietary	O
constraints	O
.	O
</s>
<s>
Typically	O
,	O
an	O
open	B-Architecture
architecture	I-Architecture
publishes	O
all	O
or	O
parts	O
of	O
its	O
architecture	O
that	O
the	O
developer	O
or	O
integrator	O
wants	O
to	O
share	O
.	O
</s>
<s>
The	O
open	O
business	O
processes	O
involved	O
with	O
an	O
open	B-Architecture
architecture	I-Architecture
may	O
require	O
some	O
license	O
agreements	O
between	O
entities	O
sharing	O
the	O
architecture	O
information	O
.	O
</s>
<s>
Open	B-Architecture
architectures	I-Architecture
have	O
been	O
successfully	O
implemented	O
in	O
many	O
diverse	O
fields	O
,	O
including	O
the	O
US	O
Navy	O
.	O
</s>
