<s>
The	O
history	B-Operating_System
of	I-Operating_System
Unix	I-Operating_System
dates	O
back	O
to	O
the	O
mid-1960s	O
,	O
when	O
the	O
Massachusetts	O
Institute	O
of	O
Technology	O
,	O
AT&T	O
Bell	O
Labs	O
,	O
and	O
General	O
Electric	O
were	O
jointly	O
developing	O
an	O
experimental	O
time-sharing	B-General_Concept
operating	I-General_Concept
system	I-General_Concept
called	O
Multics	B-Application
for	O
the	O
GE-645	B-Device
mainframe	B-Architecture
.	O
</s>
<s>
Multics	B-Application
introduced	O
many	O
innovations	O
,	O
but	O
also	O
had	O
many	O
problems	O
.	O
</s>
<s>
Bell	O
Labs	O
,	O
frustrated	O
by	O
the	O
size	O
and	O
complexity	O
of	O
Multics	B-Application
but	O
not	O
its	B-Application
aims	O
,	O
slowly	O
pulled	O
out	O
of	O
the	O
project	O
.	O
</s>
<s>
Their	O
last	O
researchers	O
to	O
leave	O
Multics	B-Application
–	O
among	O
them	O
Ken	O
Thompson	O
,	O
Dennis	O
Ritchie	O
,	O
Doug	O
McIlroy	O
,	O
and	O
Joe	O
Ossanna	O
–	O
decided	O
to	O
redo	O
the	O
work	O
,	O
but	O
on	O
a	O
much	O
smaller	O
scale	O
.	O
</s>
<s>
In	O
1979	O
,	O
Ritchie	O
described	O
the	O
group	O
's	O
vision	O
for	O
Unix	B-Application
:	O
</s>
<s>
In	O
the	O
late	O
1960s	O
,	O
Bell	O
Labs	O
was	O
involved	O
in	O
a	O
project	O
with	O
MIT	O
and	O
General	O
Electric	O
to	O
develop	O
a	O
time-sharing	B-General_Concept
system	I-General_Concept
,	O
called	O
Multiplexed	B-Application
Information	I-Application
and	I-Application
Computing	I-Application
Service	I-Application
(	O
Multics	B-Application
)	O
,	O
allowing	O
multiple	O
users	O
to	O
access	O
a	O
mainframe	B-Architecture
simultaneously	O
.	O
</s>
<s>
Ken	O
Thompson	O
,	O
a	O
programmer	O
in	O
the	O
Labs	O
 '	O
computing	O
research	O
department	O
,	O
had	O
worked	O
on	O
Multics	B-Application
.	O
</s>
<s>
While	O
he	O
still	O
had	O
access	O
to	O
the	O
Multics	B-Application
environment	O
,	O
he	O
wrote	O
simulations	O
for	O
the	O
new	O
file	O
and	O
paging	O
system	O
on	O
it	O
.	O
</s>
<s>
He	O
also	O
programmed	O
a	O
game	O
called	O
Space	B-Application
Travel	I-Application
,	O
but	O
it	O
needed	O
a	O
more	O
efficient	O
and	O
less	O
expensive	O
machine	O
to	O
run	O
on	O
,	O
and	O
eventually	O
he	O
found	O
a	O
little-used	O
Digital	O
Equipment	O
Corporation	O
PDP-7	B-Device
at	O
Bell	O
Labs	O
.	O
</s>
<s>
On	O
the	O
PDP-7	B-Device
,	O
in	O
1969	O
,	O
a	O
team	O
of	O
Bell	O
Labs	O
researchers	O
led	O
by	O
Thompson	O
and	O
Ritchie	O
,	O
including	O
Rudd	O
Canaday	O
,	O
implemented	O
a	O
hierarchical	O
file	O
system	O
,	O
the	O
concepts	O
of	O
computer	B-Operating_System
processes	I-Operating_System
and	O
device	B-Application
files	I-Application
,	O
a	O
command-line	B-Application
interpreter	O
,	O
and	O
some	O
small	O
utility	O
programs	O
,	O
modeled	O
on	O
the	O
corresponding	O
features	O
in	O
Multics	B-Application
,	O
but	O
simplified	O
.	O
</s>
<s>
The	O
resulting	O
system	O
,	O
much	O
smaller	O
and	O
simpler	O
than	O
Multics	B-Application
,	O
was	O
to	O
become	O
Unix	B-Application
.	O
</s>
<s>
In	O
about	O
a	O
month	O
's	O
time	O
,	O
in	O
August	O
1969	O
,	O
Thompson	O
had	O
implemented	O
a	O
self-hosting	O
operating	O
system	O
with	O
an	O
assembler	B-Language
,	O
editor	B-Application
and	O
shell	B-Operating_System
,	O
using	O
a	O
GECOS	B-Application
machine	O
for	O
bootstrapping	B-Application
.	O
</s>
<s>
Douglas	O
McIlroy	O
then	O
ported	O
TMG	B-Application
compiler-compiler	O
to	O
PDP-7	B-Device
assembly	O
,	O
creating	O
the	O
first	O
high-level	B-Language
language	I-Language
running	O
on	O
Unix	B-Application
.	O
</s>
<s>
Thompson	O
used	O
this	O
tool	O
to	O
develop	O
the	O
first	O
version	O
of	O
his	O
B	B-Language
programming	I-Language
language	I-Language
.	O
</s>
<s>
At	O
this	O
stage	O
,	O
the	O
new	O
operating	O
system	O
was	O
a	O
singletasking	O
operating	O
system	O
,	O
not	O
a	O
multitasking	O
one	O
such	O
as	O
Multics	B-Application
.	O
</s>
<s>
The	O
name	O
Unics	O
(	O
Uniplexed	O
Information	O
and	O
Computing	O
Service	O
,	O
pronounced	O
as	O
"	O
eunuchs	O
"	O
)	O
,	O
a	O
pun	O
on	O
Multics	B-Application
(	O
Multiplexed	O
Information	O
and	O
Computer	O
Services	O
)	O
,	O
was	O
initially	O
suggested	O
for	O
the	O
project	O
in	O
1970	O
.	O
</s>
<s>
Brian	O
Kernighan	O
claims	O
the	O
coining	O
for	O
himself	O
,	O
and	O
adds	O
that	O
"	O
no	O
one	O
can	O
remember	O
"	O
who	O
came	O
up	O
with	O
the	O
final	O
spelling	O
Unix	B-Application
.	O
</s>
<s>
When	O
the	O
Computing	O
Sciences	O
Research	O
Center	O
wanted	O
to	O
use	O
Unix	B-Application
on	O
a	O
machine	O
larger	O
than	O
the	O
PDP-7	B-Device
,	O
while	O
another	O
department	O
needed	O
a	O
word	B-General_Concept
processor	I-General_Concept
,	O
Thompson	O
and	O
Ritchie	O
added	O
text	O
processing	O
capabilities	O
to	O
Unix	B-Application
and	O
received	O
funding	O
for	O
a	O
PDP-11	B-Device
.	O
</s>
<s>
For	O
the	O
first	O
time	O
in	O
1970	O
,	O
the	O
Unix	B-Application
operating	I-Application
system	I-Application
was	O
officially	O
named	O
and	O
ran	O
on	O
the	O
PDP-11	B-Device
.	O
</s>
<s>
A	O
text-formatting	O
program	O
called	O
roff	O
and	O
a	O
text	B-Application
editor	I-Application
were	O
added	O
.	O
</s>
<s>
All	O
three	O
were	O
written	O
in	O
PDP-11	B-Device
assembly	B-Language
language	I-Language
.	O
</s>
<s>
Bell	O
Labs	O
used	O
this	O
initial	O
text-processing	O
system	O
,	O
consisting	O
of	O
Unix	B-Application
,	O
roff	O
,	O
and	O
the	O
editor	B-Application
,	O
for	O
text	O
processing	O
of	O
patent	O
applications	O
.	O
</s>
<s>
Roff	O
soon	O
evolved	O
into	O
troff	B-Language
,	O
the	O
first	O
electronic	O
publishing	O
program	O
with	O
full	O
typesetting	O
capability	O
.	O
</s>
<s>
The	O
UNIX	B-Protocol
Programmer	I-Protocol
's	I-Protocol
Manual	I-Protocol
was	O
published	O
on	O
3	O
November	O
1971	O
;	O
commands	O
were	O
documented	O
in	O
the	O
"	O
man	B-Protocol
page	I-Protocol
"	O
format	O
that	O
is	O
still	O
used	O
,	O
offering	O
terse	O
reference	O
information	O
about	O
usage	O
as	O
well	O
as	O
bugs	O
in	O
the	O
software	O
,	O
and	O
listing	O
the	O
authors	O
of	O
programs	O
to	O
channel	O
questions	O
to	O
them	O
.	O
</s>
<s>
After	O
other	O
Bell	O
Labs	O
departments	O
purchased	O
DEC	B-Device
PDP-11s	I-Device
,	O
they	O
also	O
chose	O
to	O
run	O
Unix	B-Application
instead	O
of	O
DEC	O
's	O
own	O
operating	O
system	O
.	O
</s>
<s>
By	O
Version	O
4	O
it	O
was	O
widely	O
used	O
within	O
the	O
laboratory	O
and	O
a	O
Unix	B-Application
Support	O
Group	O
was	O
formed	O
,	O
helping	O
the	O
operating	O
system	O
survive	O
by	O
formalizing	O
its	B-Application
distribution	O
.	O
</s>
<s>
In	O
1973	O
,	O
Version	B-Operating_System
4	I-Operating_System
Unix	I-Operating_System
was	O
rewritten	O
in	O
the	O
higher-level	B-Language
language	I-Language
C	B-Language
,	O
contrary	O
to	O
the	O
general	O
notion	O
at	O
the	O
time	O
that	O
an	O
operating	O
system	O
's	O
complexity	O
and	O
sophistication	O
required	O
it	O
to	O
be	O
written	O
in	O
assembly	B-Language
language	I-Language
.	O
</s>
<s>
The	O
C	B-Language
language	I-Language
appeared	O
as	O
part	O
of	O
Version	B-Operating_System
2	I-Operating_System
.	O
</s>
<s>
Thompson	O
and	O
Ritchie	O
were	O
so	O
influential	O
on	O
early	O
Unix	B-Application
that	O
McIlroy	O
estimated	O
that	O
they	O
wrote	O
and	O
debugged	O
about	O
100,000	O
lines	O
of	O
code	O
that	O
year	O
,	O
stating	O
that	O
"	O
[	O
their	O
names ]	O
may	O
safely	O
be	O
assumed	O
to	O
be	O
attached	O
to	O
almost	O
everything	O
not	O
otherwise	O
attributed	O
"	O
.	O
</s>
<s>
Although	O
assembly	O
did	O
not	O
disappear	O
from	O
the	O
man	B-Protocol
pages	I-Protocol
until	O
Version	B-Operating_System
8	I-Operating_System
,	O
the	O
migration	O
to	O
C	B-Language
suggested	O
portability	O
of	O
the	O
software	O
,	O
requiring	O
only	O
a	O
relatively	O
small	O
amount	O
of	O
machine-dependent	O
code	O
to	O
be	O
replaced	O
when	O
porting	O
Unix	B-Application
to	O
other	O
computing	B-Device
platforms	I-Device
.	O
</s>
<s>
Version	B-Operating_System
4	I-Operating_System
Unix	I-Operating_System
,	O
however	O
,	O
still	O
had	O
considerable	O
PDP-11-dependent	O
code	O
and	O
was	O
not	O
suitable	O
for	O
porting	O
.	O
</s>
<s>
The	O
first	O
port	O
to	O
other	O
platform	O
was	O
made	O
five	O
years	O
later	O
(	O
1978	O
)	O
for	O
Interdata	B-Device
8/32	I-Device
.	O
</s>
<s>
The	O
Unix	B-Application
operating	I-Application
system	I-Application
was	O
first	O
presented	O
formally	O
to	O
the	O
outside	O
world	O
at	O
the	O
1973	O
Symposium	O
on	O
Operating	O
Systems	O
Principles	O
,	O
where	O
Ritchie	O
and	O
Thompson	O
delivered	O
a	O
paper	O
.	O
</s>
<s>
Unix	B-Application
could	O
not	O
,	O
therefore	O
,	O
be	O
turned	O
into	O
a	O
product	O
.	O
</s>
<s>
In	O
1973	O
,	O
AT&T	O
released	O
Version	B-Operating_System
5	I-Operating_System
Unix	I-Operating_System
and	O
licensed	O
it	O
to	O
educational	O
institutions	O
,	O
and	O
licensed	O
1975	O
's	O
Version	B-Operating_System
6	I-Operating_System
to	O
companies	O
for	O
the	O
first	O
time	O
.	O
</s>
<s>
The	O
licenses	O
also	O
included	O
the	O
machine-dependent	O
parts	O
of	O
the	O
kernel	B-Operating_System
,	O
written	O
in	O
PDP-11	B-Device
assembly	B-Language
language	I-Language
.	O
</s>
<s>
Copies	O
of	O
the	O
Lions	O
 '	O
Commentary	O
on	O
UNIX	B-Application
6th	O
Edition	O
,	O
with	O
Source	O
Code	O
circulated	O
widely	O
,	O
which	O
led	O
to	O
considerable	O
use	O
of	O
Unix	B-Application
as	O
an	O
educational	O
example	O
.	O
</s>
<s>
The	O
first	O
meeting	O
of	O
Unix	B-Application
users	O
took	O
place	O
in	O
New	O
York	O
in	O
1974	O
,	O
attracting	O
a	O
few	O
dozen	O
people	O
;	O
this	O
would	O
later	O
grow	O
into	O
the	O
USENIX	B-Operating_System
organization	O
.	O
</s>
<s>
The	O
importance	O
of	O
the	O
user	O
group	O
stemmed	O
from	O
the	O
fact	O
that	O
Unix	B-Application
was	O
entirely	O
unsupported	O
by	O
AT&T	O
.	O
</s>
<s>
Versions	O
of	O
the	O
Unix	B-Application
system	I-Application
were	O
determined	O
by	O
editions	O
of	O
its	B-Application
user	O
manuals	O
;	O
for	O
example	O
,	O
"	O
Fifth	O
Edition	O
UNIX	B-Application
"	O
and	O
"	O
UNIX	B-Application
Version	O
5	O
"	O
have	O
both	O
been	O
used	O
to	O
designate	O
the	O
same	O
version	O
.	O
</s>
<s>
Version	O
5	O
,	O
and	O
especially	O
Version	B-Operating_System
6	I-Operating_System
,	O
led	O
to	O
a	O
plethora	O
of	O
different	O
Unix	B-Application
versions	O
both	O
inside	O
and	O
outside	O
Bell	O
Labs	O
,	O
including	O
PWB/UNIX	B-Operating_System
and	O
the	O
first	O
commercial	O
Unix	B-Application
,	O
IS/1	B-Operating_System
.	O
</s>
<s>
Unix	B-Application
still	O
only	O
ran	O
on	O
DEC	O
systems	O
.	O
</s>
<s>
As	O
more	O
of	O
the	O
operating	O
system	O
was	O
rewritten	O
in	O
C	B-Language
(	O
and	O
the	O
C	B-Language
language	I-Language
extended	O
to	O
accommodate	O
this	O
)	O
,	O
portability	O
also	O
increased	O
;	O
in	O
1977	O
,	O
Bell	O
Labs	O
procured	O
an	O
Interdata	B-Device
8/32	I-Device
with	O
the	O
aim	O
of	O
porting	O
Unix	B-Application
to	O
a	O
computer	O
that	O
was	O
as	O
different	O
from	O
the	O
PDP-11	B-Device
as	O
possible	O
,	O
making	O
the	O
operating	O
system	O
more	O
machine-independent	O
in	O
the	O
process	O
.	O
</s>
<s>
Unix	B-Application
next	O
ran	O
as	O
a	O
guest	B-General_Concept
operating	I-General_Concept
system	I-General_Concept
inside	O
a	O
VM/370	B-Application
hypervisor	O
at	O
Princeton	O
.	O
</s>
<s>
Simultaneously	O
,	O
a	O
group	O
at	O
the	O
University	O
of	O
Wollongong	O
ported	O
Unix	B-Application
to	O
the	O
similar	O
Interdata	B-Device
7/32	I-Device
.	O
</s>
<s>
Target	O
machines	O
of	O
further	O
Bell	O
Labs	O
ports	O
for	O
research	O
and	O
AT&	O
T-internal	O
use	O
included	O
an	O
Intel	O
8086-based	O
computer	O
(	O
with	O
custom-built	O
MMU	B-General_Concept
)	O
and	O
the	O
UNIVAC	O
1100	O
.	O
</s>
<s>
In	O
May	O
1975	O
,	O
ARPA	O
documented	O
the	O
benefits	O
of	O
the	O
Unix	B-Application
time-sharing	B-General_Concept
system	I-General_Concept
which	O
"	O
presents	O
several	O
interesting	O
capabilities	O
"	O
as	O
an	O
ARPA	O
network	B-Architecture
mini-host	O
in	O
RFC	O
681	O
.	O
</s>
<s>
In	O
1978	O
,	O
UNIX/32V	B-Operating_System
was	O
released	O
for	O
DEC	O
's	O
then	O
new	O
VAX	B-Device
system	O
.	O
</s>
<s>
By	O
this	O
time	O
,	O
over	O
600	O
machines	O
were	O
running	O
Unix	B-Application
in	O
some	O
form	O
.	O
</s>
<s>
Version	B-Operating_System
7	I-Operating_System
Unix	I-Operating_System
,	O
the	O
last	O
version	O
of	O
Research	B-Operating_System
Unix	I-Operating_System
to	O
be	O
released	O
widely	O
,	O
was	O
released	O
in	O
1979	O
.	O
</s>
<s>
In	O
Version	B-Operating_System
7	I-Operating_System
,	O
the	O
number	O
of	O
system	B-Operating_System
calls	I-Operating_System
was	O
only	O
around	O
50	O
,	O
although	O
later	O
Unix	B-Application
and	O
Unix-like	B-Operating_System
systems	I-Operating_System
would	O
add	O
many	O
more	O
:	O
</s>
<s>
A	O
microprocessor	O
port	O
of	O
Unix	B-Application
,	O
to	O
the	O
LSI-11	O
,	O
was	O
completed	O
in	O
1978	O
,	O
and	O
an	O
Intel	B-General_Concept
8086	I-General_Concept
version	O
was	O
reported	O
to	O
be	O
"	O
in	O
progress	O
"	O
the	O
same	O
year	O
.	O
</s>
<s>
The	O
first	O
microcomputer	O
versions	O
of	O
Unix	B-Application
,	O
and	O
Unix-like	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
like	O
Whitesmiths	O
 '	O
Idris	B-Operating_System
,	O
appeared	O
in	O
the	O
late	O
1970s	O
.	O
</s>
<s>
Bell	O
developed	O
multiple	O
versions	O
of	O
Unix	B-Application
for	O
internal	O
use	O
,	O
such	O
as	O
CB	B-Operating_System
UNIX	I-Operating_System
(	O
with	O
improved	O
support	O
for	O
databases	O
)	O
and	O
PWB/UNIX	B-Operating_System
,	O
the	O
"	O
Programmer	O
's	O
Workbench	O
"	O
,	O
aimed	O
at	O
large	O
groups	O
of	O
programmers	O
.	O
</s>
<s>
It	O
advertised	O
the	O
latter	O
version	O
,	O
as	O
well	O
as	O
32V	B-Operating_System
and	O
V7	O
,	O
stating	O
that	O
"	O
more	O
than	O
800	O
systems	O
are	O
already	O
in	O
use	O
outside	O
the	O
Bell	O
System	O
"	O
in	O
1980	O
,	O
and	O
"	O
more	O
than	O
2000	O
"	O
the	O
following	O
year	O
.	O
</s>
<s>
Research	B-Operating_System
Unix	I-Operating_System
versions	O
8	B-Operating_System
,	O
9	B-Operating_System
,	O
and	O
10	B-Operating_System
were	O
developed	O
through	O
the	O
1980s	O
but	O
were	O
only	O
released	O
to	O
a	O
few	O
universities	O
,	O
though	O
they	O
did	O
generate	O
papers	O
describing	O
the	O
new	O
work	O
.	O
</s>
<s>
This	O
research	O
focus	O
then	O
shifted	O
to	O
the	O
development	O
of	O
Plan	B-Operating_System
9	I-Operating_System
from	I-Operating_System
Bell	I-Operating_System
Labs	I-Operating_System
,	O
a	O
new	O
portable	O
distributed	O
system	O
.	O
</s>
<s>
Because	O
the	O
company	O
widely	O
and	O
inexpensively	O
licensed	O
Unix	B-Application
,	O
by	O
the	O
early	O
1980s	O
thousands	O
of	O
people	O
used	O
Unix	B-Application
at	O
AT&T	O
and	O
elsewhere	O
,	O
and	O
as	O
computer	O
science	O
students	O
moved	O
from	O
universities	O
into	O
companies	O
they	O
wanted	O
to	O
continue	O
to	O
use	O
it	O
.	O
</s>
<s>
Observers	O
began	O
to	O
see	O
Unix	B-Application
as	O
a	O
potential	O
universal	O
operating	O
system	O
,	O
suitable	O
for	O
all	O
computers	O
.	O
</s>
<s>
Less	O
than	O
20,000	O
lines	O
of	O
code	O
almost	O
all	O
in	O
C	B-Language
composed	O
the	O
Unix	B-Application
kernel	B-Operating_System
as	O
of	O
1983	O
,	O
and	O
more	O
than	O
75%	O
was	O
not	O
machine-dependent	O
.	O
</s>
<s>
By	O
that	O
year	O
Unix	B-Application
or	O
a	O
Unix-like	B-Operating_System
system	I-Operating_System
was	O
available	O
for	O
at	O
least	O
16	O
different	O
processors	O
and	O
architectures	O
from	O
about	O
60	O
vendors	O
;	O
BYTE	O
noted	O
that	O
computer	O
companies	O
"	O
may	O
support	O
other	O
 [ operating ] 	O
systems	O
,	O
but	O
a	O
Unix	B-Application
implementation	O
always	O
happens	O
to	O
be	O
available	O
"	O
,	O
and	O
that	O
DEC	O
and	O
IBM	O
supported	O
Unix	B-Application
as	O
an	O
alternative	O
to	O
their	O
proprietary	B-Application
operating	O
systems	O
.	O
</s>
<s>
Microcomputer	O
Unix	B-Application
became	O
commercially	O
available	O
in	O
1980	O
,	O
when	O
Onyx	O
Systems	O
released	O
its	B-Application
Zilog	O
Z8000-based	O
C8002	O
and	O
Microsoft	O
announced	O
its	B-Application
first	O
Unix	B-Application
for	O
16-bit	B-Device
microcomputers	O
called	O
Xenix	B-Application
,	O
which	O
the	O
Santa	O
Cruz	O
Operation	O
(	O
SCO	O
)	O
ported	O
to	O
the	O
8086	B-General_Concept
processor	O
in	O
1983	O
.	O
</s>
<s>
Other	O
companies	O
began	O
to	O
offer	O
commercial	O
versions	O
of	O
Unix	B-Application
for	O
their	O
own	O
minicomputers	O
and	O
workstations	B-Device
.	O
</s>
<s>
Many	O
of	O
these	O
new	O
Unix	B-Application
flavors	O
were	O
developed	O
from	O
the	O
System	B-Operating_System
V	I-Operating_System
base	O
under	O
a	O
license	O
from	O
AT&T	O
;	O
others	O
were	O
based	O
on	O
BSD	B-Operating_System
.	O
</s>
<s>
One	O
of	O
the	O
leading	O
developers	O
of	O
BSD	B-Operating_System
,	O
Bill	O
Joy	O
,	O
went	O
on	O
to	O
co-found	O
Sun	O
Microsystems	O
in	O
1982	O
and	O
created	O
SunOS	B-Operating_System
for	O
its	B-Application
workstations	B-Device
.	O
</s>
<s>
AT&T	O
announced	O
UNIX	B-Operating_System
System	I-Operating_System
III	I-Operating_System
based	O
on	O
Version	B-Operating_System
7	I-Operating_System
,	O
and	O
PWB	O
in	O
1981	O
.	O
</s>
<s>
Licensees	O
could	O
sell	O
binary	O
sublicenses	O
for	O
as	O
little	O
as	O
,	O
which	O
observers	O
believed	O
indicated	O
that	O
AT&T	O
now	O
viewed	O
Unix	B-Application
as	O
a	O
commercial	O
product	O
.	O
</s>
<s>
This	O
also	O
included	O
support	O
for	O
the	O
VAX	B-Device
.	O
</s>
<s>
AT&T	O
continued	O
to	O
issue	O
licenses	O
for	O
older	O
Unix	B-Application
versions	O
.	O
</s>
<s>
To	O
end	O
the	O
confusion	O
between	O
all	O
its	B-Application
differing	O
internal	O
versions	O
,	O
AT&T	O
combined	O
them	O
into	O
UNIX	B-Operating_System
System	I-Operating_System
V	I-Operating_System
Release	O
1	O
.	O
</s>
<s>
This	O
introduced	O
a	O
few	O
features	O
such	O
as	O
the	O
vi	B-Application
editor	I-Application
and	O
curses	B-Device
from	O
the	O
Berkeley	B-Operating_System
Software	I-Operating_System
Distribution	I-Operating_System
of	O
Unix	B-Application
developed	O
at	O
the	O
University	O
of	O
California	O
,	O
Berkeley	O
Computer	B-Operating_System
Systems	I-Operating_System
Research	I-Operating_System
Group	I-Operating_System
.	O
</s>
<s>
This	O
also	O
included	O
support	O
for	O
the	O
Western	O
Electric	O
3B	B-Device
series	I-Device
computers	I-Device
.	O
</s>
<s>
AT&T	O
provided	O
support	O
for	O
System	B-Operating_System
III	I-Operating_System
and	O
System	B-Operating_System
V	I-Operating_System
through	O
the	O
Unix	B-Application
Support	O
Group	O
(	O
USG	O
)	O
,	O
and	O
these	O
systems	O
were	O
sometimes	O
referred	O
to	O
as	O
USG	O
Unix	B-Application
.	O
</s>
<s>
In	O
1983	O
,	O
the	O
U.S.	O
Department	O
of	O
Justice	O
settled	O
its	B-Application
second	O
antitrust	O
case	O
against	O
AT&T	O
,	O
causing	O
the	O
breakup	O
of	O
the	O
Bell	O
System	O
.	O
</s>
<s>
This	O
relieved	O
AT&T	O
of	O
the	O
1956	O
consent	O
decree	O
that	O
had	O
prevented	O
the	O
company	O
from	O
commercializing	O
Unix	B-Application
.	O
</s>
<s>
AT&T	O
promptly	O
introduced	O
Unix	B-Operating_System
System	I-Operating_System
V	I-Operating_System
into	O
the	O
market	O
.	O
</s>
<s>
The	O
newly	O
created	O
competition	O
nearly	O
destroyed	O
the	O
long-term	O
viability	O
of	O
Unix	B-Application
,	O
because	O
it	O
stifled	O
the	O
free	O
exchanging	O
of	O
source	O
code	O
and	O
led	O
to	O
fragmentation	O
and	O
incompatibility	O
.	O
</s>
<s>
The	B-Application
GNU	I-Application
Project	I-Application
was	O
founded	O
in	O
the	O
same	O
year	O
by	O
Richard	O
Stallman	O
.	O
</s>
<s>
Since	O
the	O
newer	O
commercial	O
UNIX	B-Application
licensing	O
terms	O
were	O
not	O
as	O
favorable	O
for	O
academic	O
use	O
as	O
the	O
older	O
versions	O
of	O
Unix	B-Application
,	O
the	O
Berkeley	O
researchers	O
continued	O
to	O
develop	O
BSD	B-Operating_System
as	O
an	O
alternative	O
to	O
UNIX	B-Operating_System
System	I-Operating_System
III	I-Operating_System
and	O
V	O
.	O
Many	O
contributions	O
to	O
Unix	B-Application
first	O
appeared	O
in	O
BSD	B-Operating_System
releases	O
,	O
notably	O
the	O
C	B-Operating_System
shell	I-Operating_System
with	O
job	B-Operating_System
control	I-Operating_System
(	O
modelled	O
on	O
ITS	B-Application
)	O
.	O
</s>
<s>
Perhaps	O
the	O
most	O
important	O
aspect	O
of	O
the	O
BSD	B-Operating_System
development	O
effort	O
was	O
the	O
addition	O
of	O
TCP/IP	B-Protocol
network	I-Protocol
code	O
to	O
the	O
mainstream	O
Unix	B-Application
kernel	B-Operating_System
.	O
</s>
<s>
The	O
BSD	B-Operating_System
effort	O
produced	O
several	O
significant	O
releases	O
that	O
contained	O
network	B-Architecture
code	O
:	O
4.1cBSD	O
,	O
4.2BSD	O
,	O
4.3BSD	O
,	O
4.3BSD-Tahoe	O
(	O
"	O
Tahoe	O
"	O
being	O
the	O
nickname	O
of	O
the	O
Computer	O
Consoles	O
Inc	O
.	O
Power	O
6/32	O
architecture	O
that	O
was	O
the	O
first	O
non-DEC	O
release	O
of	O
the	O
BSD	B-Operating_System
kernel	B-Operating_System
)	O
,	O
Net/1	O
,	O
4.3BSD-Reno	O
(	O
to	O
match	O
the	O
"	O
Tahoe	O
"	O
naming	O
,	O
and	O
that	O
the	O
release	O
was	O
something	O
of	O
a	O
gamble	O
)	O
,	O
Net/2	O
,	O
4.4BSD	O
,	O
and	O
4.4BSD-lite	O
.	O
</s>
<s>
The	O
network	B-Architecture
code	O
found	O
in	O
these	O
releases	O
is	O
the	O
ancestor	O
of	O
much	O
TCP/IP	B-Protocol
network	I-Protocol
code	O
in	O
use	O
today	O
,	O
including	O
code	O
that	O
was	O
later	O
released	O
in	O
AT&T	O
System	B-Operating_System
V	I-Operating_System
UNIX	I-Operating_System
and	O
early	O
versions	O
of	O
Microsoft	B-Application
Windows	I-Application
.	O
</s>
<s>
The	O
accompanying	O
Berkeley	B-Protocol
sockets	I-Protocol
API	B-General_Concept
is	O
a	O
de	O
facto	O
standard	O
for	O
networking	O
APIs	B-General_Concept
and	O
has	O
been	O
copied	O
on	O
many	O
platforms	B-Device
.	O
</s>
<s>
During	O
this	O
period	O
,	O
many	O
observers	O
expected	O
that	O
UNIX	B-Application
,	O
with	O
its	B-Application
portability	O
,	O
rich	O
capabilities	O
,	O
and	O
support	O
from	O
companies	O
like	O
DEC	O
and	O
IBM	O
,	O
was	O
likely	O
to	O
become	O
an	O
industry-standard	O
operating	O
system	O
for	O
microcomputers	O
.	O
</s>
<s>
Citing	O
its	B-Application
much	O
smaller	O
software	O
library	O
and	O
installed	O
base	O
than	O
that	O
of	O
MS-DOS	B-Application
and	O
the	O
IBM	B-Device
PC	I-Device
,	O
others	O
expected	O
that	O
customers	O
would	O
prefer	O
personal	O
computers	O
on	O
local	B-General_Concept
area	I-General_Concept
networks	I-General_Concept
to	O
Unix	B-Application
multiuser	O
systems	O
.	O
</s>
<s>
Microsoft	O
planned	O
to	O
make	O
Xenix	B-Application
MS-DOS	B-Application
'	O
s	O
multiuser	O
successor	O
;	O
by	O
1983	O
a	O
Xenix-based	O
Altos	B-Device
586	I-Device
with	O
512	O
KB	O
RAM	O
and	O
10	B-Operating_System
MB	O
hard	O
drive	O
cost	O
.	O
</s>
<s>
BYTE	O
reported	O
that	O
the	O
Altos	O
"	O
under	O
moderate	O
load	O
approaches	O
DEC	B-Device
VAX	I-Device
performance	O
for	O
most	O
tasks	O
that	O
a	O
user	O
would	O
normally	O
invoke	O
"	O
,	O
while	O
other	O
computers	O
from	O
Sun	O
and	O
MASSCOMP	O
were	O
much	O
more	O
expensive	O
but	O
equaled	O
the	O
VAX	B-Device
.	O
</s>
<s>
The	O
magazine	O
added	O
that	O
both	O
PC/IX	B-Operating_System
and	O
Venix	B-Operating_System
on	O
the	O
IBM	B-Device
PC	I-Device
outperformed	O
Venix	B-Operating_System
on	O
the	O
PDP-11/23	O
.	O
</s>
<s>
uNETix	B-Operating_System
,	O
a	O
commercial	O
microcomputer	O
Unix	B-Application
,	O
implemented	O
the	O
first	O
Unix	B-Application
color	O
windowing	O
system	O
.	O
</s>
<s>
Thompson	O
and	O
Ritchie	O
were	O
given	O
the	O
Turing	O
Award	O
in	O
1983	O
for	O
their	O
work	O
on	O
Unix	B-Application
.	O
</s>
<s>
In	O
1986	O
,	O
Computerworld	O
wrote	O
that	O
"	O
Until	O
very	O
recently	O
,	O
almost	O
no	O
one	O
associated	O
Unix	B-Application
with	O
corporate	O
data	O
processing	O
.	O
</s>
<s>
But	O
now	O
almost	O
entirely	O
because	O
of	O
strenuous	O
efforts	O
by	O
AT&T	O
some	O
people	O
are	O
beginning	O
to	O
perceive	O
Unix	B-Application
as	O
a	O
viable	O
option	O
for	O
large	O
commercial	O
installations.	O
"	O
</s>
<s>
Unix	B-Application
became	O
commercially	O
available	O
for	O
the	O
mainframe	B-Architecture
via	O
Amdahl	B-Operating_System
UTS	I-Operating_System
in	O
1981	O
,	O
and	O
now	O
IBM	O
started	O
offering	O
Unix	B-Application
as	O
IX/370	O
and	O
VM/IX	O
.	O
</s>
<s>
The	O
total	O
installed	O
base	O
of	O
Unix	B-Application
,	O
however	O
,	O
remained	O
small	O
at	O
some	O
230,000	O
machines	O
.	O
</s>
<s>
Despite	O
its	B-Application
academic	O
reputation	O
InfoWorld	O
stated	O
in	O
1989	O
,	O
"	O
Until	O
recently	O
,	O
Unix	B-Application
conjured	O
up	O
visions	O
of	O
long-haired	O
bearded	O
technoids	O
stuck	O
in	O
the	O
bowels	O
of	O
an	O
R&D	O
lab	O
,	O
coding	O
software	O
until	O
the	O
wee	O
hours	O
of	O
the	O
morning	O
"	O
the	O
increasing	O
power	O
of	O
microcomputers	O
in	O
the	O
late	O
1980s	O
,	O
and	O
in	O
particular	O
the	O
introduction	O
of	O
the	O
32-bit	O
Intel	B-General_Concept
80386	I-General_Concept
,	O
caused	O
Unix	B-Application
to	O
"	O
explode	O
"	O
in	O
popularity	O
for	O
business	O
applications	O
;	O
Xenix	B-Application
,	O
386/ix	B-Operating_System
,	O
and	O
other	O
Unix	B-Application
systems	I-Application
for	O
the	O
PC-compatible	O
market	O
competed	O
with	O
OS/2	B-Application
in	O
terms	O
of	O
networking	O
,	O
multiuser	O
support	O
,	O
multitasking	O
,	O
and	O
MS-DOS	B-Application
compatibility	O
.	O
</s>
<s>
The	O
beginning	O
in	O
1984	O
of	O
the	O
annual	O
Unix	B-Application
Expo	O
trade	O
show	O
in	O
New	O
York	O
reflected	O
the	O
growing	O
commercial	O
presence	O
of	O
Unix	B-Application
.	O
</s>
<s>
During	O
this	O
time	O
a	O
number	O
of	O
vendors	O
including	O
Digital	O
Equipment	O
,	O
Sun	O
,	O
Addamax	O
and	O
others	O
began	O
building	O
trusted	O
versions	O
of	O
UNIX	B-Application
for	O
high	O
security	O
applications	O
,	O
mostly	O
designed	O
for	O
military	O
and	O
law	O
enforcement	O
applications	O
.	O
</s>
<s>
A	O
problem	O
that	O
plagued	O
Unix	B-Application
in	O
this	O
period	O
was	O
the	O
multitude	O
of	O
implementations	O
,	O
based	O
on	O
either	O
System	B-Operating_System
V	I-Operating_System
,	O
BSD	B-Operating_System
,	O
or	O
what	O
Poul-Henning	O
Kamp	O
later	O
described	O
as	O
a	O
"	O
more	O
or	O
less	O
competently	O
executed	O
"	O
combination	O
of	O
the	O
two	O
,	O
usually	O
with	O
home-grown	O
extensions	O
to	O
the	O
base	O
systems	O
from	O
AT&T	O
or	O
Berkeley	O
.	O
</s>
<s>
Xenix	B-Application
was	O
effectively	O
a	O
third	O
lineage	O
,	O
being	O
based	O
on	O
the	O
earlier	O
System	B-Operating_System
III	I-Operating_System
.	O
</s>
<s>
The	O
rivalry	O
between	O
vendors	O
was	O
called	O
the	O
Unix	B-Application
wars	O
;	O
customers	O
soon	O
demanded	O
standardization	O
.	O
</s>
<s>
AT&T	O
responded	O
by	O
issuing	O
a	O
standard	O
,	O
the	O
System	B-Operating_System
V	I-Operating_System
Interface	I-Operating_System
Definition	I-Operating_System
(	O
SVID	B-Operating_System
,	O
1985	O
)	O
,	O
and	O
required	O
conformance	O
for	O
operating	O
systems	O
to	O
be	O
branded	O
"	O
System	B-Operating_System
V	I-Operating_System
"	O
.	O
</s>
<s>
In	O
1984	O
,	O
several	O
European	O
computer	O
vendors	O
established	O
the	O
X/Open	O
consortium	O
with	O
the	O
goal	O
of	O
creating	O
an	O
open	O
system	O
specification	O
based	O
on	O
Unix	B-Application
(	O
and	O
eventually	O
the	O
SVID	B-Operating_System
)	O
.	O
</s>
<s>
Yet	O
another	O
standardization	O
effort	O
was	O
the	O
IEEE	O
's	O
POSIX	O
specification	O
(	O
1988	O
)	O
,	O
designed	O
as	O
a	O
compromise	O
API	B-General_Concept
readily	O
implemented	O
on	O
both	O
BSD	B-Operating_System
and	O
System	B-Operating_System
V	I-Operating_System
platforms	B-Device
.	O
</s>
<s>
In	O
1993	O
,	O
POSIX	O
was	O
mandated	O
by	O
the	O
United	O
States	O
government	O
for	O
many	O
of	O
its	B-Application
own	O
systems	O
.	O
</s>
<s>
First	O
,	O
it	O
collaborated	O
with	O
SCO	O
to	O
merge	O
System	B-Operating_System
V	I-Operating_System
and	O
Xenix	B-Application
into	O
System	O
V/386	O
.	O
</s>
<s>
Next	O
,	O
it	O
sought	O
collaboration	O
with	O
Sun	O
Microsystems	O
(	O
vendor	O
of	O
the	O
4.2BSD	O
derivative	O
SunOS	B-Operating_System
and	O
its	B-Application
Network	B-Protocol
File	I-Protocol
System	I-Protocol
)	O
to	O
merge	O
System	B-Operating_System
V	I-Operating_System
,	O
BSD/SunOS	O
and	O
Xenix	B-Application
into	O
a	O
single	O
unified	O
Unix	B-Application
,	O
which	O
would	O
become	O
System	B-Operating_System
V	I-Operating_System
Release	O
4	O
.	O
</s>
<s>
AT&T	O
and	O
Sun	O
,	O
as	O
UNIX	B-Application
International	O
(	O
UI	O
)	O
,	O
acted	O
independently	O
of	O
X/Open	O
and	O
drew	O
ire	O
from	O
other	O
vendors	O
,	O
which	O
started	O
the	O
Open	B-Application
Software	I-Application
Foundation	I-Application
to	O
work	O
on	O
their	O
own	O
unified	O
Unix	B-Application
,	O
OSF/1	B-Operating_System
,	O
ushering	O
in	O
a	O
new	O
phase	O
of	O
the	O
Unix	B-Application
wars	O
.	O
</s>
<s>
The	O
Unix	B-Application
wars	O
continued	O
into	O
the	O
1990s	O
,	O
but	O
turned	O
out	O
to	O
be	O
less	O
of	O
a	O
threat	O
than	O
originally	O
thought	O
:	O
AT&T	O
and	O
Sun	O
went	O
their	O
own	O
ways	O
after	O
System	B-Operating_System
V.4	I-Operating_System
,	O
while	O
OSF/1	B-Operating_System
'	O
s	O
schedule	O
slipped	O
behind	O
.	O
</s>
<s>
By	O
1993	O
,	O
most	O
commercial	O
vendors	O
changed	O
their	O
variants	O
of	O
Unix	B-Application
to	O
be	O
based	O
on	O
System	B-Operating_System
V	I-Operating_System
with	O
many	O
BSD	B-Operating_System
features	O
added	O
.	O
</s>
<s>
The	O
creation	O
of	O
the	O
Common	B-Operating_System
Open	I-Operating_System
Software	I-Operating_System
Environment	I-Operating_System
(	O
COSE	O
)	O
initiative	O
that	O
year	O
,	O
by	O
the	O
major	O
players	O
in	O
Unix	B-Application
,	O
marked	O
the	O
end	O
of	O
the	O
most	O
notorious	O
phase	O
of	O
the	O
Unix	B-Application
wars	O
,	O
and	O
was	O
followed	O
by	O
the	O
merger	O
of	O
UI	O
and	O
OSF	B-Application
in	O
1994	O
.	O
</s>
<s>
The	O
new	O
combined	O
entity	O
retained	O
the	O
OSF	B-Application
name	O
and	O
stopped	O
work	O
on	O
OSF/1	B-Operating_System
.	O
</s>
<s>
By	O
that	O
time	O
the	O
only	O
vendor	O
using	O
it	O
was	O
Digital	O
Equipment	O
Corporation	O
,	O
which	O
continued	O
its	B-Application
own	O
development	O
,	O
rebranding	O
their	O
product	O
Digital	B-Operating_System
UNIX	I-Operating_System
in	O
early	O
1995	O
.	O
</s>
<s>
POSIX	O
became	O
the	O
unifying	O
standard	O
for	O
Unix	B-Application
systems	I-Application
(	O
and	O
some	O
other	O
operating	O
systems	O
)	O
.	O
</s>
<s>
Meanwhile	O
,	O
the	O
BSD	B-Operating_System
world	O
saw	O
its	B-Application
own	O
developments	O
.	O
</s>
<s>
The	O
group	O
at	O
Berkeley	O
moved	O
its	B-Application
operating	O
system	O
toward	O
POSIX	O
compliance	O
and	O
released	O
a	O
stripped-down	O
version	O
of	O
its	B-Application
networking	O
code	O
,	O
supposedly	O
without	O
any	O
code	O
that	O
was	O
the	O
property	O
of	O
AT&T	O
.	O
</s>
<s>
In	O
1991	O
,	O
a	O
group	O
of	O
BSD	B-Operating_System
developers	O
(	O
Donn	O
Seeley	O
,	O
Mike	O
Karels	O
,	O
Bill	O
Jolitz	O
,	O
and	O
Trent	O
Hein	O
)	O
left	O
the	O
University	O
of	O
California	O
to	O
found	O
Berkeley	O
Software	O
Design	O
,	O
Inc	O
.	O
(	O
BSDi	O
)	O
,	O
which	O
sold	O
a	O
fully	O
functional	O
commercial	O
version	O
of	O
BSD	B-Operating_System
Unix	I-Operating_System
for	O
the	O
Intel	O
platform	O
,	O
which	O
they	O
advertised	O
as	O
free	O
of	O
AT&T	O
code	O
.	O
</s>
<s>
They	O
ran	O
into	O
legal	O
trouble	O
when	O
T	O
's	O
Unix	B-Application
subsidiary	O
sued	B-Operating_System
BSDi	I-Operating_System
for	O
copyright	O
infringement	O
and	O
various	O
other	O
charges	O
in	O
relation	O
to	O
BSD	B-Operating_System
;	O
subsequently	O
,	O
the	O
University	O
of	O
California	O
countersued	O
.	O
</s>
<s>
Shortly	O
after	O
it	O
was	O
founded	O
,	O
Bill	O
Jolitz	O
left	O
BSDi	O
to	O
pursue	O
distribution	O
of	O
386BSD	B-Operating_System
,	O
the	O
free	O
software	O
ancestor	O
of	O
FreeBSD	B-Operating_System
,	O
OpenBSD	B-Operating_System
,	O
and	O
NetBSD	B-Device
.	O
</s>
<s>
In	O
1991	O
,	O
USL	O
and	O
Novell	O
teamed	O
up	O
to	O
develop	O
a	O
version	O
of	O
System	O
4	O
for	O
i386	B-General_Concept
and	O
i486	O
computers	O
that	O
would	O
combine	O
TCP/IP	B-Protocol
and	O
Novell	O
's	O
IPX/SPX	O
networking	O
protocols	O
,	O
called	O
the	O
Destiny	O
Project	O
.	O
</s>
<s>
Shortly	O
after	O
Univel	O
released	O
UnixWare	O
1.0	O
produced	O
,	O
AT&T	O
sold	O
USL	O
and	O
it	O
's	O
share	O
of	O
Univel	O
to	O
Novell	O
meaning	O
Novell	O
now	O
owned	O
all	O
of	O
T	O
's	O
rights	O
to	O
Unix	B-Application
.	O
</s>
<s>
Novell	O
tried	O
to	O
use	O
the	O
fact	O
that	O
UnixWare	O
combined	O
both	O
TCP/IP	B-Protocol
and	O
NetWare	O
networking	O
technologies	O
as	O
a	O
marketing	O
tool	O
against	O
Windows	B-Device
NT	I-Device
,	O
but	O
their	O
core	O
markets	O
suffered	O
considerably	O
.	O
</s>
<s>
In	O
1993	O
,	O
Novell	O
decided	O
to	O
transfer	O
the	O
UNIX	B-Application
trademark	O
and	O
certification	O
rights	O
to	O
the	O
X/Open	O
Consortium	O
.	O
</s>
<s>
In	O
1996	O
,	O
X/Open	O
merged	O
with	O
OSF	B-Application
,	O
creating	O
the	B-Application
Open	I-Application
Group	I-Application
.	O
</s>
<s>
Various	O
standards	O
by	O
the	B-Application
Open	I-Application
Group	I-Application
now	O
define	O
what	O
is	O
and	O
what	O
is	O
not	O
a	O
UNIX	B-Application
operating	I-Application
system	I-Application
,	O
notably	O
the	O
post-1998	O
Single	O
UNIX	B-Application
Specification	O
.	O
</s>
<s>
In	O
1993	O
,	O
Unix	B-Application
was	O
used	O
as	O
a	O
minor	O
plot	O
element	O
in	O
the	O
blockbuster	O
film	O
Jurassic	O
Park	O
.	O
</s>
<s>
In	O
1995	O
,	O
the	O
business	O
of	O
administering	O
and	O
supporting	O
the	O
existing	O
UNIX	B-Application
licenses	O
,	O
plus	O
rights	O
to	O
further	O
develop	O
the	O
System	B-Operating_System
V	I-Operating_System
code	O
base	O
,	O
were	O
sold	O
by	O
Novell	O
to	O
the	O
Santa	O
Cruz	O
Operation	O
.	O
</s>
<s>
With	O
the	O
legal	O
troubles	O
between	O
AT&	O
T/Novell	O
and	O
the	O
University	O
of	O
California	O
over	O
,	O
the	O
latter	O
did	O
two	O
more	O
releases	O
of	O
BSD	B-Operating_System
before	O
disbanding	O
its	B-Application
Computer	B-Operating_System
Systems	I-Operating_System
Research	I-Operating_System
Group	I-Operating_System
in	O
1995	O
.	O
</s>
<s>
The	O
BSD	B-Operating_System
code	O
lived	O
on	O
,	O
however	O
,	O
in	O
its	B-Application
free	O
derivatives	O
and	O
in	O
what	O
Garfinkel	O
et	O
al	O
.	O
</s>
<s>
call	O
a	O
second	O
generation	O
of	O
commercial	O
Unix	B-Application
systems	I-Application
,	O
based	O
on	O
BSD	B-Operating_System
.	O
</s>
<s>
In	O
1997	O
,	O
Apple	O
sought	O
a	O
new	O
foundation	O
for	O
its	B-Application
Macintosh	O
operating	O
system	O
and	O
chose	O
NeXTSTEP	B-Application
,	O
an	O
operating	O
system	O
developed	O
by	O
NeXT	O
.	O
</s>
<s>
The	O
core	O
operating	O
system	O
,	O
which	O
was	O
based	O
on	O
BSD	B-Operating_System
and	O
the	O
Mach	B-Operating_System
kernel	I-Operating_System
,	O
was	O
renamed	O
Darwin	B-Operating_System
after	O
Apple	O
acquired	O
it	O
.	O
</s>
<s>
The	O
deployment	O
of	O
Darwin	B-Operating_System
in	O
Mac	B-Application
OS	I-Application
X	I-Application
makes	O
it	O
,	O
according	O
to	O
a	O
statement	O
made	O
by	O
an	O
Apple	O
employee	O
at	O
a	O
USENIX	B-Operating_System
conference	O
,	O
the	O
most	O
widely	O
used	O
Unix-based	O
system	O
in	O
the	O
desktop	B-Device
computer	I-Device
market	O
.	O
</s>
<s>
Meanwhile	O
,	O
Unix	B-Application
got	O
competition	O
from	O
the	O
copyleft	O
Linux	B-Application
kernel	B-Operating_System
,	O
a	O
reimplementation	O
of	O
Unix	B-Application
from	O
scratch	O
,	O
using	O
parts	O
of	O
the	B-Application
GNU	I-Application
project	I-Application
that	O
had	O
been	O
underway	O
since	O
the	O
mid-1980s	O
.	O
</s>
<s>
Work	O
on	O
Linux	B-Application
began	O
in	O
1991	O
by	O
Linus	O
Torvalds	O
;	O
in	O
1998	O
,	O
a	O
confidential	O
memo	O
at	O
Microsoft	O
stated	O
,	O
"	O
Linux	B-Application
is	O
on	O
track	O
to	O
eventually	O
own	O
the	O
x86	O
UNIX	B-Application
market	O
,	O
"	O
and	O
further	O
predicted	O
,	O
"	O
I	O
believe	O
that	O
Linux	B-Application
–	O
moreso	O
than	O
NT	O
–	O
will	O
be	O
the	O
biggest	O
threat	O
to	O
SCO	O
in	O
the	O
near	O
future.	O
"	O
</s>
<s>
In	O
2000	O
,	O
SCO	O
sold	O
its	B-Application
entire	O
UNIX	B-Application
business	O
and	O
assets	O
to	O
Caldera	O
Systems	O
,	O
which	O
later	O
changed	O
its	B-Application
name	O
to	O
The	O
SCO	O
Group	O
.	O
</s>
<s>
The	O
bursting	O
of	O
the	O
dot-com	O
bubble	O
(	O
2001	O
–	O
03	O
)	O
led	O
to	O
significant	O
consolidation	O
of	O
versions	O
of	O
Unix	B-Application
.	O
</s>
<s>
Of	O
the	O
many	O
commercial	O
variants	O
of	O
Unix	B-Application
that	O
were	O
born	O
in	O
the	O
1980s	O
,	O
only	O
Solaris	B-Application
,	O
HP-UX	B-Application
,	O
and	O
AIX	B-Application
were	O
still	O
doing	O
relatively	O
well	O
in	O
the	O
market	O
,	O
though	O
SGI	O
's	O
IRIX	B-Operating_System
persisted	O
for	O
quite	O
some	O
time	O
.	O
</s>
<s>
Of	O
these	O
,	O
Solaris	B-Application
had	O
the	O
largest	O
market	O
share	O
in	O
2005	O
.	O
</s>
<s>
In	O
2003	O
,	O
the	O
SCO	O
Group	O
started	O
legal	O
action	O
against	O
various	O
users	O
and	O
vendors	O
of	O
Linux	B-Application
.	O
</s>
<s>
SCO	O
had	O
alleged	O
that	O
Linux	B-Application
contained	O
copyrighted	O
Unix	B-Application
code	O
now	O
owned	O
by	O
the	O
SCO	O
Group	O
.	O
</s>
<s>
Other	O
allegations	O
included	O
trade-secret	O
violations	O
by	O
IBM	O
,	O
or	O
contract	O
violations	O
by	O
former	O
Santa	O
Cruz	O
customers	O
who	O
had	O
since	O
converted	O
to	O
Linux	B-Application
.	O
</s>
<s>
However	O
,	O
Novell	O
disputed	O
the	O
SCO	O
Group	O
's	O
claim	O
to	O
hold	O
copyright	O
on	O
the	O
UNIX	B-Application
source	O
base	O
.	O
</s>
<s>
On	O
10	B-Operating_System
August	O
2007	O
,	O
a	O
major	O
portion	O
of	O
the	O
case	O
was	O
decided	O
in	O
Novell	O
's	O
favor	O
(	O
that	O
Novell	O
had	O
the	O
copyright	O
to	O
UNIX	B-Application
,	O
and	O
that	O
the	O
SCO	O
Group	O
had	O
improperly	O
kept	O
money	O
that	O
was	O
due	O
to	O
Novell	O
)	O
.	O
</s>
<s>
After	O
the	O
ruling	O
,	O
Novell	O
announced	O
they	O
have	O
no	O
interest	O
in	O
suing	O
people	O
over	O
Unix	B-Application
and	O
stated	O
,	O
"	O
We	O
do	O
n't	O
believe	O
there	O
is	O
Unix	B-Application
in	O
Linux	B-Application
"	O
.	O
</s>
<s>
On	O
30	O
March	O
2010	O
,	O
following	O
a	O
jury	O
trial	O
,	O
Novell	O
,	O
and	O
not	O
The	O
SCO	O
Group	O
,	O
was	O
"	O
unanimously	O
 [ found ] 	O
 "	O
to	O
be	O
the	O
owner	O
of	O
the	O
UNIX	B-Application
and	O
UnixWare	O
copyrights	O
.	O
</s>
<s>
In	O
2005	O
,	O
Sun	O
Microsystems	O
released	O
the	O
bulk	O
of	O
its	B-Application
Solaris	B-Application
system	O
code	O
(	O
based	O
on	O
UNIX	B-Operating_System
System	I-Operating_System
V	I-Operating_System
Release	O
4	O
)	O
into	O
an	O
open	B-Application
source	I-Application
project	O
called	O
OpenSolaris	B-Operating_System
.	O
</s>
<s>
New	O
SunOS	B-Operating_System
technologies	O
,	O
notably	O
the	O
ZFS	B-Application
file	O
system	O
,	O
were	O
first	O
released	O
as	O
open	B-Application
source	I-Application
code	I-Application
via	O
the	O
OpenSolaris	B-Operating_System
project	O
.	O
</s>
<s>
Soon	O
afterwards	O
,	O
OpenSolaris	B-Operating_System
spawned	O
several	O
non-Sun	O
distributions	O
.	O
</s>
<s>
In	O
2010	O
,	O
after	O
Oracle	O
acquired	O
Sun	O
,	O
OpenSolaris	B-Operating_System
was	O
officially	O
discontinued	O
,	O
but	O
the	O
development	O
of	O
derivatives	O
continued	O
.	O
</s>
<s>
Since	O
the	O
early	O
2000s	O
,	O
Linux	B-Application
is	O
the	O
leading	O
Unix-like	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
,	O
with	O
other	O
variants	O
of	O
Unix	B-Application
(	O
apart	O
from	O
macOS	B-Application
)	O
having	O
only	O
a	O
negligible	O
market	O
share	O
(	O
see	O
Usage	B-Operating_System
share	I-Operating_System
of	I-Operating_System
operating	I-Operating_System
systems	I-Operating_System
)	O
.	O
</s>
