<s>
The	O
V	B-Operating_System
operating	B-General_Concept
system	I-General_Concept
(	O
sometimes	O
written	O
V-System	B-Operating_System
)	O
is	O
a	O
discontinued	O
microkernel	B-Operating_System
distributed	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
that	O
was	O
developed	O
by	O
faculty	O
and	O
students	O
in	O
the	O
Distributed	B-Architecture
Systems	I-Architecture
Group	O
at	O
Stanford	O
University	O
from	O
1981	O
to	O
1988	O
,	O
led	O
by	O
Professors	O
David	O
Cheriton	O
and	O
Keith	O
A	O
.	O
Lantz	O
.	O
</s>
<s>
V	B-Operating_System
was	O
the	O
successor	O
to	O
the	O
Thoth	B-Operating_System
operating	B-General_Concept
system	I-General_Concept
and	O
Verex	O
kernel	B-Operating_System
that	O
Cheriton	O
had	O
developed	O
in	O
the	O
1970s	O
.	O
</s>
<s>
Despite	O
similar	O
names	O
and	O
close	O
development	O
dates	O
,	O
it	O
is	O
unrelated	O
to	O
UNIX	B-Operating_System
System	I-Operating_System
V	I-Operating_System
.	O
</s>
<s>
The	O
key	O
concepts	O
in	O
V	B-Operating_System
are	O
multithreading	B-Operating_System
and	O
synchronous	O
message	B-Architecture
passing	I-Architecture
.	O
</s>
<s>
The	O
original	O
V	B-Operating_System
terminology	O
uses	O
process	B-Operating_System
for	O
what	O
is	O
now	O
commonly	O
called	O
a	O
thread	B-Operating_System
,	O
and	O
team	O
for	O
what	O
is	O
now	O
commonly	O
called	O
a	O
process	B-Operating_System
consisting	O
of	O
multiple	O
threads	B-Operating_System
sharing	O
an	O
address	O
space	O
.	O
</s>
<s>
Communication	O
between	O
threads	B-Operating_System
in	O
V	B-Operating_System
uses	O
synchronous	O
message	B-Architecture
passing	I-Architecture
,	O
with	O
short	O
,	O
fixed-length	O
messages	O
that	O
can	O
include	O
access	O
rights	O
for	O
the	O
receiver	O
to	O
read	O
or	O
write	O
part	O
of	O
the	O
sender	O
's	O
address	O
space	O
before	O
replying	O
.	O
</s>
<s>
The	O
same	O
message-passing	B-Architecture
interface	O
is	O
used	O
both	O
between	O
threads	B-Operating_System
within	O
one	O
process	B-Operating_System
,	O
between	O
threads	B-Operating_System
of	O
different	O
processes	O
within	O
one	O
machine	O
,	O
and	O
between	O
threads	B-Operating_System
on	O
different	O
machines	O
connected	O
by	O
a	O
local	O
Ethernet	O
.	O
</s>
<s>
A	O
thread	B-Operating_System
receiving	O
a	O
message	O
is	O
not	O
required	O
to	O
reply	O
to	O
it	O
before	O
receiving	O
other	O
messages	O
;	O
this	O
distinguished	O
the	O
model	O
from	O
Ada	B-Language
rendezvous	O
.	O
</s>
<s>
From	O
the	O
client	O
side	O
,	O
this	O
looks	O
much	O
like	O
a	O
remote	B-Operating_System
procedure	I-Operating_System
call	I-Operating_System
(	O
RPC	O
)	O
.	O
</s>
<s>
From	O
the	O
server	O
side	O
the	O
model	O
differs	O
more	O
from	O
RPC	O
,	O
since	O
by	O
default	O
all	O
client	O
requests	O
are	O
multiplexed	O
onto	O
one	O
server	O
thread	B-Operating_System
.	O
</s>
<s>
The	O
server	O
is	O
free	O
to	O
explicitly	O
fork	O
threads	B-Operating_System
to	O
handle	O
client	O
requests	O
in	O
parallel	O
,	O
however	O
;	O
if	O
this	O
is	O
done	O
,	O
the	O
server-side	O
model	O
is	O
much	O
like	O
RPC	O
too	O
.	O
</s>
<s>
V	B-Operating_System
was	O
never	O
an	O
end	O
in	O
itself	O
for	O
the	O
Stanford	O
group	O
;	O
rather	O
,	O
it	O
was	O
used	O
as	O
a	O
vehicle	O
for	O
many	O
different	O
research	O
projects	O
in	O
distributed	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
and	O
networking	O
.	O
</s>
<s>
Much	O
like	O
other	O
operating	B-General_Concept
system	I-General_Concept
efforts	O
of	O
its	O
day	O
(	O
such	O
as	O
Sprite	B-Operating_System
)	O
,	O
V	B-Operating_System
was	O
a	O
complete	O
system	O
that	O
was	O
mostly	O
self	O
hosting	O
.	O
</s>
<s>
Many	O
students	O
ran	O
V	B-Operating_System
as	O
the	O
only	O
operating	B-General_Concept
system	I-General_Concept
on	O
their	O
diskless	O
SUN	B-Device
workstations	I-Device
or	O
MicroVAX	B-Device
workstations	B-Device
.	O
</s>
<s>
Compiles	O
could	O
be	O
done	O
either	O
on	O
V	B-Operating_System
,	O
or	O
on	O
VAX	B-Device
Unix	B-Application
machines	O
that	O
provided	O
file	O
service	O
in	O
a	O
more	O
stable	O
environment	O
than	O
the	O
ever-changing	O
research	O
system	O
.	O
</s>
<s>
V	B-Operating_System
did	O
have	O
some	O
notable	O
impacts	O
.	O
</s>
<s>
After	O
the	O
initial	O
implementation	O
on	O
one	O
computer	O
,	O
the	O
Versatile	O
Message	O
Transaction	O
Protocol	O
(	O
VMTP	O
)	O
was	O
developed	O
to	O
extend	O
the	O
send-receive-reply	O
system	O
call	O
semantics	O
over	O
a	O
local	B-General_Concept
area	I-General_Concept
network	I-General_Concept
.	O
</s>
<s>
The	O
Internet	B-Protocol
Protocol	I-Protocol
layer	O
to	O
support	O
this	O
evolved	O
into	O
the	O
IP	B-Protocol
multicast	I-Protocol
standard	O
.	O
</s>
<s>
The	O
V	B-Operating_System
system	O
was	O
used	O
for	O
graphical	B-Application
user	I-Application
interface	I-Application
(	O
GUI	B-Application
)	O
research	O
.	O
</s>
<s>
The	O
Virtual	O
Graphics	O
Terminal	O
Service	O
(	O
VGTS	O
)	O
provided	O
a	O
modular	O
windowing	B-Application
system	I-Application
for	O
both	O
local	O
and	O
remote	O
applications	O
.	O
</s>
<s>
The	O
little-known	O
W	B-Application
Window	I-Application
System	I-Application
got	O
its	O
name	O
because	O
it	O
was	O
first	O
hosted	O
on	O
the	O
V	B-Operating_System
operating	B-General_Concept
system	I-General_Concept
,	O
and	O
the	O
better-known	O
X	B-Operating_System
Window	I-Operating_System
System	I-Operating_System
in	O
turn	O
got	O
its	O
name	O
because	O
its	O
first	O
version	O
was	O
based	O
partly	O
on	O
W	O
.	O
V	B-Operating_System
also	O
spawned	O
another	O
pure	O
microkernel	B-Operating_System
effort	O
at	O
Apple	O
Computer	O
known	O
as	O
Vanguard	B-Operating_System
,	O
which	O
added	O
a	O
number	O
of	O
improvements	O
to	O
the	O
basic	O
system	O
.	O
</s>
<s>
Vanguard	B-Operating_System
later	O
disappeared	O
in	O
a	O
reorganization	O
.	O
</s>
<s>
The	O
Tektronix	O
VM700	O
television	O
measurement	O
instrument	O
was	O
developed	O
in	O
a	O
networked	O
V	B-Operating_System
environment	O
in	O
the	O
late	O
1980s	O
and	O
ran	O
a	O
lightly	O
modified	O
version	O
of	O
the	O
V	B-Operating_System
operating	B-General_Concept
system	I-General_Concept
;	O
this	O
device	O
was	O
manufactured	O
and	O
sold	O
for	O
many	O
years	O
.	O
</s>
<s>
The	O
following	O
is	O
a	O
list	O
of	O
workstation	B-Device
commands	B-Application
that	O
are	O
supported	O
by	O
the	O
V	B-Operating_System
operating	B-General_Concept
system	I-General_Concept
version	O
6.0	O
command-line	B-Application
interface	I-Application
.	O
</s>
