<s>
Amoeba	B-Operating_System
is	O
a	O
distributed	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
developed	O
by	O
Andrew	O
S	O
.	O
Tanenbaum	O
and	O
others	O
at	O
the	O
Vrije	O
Universiteit	O
Amsterdam	O
.	O
</s>
<s>
The	O
aim	O
of	O
the	O
Amoeba	B-Operating_System
project	O
was	O
to	O
build	O
a	O
timesharing	B-General_Concept
system	O
that	O
makes	O
an	O
entire	O
network	O
of	O
computers	O
appear	O
to	O
the	O
user	O
as	O
a	O
single	B-Operating_System
machine	I-Operating_System
.	O
</s>
<s>
The	O
Python	B-Language
programming	I-Language
language	I-Language
was	O
originally	O
developed	O
for	O
this	O
platform	O
.	O
</s>
<s>
The	O
goal	O
of	O
the	O
Amoeba	B-Operating_System
project	O
was	O
to	O
construct	O
an	O
operating	O
system	O
for	O
networks	O
of	O
computers	O
that	O
would	O
present	O
the	O
network	O
to	O
the	O
user	O
as	O
if	O
it	O
were	O
a	O
single	B-Operating_System
machine	I-Operating_System
.	O
</s>
<s>
An	O
Amoeba	B-Operating_System
network	O
consists	O
of	O
a	O
number	O
of	O
workstations	B-Device
connected	O
to	O
a	O
"	O
pool	O
"	O
of	O
processors	O
,	O
and	O
executing	O
a	O
program	O
from	O
a	O
terminal	O
causes	O
it	O
to	O
run	O
on	O
any	O
of	O
the	O
available	O
processors	O
,	O
with	O
the	O
operating	O
system	O
providing	O
load	B-Application
balancing	I-Application
.	O
</s>
<s>
Unlike	O
the	O
contemporary	O
Sprite	B-Operating_System
,	O
Amoeba	B-Operating_System
does	O
not	O
support	O
process	B-Operating_System
migration	I-Operating_System
.	O
</s>
<s>
The	O
workstations	B-Device
would	O
typically	O
function	O
as	O
networked	O
terminals	B-General_Concept
only	O
.	O
</s>
<s>
Aside	O
from	O
workstations	B-Device
and	O
processors	O
,	O
additional	O
machines	O
operate	O
as	O
servers	O
for	O
files	O
,	O
directory	O
services	O
,	O
TCP/IP	B-Protocol
communications	O
etc	O
.	O
</s>
<s>
Amoeba	B-Operating_System
is	O
a	O
microkernel-based	O
operating	O
system	O
.	O
</s>
<s>
It	O
offers	O
multithreaded	B-Operating_System
programs	O
and	O
a	O
remote	B-Operating_System
procedure	I-Operating_System
call	I-Operating_System
(	O
RPC	O
)	O
mechanism	O
for	O
communication	O
between	O
threads	B-Operating_System
,	O
potentially	O
across	O
the	O
network	O
;	O
even	O
kernel-threads	O
use	O
this	O
RPC	O
mechanism	O
for	O
communication	O
.	O
</s>
<s>
Each	O
thread	B-Operating_System
is	O
assigned	O
a	O
48-bit	O
number	O
called	O
its	O
"	O
port	O
"	O
,	O
which	O
serves	O
as	O
its	O
unique	O
,	O
network-wide	O
"	O
address	O
"	O
for	O
communication	O
.	O
</s>
<s>
The	O
user	O
interface	O
and	O
APIs	B-Application
of	O
Amoeba	B-Operating_System
were	O
modeled	O
after	O
Unix	B-Application
and	O
compliance	O
with	O
the	O
POSIX	O
standard	O
was	O
partially	O
implemented	O
;	O
some	O
of	O
the	O
Unix	B-Application
emulation	O
code	O
consists	O
of	O
utilities	O
ported	O
over	O
from	O
Tanenbaum	O
's	O
other	O
operating	O
system	O
,	O
MINIX	B-Operating_System
.	O
</s>
<s>
Early	O
versions	O
used	O
a	O
"	O
homebrew	O
"	O
window	O
system	O
,	O
which	O
the	O
Amoeba	B-Operating_System
authors	O
considered	O
"	O
faster	O
...	O
in	O
our	O
view	O
,	O
cleaner	O
...	O
smaller	O
and	O
much	O
easier	O
to	O
understand	O
"	O
,	O
but	O
version	O
4.0	O
uses	O
the	O
X	B-Operating_System
Window	I-Operating_System
System	I-Operating_System
(	O
and	O
allows	O
X	B-Protocol
terminals	I-Protocol
as	O
terminals	B-General_Concept
)	O
.	O
</s>
<s>
The	O
system	O
uses	O
FLIP	B-Protocol
as	O
a	O
network	O
protocol	O
.	O
</s>
