<s>
Version	B-Operating_System
7	I-Operating_System
Unix	I-Operating_System
,	O
also	O
called	O
Seventh	B-Operating_System
Edition	I-Operating_System
Unix	I-Operating_System
,	O
Version	B-Operating_System
7	I-Operating_System
or	O
just	O
V7	O
,	O
was	O
an	O
important	O
early	O
release	O
of	O
the	O
Unix	B-Application
operating	I-Application
system	I-Application
.	O
</s>
<s>
V7	O
,	O
released	O
in	O
1979	O
,	O
was	O
the	O
last	O
Bell	O
Laboratories	O
release	O
to	O
see	O
widespread	O
distribution	O
before	O
the	O
commercialization	O
of	O
Unix	B-Application
by	O
AT&T	O
Corporation	O
in	O
the	O
early	O
1980s	O
.	O
</s>
<s>
V7	O
was	O
originally	O
developed	O
for	O
Digital	O
Equipment	O
Corporation	O
's	O
PDP-11	B-Device
minicomputers	B-Architecture
and	O
was	O
later	O
ported	O
to	O
other	O
platforms	O
.	O
</s>
<s>
Unix	B-Application
versions	O
from	O
Bell	O
Labs	O
were	O
designated	O
by	O
the	O
edition	O
of	O
the	O
user	O
's	O
manual	O
with	O
which	O
they	O
were	O
accompanied	O
.	O
</s>
<s>
Released	O
in	O
1979	O
,	O
the	O
Seventh	O
Edition	O
was	O
preceded	O
by	O
Sixth	B-Operating_System
Edition	I-Operating_System
,	O
which	O
was	O
the	O
first	O
version	O
licensed	O
to	O
commercial	O
users	O
.	O
</s>
<s>
Development	O
of	O
the	O
Research	B-Operating_System
Unix	I-Operating_System
line	O
continued	O
with	O
the	O
Eighth	B-Operating_System
Edition	I-Operating_System
,	O
which	O
incorporated	O
development	O
from	O
4.1BSD	B-Operating_System
,	O
through	O
the	O
Tenth	O
Edition	O
,	O
after	O
which	O
the	O
Bell	O
Labs	O
researchers	O
concentrated	O
on	O
developing	O
Plan	B-Operating_System
9	I-Operating_System
.	O
</s>
<s>
V7	O
was	O
the	O
first	O
readily	O
portable	O
version	O
of	O
Unix	B-Application
.	O
</s>
<s>
As	O
this	O
was	O
the	O
era	O
of	O
minicomputers	B-Architecture
,	O
with	O
their	O
many	O
architectural	O
variations	O
,	O
and	O
also	O
the	O
beginning	O
of	O
the	O
market	O
for	O
16-bit	O
microprocessors	O
,	O
many	O
ports	O
were	O
completed	O
within	O
the	O
first	O
few	O
years	O
of	O
its	O
release	O
.	O
</s>
<s>
The	O
first	O
Sun	O
workstations	O
(	O
then	O
based	O
on	O
the	O
Motorola	B-Device
68000	I-Device
)	O
ran	O
a	O
V7	O
port	O
by	O
UniSoft	B-Operating_System
;	O
the	O
first	O
version	O
of	O
Xenix	B-Application
for	O
the	O
Intel	B-General_Concept
8086	I-General_Concept
was	O
derived	O
from	O
V7	O
and	O
Onyx	O
Systems	O
soon	O
produced	O
a	O
Zilog	B-Device
Z8000	I-Device
computer	O
running	O
V7	O
.	O
</s>
<s>
The	O
VAX	B-Device
port	O
of	O
V7	O
,	O
called	O
UNIX/32V	B-Operating_System
,	O
was	O
the	O
direct	O
ancestor	O
of	O
the	O
popular	O
4BSD	B-Operating_System
family	I-Operating_System
of	O
Unix	B-Application
systems	I-Application
.	O
</s>
<s>
The	O
group	O
at	O
the	O
University	O
of	O
Wollongong	O
that	O
had	O
ported	O
V6	O
to	O
the	O
Interdata	B-Device
7/32	I-Device
ported	O
V7	O
to	O
that	O
machine	O
as	O
well	O
.	O
</s>
<s>
Interdata	B-Device
sold	O
the	O
port	O
as	O
Edition	O
VII	O
,	O
making	O
it	O
the	O
first	O
commercial	O
UNIX	B-Application
offering	O
.	O
</s>
<s>
DEC	O
distributed	O
their	O
own	O
PDP-11	B-Device
version	O
of	O
V7	O
,	O
called	O
V7M	O
(	O
for	O
modified	O
)	O
.	O
</s>
<s>
V7M	O
,	O
developed	O
by	O
DEC	O
's	O
original	O
Unix	B-Application
Engineering	O
Group	O
(	O
UEG	O
)	O
,	O
contained	O
many	O
enhancements	O
to	O
the	O
kernel	O
for	O
the	O
PDP-11	B-Device
line	O
of	O
computers	O
including	O
significantly	O
improved	O
hardware	O
error	O
recovery	O
and	O
many	O
additional	O
device	O
drivers	O
.	O
</s>
<s>
UEG	O
evolved	O
into	O
the	O
group	O
that	O
later	O
developed	O
Ultrix	B-Operating_System
.	O
</s>
<s>
Due	O
to	O
its	O
power	O
yet	O
elegant	O
simplicity	O
,	O
many	O
old-time	O
Unix	B-Application
users	O
remember	O
V7	O
as	O
the	O
pinnacle	O
of	O
Unix	B-Application
development	O
and	O
have	O
dubbed	O
it	O
"	O
the	O
last	O
true	O
Unix	B-Application
"	O
,	O
an	O
improvement	O
over	O
all	O
preceding	O
and	O
following	O
Unices	O
.	O
</s>
<s>
The	O
number	O
of	O
system	B-Operating_System
calls	I-Operating_System
in	O
Version	B-Operating_System
7	I-Operating_System
was	O
only	O
around	O
50	O
,	O
while	O
later	O
Unix	B-Application
and	O
Unix-like	O
systems	O
continued	O
to	O
add	O
many	O
more	O
:	O
</s>
<s>
In	O
2002	O
,	O
Caldera	O
International	O
released	O
V7	O
as	O
FOSS	B-Application
under	O
a	O
permissive	B-License
BSD-like	B-Operating_System
software	B-License
license	I-License
.	O
</s>
<s>
Bootable	O
images	O
for	O
V7	O
can	O
still	O
be	O
today	O
,	O
and	O
can	O
be	O
run	O
on	O
modern	O
hosts	O
using	O
PDP-11	B-Device
emulators	O
such	O
as	O
SIMH	B-Application
.	O
</s>
<s>
An	O
x86	B-Operating_System
port	O
has	O
been	O
developed	O
by	O
Nordier	O
&	O
Associates	O
.	O
</s>
<s>
Paul	O
Allen	O
maintained	O
several	O
publicly	O
accessible	O
historic	O
computer	O
systems	O
,	O
including	O
a	O
PDP-11/70	B-Device
running	O
Unix	B-Operating_System
Version	I-Operating_System
7	I-Operating_System
.	O
</s>
<s>
Many	O
new	O
features	O
were	O
introduced	O
in	O
Version	B-Operating_System
7	I-Operating_System
.	O
</s>
<s>
Programming	O
tools	O
:	O
lex	B-General_Concept
,	O
lint	B-Device
,	O
and	O
make.	O
<	O
p>The	O
Portable	B-Application
C	I-Application
Compiler	I-Application
(	O
pcc	O
)	O
was	O
provided	O
along	O
with	O
the	O
earlier	O
,	O
PDP-11-specific	O
,	O
C	B-Language
compiler	O
by	O
Ritchie.	O
<	O
p>These	O
first	O
appeared	O
in	O
the	O
Research	B-Operating_System
Unix	I-Operating_System
lineage	O
in	O
Version	B-Operating_System
7	I-Operating_System
,	O
although	O
early	O
versions	O
of	O
some	O
of	O
them	O
had	O
already	O
been	O
picked	O
up	O
by	O
PWB/UNIX	B-Operating_System
.	O
</s>
<s>
A	O
feature	O
that	O
did	O
not	O
survive	O
long	O
was	O
a	O
second	O
way	O
(	O
besides	O
pipes	O
)	O
to	O
do	O
inter-process	B-Operating_System
communication	I-Operating_System
:	O
multiplexed	O
files	O
.	O
</s>
<s>
A	O
process	O
could	O
create	O
a	O
special	O
type	O
of	O
file	O
with	O
the	O
mpx	O
system	B-Operating_System
call	I-Operating_System
;	O
other	O
processes	O
could	O
then	O
open	O
this	O
file	O
to	O
get	O
a	O
"	O
channel	O
"	O
,	O
denoted	O
by	O
a	O
file	B-Application
descriptor	I-Application
,	O
which	O
could	O
be	O
used	O
to	O
communicate	O
with	O
the	O
process	O
that	O
created	O
the	O
multiplexed	O
file	O
.	O
</s>
<s>
Mpx	O
files	O
were	O
considered	O
experimental	O
,	O
not	O
enabled	O
in	O
the	O
default	O
kernel	O
,	O
and	O
disappeared	O
from	O
later	O
versions	O
,	O
which	O
offered	O
sockets	B-Protocol
(	O
BSD	B-Operating_System
)	O
or	O
CB	B-Operating_System
UNIX	I-Operating_System
's	O
IPC	O
facilities	O
(	O
System	O
V	O
)	O
instead	O
(	O
although	O
mpx	O
files	O
were	O
still	O
present	O
in	O
4.1BSD	B-Operating_System
)	O
.	O
</s>
