<s>
OpenStep	B-Operating_System
is	O
a	O
defunct	O
object-oriented	B-Language
application	B-Application
programming	I-Application
interface	I-Application
(	O
API	B-Application
)	O
specification	O
for	O
a	O
legacy	O
object-oriented	B-Application
operating	I-Application
system	I-Application
,	O
with	O
the	O
basic	O
goal	O
of	O
offering	O
a	O
NeXTSTEP-like	O
environment	O
on	O
non-NeXTSTEP	O
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
OpenStep	B-Operating_System
was	O
principally	O
developed	O
by	O
NeXT	O
with	O
Sun	O
Microsystems	O
,	O
to	O
allow	O
advanced	O
application	O
development	O
on	O
Sun	O
's	O
operating	B-General_Concept
systems	I-General_Concept
,	O
specifically	O
Solaris	B-Application
.	O
</s>
<s>
NeXT	O
produced	O
a	O
version	O
of	O
OpenStep	B-Operating_System
for	O
its	O
own	O
Mach-based	O
Unix	B-Application
,	O
stylized	O
as	O
OPENSTEP	B-Operating_System
,	O
as	O
well	O
as	O
a	O
version	O
for	O
Windows	B-Device
NT	I-Device
.	O
</s>
<s>
The	O
software	B-Library
libraries	I-Library
that	O
shipped	O
with	O
OPENSTEP	B-Operating_System
are	O
a	O
superset	O
of	O
the	O
original	O
OpenStep	B-Operating_System
specification	O
,	O
including	O
many	O
features	O
from	O
the	O
original	O
NeXTSTEP	B-Application
.	O
</s>
<s>
In	O
the	O
early	O
era	O
of	O
the	O
Sun	O
Microsystems	O
history	O
,	O
Sun	O
machines	O
had	O
been	O
programmed	O
at	O
a	O
relatively	O
low-level	O
making	O
calls	O
directly	O
to	O
the	O
underlying	O
Unix	B-Application
operating	I-Application
system	I-Application
and	O
producing	O
a	O
graphical	B-Application
user	I-Application
interface	I-Application
(	O
GUI	B-Application
)	O
using	O
the	O
X11	B-Operating_System
system	O
.	O
</s>
<s>
An	O
attempt	O
to	O
address	O
this	O
with	O
an	O
object	B-Language
oriented	I-Language
programming	I-Language
model	O
was	O
made	O
in	O
the	O
mid-1980s	O
with	O
Sun	O
's	O
NeWS	O
windowing	B-Application
system	I-Application
,	O
but	O
the	O
combination	O
of	O
a	O
complex	O
application	B-Application
programming	I-Application
interface	I-Application
(	O
API	B-Application
)	O
and	O
generally	O
poor	O
performance	O
led	O
to	O
little	O
real-world	O
use	O
and	O
the	O
system	O
was	O
eventually	O
abandoned	O
.	O
</s>
<s>
Taligent	B-Operating_System
was	O
considered	O
to	O
be	O
a	O
competitor	O
in	O
the	O
operating	B-General_Concept
system	I-General_Concept
and	O
object	O
markets	O
,	O
and	O
Microsoft	O
's	O
Cairo	B-Application
was	O
at	O
least	O
a	O
consideration	O
,	O
even	O
without	O
any	O
product	O
releases	O
from	O
either	O
.	O
</s>
<s>
Taligent	B-Operating_System
's	O
theoretical	O
newness	O
was	O
often	O
compared	O
to	O
NeXT	O
's	O
older	O
but	O
mature	O
and	O
commercially	O
established	O
platform	O
.	O
</s>
<s>
Sun	O
held	O
exploratory	O
meetings	O
with	O
Taligent	B-Operating_System
before	O
deciding	O
upon	O
building	O
out	O
its	O
object	O
application	O
framework	O
OpenStep	B-Operating_System
in	O
partnership	O
with	O
NeXT	O
as	O
a	O
"	O
preemptive	O
move	O
against	O
Taligent	B-Operating_System
and	O
Cairo	B-Application
"	O
.	O
</s>
<s>
Bud	O
Tribble	O
,	O
a	O
founding	O
designer	O
of	O
the	O
Macintosh	B-Device
and	O
of	O
NeXTStep	B-Application
,	O
was	O
now	O
SunSoft	O
's	O
Vice	O
President	O
of	O
Object	O
Products	O
to	O
lead	O
this	O
decision	O
.	O
</s>
<s>
The	O
basic	O
concept	O
was	O
to	O
take	O
a	O
cut-down	O
version	O
of	O
the	O
NeXTSTEP	B-Application
operating	B-General_Concept
system	I-General_Concept
's	O
object	O
layers	O
and	O
adapt	O
them	O
to	O
run	O
on	O
Sun	O
's	O
Solaris	B-Application
operating	I-Application
system	I-Application
,	O
more	O
specifically	O
,	O
Solaris	B-Application
on	O
SPARC-based	O
hardware	O
.	O
</s>
<s>
Most	O
of	O
the	O
OpenStep	B-Operating_System
effort	O
was	O
to	O
strip	O
away	O
those	O
portions	O
of	O
NeXTSTEP	B-Application
that	O
depended	O
on	O
Mach	B-Operating_System
or	O
NeXT-specific	O
hardware	O
being	O
present	O
.	O
</s>
<s>
This	O
resulted	O
in	O
a	O
smaller	O
system	O
that	O
consisted	O
primarily	O
of	O
Display	O
PostScript	O
,	O
the	O
Objective-C	B-Language
runtime	O
and	O
compilers	O
,	O
and	O
the	O
majority	O
of	O
the	O
NeXTSTEP	B-Application
Objective-C	B-Language
libraries	O
.	O
</s>
<s>
Not	O
included	O
was	O
the	O
basic	O
operating	B-General_Concept
system	I-General_Concept
,	O
or	O
the	O
lower-level	O
display	O
system	O
.	O
</s>
<s>
...	O
[	O
In	O
1996	O
,	O
]	O
Cairo	B-Application
will	O
be	O
very	O
close	O
behind	O
,	O
and	O
Taligent	B-Operating_System
will	O
be	O
very	O
far	O
behind.	O
"	O
</s>
<s>
We	O
have	O
made	O
a	O
firm	O
one-company	O
,	O
one-architecture	O
decision	O
,	O
not	O
like	O
Taligent	B-Operating_System
getting	O
a	O
trophy	O
spouse	O
by	O
signing	O
up	O
HP.	O
"	O
</s>
<s>
The	O
first	O
draft	O
of	O
the	O
API	B-Application
was	O
published	O
by	O
NeXT	O
in	O
mid	O
1994	O
.	O
</s>
<s>
Later	O
that	O
year	O
they	O
released	O
an	O
OpenStep	B-Operating_System
compliant	O
version	O
of	O
NeXTSTEP	B-Application
as	O
OPENSTEP	B-Operating_System
,	O
supported	O
on	O
several	O
of	O
their	O
platforms	O
as	O
well	O
as	O
Sun	B-Architecture
SPARC	I-Architecture
systems	O
.	O
</s>
<s>
NeXT	O
submitted	O
the	O
OpenStep	B-Operating_System
specification	O
to	O
the	O
industry	O
's	O
object	O
standards	O
bodies	O
.	O
</s>
<s>
The	O
official	O
OpenStep	B-Operating_System
API	B-Application
,	O
published	O
in	O
September	O
1994	O
,	O
was	O
the	O
first	O
to	O
split	O
the	O
API	B-Application
between	O
Foundation	O
and	O
Application	B-Operating_System
Kit	I-Operating_System
and	O
the	O
first	O
to	O
use	O
the	O
"	O
NS	O
"	O
prefix	O
.	O
</s>
<s>
Early	O
versions	O
of	O
NeXTSTEP	B-Application
use	O
an	O
"	O
NX	O
"	O
prefix	O
and	O
contain	O
only	O
the	O
Application	B-Operating_System
Kit	I-Operating_System
,	O
relying	O
on	O
standard	O
Unix	B-Application
libc	B-Language
types	O
for	O
low-level	O
data	O
structures	O
.	O
</s>
<s>
OPENSTEP	B-Operating_System
remained	O
NeXT	O
's	O
primary	O
operating	B-General_Concept
system	I-General_Concept
product	O
until	O
the	O
company	O
was	O
purchased	O
by	O
Apple	O
Computer	O
in	O
1997	O
.	O
</s>
<s>
OPENSTEP	B-Operating_System
was	O
then	O
combined	O
with	O
technologies	O
from	O
the	O
existing	O
classic	B-Application
Mac	I-Application
OS	I-Application
to	O
produce	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
.	O
iPhone	B-Device
and	O
iPad	B-Device
's	O
iOS	B-Application
is	O
also	O
a	O
descendant	O
of	O
OPENSTEP	B-Operating_System
,	O
but	O
targeted	O
at	O
touch	O
devices	O
.	O
</s>
<s>
Sun	O
originally	O
adopted	O
the	O
OpenStep	B-Operating_System
environment	O
with	O
the	O
intent	O
of	O
complementing	O
Sun	O
's	O
CORBA-compliant	O
object	B-Language
system	I-Language
,	O
Solaris	B-Application
NEO	I-Application
(	O
formerly	O
known	O
as	O
Project	O
DOE	O
)	O
,	O
by	O
providing	O
an	O
object-oriented	B-Language
user	O
interface	O
toolkit	O
to	O
complement	O
the	O
object-oriented	B-Language
CORBA	B-Architecture
plumbing	O
.	O
</s>
<s>
The	O
port	O
involved	O
integrating	O
the	O
OpenStep	B-Operating_System
AppKit	B-Operating_System
with	O
the	O
Display	O
PostScript	O
layer	O
of	O
the	O
Sun	O
X11	B-Operating_System
server	I-Operating_System
,	O
making	O
the	O
AppKit	B-Operating_System
tolerant	O
of	O
multi-threaded	O
code	O
(	O
as	O
Project	O
DOE	O
was	O
inherently	O
heavily	O
multi-threaded	O
)	O
,	O
implementing	O
a	O
Solaris	B-Application
daemon	O
to	O
simulate	O
the	O
behavior	O
of	O
Mach	B-Operating_System
ports	O
,	O
extending	O
the	O
SunPro	O
C++	O
compiler	O
to	O
support	O
Objective-C	B-Language
using	O
NeXT	O
's	O
ObjC	B-Language
runtime	O
,	O
writing	O
an	O
X11	B-Operating_System
window	B-Application
manager	I-Application
to	O
implement	O
the	O
NeXTSTEP	B-Application
look	O
and	O
feel	O
as	O
much	O
as	O
possible	O
,	O
and	O
integrating	O
the	O
NeXT	O
development	O
tools	O
,	O
such	O
as	O
Project	O
Builder	O
and	O
Interface	O
Builder	O
,	O
with	O
the	O
SunPro	O
compiler	O
.	O
</s>
<s>
In	O
order	O
to	O
provide	O
a	O
complete	O
end-user	O
environment	O
,	O
Sun	O
also	O
ported	O
the	O
NeXTSTEP-3.3	O
versions	O
of	O
several	O
end-user	O
applications	O
,	O
including	O
Mail.app	O
,	O
Preview.app	O
,	O
Edit.app	O
,	O
Workspace	B-Application
Manager	I-Application
,	O
and	O
the	O
Dock	O
.	O
</s>
<s>
The	O
OpenStep	B-Operating_System
and	O
CORBA	B-Architecture
parts	O
of	O
the	O
products	O
were	O
later	O
split	O
,	O
and	O
NEO	O
was	O
released	O
in	O
late	O
1995	O
without	O
the	O
OpenStep	B-Operating_System
environment	O
.	O
</s>
<s>
In	O
March	O
1996	O
,	O
Sun	O
announced	O
Joe	O
,	O
a	O
product	O
to	O
integrate	O
NEO	O
with	O
Java	B-Language
.	O
</s>
<s>
Sun	O
shipped	O
a	O
beta	O
release	O
of	O
the	O
OpenStep	B-Operating_System
environment	O
for	O
Solaris	B-Application
on	O
July	O
22	O
,	O
1996	O
,	O
and	O
made	O
it	O
freely	O
available	O
for	O
download	O
in	O
August	O
1996	O
for	O
non-commercial	O
use	O
,	O
and	O
for	O
sale	O
in	O
September	O
1996	O
.	O
</s>
<s>
OpenStep/Solaris	O
was	O
shipped	O
only	O
for	O
the	O
SPARC	B-Architecture
architecture	O
.	O
</s>
<s>
OpenStep	B-Operating_System
differs	O
from	O
NeXTSTEP	B-Application
in	O
various	O
ways	O
:	O
</s>
<s>
NeXTSTEP	B-Application
is	O
an	O
operating	B-General_Concept
system	I-General_Concept
,	O
whereas	O
OpenStep	B-Operating_System
is	O
an	O
API	B-Application
.	O
</s>
<s>
Unlike	O
NeXTSTEP	B-Application
,	O
OpenStep	B-Operating_System
does	O
not	O
require	O
the	O
Mach	B-Operating_System
kernel	I-Operating_System
.	O
</s>
<s>
Each	O
version	O
of	O
NeXTSTEP	B-Application
has	O
a	O
specific	O
endianness	O
:	O
big	O
endian	O
for	O
Motorola	B-Device
68K	I-Device
processors	O
,	O
and	O
little	O
endian	O
for	O
x86	B-Operating_System
processors	O
,	O
for	O
example	O
.	O
</s>
<s>
OpenStep	B-Operating_System
is	O
"	O
endian-free	O
"	O
.	O
</s>
<s>
OpenStep	B-Operating_System
introduces	O
new	O
classes	O
and	O
memory	B-General_Concept
management	I-General_Concept
capabilities	O
.	O
</s>
<s>
The	O
OpenStep	B-Operating_System
API	B-Application
specification	O
defines	O
three	O
major	O
components	O
:	O
Foundation	O
Kit	O
,	O
the	O
software	B-Architecture
framework	I-Architecture
;	O
Application	B-Operating_System
Kit	I-Operating_System
,	O
the	O
GUI	B-Application
and	O
graphics	O
front-end	O
;	O
and	O
Display	O
PostScript	O
,	O
a	O
2D	O
graphics	O
system	O
(	O
for	O
drawing	O
windows	O
and	O
other	O
graphics	O
on	O
the	O
screen	O
)	O
.	O
</s>
<s>
The	O
standardization	O
on	O
OpenStep	B-Operating_System
also	O
allowed	O
for	O
the	O
creation	O
of	O
several	O
new	O
library	O
packages	O
that	O
were	O
delivered	O
on	O
the	O
OPENSTEP	B-Operating_System
platform	O
.	O
</s>
<s>
Unlike	O
the	O
operating	B-General_Concept
system	I-General_Concept
as	O
a	O
whole	O
,	O
these	O
packages	O
were	O
designed	O
to	O
run	O
stand-alone	B-General_Concept
on	O
practically	O
any	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
The	O
idea	O
was	O
to	O
use	O
OpenStep	B-Operating_System
code	O
as	O
a	O
basis	O
for	O
network-wide	O
applications	O
running	O
across	O
different	O
platforms	O
,	O
as	O
opposed	O
to	O
using	O
CORBA	B-Architecture
or	O
some	O
other	O
system	O
.	O
</s>
<s>
Primary	O
among	O
these	O
packages	O
was	O
Portable	B-Application
Distributed	I-Application
Objects	I-Application
(	O
PDO	O
)	O
.	O
</s>
<s>
PDO	O
was	O
essentially	O
an	O
even	O
more	O
"	O
stripped	O
down	O
"	O
version	O
of	O
OpenStep	B-Operating_System
containing	O
only	O
the	O
Foundation	O
Kit	O
technologies	O
,	O
combined	O
with	O
new	O
libraries	O
to	O
provide	O
remote	B-Operating_System
invocation	I-Operating_System
with	O
very	O
little	O
code	O
.	O
</s>
<s>
Unlike	O
OpenStep	B-Operating_System
,	O
which	O
defined	O
an	O
operating	B-General_Concept
system	I-General_Concept
that	O
applications	O
would	O
run	O
in	O
,	O
under	O
PDO	O
the	O
libraries	O
were	O
compiled	O
into	O
the	O
application	O
itself	O
,	O
creating	O
a	O
stand-alone	B-General_Concept
"	O
native	O
"	O
application	O
for	O
a	O
particular	O
platform	O
.	O
</s>
<s>
In	O
the	O
mid-1990s	O
,	O
NeXT	O
staff	O
took	O
to	O
writing	O
in	O
solutions	O
to	O
various	O
CORBA	B-Architecture
magazine	O
articles	O
in	O
a	O
few	O
lines	O
of	O
code	O
,	O
whereas	O
the	O
original	O
article	O
would	O
fill	O
several	O
pages	O
.	O
</s>
<s>
Even	O
though	O
using	O
PDO	O
required	O
the	O
installation	O
of	O
a	O
considerable	O
amount	O
of	O
supporting	O
code	O
(	O
Objective-C	B-Language
and	O
the	O
libraries	O
)	O
,	O
PDO	O
applications	O
were	O
nevertheless	O
considerably	O
smaller	O
than	O
similar	O
CORBA	B-Architecture
solutions	O
,	O
typically	O
about	O
one-half	O
to	O
one-third	O
the	O
size	O
.	O
</s>
<s>
The	O
similar	O
D'OLE	O
provided	O
the	O
same	O
types	O
of	O
services	O
,	O
but	O
presented	O
the	O
resulting	O
objects	O
as	O
COM	B-Application
objects	I-Application
,	O
with	O
the	O
goal	O
of	O
allowing	O
programmers	O
to	O
create	O
COM	B-Application
services	O
running	O
on	O
high-powered	O
platforms	O
,	O
called	O
from	O
Microsoft	B-Application
Windows	I-Application
applications	O
.	O
</s>
<s>
For	O
instance	O
one	O
could	O
develop	O
a	O
high-powered	O
financial	O
modeling	O
application	O
using	O
D'OLE	O
,	O
and	O
then	O
call	O
it	O
directly	O
from	O
within	O
Microsoft	B-Application
Excel	I-Application
.	O
</s>
<s>
PDO	O
enabled	O
NeXT	O
to	O
demonstrate	O
Excel	B-Application
talking	O
to	O
other	O
Microsoft	O
applications	O
across	O
a	O
network	O
before	O
Microsoft	O
themselves	O
were	O
able	O
to	O
implement	O
this	O
functionality	O
(	O
DCOM	O
)	O
.	O
</s>
<s>
Another	O
package	O
developed	O
on	O
OpenStep	B-Operating_System
was	O
Enterprise	B-General_Concept
Objects	I-General_Concept
Framework	I-General_Concept
(	O
EOF	O
)	O
,	O
a	O
tremendously	O
powerful	O
(	O
for	O
the	O
time	O
)	O
object-relational	B-General_Concept
mapping	I-General_Concept
product	O
.	O
</s>
<s>
EOF	O
became	O
very	O
popular	O
in	O
the	O
enterprise	O
market	O
,	O
notably	O
in	O
the	O
financial	O
sector	O
where	O
OPENSTEP	B-Operating_System
caused	O
something	O
of	O
a	O
minor	O
revolution	O
.	O
</s>
<s>
NeXT	O
's	O
first	O
operating	B-General_Concept
system	I-General_Concept
was	O
NeXTSTEP	B-Application
,	O
a	O
sophisticated	O
Mach-UNIX	O
based	O
operating	B-General_Concept
system	I-General_Concept
that	O
originally	O
ran	O
only	O
on	O
NeXT	O
's	O
Motorola	O
68k-based	O
workstations	O
and	O
that	O
was	O
then	O
ported	O
to	O
run	O
on	O
32-bit	O
Intel	O
x86-based	O
"	O
IBM-compatible	O
"	O
personal	O
computers	O
,	O
PA-RISC-based	O
workstations	O
from	O
Hewlett-Packard	O
,	O
and	O
SPARC-based	O
workstations	O
from	O
Sun	O
Microsystems	O
.	O
</s>
<s>
NeXT	O
completed	O
an	O
implementation	O
of	O
OpenStep	B-Operating_System
on	O
their	O
existing	O
Mach-based	O
OS	O
and	O
called	O
it	O
OPENSTEP	B-Operating_System
for	O
Mach	B-Operating_System
4.0	O
(	O
July	O
,	O
1996	O
)	O
,	O
4.1	O
(	O
December	O
,	O
1996	O
)	O
,	O
and	O
4.2	O
(	O
January	O
,	O
1997	O
)	O
.	O
</s>
<s>
It	O
was	O
,	O
for	O
all	O
intents	O
,	O
NeXTSTEP	B-Application
4.0	O
,	O
and	O
still	O
retained	O
flagship	O
NeXTSTEP	B-Application
technologies	O
(	O
such	O
as	O
DPS	O
,	O
UNIX	B-Application
underpinnings	O
,	O
user	O
interface	O
characteristics	O
like	O
the	O
Dock	O
and	O
Shelf	O
,	O
and	O
so	O
on	O
)	O
,	O
and	O
retained	O
the	O
classic	O
NeXTSTEP	B-Application
user	O
interface	O
and	O
styles	O
.	O
</s>
<s>
OPENSTEP	B-Operating_System
for	O
Mach	B-Operating_System
was	O
further	O
improved	O
,	O
in	O
comparison	O
to	O
NeXTSTEP	B-Application
3.3	O
,	O
with	O
vastly	O
improved	O
driver	O
support	O
however	O
the	O
environment	O
to	O
actually	O
write	O
drivers	O
was	O
changed	O
with	O
the	O
introduction	O
of	O
the	O
object-oriented	B-Language
DriverKit	O
.	O
</s>
<s>
OPENSTEP	B-Operating_System
for	O
Mach	B-Operating_System
supported	O
Intel	O
x86-based	O
PC	O
's	O
,	O
Sun	O
's	O
SPARC	B-Architecture
workstations	O
,	O
and	O
NeXT	O
's	O
own	O
68k-based	O
architectures	O
,	O
while	O
the	O
HP	B-Device
PA-RISC	I-Device
version	O
was	O
dropped	O
.	O
</s>
<s>
These	O
versions	O
continued	O
to	O
run	O
on	O
the	O
underlying	O
Mach-based	O
OS	O
used	O
in	O
NeXTSTEP	B-Application
.	O
</s>
<s>
OPENSTEP	B-Operating_System
for	O
Mach	B-Operating_System
became	O
NeXT	O
's	O
primary	O
OS	O
from	O
1995	O
on	O
,	O
and	O
was	O
used	O
mainly	O
on	O
the	O
Intel	O
platform	O
.	O
</s>
<s>
In	O
addition	O
to	O
being	O
a	O
complete	O
OpenStep	B-Operating_System
implementation	O
,	O
the	O
system	O
was	O
delivered	O
with	O
a	O
complete	O
set	O
of	O
NeXTSTEP	B-Application
libraries	O
for	O
backward	O
compatibility	O
.	O
</s>
<s>
This	O
was	O
an	O
easy	O
thing	O
to	O
do	O
in	O
OpenStep	B-Operating_System
due	O
to	O
library	O
versioning	O
,	O
and	O
OPENSTEP	B-Operating_System
did	O
not	O
suffer	O
in	O
bloat	O
because	O
of	O
it	O
.	O
</s>
<s>
In	O
addition	O
to	O
the	O
OPENSTEP	B-Operating_System
for	O
Mach	B-Operating_System
port	O
for	O
SPARC	B-Architecture
,	O
Sun	O
and	O
NeXT	O
developed	O
an	O
OpenStep	B-Operating_System
compliant	O
set	O
of	O
frameworks	O
to	O
run	O
on	O
Sun	O
's	O
Solaris	B-Application
operating	I-Application
system	I-Application
.	O
</s>
<s>
After	O
developing	O
Solaris	B-Application
OpenStep	B-Operating_System
,	O
Sun	O
lost	O
interest	O
in	O
OpenStep	B-Operating_System
and	O
shifted	O
its	O
attention	O
toward	O
Java	B-Language
.	O
</s>
<s>
As	O
a	O
virtual	O
machine	O
development	O
environment	O
,	O
Java	B-Language
served	O
as	O
a	O
direct	O
competitor	O
to	O
OpenStep	B-Operating_System
.	O
</s>
<s>
NeXT	O
also	O
delivered	O
an	O
implementation	O
running	O
on	O
top	O
of	O
Windows	B-Device
NT	I-Device
4.0	I-Device
called	O
OPENSTEP	B-Operating_System
Enterprise	I-Operating_System
(	O
often	O
abbreviated	O
OSE	O
)	O
.	O
</s>
<s>
This	O
was	O
an	O
unintentional	O
demonstration	O
on	O
the	O
true	O
nature	O
of	O
the	O
portability	O
of	O
programs	O
created	O
under	O
the	O
OpenStep	B-Operating_System
specification	O
.	O
</s>
<s>
Programs	O
for	O
OPENSTEP	B-Operating_System
for	O
Mach	B-Operating_System
could	O
be	O
ported	O
to	O
OSE	O
with	O
little	O
difficulty	O
.	O
</s>
<s>
Never	O
a	O
clean	O
match	O
from	O
the	O
UI	O
perspective	O
,	O
probably	O
due	O
to	O
OPENSTEP	B-Operating_System
's	O
routing	O
of	O
window	O
graphics	O
through	O
the	O
Display	O
Postscript	O
serverwhich	O
was	O
also	O
ported	O
to	O
WindowsOSE	O
nevertheless	O
managed	O
to	O
work	O
fairly	O
well	O
and	O
extended	O
OpenStep	B-Operating_System
's	O
commercial	O
lifespan	O
.	O
</s>
<s>
OPENSTEP	B-Operating_System
and	O
OSE	O
had	O
two	O
revisions	O
(	O
and	O
one	O
major	O
one	O
that	O
was	O
never	O
released	O
)	O
before	O
NeXT	O
was	O
purchased	O
by	O
Apple	O
in	O
1997	O
.	O
</s>
<s>
After	O
acquiring	O
NeXT	O
,	O
Apple	O
intended	O
to	O
ship	O
Rhapsody	B-Operating_System
as	O
a	O
reworked	O
version	O
of	O
OPENSTEP	B-Operating_System
for	O
Mach	B-Operating_System
for	O
both	O
the	O
Mac	O
and	O
standard	O
PCs	O
.	O
</s>
<s>
Rhapsody	B-Operating_System
was	O
OPENSTEP	B-Operating_System
for	O
Mach	B-Operating_System
with	O
a	O
Copland	B-Application
appearance	O
from	O
Mac	B-Operating_System
OS	I-Operating_System
8	I-Operating_System
and	O
support	O
for	O
Java	B-Language
and	O
Apple	O
's	O
own	O
technologies	O
,	O
including	O
ColorSync	O
and	O
QuickTime	B-Application
;	O
it	O
could	O
be	O
regarded	O
as	O
OPENSTEP	B-Operating_System
5	O
.	O
</s>
<s>
Two	O
developer	O
versions	O
of	O
Rhapsody	B-Operating_System
were	O
released	O
,	O
known	O
as	O
Developer	O
Preview	O
1	O
and	O
2	O
;	O
these	O
ran	O
on	O
a	O
limited	O
subset	O
of	O
both	O
Intel	O
and	O
PowerPC	O
hardware	O
.	O
</s>
<s>
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
Server	I-Operating_System
1.0	I-Operating_System
was	O
the	O
first	O
commercial	O
release	O
of	O
this	O
operating	B-General_Concept
system	I-General_Concept
,	O
and	O
was	O
delivered	O
exclusively	O
for	O
PowerPC	O
Mac	O
hardware	O
.	O
</s>
<s>
After	O
replacing	O
the	O
Display	O
Postscript	O
WindowServer	O
with	O
Quartz	B-Operating_System
,	O
and	O
responding	O
to	O
developers	O
by	O
including	O
better	O
backward	O
compatibility	O
for	O
classic	B-Application
Mac	I-Application
OS	I-Application
applications	O
through	O
the	O
addition	O
of	O
Carbon	B-Operating_System
,	O
Apple	O
released	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
and	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
Server	I-Operating_System
,	O
starting	O
at	O
version	O
10.0	O
;	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
is	O
now	O
named	O
macOS	B-Operating_System
.	O
</s>
<s>
macOS	B-Operating_System
's	O
primary	O
programming	O
environment	O
is	O
essentially	O
OpenStep	B-Operating_System
(	O
with	O
certain	O
additions	O
such	O
as	O
XML	O
property	O
lists	O
and	O
URL	O
classes	O
for	O
Internet	O
connections	O
)	O
with	O
macOS	B-Operating_System
ports	O
of	O
the	O
development	O
libraries	O
and	O
tools	O
,	O
now	O
called	O
Cocoa	B-Operating_System
.	O
</s>
<s>
macOS	B-Operating_System
has	O
since	O
become	O
the	O
single	O
most	O
popular	O
desktop	O
Unix-like	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
in	O
the	O
world	O
,	O
although	O
macOS	B-Operating_System
is	O
no	O
longer	O
an	O
OpenStep	B-Operating_System
compliant	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
GNUstep	O
,	O
a	O
free	B-Application
software	I-Application
implementation	O
of	O
the	O
NeXT	O
libraries	O
,	O
began	O
at	O
the	O
time	O
of	O
NeXTSTEP	B-Application
,	O
predating	O
OPENSTEP	B-Operating_System
.	O
</s>
<s>
While	O
OPENSTEP	B-Operating_System
and	O
OSE	O
were	O
purchased	O
by	O
Apple	O
,	O
who	O
effectively	O
ended	O
the	O
commercial	O
development	O
of	O
implementing	O
OpenStep	B-Operating_System
for	O
other	O
platforms	O
,	O
GNUstep	O
is	O
an	O
ongoing	O
open	O
source	O
project	O
aiming	O
to	O
create	O
a	O
portable	O
,	O
free	B-Application
software	I-Application
implementation	O
of	O
the	O
Cocoa/OPENSTEP	O
libraries	O
.	O
</s>
<s>
GNUstep	O
also	O
features	O
a	O
fully	O
functional	O
development	O
environment	O
,	O
reimplementations	O
of	O
some	O
of	O
the	O
newer	O
innovations	O
from	O
macOS	B-Operating_System
's	O
Cocoa	B-Operating_System
framework	O
,	O
as	O
well	O
as	O
its	O
own	O
extensions	O
to	O
the	O
API	B-Application
.	O
</s>
