<s>
The	O
Computer	B-Operating_System
Systems	I-Operating_System
Research	I-Operating_System
Group	I-Operating_System
(	O
CSRG	B-Operating_System
)	O
was	O
a	O
research	O
group	O
at	O
the	O
University	O
of	O
California	O
,	O
Berkeley	O
that	O
was	O
dedicated	O
to	O
enhancing	O
AT&T	B-Operating_System
Unix	I-Operating_System
operating	B-General_Concept
system	I-General_Concept
and	O
funded	O
by	O
Defense	O
Advanced	O
Research	O
Projects	O
Agency	O
.	O
</s>
<s>
Professor	O
Bob	O
Fabry	O
of	O
Berkeley	O
acquired	O
a	O
UNIX	B-Application
source	O
license	O
from	O
AT&T	O
in	O
1974	O
.	O
</s>
<s>
His	O
group	O
started	O
to	O
modify	O
UNIX	B-Application
,	O
and	O
distributed	O
their	O
version	O
as	O
the	O
Berkeley	B-Operating_System
Software	I-Operating_System
Distribution	I-Operating_System
(	O
BSD	B-Operating_System
)	O
.	O
</s>
<s>
In	O
April	O
1980	O
,	O
Fabry	O
signed	O
a	O
contract	O
with	O
DARPA	O
to	O
develop	O
UNIX	B-Application
even	O
further	O
and	O
accommodate	O
the	O
specific	O
requirements	O
of	O
the	O
ARPAnet	O
.	O
</s>
<s>
With	O
this	O
funding	O
,	O
Fabry	O
created	O
the	O
Computer	B-Operating_System
Systems	I-Operating_System
Research	I-Operating_System
Group	I-Operating_System
.	O
</s>
<s>
The	O
Berkeley	B-Protocol
Sockets	I-Protocol
API	B-General_Concept
and	O
Berkeley	B-Operating_System
Fast	I-Operating_System
File	I-Operating_System
System	I-Operating_System
are	O
some	O
of	O
the	O
group	O
's	O
most	O
significant	O
innovations	O
.	O
</s>
<s>
XNS	B-Protocol
and	O
TCP/IP	B-Protocol
)	O
,	O
and	O
extended	O
UNIX	B-Application
's	O
"	O
everything	O
is	O
a	O
file	O
"	O
notion	O
to	O
these	O
network	O
protocols	O
,	O
while	O
the	O
Fast	O
File	O
System	O
increased	O
the	O
block	O
allocation	O
size	O
from	O
512	O
bytes	O
to	O
4096	O
bytes	O
(	O
or	O
larger	O
)	O
,	O
improving	O
disk	O
transfer	O
performance	O
,	O
while	O
also	O
allowing	O
"	O
micro-blocks	O
"	O
as	O
small	O
as	O
128	O
bytes	O
,	O
which	O
improved	O
disk	O
use	O
.	O
</s>
<s>
Another	O
noteworthy	O
contribution	O
was	O
job	O
control	O
signals	O
,	O
which	O
allowed	O
a	O
user	O
to	O
suspend	O
a	O
job	O
with	O
a	O
key-press	O
(	O
control-Z	O
)	O
,	O
and	O
then	O
continue	O
running	O
the	O
job	O
in	O
the	O
background	O
under	O
the	O
C	B-Operating_System
shell	I-Operating_System
.	O
</s>
<s>
Noteworthy	O
versions	O
of	O
BSD	B-Operating_System
were	O
3.0	O
BSD	B-Operating_System
(	O
the	O
first	O
version	O
of	O
BSD	B-Operating_System
to	O
support	O
virtual	O
memory	O
)	O
,	O
4.0	O
BSD	B-Operating_System
(	O
which	O
included	O
the	O
job-control	O
CTRL-Z	O
functionality	O
,	O
to	O
suspend	O
and	O
restart	O
a	O
running	O
job	O
)	O
,	O
a	O
special	O
4.15	O
(	O
interim	O
)	O
BSD	B-Operating_System
version	O
which	O
had	O
been	O
released	O
using	O
BBN	O
's	O
TCP/IP	B-Protocol
,	O
and	O
4.2	O
BSD	B-Operating_System
(	O
which	O
included	O
a	O
full	O
TCP/IP	B-Protocol
stack	I-Protocol
,	O
FFS	O
,	O
and	O
NFS	O
support	O
.	O
)	O
</s>
<s>
By	O
the	O
early	O
1980s	O
,	O
CSRG	B-Operating_System
was	O
the	O
best-known	O
non-commercial	O
Unix	B-Application
developer	O
,	O
and	O
a	O
majority	O
of	O
Unix	B-Application
sites	O
used	O
at	O
least	O
some	O
Berkeley	O
software	O
.	O
</s>
<s>
AT&T	O
included	O
some	O
CSRG	B-Operating_System
work	O
in	O
Unix	B-Operating_System
System	I-Operating_System
V	I-Operating_System
.	O
During	O
the	O
1970s	O
and	O
1980s	O
,	O
AT&	O
T/USL	O
raised	O
the	O
commercial	O
licensing	O
fee	O
for	O
UNIX	B-Application
from	O
$	O
20,000	O
to	O
$	O
100,000	O
–	O
$	O
200,000	O
.	O
</s>
<s>
This	O
became	O
a	O
big	O
problem	O
for	O
small	O
research	O
labs	O
and	O
companies	O
who	O
used	O
BSD	B-Operating_System
,	O
and	O
the	O
CSRG	B-Operating_System
decided	O
to	O
replace	O
all	O
the	O
source	O
code	O
that	O
originated	O
from	O
AT&T	O
.	O
</s>
<s>
They	O
succeeded	O
in	O
1994	O
,	O
but	O
AT&T	O
disagreed	O
and	O
sued	B-Operating_System
Berkeley	I-Operating_System
.	O
</s>
<s>
After	O
a	O
court	O
settlement	O
in	O
1994	O
,	O
CSRG	B-Operating_System
distributed	O
the	O
final	O
version	O
of	O
BSD	B-Operating_System
,	O
called	O
4.4BSD-Lite2	O
.	O
</s>
<s>
The	O
group	O
was	O
disbanded	O
in	O
1995	O
,	O
leaving	O
a	O
significant	O
legacy	O
:	O
FreeBSD	B-Operating_System
,	O
OpenBSD	B-Operating_System
,	O
NetBSD	B-Device
,	O
and	O
DragonFly	B-Application
BSD	I-Application
are	O
based	O
on	O
the	O
4.4BSD-Lite	O
distribution	O
and	O
continue	O
to	O
play	O
an	O
important	O
role	O
in	O
the	O
open-source	B-Application
UNIX	B-Application
community	O
today	O
,	O
including	O
dictating	O
the	O
style	O
of	O
C	B-Language
programming	I-Language
used	O
via	O
KNF	B-Operating_System
in	O
the	O
style	O
man	B-Protocol
page	I-Protocol
.	O
</s>
<s>
Alongside	O
the	B-Operating_System
Free	I-Operating_System
Software	I-Operating_System
Foundation	I-Operating_System
and	O
Linux	B-Application
,	O
the	O
CSRG	B-Operating_System
laid	O
the	O
foundations	O
of	O
the	O
open	B-Application
source	I-Application
community	O
.	O
</s>
<s>
The	O
corporations	O
Sun	O
Microsystems	O
,	O
Berkeley	O
Software	O
Design	O
and	O
Sleepycat	O
Software	O
(	O
later	O
acquired	O
by	O
Oracle	B-Application
)	O
can	O
be	O
considered	O
spin-off	O
companies	O
of	O
CSRG	B-Operating_System
.	O
</s>
<s>
Berkeley	O
Software	O
Design	O
was	O
led	O
by	O
Robert	O
Kolstad	O
,	O
who	O
led	O
the	O
development	O
of	O
BSD	B-Operating_System
Unix	I-Operating_System
for	O
supercomputers	O
at	O
Convex	O
Computer	O
.	O
</s>
