<s>
The	O
History	O
of	O
the	O
Berkeley	B-Operating_System
Software	I-Operating_System
Distribution	I-Operating_System
begins	O
in	O
the	O
1970s	O
.	O
</s>
<s>
The	O
earliest	B-Operating_System
distributions	I-Operating_System
of	O
Unix	B-Application
from	O
Bell	O
Labs	O
in	O
the	O
1970s	O
included	O
the	O
source	O
code	O
to	O
the	O
operating	O
system	O
,	O
allowing	O
researchers	O
at	O
universities	O
to	O
modify	O
and	O
extend	O
Unix	B-Application
.	O
</s>
<s>
The	O
operating	O
system	O
arrived	O
at	O
Berkeley	O
in	O
1974	O
,	O
at	O
the	O
request	O
of	O
computer	O
science	O
professor	O
Bob	O
Fabry	O
who	O
had	O
been	O
on	O
the	O
program	O
committee	O
for	O
the	O
Symposium	O
on	O
Operating	O
Systems	O
Principles	O
where	O
Unix	B-Application
was	O
first	O
presented	O
.	O
</s>
<s>
A	O
PDP-11/45	B-Device
was	O
bought	O
to	O
run	O
the	O
system	O
,	O
but	O
for	O
budgetary	O
reasons	O
,	O
this	O
machine	O
was	O
shared	O
with	O
the	O
mathematics	O
and	O
statistics	O
groups	O
at	O
Berkeley	O
,	O
who	O
used	O
RSTS	B-Operating_System
,	O
so	O
that	O
Unix	B-Application
only	O
ran	O
on	O
the	O
machine	O
eight	O
hours	O
per	O
day	O
(	O
sometimes	O
during	O
the	O
day	O
,	O
sometimes	O
during	O
the	O
night	O
)	O
.	O
</s>
<s>
A	O
larger	O
PDP-11/70	B-Device
was	O
installed	O
at	O
Berkeley	O
the	O
following	O
year	O
,	O
using	O
money	O
from	O
the	O
Ingres	B-Application
database	I-Application
project	O
.	O
</s>
<s>
He	O
helped	O
to	O
install	O
Version	B-Operating_System
6	I-Operating_System
Unix	I-Operating_System
and	O
started	O
working	O
on	O
a	O
Pascal	B-Application
implementation	O
for	O
the	O
system	O
.	O
</s>
<s>
Graduate	O
students	O
Chuck	O
Haley	O
and	O
Bill	O
Joy	O
improved	O
Thompson	O
's	O
Pascal	B-Application
and	O
implemented	O
an	O
improved	O
text	O
editor	O
,	O
ex	B-Device
.	O
</s>
<s>
Other	O
universities	O
became	O
interested	O
in	O
the	O
software	O
at	O
Berkeley	O
,	O
and	O
so	O
in	O
1977	O
Joy	O
started	O
compiling	O
the	O
first	O
Berkeley	B-Operating_System
Software	I-Operating_System
Distribution	I-Operating_System
(	O
1BSD	O
)	O
,	O
which	O
was	O
released	O
on	O
March	O
9	O
,	O
1978	O
.	O
</s>
<s>
1BSD	O
was	O
an	O
add-on	O
to	O
Version	B-Operating_System
6	I-Operating_System
Unix	I-Operating_System
rather	O
than	O
a	O
complete	O
operating	O
system	O
in	O
its	O
own	O
right	O
.	O
</s>
<s>
The	O
Second	O
Berkeley	B-Operating_System
Software	I-Operating_System
Distribution	I-Operating_System
(	O
2BSD	O
)	O
,	O
released	O
in	O
May	O
1979	O
,	O
included	O
updated	O
versions	O
of	O
the	O
1BSD	O
software	O
as	O
well	O
as	O
two	O
new	O
programs	O
by	O
Joy	O
that	O
persist	O
on	O
Unix	B-Application
systems	I-Application
to	O
this	O
day	O
:	O
the	O
vi	B-Application
text	O
editor	O
(	O
a	O
visual	B-Application
version	O
of	O
ex	B-Device
)	O
and	O
the	O
C	B-Operating_System
shell	I-Operating_System
.	O
</s>
<s>
A	O
further	O
feature	O
was	O
a	O
networking	O
package	O
called	O
Berknet	B-Operating_System
,	O
developed	O
by	O
Eric	O
Schmidt	O
as	O
part	O
of	O
his	O
master	O
's	O
thesis	O
work	O
,	O
that	O
could	O
connect	O
up	O
to	O
twenty-six	O
computers	O
and	O
provided	O
email	O
and	O
file	O
transfer	O
.	O
</s>
<s>
After	O
3BSD	O
(	O
see	O
below	O
)	O
had	O
come	O
out	O
for	O
the	O
VAX	B-Device
line	O
of	O
computers	O
,	O
new	O
releases	O
of	O
2BSD	O
for	O
the	O
PDP-11	B-Device
were	O
still	O
issued	O
and	O
distributed	O
through	O
USENIX	B-Operating_System
;	O
for	O
example	O
,	O
1982	O
's	O
2.8.1BSD	O
included	O
a	O
collection	O
of	O
fixes	O
for	O
performance	O
problems	O
in	O
Version	B-Operating_System
7	I-Operating_System
Unix	I-Operating_System
,	O
and	O
later	O
releases	O
contained	O
ports	O
of	O
changes	O
from	O
the	O
VAX-based	O
releases	O
of	O
BSD	B-Operating_System
back	O
to	O
the	O
PDP-11	B-Device
architecture	O
.	O
</s>
<s>
2.9BSD	O
from	O
1983	O
included	O
code	O
from	O
4.1cBSD	O
,	O
and	O
was	O
the	O
first	O
release	O
that	O
was	O
a	O
full	O
OS	O
(	O
a	O
modified	O
V7	B-Operating_System
Unix	I-Operating_System
)	O
rather	O
than	O
a	O
set	O
of	O
applications	O
and	O
patches	O
.	O
</s>
<s>
A	O
VAX	B-Device
computer	O
was	O
installed	O
at	O
Berkeley	O
in	O
1978	O
,	O
but	O
the	O
port	O
of	O
Unix	B-Application
to	O
the	O
VAX	B-Device
architecture	O
,	O
UNIX/32V	B-Operating_System
,	O
did	O
not	O
take	O
advantage	O
of	O
the	O
VAX	B-Device
's	O
virtual	B-Architecture
memory	I-Architecture
capabilities	O
.	O
</s>
<s>
The	O
kernel	B-Operating_System
of	O
32V	B-Operating_System
was	O
largely	O
rewritten	O
by	O
Berkeley	O
graduate	O
student	O
Özalp	O
Babaoğlu	O
to	O
include	O
a	O
virtual	B-Architecture
memory	I-Architecture
implementation	O
,	O
and	O
a	O
complete	O
operating	O
system	O
including	O
the	O
new	O
kernel	B-Operating_System
,	O
ports	O
of	O
the	O
2BSD	O
utilities	O
to	O
the	O
VAX	B-Device
,	O
and	O
the	O
utilities	O
from	O
32V	B-Operating_System
was	O
released	O
as	O
3BSD	O
at	O
the	O
end	O
of	O
1979	O
.	O
</s>
<s>
3BSD	O
was	O
also	O
alternatively	O
called	O
Virtual	O
VAX/UNIX	O
or	O
VMUNIX	O
(	O
for	O
Virtual	B-Architecture
Memory	I-Architecture
Unix	B-Application
)	O
,	O
and	O
BSD	B-Operating_System
kernel	B-Operating_System
images	I-Operating_System
were	O
normally	O
called	O
/vmunix	O
until	O
4.4BSD	O
.	O
</s>
<s>
The	O
success	O
of	O
3BSD	O
was	O
a	O
major	O
factor	O
in	O
the	O
Defense	O
Advanced	O
Research	O
Projects	O
Agency	O
's	O
(	O
DARPA	O
)	O
decision	O
to	O
fund	O
Berkeley	O
's	O
Computer	B-Operating_System
Systems	I-Operating_System
Research	I-Operating_System
Group	I-Operating_System
(	O
CSRG	B-Operating_System
)	O
,	O
which	O
would	O
develop	O
a	O
standard	O
Unix	B-Application
platform	O
for	O
future	O
DARPA	O
research	O
in	O
the	O
VLSI	O
Project	O
.	O
</s>
<s>
4BSD	O
(	O
November	O
1980	O
)	O
offered	O
a	O
number	O
of	O
enhancements	O
over	O
3BSD	O
,	O
notably	O
job	B-Operating_System
control	I-Operating_System
in	O
the	O
previously	O
released	O
csh	B-Operating_System
,	O
delivermail	B-Protocol
(	O
the	O
antecedent	O
of	O
sendmail	B-Application
)	O
,	O
"	O
reliable	O
"	O
signals	B-Operating_System
,	O
and	O
the	O
Curses	B-Device
programming	I-Device
library	I-Device
.	O
</s>
<s>
In	O
a	O
1985	O
review	O
of	O
BSD	B-Operating_System
releases	O
,	O
John	O
Quarterman	O
et	O
al.	O
,	O
wrote	O
:	O
</s>
<s>
4.1BSD	O
(	O
June	O
1981	O
)	O
was	O
a	O
response	O
to	O
criticisms	O
of	O
BSD	B-Operating_System
's	O
performance	O
relative	O
to	O
the	O
dominant	O
VAX	B-Device
operating	O
system	O
,	O
VMS	B-Operating_System
.	O
</s>
<s>
The	O
4.1BSD	O
kernel	B-Operating_System
was	O
systematically	O
tuned	O
up	O
by	O
Bill	O
Joy	O
until	O
it	O
could	O
perform	O
as	O
well	O
as	O
VMS	B-Operating_System
on	O
several	O
benchmarks	O
.	O
</s>
<s>
The	O
release	O
would	O
have	O
been	O
called	O
5BSD	O
,	O
but	O
after	O
objections	O
from	O
AT&T	O
the	O
name	O
was	O
changed	O
;	O
AT&T	O
feared	O
confusion	O
with	O
T	O
's	O
UNIX	B-Operating_System
System	I-Operating_System
V	I-Operating_System
.	O
</s>
<s>
Before	O
its	O
official	O
release	O
came	O
three	O
intermediate	O
versions	O
:	O
4.1a	O
from	O
April	O
1982	O
incorporated	O
a	O
modified	O
version	O
of	O
BBN	O
's	O
preliminary	O
TCP/IP	B-Protocol
implementation	O
;	O
4.1b	O
from	O
June	O
1982	O
included	O
the	O
new	O
Berkeley	B-Operating_System
Fast	I-Operating_System
File	I-Operating_System
System	I-Operating_System
,	O
implemented	O
by	O
Marshall	O
Kirk	O
McKusick	O
;	O
and	O
4.1c	O
in	O
April	O
1983	O
was	O
an	O
interim	O
release	O
during	O
the	O
last	O
few	O
months	O
of	O
4.2BSD	O
'	O
s	O
development	O
.	O
</s>
<s>
Back	O
at	O
Bell	O
Labs	O
,	O
4.1cBSD	O
became	O
the	O
basis	O
of	O
the	O
8th	B-Operating_System
Edition	I-Operating_System
of	O
Research	B-Operating_System
Unix	I-Operating_System
,	O
and	O
a	O
commercially	O
supported	O
version	O
was	O
available	O
from	O
mt	B-Operating_System
Xinu	I-Operating_System
.	O
</s>
<s>
Apart	O
from	O
the	O
Fast	O
File	O
System	O
,	O
several	O
features	O
from	O
outside	O
contributors	O
were	O
accepted	O
,	O
including	O
disk	O
quotas	O
and	O
job	B-Operating_System
control	I-Operating_System
.	O
</s>
<s>
Sun	O
Microsystems	O
provided	O
testing	O
on	O
its	O
Motorola	B-Device
68000	I-Device
machines	O
prior	O
to	O
release	O
,	O
ensuring	O
portability	O
of	O
the	O
system	O
.	O
</s>
<s>
On	O
a	O
lighter	O
note	O
,	O
it	O
also	O
marked	O
the	O
debut	O
of	O
BSD	B-Operating_System
's	O
daemon	O
mascot	O
in	O
a	O
drawing	O
by	O
John	O
Lasseter	O
that	O
appeared	O
on	O
the	O
cover	O
of	O
the	O
printed	O
manuals	O
distributed	O
by	O
USENIX	B-Operating_System
.	O
</s>
<s>
4.3BSD	B-Operating_System
was	O
released	O
in	O
June	O
1986	O
.	O
</s>
<s>
Prior	O
to	O
the	O
release	O
,	O
BSD	B-Operating_System
's	O
implementation	O
of	O
TCP/IP	B-Protocol
had	O
diverged	O
considerably	O
from	O
BBN	O
's	O
official	O
implementation	O
.	O
</s>
<s>
After	O
several	O
months	O
of	O
testing	O
,	O
DARPA	O
determined	O
that	O
the	O
4.2BSD	O
version	O
was	O
superior	O
and	O
would	O
remain	O
in	O
4.3BSD	B-Operating_System
.	O
</s>
<s>
After	O
4.3BSD	B-Operating_System
,	O
it	O
was	O
determined	O
that	O
BSD	B-Operating_System
would	O
move	O
away	O
from	O
the	O
aging	O
VAX	B-Device
platform	O
.	O
</s>
<s>
Nonetheless	O
,	O
the	O
4.3BSD-Tahoe	O
port	O
(	O
June	O
1988	O
)	O
proved	O
valuable	O
,	O
as	O
it	O
led	O
to	O
a	O
separation	O
of	O
machine-dependent	O
and	O
machine-independent	O
code	O
in	O
BSD	B-Operating_System
which	O
would	O
improve	O
the	O
system	O
's	O
future	O
portability	O
.	O
</s>
<s>
Apart	O
from	O
portability	O
,	O
the	O
CSRG	B-Operating_System
worked	O
on	O
an	O
implementation	O
of	O
the	O
OSI	O
network	O
protocol	O
stack	O
,	O
improvements	O
to	O
the	O
kernel	B-Operating_System
virtual	B-Operating_System
memory	I-Operating_System
system	I-Operating_System
and	O
(	O
with	O
Van	O
Jacobson	O
of	O
LBL	O
)	O
new	O
TCP/IP	B-Protocol
algorithms	O
to	O
accommodate	O
the	O
growth	O
of	O
the	O
Internet	O
.	O
</s>
<s>
Until	O
then	O
,	O
all	O
versions	O
of	O
BSD	B-Operating_System
incorporated	O
proprietary	B-Application
AT&T	B-Operating_System
Unix	I-Operating_System
code	O
and	O
were	O
,	O
therefore	O
,	O
subject	O
to	O
an	O
AT&T	O
software	O
license	O
.	O
</s>
<s>
This	O
led	O
to	O
Networking	O
Release	O
1	O
(	O
Net/1	O
)	O
,	O
which	O
was	O
made	O
available	O
to	O
non-licensees	O
of	O
AT&T	O
code	O
and	O
was	O
freely	B-Application
redistributable	I-Application
under	O
the	O
terms	O
of	O
the	O
BSD	B-Operating_System
license	I-Operating_System
.	O
</s>
<s>
4.3BSD-Reno	O
came	O
in	O
early	O
1990	O
.	O
</s>
<s>
Among	O
the	O
new	O
features	O
were	O
an	O
NFS	B-Protocol
implementation	O
from	O
the	O
University	O
of	O
Guelph	O
,	O
a	O
status	B-Device
key	I-Device
(	O
"	O
Ctrl-T	O
"	O
)	O
and	O
support	O
for	O
the	O
HP	B-Device
9000	I-Device
range	O
of	O
computers	O
,	O
originating	O
in	O
the	O
University	O
of	O
Utah	O
's	O
"	O
HPBSD	O
"	O
port	O
.	O
</s>
<s>
In	O
August	O
2006	O
,	O
InformationWeek	O
magazine	O
rated	O
4.3BSD	B-Operating_System
as	O
the	O
"	O
Greatest	O
Software	O
Ever	O
Written	O
"	O
.	O
</s>
<s>
They	O
commented	O
:	O
"	O
BSD	B-Operating_System
4.3	O
represents	O
the	O
single	O
biggest	O
theoretical	O
undergirder	O
of	O
the	O
Internet.	O
"	O
</s>
<s>
After	O
Net/1	O
,	O
BSD	B-Operating_System
developer	O
Keith	O
Bostic	O
proposed	O
that	O
more	O
non-AT	O
&T	O
sections	O
of	O
the	O
BSD	B-Operating_System
system	O
be	O
released	O
under	O
the	O
same	O
license	O
as	O
Net/1	O
.	O
</s>
<s>
To	O
this	O
end	O
,	O
he	O
started	O
a	O
project	O
to	O
reimplement	O
most	O
of	O
the	O
standard	O
Unix	B-Application
utilities	O
without	O
using	O
the	O
AT&T	O
code	O
.	O
</s>
<s>
For	O
example	O
,	O
vi	B-Application
,	O
which	O
had	O
been	O
based	O
on	O
the	O
original	O
Unix	B-Application
version	O
of	O
ed	B-Application
,	O
was	O
rewritten	O
as	O
nvi	B-Device
(	O
new	B-Device
vi	I-Device
)	O
.	O
</s>
<s>
Within	O
eighteen	O
months	O
,	O
all	O
of	O
the	O
AT&T	O
utilities	O
had	O
been	O
replaced	O
,	O
and	O
it	O
was	O
determined	O
that	O
only	O
a	O
few	O
AT&T	O
files	O
remained	O
in	O
the	O
kernel	B-Operating_System
.	O
</s>
<s>
Net/2	O
was	O
the	O
basis	O
for	O
two	O
separate	O
ports	O
of	O
BSD	B-Operating_System
to	O
the	O
Intel	B-General_Concept
80386	I-General_Concept
architecture	O
:	O
the	O
free	O
386BSD	B-Operating_System
by	O
William	O
Jolitz	O
and	O
the	O
proprietary	B-Application
BSD/386	B-Operating_System
(	O
later	O
renamed	O
BSD/OS	B-Operating_System
)	O
by	O
Berkeley	O
Software	O
Design	O
(	O
BSDi	O
)	O
.	O
</s>
<s>
386BSD	B-Operating_System
itself	O
was	O
short-lived	O
,	O
but	O
became	O
the	O
initial	O
code	O
base	O
of	O
the	O
NetBSD	B-Device
and	O
FreeBSD	B-Operating_System
projects	I-Operating_System
that	O
were	O
started	O
shortly	O
thereafter	O
.	O
</s>
<s>
BSDi	O
soon	O
found	O
itself	O
in	O
legal	O
trouble	O
with	O
T	O
's	O
Unix	B-Application
System	I-Application
Laboratories	O
(	O
USL	O
)	O
subsidiary	O
,	O
then	O
the	O
owners	O
of	O
the	O
System	B-Operating_System
V	I-Operating_System
copyright	O
and	O
the	O
Unix	B-Application
trademark	O
.	O
</s>
<s>
The	O
USL	B-Operating_System
v	I-Operating_System
.	I-Operating_System
BSDi	I-Operating_System
lawsuit	O
was	O
filed	O
in	O
April	O
1992	O
and	O
led	O
to	O
an	O
injunction	O
on	O
the	O
distribution	O
of	O
Net/2	O
until	O
the	O
validity	O
of	O
USL	O
's	O
copyright	O
claims	O
on	O
the	O
source	O
could	O
be	O
determined	O
.	O
</s>
<s>
The	O
lawsuit	O
slowed	O
development	O
of	O
the	O
free-software	B-Application
descendants	O
of	O
BSD	B-Operating_System
for	O
nearly	O
two	O
years	O
while	O
their	O
legal	O
status	O
was	O
in	O
question	O
,	O
and	O
as	O
a	O
result	O
systems	O
based	O
on	O
the	O
Linux	B-Operating_System
kernel	I-Operating_System
,	O
which	O
did	O
not	O
have	O
such	O
legal	O
ambiguity	O
,	O
gained	O
greater	O
support	O
.	O
</s>
<s>
Although	O
not	O
released	O
until	O
1992	O
,	O
development	O
of	O
386BSD	B-Operating_System
predated	O
that	O
of	O
Linux	B-Operating_System
.	O
</s>
<s>
Linus	O
Torvalds	O
has	O
said	O
that	O
if	O
386BSD	B-Operating_System
or	O
the	O
GNU	B-Application
kernel	I-Application
had	O
been	O
available	O
at	O
the	O
time	O
,	O
he	O
probably	O
would	O
not	O
have	O
created	O
Linux	B-Operating_System
.	O
</s>
<s>
The	O
final	O
release	O
from	O
Berkeley	O
was	O
1995	O
's	O
4.4BSD-Lite	O
Release	O
2	O
,	O
after	O
which	O
the	O
CSRG	B-Operating_System
was	O
dissolved	O
and	O
development	O
of	O
BSD	B-Operating_System
at	O
Berkeley	O
ceased	O
.	O
</s>
<s>
Since	O
then	O
,	O
several	O
variants	O
based	O
directly	O
or	O
indirectly	O
on	O
4.4BSD-Lite	O
(	O
such	O
as	O
FreeBSD	B-Operating_System
,	O
NetBSD	B-Device
,	O
OpenBSD	B-Operating_System
and	O
DragonFly	B-Application
BSD	I-Application
)	O
have	O
been	O
maintained	O
.	O
</s>
<s>
In	O
addition	O
,	O
the	O
permissive	O
nature	O
of	O
the	O
BSD	B-Operating_System
license	I-Operating_System
has	O
allowed	O
many	O
other	O
operating	O
systems	O
,	O
both	O
free	O
and	O
proprietary	B-Application
,	O
to	O
incorporate	O
BSD	B-Operating_System
code	O
.	O
</s>
<s>
For	O
example	O
,	O
Microsoft	B-Application
Windows	I-Application
has	O
used	O
BSD-derived	O
code	O
in	O
its	O
implementation	O
of	O
TCP/IP	B-Protocol
and	O
bundles	O
recompiled	O
versions	O
of	O
BSD	B-Operating_System
's	O
command-line	B-Application
networking	O
tools	O
since	O
Windows	B-Application
2000	I-Application
.	O
</s>
<s>
Also	O
Darwin	B-Operating_System
,	O
the	O
system	O
on	O
which	O
Apple	O
's	O
macOS	B-Application
is	O
built	O
,	O
is	O
a	O
derivative	O
of	O
4.4BSD-Lite2	O
and	O
FreeBSD	B-Operating_System
.	O
</s>
<s>
Various	O
commercial	O
Unix	B-Application
operating	I-Application
systems	I-Application
,	O
such	O
as	O
Solaris	B-Application
,	O
also	O
contain	O
varying	O
amounts	O
of	O
BSD	B-Operating_System
code	O
.	O
</s>
<s>
BSD	B-Operating_System
has	O
been	O
the	O
base	O
of	O
a	O
large	O
number	O
of	O
operating	O
systems	O
.	O
</s>
<s>
Most	O
notable	O
among	O
these	O
today	O
are	O
perhaps	O
the	O
major	O
open	B-Application
source	I-Application
BSDs	B-Operating_System
:	O
FreeBSD	B-Operating_System
,	O
NetBSD	B-Device
and	O
OpenBSD	B-Operating_System
,	O
which	O
are	O
all	O
derived	O
from	O
386BSD	B-Operating_System
and	O
4.4BSD-Lite	O
by	O
various	O
routes	O
.	O
</s>
<s>
Both	O
NetBSD	B-Device
and	O
FreeBSD	B-Operating_System
started	O
life	O
in	O
1993	O
,	O
initially	O
derived	O
from	O
386BSD	B-Operating_System
,	O
but	O
in	O
1994	O
migrating	O
to	O
a	O
4.4BSD-Lite	O
code	O
base	O
.	O
</s>
<s>
OpenBSD	B-Operating_System
was	O
forked	B-Application
in	O
1995	O
from	O
NetBSD	B-Device
.	O
</s>
<s>
A	O
number	O
of	O
commercial	O
operating	O
systems	O
are	O
also	O
partly	O
or	O
wholly	O
based	O
on	O
BSD	B-Operating_System
or	O
its	O
descendants	O
,	O
including	O
Sun	O
's	O
SunOS	B-Operating_System
and	O
Apple	O
Inc.	O
'	O
s	O
macOS	B-Application
.	O
</s>
<s>
Most	O
of	O
the	O
current	O
BSD	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
are	O
open	B-Application
source	I-Application
and	O
available	O
for	O
download	O
,	O
free	O
of	O
charge	O
,	O
under	O
the	O
BSD	B-Operating_System
License	I-Operating_System
,	O
the	O
most	O
notable	O
exception	O
being	O
macOS	B-Application
.	O
</s>
<s>
They	O
also	O
generally	O
use	O
a	O
monolithic	B-Operating_System
kernel	I-Operating_System
architecture	O
,	O
apart	O
from	O
macOS	B-Application
and	O
DragonFly	B-Application
BSD	I-Application
which	O
feature	O
hybrid	B-Operating_System
kernels	I-Operating_System
.	O
</s>
<s>
The	O
various	O
open	B-Application
source	I-Application
BSD	B-Operating_System
projects	O
generally	O
develop	O
the	O
kernel	B-Operating_System
and	O
userland	B-Operating_System
programs	O
and	O
libraries	O
together	O
,	O
the	O
source	O
code	O
being	O
managed	O
using	O
a	O
single	O
central	O
source	O
repository	O
.	O
</s>
<s>
In	O
the	O
past	O
,	O
BSD	B-Operating_System
was	O
also	O
used	O
as	O
a	O
basis	O
for	O
several	O
proprietary	B-Application
versions	O
of	O
Unix	B-Application
,	O
such	O
as	O
Sun	O
's	O
SunOS	B-Operating_System
,	O
Sequent	O
's	O
Dynix	B-Library
,	O
NeXT	O
's	O
NeXTSTEP	B-Application
,	O
DEC	O
's	O
Ultrix	B-Operating_System
and	O
OSF/1	B-Operating_System
AXP	I-Operating_System
(	O
now	O
Tru64	B-Operating_System
UNIX	I-Operating_System
)	O
.	O
</s>
<s>
Parts	O
of	O
NeXT	O
's	O
software	O
became	O
the	O
foundation	O
for	O
macOS	B-Application
,	O
among	O
the	O
most	O
commercially	O
successful	O
BSD	B-Operating_System
variants	O
in	O
the	O
general	O
market	O
.	O
</s>
<s>
A	O
selection	O
of	O
significant	O
Unix	B-Application
versions	O
and	O
Unix-like	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
that	O
descend	O
from	O
BSD	B-Operating_System
includes	O
:	O
</s>
<s>
FreeBSD	B-Operating_System
,	O
an	O
open	B-Application
source	I-Application
general	O
purpose	O
operating	O
system	O
.	O
</s>
<s>
Orbis	B-Device
OS	I-Device
,	O
Sony	O
's	O
fork	B-Application
of	O
FreeBSD	B-Operating_System
9	O
is	O
the	O
operating	O
system	O
for	O
the	O
PS4	O
.	O
</s>
<s>
TrueOS	B-Application
,	O
GhostBSD	B-Application
and	O
DesktopBSD	B-Application
,	O
distributions	O
of	O
FreeBSD	B-Operating_System
with	O
emphasis	O
on	O
ease	O
of	O
use	O
and	O
user	O
friendly	O
interfaces	O
for	O
the	O
desktop/laptop	O
PC	O
user	O
.	O
</s>
<s>
DragonFly	B-Application
BSD	I-Application
,	O
a	O
fork	B-Application
of	O
FreeBSD	B-Operating_System
to	O
follow	O
an	O
alternative	O
design	O
,	O
particularly	O
related	O
to	O
SMP	B-Operating_System
.	O
</s>
<s>
NextBSD	B-Operating_System
,	O
new	O
BSD	B-Operating_System
distribution	O
derived	O
from	O
FreeBSD	B-Operating_System
10.1	O
and	O
various	O
macOS	B-Application
components	O
.	O
</s>
<s>
FreeNAS	B-Application
a	O
free	O
network-attached	O
storage	O
server	O
based	O
on	O
a	O
minimal	O
version	O
of	O
FreeBSD	B-Operating_System
.	O
</s>
<s>
NAS4Free	B-Application
fork	B-Application
of	O
0.7	O
FreeNAS	B-Application
version	O
,	O
Network	O
attached	O
storage	O
server	O
.	O
</s>
<s>
Nokia	B-Operating_System
IPSO	I-Operating_System
(	O
IPSO	O
SB	O
variant	O
)	O
,	O
the	O
FreeBSD-based	O
OS	O
used	O
in	O
Nokia	O
Firewall	O
Appliances	O
.	O
</s>
<s>
Isilon	O
Systems	O
 '	O
OneFS	O
,	O
the	O
operating	O
system	O
used	O
on	O
Isilon	O
IQ-series	O
clustered	O
storage	O
systems	O
,	O
is	O
a	O
heavily	O
customized	O
version	O
of	O
FreeBSD	B-Operating_System
.	O
</s>
<s>
NetApp	O
's	O
Data	O
ONTAP	O
,	O
the	O
operating	O
system	O
for	O
NetApp	O
filers	O
,	O
is	O
a	O
customized	O
version	O
of	O
FreeBSD	B-Operating_System
with	O
the	O
ONTAP	O
architecture	O
built	O
on	O
top	O
.	O
</s>
<s>
m0n0wall	B-Protocol
,	O
a	O
FreeBSD	B-Operating_System
distribution	O
tweaked	O
for	O
usage	O
as	O
a	O
firewall	O
.	O
</s>
<s>
pfSense	B-Protocol
free	O
open	B-Application
source	I-Application
FreeBSD	B-Operating_System
based	O
firewall/router	O
.	O
</s>
<s>
Coyote	O
Point	O
Systems	O
EQ/OS	O
,	O
a	O
hardened	O
high-performance	O
runtime	O
for	O
server	B-Application
load	I-Application
balancing	I-Application
.	O
</s>
<s>
NetBSD	B-Device
,	O
an	O
open	B-Application
source	I-Application
BSD	B-Operating_System
focused	O
on	O
clean	O
design	O
and	O
portability	O
.	O
</s>
<s>
OpenBSD	B-Operating_System
,	O
a	O
1995	O
fork	B-Application
of	O
NetBSD	B-Device
,	O
focused	O
on	O
security	O
.	O
</s>
<s>
Force10	O
FTOS	B-Protocol
,	O
the	O
operating	O
system	O
for	O
Force	O
10	O
and	O
Dell	O
datacenter	O
network	O
switches	O
.	O
</s>
<s>
Dell	O
DNOS	B-Protocol
version	O
9	O
and	O
above	O
,	O
the	O
successor	O
to	O
FTOS	B-Protocol
.	O
</s>
<s>
F5	O
Networks	O
,	O
F5	O
BIGIP	O
Appliances	O
used	O
a	O
BSD	B-Operating_System
OS	O
as	O
the	O
management	O
OS	O
until	O
version	O
9.0	O
was	O
released	O
,	O
which	O
is	O
built	O
on	O
top	O
of	O
Linux	B-Operating_System
.	O
</s>
<s>
Tru64	B-Operating_System
UNIX	I-Operating_System
(	O
formerly	O
DEC	B-Operating_System
OSF/1	I-Operating_System
AXP	I-Operating_System
or	O
Digital	B-Operating_System
UNIX	I-Operating_System
)	O
,	O
the	O
port	O
of	O
OSF/1	B-Operating_System
for	O
DEC	O
Alpha-based	O
systems	O
from	O
DEC	O
,	O
Compaq	O
and	O
HP	O
.	O
</s>
