<s>
Mac	B-Application
OS	I-Application
(	O
originally	O
System	B-Application
Software	I-Application
;	O
retronym	O
:	O
Classic	B-Application
Mac	I-Application
OS	I-Application
)	O
is	O
the	O
series	O
of	O
operating	B-General_Concept
systems	I-General_Concept
developed	O
for	O
the	O
Macintosh	B-Device
family	O
of	O
personal	B-Device
computers	I-Device
by	O
Apple	O
Computer	O
from	O
1984	O
to	O
2001	O
,	O
starting	O
with	O
System	B-Operating_System
1	I-Operating_System
and	O
ending	O
with	O
Mac	B-Operating_System
OS	I-Operating_System
9	I-Operating_System
.	O
</s>
<s>
The	O
Macintosh	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
is	O
credited	O
with	O
having	O
popularized	O
the	O
graphical	B-Application
user	I-Application
interface	I-Application
concept	O
.	O
</s>
<s>
It	O
was	O
included	O
with	O
every	O
Macintosh	B-Device
that	O
was	O
sold	O
during	O
the	O
era	O
in	O
which	O
it	O
was	O
developed	O
,	O
and	O
many	O
updates	O
to	O
the	O
system	B-Application
software	I-Application
were	O
done	O
in	O
conjunction	O
with	O
the	O
introduction	O
of	O
new	O
Macintosh	B-Application
systems	I-Application
.	O
</s>
<s>
Apple	O
released	O
the	O
original	B-Device
Macintosh	I-Device
on	O
January	O
24	O
,	O
1984	O
.	O
</s>
<s>
The	O
first	B-Operating_System
version	I-Operating_System
of	I-Operating_System
the	I-Operating_System
system	I-Operating_System
software	I-Operating_System
,	O
which	O
had	O
no	O
official	O
name	O
,	O
was	O
partially	O
based	O
on	O
the	O
Lisa	B-Device
OS	O
,	O
which	O
Apple	O
previously	O
released	O
for	O
the	O
Lisa	B-Device
computer	O
in	O
1983	O
.	O
</s>
<s>
As	O
part	O
of	O
an	O
agreement	O
allowing	O
Xerox	O
to	O
buy	O
shares	O
in	O
Apple	O
at	O
a	O
favorable	O
price	O
,	O
it	O
also	O
used	O
concepts	O
from	O
the	O
Xerox	O
PARC	O
Alto	B-Device
computer	O
,	O
which	O
former	O
Apple	O
CEO	O
Steve	O
Jobs	O
and	O
other	O
Lisa	B-Device
team	O
members	O
had	O
previewed	O
.	O
</s>
<s>
This	O
operating	B-General_Concept
system	I-General_Concept
consisted	O
of	O
the	O
Macintosh	B-Device
Toolbox	I-Device
ROM	B-Device
and	O
the	O
"	O
System	B-Operating_System
Folder	I-Operating_System
"	O
,	O
a	O
set	O
of	O
files	O
that	O
were	O
loaded	O
from	O
disk	O
.	O
</s>
<s>
The	O
name	O
Macintosh	B-Application
System	I-Application
Software	I-Application
came	O
into	O
use	O
in	O
1987	O
with	O
System	O
5	O
.	O
</s>
<s>
Apple	O
rebranded	O
the	O
system	O
as	O
Mac	B-Application
OS	I-Application
in	O
1996	O
,	O
starting	O
officially	O
with	O
version	O
7.6	O
,	O
due	O
in	O
part	O
to	O
its	O
Macintosh	B-Device
clone	I-Device
program	O
.	O
</s>
<s>
That	O
program	O
ended	O
after	O
the	O
release	O
of	O
Mac	B-Operating_System
OS	I-Operating_System
8	I-Operating_System
in	O
1997	O
.	O
</s>
<s>
The	O
last	O
major	O
release	O
of	O
the	O
system	O
was	O
Mac	B-Operating_System
OS	I-Operating_System
9	I-Operating_System
in	O
1999	O
.	O
</s>
<s>
Initial	O
versions	O
of	O
the	O
System	B-Application
Software	I-Application
ran	O
one	O
application	B-Application
at	O
a	O
time	O
.	O
</s>
<s>
With	O
the	O
Macintosh	B-Device
512K	I-Device
,	O
a	O
system	O
extension	O
called	O
the	O
Switcher	O
was	O
developed	O
to	O
use	O
this	O
additional	O
memory	O
to	O
allow	O
multiple	O
programs	O
to	O
remain	O
loaded	O
.	O
</s>
<s>
The	O
software	O
of	O
each	O
loaded	O
program	O
used	O
the	O
memory	O
exclusively	O
;	O
only	O
when	O
activated	O
by	O
the	O
Switcher	O
did	O
the	O
program	O
appear	O
,	O
even	O
the	O
Finder	B-Application
's	O
desktop	B-Application
.	O
</s>
<s>
With	O
the	O
Switcher	O
,	O
the	O
now	O
familiar	O
Clipboard	O
feature	O
allowed	O
copy	O
and	O
paste	O
between	O
the	O
loaded	O
programs	O
across	O
switches	O
including	O
the	O
desktop	B-Application
.	O
</s>
<s>
With	O
the	O
introduction	O
of	O
System	O
5	O
,	O
a	O
cooperative	B-Operating_System
multitasking	I-Operating_System
extension	O
called	O
MultiFinder	O
was	O
added	O
,	O
which	O
allowed	O
content	O
in	O
windows	O
of	O
each	O
program	O
to	O
remain	O
in	O
a	O
layered	O
view	O
over	O
the	O
desktop	B-Application
,	O
and	O
was	O
later	O
integrated	O
into	O
System	B-Operating_System
7	I-Operating_System
as	O
part	O
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
along	O
with	O
support	O
for	O
virtual	B-Architecture
memory	I-Architecture
.	O
</s>
<s>
By	O
the	O
mid-1990s	O
,	O
however	O
,	O
contemporary	O
operating	B-General_Concept
systems	I-General_Concept
such	O
as	O
Windows	B-Device
NT	I-Device
,	O
OS/2	B-Application
,	O
and	O
NeXTSTEP	B-Application
had	O
all	O
brought	O
pre-emptive	O
multitasking	O
,	O
protected	B-General_Concept
memory	I-General_Concept
,	O
access	O
controls	O
,	O
and	O
multi-user	O
capabilities	O
to	O
desktop	B-Application
computers	O
.	O
</s>
<s>
The	O
Macintosh	B-Device
's	O
limited	O
memory	B-General_Concept
management	I-General_Concept
and	O
susceptibility	O
to	O
conflicts	O
among	O
extensions	B-Operating_System
that	O
provide	O
additional	O
functionality	O
,	O
such	O
as	O
networking	O
or	O
support	O
for	O
a	O
particular	O
device	O
,	O
led	O
to	O
significant	O
criticism	O
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
,	O
and	O
was	O
a	O
factor	O
in	O
Apple	O
's	O
declining	O
market	O
share	O
at	O
the	O
time	O
.	O
</s>
<s>
After	O
two	O
aborted	O
attempts	O
at	O
creating	O
a	O
successor	O
to	O
the	O
Macintosh	B-Application
System	I-Application
Software	I-Application
called	O
Taligent	B-Operating_System
and	O
Copland	B-Application
,	O
and	O
a	O
four-year	B-Operating_System
development	I-Operating_System
effort	I-Operating_System
spearheaded	O
by	O
Steve	O
Jobs	O
's	O
return	O
to	O
Apple	O
in	O
1997	O
,	O
Apple	O
replaced	O
Mac	B-Application
OS	I-Application
with	O
a	O
new	O
operating	B-General_Concept
system	I-General_Concept
in	O
2001	O
named	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
;	O
the	O
X	O
signifying	O
the	O
underlying	O
Unix	B-Application
system	I-Application
family	O
base	O
shared	O
with	O
Jobs	O
's	O
development	O
of	O
the	O
NeXTSTEP	B-Application
operating	B-General_Concept
systems	I-General_Concept
on	O
the	O
NeXT	O
computer	O
.	O
</s>
<s>
It	O
retained	O
most	O
of	O
the	O
user	B-Application
interface	I-Application
design	O
elements	O
of	O
the	O
Classic	B-Application
Mac	I-Application
OS	I-Application
,	O
and	O
there	O
was	O
some	O
overlap	O
of	O
application	B-Application
frameworks	I-Application
for	O
compatibility	O
,	O
but	O
the	O
two	O
operating	B-General_Concept
systems	I-General_Concept
otherwise	O
have	O
completely	O
different	O
origins	O
and	O
architectures	O
.	O
</s>
<s>
The	O
final	O
updates	O
to	O
Mac	B-Operating_System
OS	I-Operating_System
9	I-Operating_System
released	O
in	O
2001	O
provided	O
interoperability	O
with	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
.	O
</s>
<s>
The	O
name	O
"	O
Classic	B-Device
"	O
that	O
now	O
signifies	O
the	O
historical	O
Mac	B-Application
OS	I-Application
as	O
a	O
whole	O
is	O
a	O
reference	O
to	O
the	O
Classic	B-Device
Environment	O
,	O
a	O
compatibility	B-General_Concept
layer	I-General_Concept
that	O
helped	O
ease	O
the	O
transition	O
to	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
(	O
now	O
macOS	B-Application
)	O
.	O
</s>
<s>
The	O
Macintosh	B-Device
project	O
started	O
in	O
late	O
1978	O
with	O
Jef	O
Raskin	O
,	O
who	O
envisioned	O
an	O
easy-to-use	O
,	O
low-cost	O
computer	O
for	O
the	O
average	O
consumer	O
.	O
</s>
<s>
Bill	O
Atkinson	O
,	O
a	O
member	O
of	O
the	O
Apple	B-Device
Lisa	I-Device
team	O
,	O
introduced	O
Raskin	O
to	O
Burrell	O
Smith	O
,	O
a	O
service	O
technician	O
who	O
had	O
been	O
hired	O
earlier	O
that	O
year	O
.	O
</s>
<s>
Apple	O
's	O
concept	O
for	O
the	O
Macintosh	B-Device
deliberately	O
sought	O
to	O
minimize	O
the	O
user	O
's	O
awareness	O
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
Many	O
basic	O
tasks	O
that	O
required	O
more	O
operating	B-General_Concept
system	I-General_Concept
knowledge	O
on	O
other	O
systems	O
could	O
be	O
accomplished	O
by	O
mouse	O
gestures	O
and	O
graphic	O
controls	O
on	O
a	O
Macintosh	B-Device
.	O
</s>
<s>
This	O
would	O
differentiate	O
it	O
from	O
its	O
contemporaries	O
such	O
as	O
MS-DOS	B-Application
,	O
which	O
use	O
a	O
command-line	B-Application
interface	I-Application
consisting	O
of	O
terse	O
,	O
abbreviated	O
textual	O
commands	O
.	O
</s>
<s>
In	O
January	O
1981	O
,	O
Steve	O
Jobs	O
completely	O
took	O
over	O
the	O
Macintosh	B-Device
project	O
.	O
</s>
<s>
Jobs	O
and	O
a	O
number	O
of	O
Apple	O
engineers	O
visited	O
Xerox	O
PARC	O
in	O
December	O
1979	O
,	O
three	O
months	O
after	O
the	O
Lisa	B-Device
and	O
Macintosh	B-Device
projects	O
had	O
begun	O
.	O
</s>
<s>
After	O
hearing	O
about	O
the	O
pioneering	O
GUI	B-Application
technology	O
being	O
developed	O
at	O
Xerox	O
PARC	O
from	O
former	O
Xerox	O
employees	O
like	O
Raskin	O
,	O
Jobs	O
negotiated	O
a	O
visit	O
to	O
see	O
the	O
Xerox	B-Device
Alto	I-Device
computer	O
and	O
Smalltalk	B-Application
development	O
tools	O
in	O
exchange	O
for	O
Apple	O
stock	O
options	O
.	O
</s>
<s>
The	O
final	O
Lisa	B-Device
and	O
Macintosh	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
use	O
concepts	O
from	O
the	O
Xerox	B-Device
Alto	I-Device
,	O
but	O
many	O
elements	O
of	O
the	O
graphical	B-Application
user	I-Application
interface	I-Application
were	O
created	O
by	O
Apple	O
including	O
the	O
menu	O
bar	O
,	O
pull-down	O
menus	O
,	O
and	O
the	O
concepts	O
of	O
drag	O
and	O
drop	O
and	O
direct	O
manipulation	O
.	O
</s>
<s>
Unlike	O
the	O
IBM	B-Device
PC	I-Device
,	O
which	O
uses	O
8	O
kB	O
of	O
system	O
ROM	B-Device
for	O
power-on	B-Device
self-test	I-Device
(	O
POST	O
)	O
and	O
basic	B-Operating_System
input/output	I-Operating_System
system	I-Operating_System
(	O
BIOS	B-Operating_System
)	O
,	O
the	O
Mac	O
ROM	B-Device
is	O
significantly	O
larger	O
(	O
64	O
kB	O
)	O
and	O
holds	O
key	O
OS	O
code	O
.	O
</s>
<s>
Much	O
of	O
the	O
original	O
Mac	O
ROM	B-Device
was	O
coded	O
by	O
Andy	O
Hertzfeld	O
,	O
a	O
member	O
of	O
the	O
original	B-Device
Macintosh	I-Device
team	O
.	O
</s>
<s>
He	O
was	O
able	O
to	O
conserve	O
precious	O
ROM	B-Device
space	O
by	O
writing	O
routines	O
in	O
assembly	B-Language
language	I-Language
code	O
optimized	O
with	O
"	O
hacks	O
,	O
"	O
or	O
clever	O
programming	O
tricks	O
.	O
</s>
<s>
In	O
addition	O
to	O
the	O
ROM	B-Device
,	O
he	O
also	O
coded	O
the	O
kernel	O
,	O
the	O
Macintosh	B-Device
Toolbox	I-Device
,	O
and	O
some	O
of	O
the	O
desktop	B-Application
accessories	I-Application
(	O
DAs	O
)	O
.	O
</s>
<s>
The	O
icons	O
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
,	O
which	O
represent	O
folders	O
and	O
application	B-Application
software	I-Application
,	O
were	O
designed	O
by	O
Susan	O
Kare	O
,	O
who	O
later	O
designed	O
the	O
icons	O
for	O
Microsoft	B-Application
Windows	I-Application
3.0	I-Application
.	O
</s>
<s>
Bruce	O
Horn	O
and	O
Steve	O
Capps	O
wrote	O
the	O
Macintosh	B-Application
Finder	I-Application
,	O
as	O
well	O
as	O
a	O
number	O
of	O
Macintosh	B-Application
system	I-Application
utilities	O
.	O
</s>
<s>
The	O
Macintosh	B-Device
quickly	O
outsold	O
its	O
more	O
sophisticated	O
but	O
much	O
more	O
expensive	O
predecessor	O
,	O
the	O
Lisa	B-Device
.	O
</s>
<s>
Apple	O
quickly	O
developed	O
MacWorks	B-Application
,	O
a	O
product	O
that	O
allowed	O
the	O
Lisa	B-Device
to	O
emulate	O
Macintosh	B-Application
system	I-Application
software	I-Application
through	O
System	O
3	O
,	O
by	O
which	O
time	O
it	O
had	O
been	O
discontinued	O
as	O
the	O
rebranded	O
Macintosh	B-Device
XL	I-Device
.	O
</s>
<s>
Many	O
of	O
the	O
Lisa	B-Device
's	O
operating	B-General_Concept
system	I-General_Concept
advances	O
would	O
not	O
appear	O
in	O
the	O
Macintosh	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
until	O
System	B-Operating_System
7	I-Operating_System
or	O
later	O
.	O
</s>
<s>
Early	O
versions	O
of	O
Mac	B-Application
OS	I-Application
are	O
compatible	O
only	O
with	O
Motorola	O
68000-family	O
Macintoshes	B-Device
.	O
</s>
<s>
As	O
Apple	O
introduced	O
computers	O
with	O
PowerPC	B-Architecture
hardware	O
,	O
the	O
OS	O
was	O
ported	O
to	O
support	O
this	O
architecture	O
.	O
</s>
<s>
Mac	O
OS	O
8.1	O
is	O
the	O
last	O
version	O
that	O
could	O
run	O
on	O
a	O
68k	B-Device
processor	O
(	O
the	O
68040	B-Device
)	O
.	O
</s>
<s>
In	O
systems	O
prior	O
to	O
PowerPC	O
G3-based	O
systems	O
,	O
significant	O
parts	O
of	O
the	O
system	O
are	O
stored	O
in	O
physical	O
ROM	B-Device
on	O
the	O
motherboard	O
.	O
</s>
<s>
The	O
initial	O
purpose	O
of	O
this	O
is	O
to	O
avoid	O
having	O
the	O
OS	O
use	O
up	O
most	O
of	O
the	O
128KiB	O
RAM	B-Architecture
of	O
the	O
initial	O
Macintosh	B-Device
—	O
the	O
initial	O
ROMs	O
were	O
64KiB	O
.	O
</s>
<s>
This	O
architecture	O
also	O
allows	O
for	O
a	O
completely	O
graphical	B-Application
OS	O
interface	O
at	O
the	O
lowest	O
level	O
without	O
the	O
need	O
for	O
a	O
text-only	O
console	O
or	O
command-line	B-Application
mode	O
:	O
boot	O
time	O
errors	O
,	O
such	O
as	O
finding	O
no	O
functioning	O
disk	O
drives	O
,	O
are	O
communicated	O
to	O
the	O
user	O
graphically	O
,	O
usually	O
with	O
an	O
icon	O
or	O
the	O
distinctive	O
Chicago	O
bitmap	O
font	O
and	O
a	O
Chime	O
of	O
Death	O
or	O
a	O
series	O
of	O
beeps	O
.	O
</s>
<s>
This	O
is	O
in	O
contrast	O
to	O
MS-DOS	B-Application
and	O
CP/M	B-Application
computers	O
of	O
the	O
time	O
,	O
which	O
display	O
such	O
messages	O
in	O
a	O
mono-spaced	O
font	O
on	O
a	O
black	O
background	O
,	O
and	O
require	O
the	O
use	O
of	O
the	O
keyboard	O
rather	O
than	O
a	O
mouse	O
,	O
for	O
input	O
.	O
</s>
<s>
To	O
provide	O
such	O
niceties	O
at	O
a	O
low	O
level	O
,	O
early	O
Mac	B-Application
OS	I-Application
depends	O
on	O
core	O
system	B-Application
software	I-Application
in	O
ROM	B-Device
on	O
the	O
motherboard	O
,	O
which	O
also	O
ensured	O
that	O
only	O
Apple	O
computers	O
or	O
licensed	O
clones	O
(	O
with	O
the	O
copyright-protected	O
ROMs	O
from	O
Apple	O
)	O
can	O
run	O
Mac	B-Application
OS	I-Application
.	O
</s>
<s>
Several	O
computer	O
manufacturers	O
over	O
the	O
years	O
made	O
Macintosh	B-Device
clones	I-Device
that	O
were	O
capable	O
of	O
running	O
Mac	B-Application
OS	I-Application
.	O
</s>
<s>
From	O
1995	O
to	O
1997	O
,	O
Apple	O
licensed	O
Macintosh	B-Device
ROMs	O
to	O
several	O
companies	O
,	O
notably	O
Power	O
Computing	O
,	O
UMAX	O
and	O
Motorola	O
.	O
</s>
<s>
These	O
machines	O
normally	O
ran	O
various	O
versions	O
of	O
Classic	B-Application
Mac	I-Application
OS	I-Application
.	O
</s>
<s>
Support	O
for	O
Macintosh	B-Device
clones	I-Device
was	O
first	O
exhibited	O
in	O
System	B-Operating_System
7.5.1	I-Operating_System
,	O
which	O
was	O
the	O
first	O
version	O
to	O
include	O
the	O
"	O
Mac	B-Application
OS	I-Application
"	O
logo	O
(	O
a	O
variation	O
on	O
the	O
original	O
Happy	O
Mac	O
startup	O
icon	O
)	O
,	O
and	O
Mac	B-Application
OS	I-Application
7.6	O
was	O
the	O
first	O
to	O
be	O
named	O
"	O
Mac	B-Application
OS	I-Application
"	O
instead	O
of	O
"	O
System	O
"	O
.	O
</s>
<s>
These	O
changes	O
were	O
made	O
to	O
disassociate	O
the	O
operating	B-General_Concept
system	I-General_Concept
from	O
Apple	O
's	O
own	O
Macintosh	B-Device
models	O
.	O
</s>
<s>
The	O
Macintosh	B-Device
originally	O
used	O
the	O
Macintosh	B-Application
File	I-Application
System	I-Application
(	O
MFS	O
)	O
,	O
a	O
flat	O
file	B-Application
system	I-Application
with	O
only	O
one	O
level	O
of	O
folders	O
.	O
</s>
<s>
This	O
was	O
quickly	O
replaced	O
in	O
1985	O
by	O
the	O
Hierarchical	B-Application
File	I-Application
System	I-Application
(	O
HFS	B-Application
)	O
,	O
which	O
had	O
a	O
true	O
directory	B-Application
tree	I-Application
.	O
</s>
<s>
Both	O
file	B-Application
systems	I-Application
are	O
otherwise	O
compatible	O
.	O
</s>
<s>
An	O
improved	O
file	B-Application
system	I-Application
named	O
HFS	B-Application
Plus	I-Application
(	O
"	O
HFS+	B-Application
"	O
or	O
"	O
Mac	B-Application
OS	I-Application
Extended	I-Application
"	O
)	O
was	O
announced	O
in	O
1997	O
and	O
implemented	O
in	O
1998	O
.	O
</s>
<s>
Files	O
in	O
most	O
file	B-Application
systems	I-Application
used	O
with	O
DOS	B-Device
,	O
Windows	O
,	O
Unix	B-Application
,	O
or	O
other	O
operating	B-General_Concept
systems	I-General_Concept
have	O
only	O
one	O
"	O
fork	B-Application
"	O
.	O
</s>
<s>
By	O
contrast	O
,	O
MFS	O
and	O
HFS	B-Application
give	O
files	O
two	O
different	O
"	O
forks	B-Application
"	O
.	O
</s>
<s>
The	O
data	B-Operating_System
fork	I-Operating_System
contains	O
the	O
same	O
sort	O
of	O
information	O
as	O
a	O
file	O
in	O
other	O
file	B-Application
systems	I-Application
,	O
such	O
as	O
the	O
text	O
of	O
a	O
document	O
or	O
the	O
bitmaps	O
of	O
an	O
image	O
file	O
.	O
</s>
<s>
The	O
resource	B-Operating_System
fork	I-Operating_System
contains	O
other	O
structured	O
data	O
such	O
as	O
menu	O
definitions	O
,	O
graphics	O
,	O
sounds	O
,	O
or	O
code	B-General_Concept
segments	I-General_Concept
that	O
would	O
be	O
incorporated	O
into	O
a	O
program	O
's	O
file	O
format	O
on	O
other	O
systems	O
.	O
</s>
<s>
An	O
executable	B-Application
file	I-Application
might	O
consist	O
only	O
of	O
resources	O
(	O
including	O
code	B-General_Concept
segments	I-General_Concept
)	O
with	O
an	O
empty	O
data	B-Operating_System
fork	I-Operating_System
,	O
while	O
a	O
data	B-General_Concept
file	I-General_Concept
might	O
have	O
only	O
a	O
data	B-Operating_System
fork	I-Operating_System
with	O
no	O
resource	B-Operating_System
fork	I-Operating_System
.	O
</s>
<s>
A	O
word	B-General_Concept
processor	I-General_Concept
file	O
could	O
contain	O
its	O
text	O
in	O
the	O
data	B-Operating_System
fork	I-Operating_System
and	O
styling	O
information	O
in	O
the	O
resource	B-Operating_System
fork	I-Operating_System
,	O
so	O
that	O
an	O
application	B-Application
which	O
does	O
n't	O
recognize	O
the	O
styling	O
information	O
can	O
still	O
read	O
the	O
raw	O
text	O
.	O
</s>
<s>
On	O
the	O
other	O
hand	O
,	O
these	O
forks	B-Application
would	O
provide	O
a	O
challenge	O
to	O
interoperability	O
with	O
other	O
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
In	O
copying	O
or	O
transferring	O
a	O
Mac	B-Application
OS	I-Application
file	O
to	O
a	O
non-Mac	O
system	O
,	O
the	O
default	O
implementations	O
would	O
simply	O
strip	O
the	O
file	O
of	O
its	O
resource	B-Operating_System
fork	I-Operating_System
.	O
</s>
<s>
Most	O
data	B-General_Concept
files	I-General_Concept
contained	O
only	O
nonessential	O
information	O
in	O
their	O
resource	B-Operating_System
fork	I-Operating_System
,	O
such	O
as	O
window	O
size	O
and	O
location	O
,	O
but	O
program	O
files	O
would	O
be	O
inoperative	O
without	O
their	O
resources	O
.	O
</s>
<s>
This	O
necessitated	O
such	O
encoding	O
schemes	O
as	O
BinHex	O
and	O
MacBinary	B-General_Concept
,	O
which	O
allowed	O
a	O
user	O
to	O
encode	O
a	O
dual-forked	O
file	O
into	O
a	O
single	O
stream	O
,	O
or	O
inversely	O
take	O
a	O
single	O
stream	O
so-encoded	O
and	O
reconstitute	O
it	O
into	O
a	O
dual-forked	O
file	O
usable	O
by	O
Mac	B-Application
OS	I-Application
.	O
</s>
<s>
As	O
part	O
of	O
Apple	O
's	O
goal	O
of	O
creating	O
a	O
computer	O
with	O
appliance-like	O
simplicity	O
,	O
there	O
is	O
no	O
explicit	O
distinction	O
made	O
between	O
the	O
operating	B-General_Concept
system	I-General_Concept
software	O
and	O
the	O
hardware	O
it	O
runs	O
on	O
.	O
</s>
<s>
Because	O
of	O
this	O
,	O
early	O
versions	O
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
do	O
not	O
have	O
a	O
distinct	O
name	O
.	O
</s>
<s>
The	O
software	O
consists	O
of	O
two	O
user-visible	O
files	O
:	O
the	O
System	O
file	O
,	O
and	O
the	O
Finder	B-Application
,	O
an	O
application	B-Application
used	O
for	O
file	O
management	O
that	O
also	O
displays	O
the	O
Desktop	B-Application
.	O
</s>
<s>
The	O
two	O
files	O
are	O
contained	O
in	O
a	O
folder	O
directory	B-Application
labeled	O
"	O
System	B-Operating_System
Folder	I-Operating_System
"	O
,	O
which	O
contains	O
other	O
resource	O
files	O
,	O
like	O
a	O
printer	B-Application
driver	I-Application
,	O
needed	O
to	O
interact	O
with	O
the	O
System	O
.	O
</s>
<s>
Version	O
numbers	O
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
are	O
based	O
on	O
the	O
version	O
numbers	O
of	O
these	O
two	O
files	O
.	O
</s>
<s>
System	B-Operating_System
1.0	I-Operating_System
,	I-Operating_System
1.1	I-Operating_System
,	O
and	O
2.0	O
use	O
a	O
flat	O
file	B-Application
system	I-Application
named	O
Macintosh	B-Application
File	I-Application
System	I-Application
(	O
MFS	O
)	O
.	O
</s>
<s>
The	O
Finder	B-Application
provides	O
virtual	O
folders	O
that	O
could	O
be	O
used	O
to	O
organize	O
files	O
,	O
but	O
these	O
folders	O
are	O
not	O
visible	O
from	O
any	O
other	O
application	B-Application
and	O
do	O
not	O
actually	O
exist	O
on	O
the	O
disk	O
.	O
</s>
<s>
System	O
2.0	O
added	O
support	O
for	O
AppleTalk	B-Application
and	O
the	O
newly	O
introduced	O
LaserWriter	O
to	O
use	O
it	O
.	O
</s>
<s>
System	O
2.1	O
(	O
Finder	B-Application
5.0	O
)	O
introduced	O
the	O
Hierarchical	B-Application
File	I-Application
System	I-Application
(	O
HFS	B-Application
)	O
which	O
has	O
real	O
directories	B-Application
.	O
</s>
<s>
This	O
version	O
was	O
specifically	O
to	O
support	O
the	O
Hard	B-Device
Disk	I-Device
20	I-Device
and	O
only	O
implements	O
HFS	B-Application
in	O
RAM	B-Architecture
;	O
startup	O
and	O
most	O
floppy	O
disks	O
remain	O
MFS	O
400K	O
volumes	O
.	O
</s>
<s>
System	O
3.0	O
(	O
Finder	B-Application
5.1	O
)	O
was	O
introduced	O
with	O
the	O
Macintosh	B-Device
Plus	I-Device
,	O
officially	O
implementing	O
HFS	B-Application
,	O
800K	O
startup	O
drives	O
,	O
support	O
for	O
several	O
new	O
technologies	O
including	O
SCSI	B-Architecture
and	O
AppleShare	B-General_Concept
,	O
and	O
Trash	O
"	O
bulging	O
"	O
(	O
i.e.	O
,	O
when	O
the	O
Trash	O
contains	O
files	O
,	O
it	O
gains	O
a	O
bulged	O
appearance	O
)	O
.	O
</s>
<s>
System	O
4.0	O
was	O
released	O
with	O
the	O
Macintosh	B-Device
SE	I-Device
and	O
System	O
4.1	O
first	O
shipped	O
with	O
the	O
Macintosh	B-Device
II	I-Device
—	O
these	O
new	O
machines	O
required	O
additional	O
support	O
for	O
the	O
first	O
expansion	B-Device
slots	I-Device
,	O
the	O
Apple	B-Device
Desktop	I-Device
Bus	I-Device
(	O
ADB	O
)	O
,	O
internal	O
hard	O
drives	O
and	O
,	O
on	O
the	O
Macintosh	B-Device
II	I-Device
,	O
external	O
color	O
displays	O
and	O
the	O
first	O
Motorola	B-Device
68020	I-Device
processor	O
.	O
</s>
<s>
These	O
releases	O
can	O
only	O
run	O
one	O
application	B-Application
at	O
a	O
time	O
,	O
except	O
for	O
desk	B-Application
accessories	I-Application
,	O
though	O
special	O
application	B-Application
shells	O
such	O
as	O
Multi-Mac	O
or	O
Switcher	O
(	O
discussed	O
under	O
MultiFinder	O
)	O
could	O
work	O
around	O
this	O
.	O
</s>
<s>
Visible	O
changes	O
are	O
best	O
reflected	O
in	O
the	O
version	O
number	O
of	O
the	O
Finder	B-Application
,	O
where	O
major	O
leaps	O
are	O
found	O
between	O
1.x	O
,	O
4.x	O
,	O
5.x	O
,	O
and	O
6.x	O
.	O
</s>
<s>
System	O
:	O
Introduced	O
screenshots	O
using	O
Macintosh	B-Application
System	I-Application
Software	I-Application
;	O
2.1	O
September	O
1985	O
5.0	O
Release	O
for	O
Hard	B-Device
Disk	I-Device
20	I-Device
support	O
Macintosh	B-Application
System	I-Application
Software	I-Application
(	O
0.7	O
)	O
3.0	O
January	O
1986	O
5.1	O
1.1	O
Introduced	O
with	O
Macintosh	B-Device
Plus	I-Device
System	O
Software	O
1.0	O
3.1	O
February	O
1986	O
5.2	O
1.1	O
System	O
Software	O
1.1	O
3.2	O
June	O
1986	O
5.3	O
3.1	O
Fixed	O
problems	O
with	O
data	O
loss	O
,	O
system	O
crashes	O
;	O
updated	O
Chooser	O
and	O
Calculator	O
.	O
</s>
<s>
AppleShare	B-General_Concept
1.0	B-Operating_System
3.3	O
January	O
1987	O
5.4	O
AppleShare	B-General_Concept
1.0	B-Operating_System
Work	O
Station	O
Installer	O
disk	O
(	O
for	O
the	O
Macintosh	B-Device
512K	I-Device
)	O
AppleShare	B-General_Concept
1.1	O
3.3	O
1987	O
5.5	O
AppleShare	B-General_Concept
1.1	O
Work	O
Station	O
Installer	O
disk	O
(	O
for	O
the	O
Macintosh	B-Device
512K	I-Device
)	O
AppleShare	B-General_Concept
2.0	O
3.4	O
1988	O
6.1AppleShare	O
2.0	O
Macintosh	B-Device
512Ke	I-Device
Work	O
Station	O
Installer	O
disk	O
System	B-Application
Software	I-Application
2.0	O
4.0	O
January	O
1987	O
5.4	O
3.3	O
Release	O
for	O
Macintosh	B-Device
SE	I-Device
.	O
</s>
<s>
Introduced	O
AppleShare	B-General_Concept
System	B-Application
Software	I-Application
2.0.1	O
4.1	O
March	O
2	O
,	O
1987	O
5.5	O
4.0	O
Release	O
for	O
Macintosh	B-Device
II	I-Device
.	O
</s>
<s>
Towards	O
the	O
end	O
of	O
1987	O
,	O
Apple	O
introduced	O
a	O
package	O
titled	O
"	O
Apple	O
Macintosh	B-Application
System	I-Application
Software	I-Application
Update	O
5.0	O
"	O
.	O
</s>
<s>
For	O
the	O
first	O
time	O
,	O
the	O
Macintosh	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
was	O
offered	O
as	O
a	O
distinct	O
retail	O
product	O
that	O
included	O
four	O
800K	O
disks	O
and	O
three	O
manuals	O
,	O
at	O
a	O
cost	O
of	O
US$49	O
.	O
</s>
<s>
While	O
the	O
product	O
box	O
presented	O
this	O
update	O
to	O
the	O
operating	B-General_Concept
system	I-General_Concept
as	O
"	O
version	O
5.0	O
"	O
,	O
this	O
number	O
does	O
not	O
appear	O
in	O
the	O
software	O
itself	O
.	O
</s>
<s>
For	O
instance	O
,	O
System	O
Tools	O
2	O
is	O
the	O
only	O
disk	O
with	O
printer	B-Application
drivers	I-Application
,	O
and	O
Utilities	O
1	O
is	O
the	O
only	O
disk	O
with	O
Disk	B-Operating_System
First	I-Operating_System
Aid	I-Operating_System
and	O
Apple	B-Operating_System
HD	I-Operating_System
SC	I-Operating_System
Setup	I-Operating_System
.	O
</s>
<s>
The	O
system	O
uses	O
a	O
cooperative	B-Operating_System
multitasking	I-Operating_System
model	O
,	O
meaning	O
that	O
time	O
is	O
given	O
to	O
the	O
background	O
applications	O
only	O
when	O
the	O
foreground	O
application	B-Application
yields	O
control	O
.	O
</s>
<s>
Users	O
can	O
also	O
choose	O
not	O
to	O
use	O
MultiFinder	O
,	O
thereby	O
using	O
a	O
single	O
application	B-Application
at	O
a	O
time	O
.	O
</s>
<s>
System	B-Application
Software	I-Application
6	O
(	O
also	O
referred	O
to	O
as	O
"	O
System	O
6	O
"	O
)	O
is	O
a	O
consolidation	O
release	O
of	O
the	O
Macintosh	B-Application
system	I-Application
software	I-Application
,	O
producing	O
a	O
complete	O
,	O
stable	O
,	O
and	O
long-lasting	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
Two	O
major	O
hardware	O
introductions	O
requiring	O
additional	O
support	O
under	O
System	O
6	O
are	O
the	O
68030	B-Device
processor	O
and	O
1.44MB	O
SuperDrive	O
debuting	O
with	O
the	O
Macintosh	B-Device
IIx	I-Device
and	O
Macintosh	B-Device
SE/30	I-Device
.	O
</s>
<s>
Later	O
updates	O
include	O
support	O
for	O
the	O
first	O
specialized	O
laptop	O
features	O
with	O
the	O
introduction	O
of	O
the	O
Macintosh	B-Device
Portable	I-Device
.	O
</s>
<s>
From	O
System	O
6	O
forward	O
,	O
the	O
Finder	B-Application
has	O
a	O
unified	O
version	O
number	O
closely	O
matching	O
that	O
of	O
the	O
System	O
,	O
alleviating	O
much	O
of	O
the	O
confusion	O
caused	O
by	O
the	O
often	O
considerable	O
differences	O
between	O
earlier	O
Systems	O
.	O
</s>
<s>
On	O
May	O
13	O
,	O
1991	O
,	O
System	B-Operating_System
7	I-Operating_System
was	O
released	O
.	O
</s>
<s>
It	O
was	O
a	O
major	O
upgrade	O
over	O
System	O
6	O
,	O
adding	O
a	O
significant	O
user	B-Application
interface	I-Application
overhaul	O
,	O
new	O
applications	O
,	O
stability	O
improvements	O
and	O
many	O
new	O
features	O
.	O
</s>
<s>
Its	O
introduction	O
coincides	O
with	O
the	O
release	O
of	O
and	O
provided	O
support	O
for	O
the	O
68040	B-Device
Macintosh	B-Device
line	O
.	O
</s>
<s>
The	O
System	B-Operating_System
7	I-Operating_System
era	O
saw	O
numerous	O
changes	O
in	O
the	O
Macintosh	B-Device
platform	O
including	O
a	B-Device
proliferation	I-Device
of	I-Device
Macintosh	I-Device
models	I-Device
,	O
the	O
68k	B-Device
to	O
Power	B-Device
Macintosh	I-Device
transition	O
as	O
well	O
as	O
the	O
rise	O
of	O
Microsoft	B-Application
Windows	I-Application
,	O
increasing	O
use	O
of	O
computer	B-Architecture
networking	I-Architecture
and	O
the	O
explosion	O
in	O
the	O
popularity	O
of	O
the	O
Internet	O
.	O
</s>
<s>
One	O
of	O
the	O
most	O
significant	O
features	O
of	O
System	B-Operating_System
7	I-Operating_System
is	O
virtual	B-Architecture
memory	I-Architecture
support	O
,	O
an	O
essential	O
subsystem	O
anticipated	O
for	O
years	O
,	O
which	O
only	O
exists	O
for	O
previous	O
Systems	O
in	O
a	O
third	O
party	O
extension	O
named	O
Virtual	O
from	O
Connectix	O
.	O
</s>
<s>
Accompanying	O
this	O
was	O
a	O
move	O
to	O
32-bit	O
memory	B-General_Concept
addressing	I-General_Concept
,	O
necessary	O
for	O
the	O
ever-increasing	O
amounts	O
of	O
RAM	B-Architecture
available	O
to	O
the	O
Motorola	B-Device
68030	I-Device
CPU	O
,	O
and	O
68020	B-Device
CPUs	O
with	O
a	O
68851	B-General_Concept
PMMU	B-General_Concept
.	O
</s>
<s>
While	O
System	B-Operating_System
7	I-Operating_System
itself	O
is	O
32-bit	O
clean	O
,	O
many	O
existing	O
machines	O
and	O
thousands	O
of	O
applications	O
were	O
not	O
,	O
so	O
it	O
was	O
some	O
time	O
before	O
the	O
process	O
was	O
completed	O
.	O
</s>
<s>
To	O
ease	O
the	O
transition	O
,	O
the	O
"	O
Memory	O
"	O
control	B-Operating_System
panel	I-Operating_System
contains	O
a	O
switch	O
to	O
disable	O
this	O
feature	O
,	O
allowing	O
for	O
compatibility	O
with	O
older	O
applications	O
.	O
</s>
<s>
Another	O
notable	O
System	B-Operating_System
7	I-Operating_System
feature	O
is	O
built-in	O
cooperative	B-Operating_System
multitasking	I-Operating_System
.	O
</s>
<s>
In	O
System	B-Application
Software	I-Application
6	O
,	O
this	O
function	O
was	O
optional	O
through	O
the	O
MultiFinder	O
.	O
</s>
<s>
System	B-Operating_System
7	I-Operating_System
also	O
introduced	O
aliases	B-Application
,	O
similar	O
to	O
symbolic	B-Application
links	I-Application
on	O
Unix	B-Application
,	O
shortcuts	O
that	O
were	O
introduced	O
in	O
later	O
versions	O
of	O
Microsoft	B-Application
Windows	I-Application
,	O
and	O
shadows	B-Device
in	O
IBM	B-Application
OS/2	I-Application
.	O
</s>
<s>
System	B-Operating_System
extensions	I-Operating_System
were	O
enhanced	O
by	O
being	O
moved	O
to	O
their	O
own	O
subfolder	B-Application
;	O
a	O
subfolder	B-Application
in	O
the	O
System	B-Operating_System
Folder	I-Operating_System
was	O
also	O
created	O
for	O
the	O
control	B-Operating_System
panels	I-Operating_System
.	O
</s>
<s>
In	O
System	O
7.5	O
,	O
Apple	O
includes	O
the	O
Extensions	B-Operating_System
Manager	I-Operating_System
,	O
a	O
previously	O
third-party	O
program	O
which	O
simplified	O
the	O
process	O
of	O
enabling	O
and	O
disabling	O
extensions	B-Operating_System
.	O
</s>
<s>
The	O
Apple	O
menu	O
,	O
home	O
only	O
to	O
desk	B-Application
accessories	I-Application
in	O
System	O
6	O
,	O
was	O
made	O
more	O
general-purpose	O
:	O
the	O
user	O
could	O
now	O
make	O
often-used	O
folders	O
and	O
applications	O
—	O
or	O
anything	O
else	O
they	O
desired	O
—	O
appear	O
in	O
the	O
menu	O
by	O
placing	O
aliases	B-Application
to	O
them	O
in	O
an	O
"	O
Apple	O
Menu	O
Items	O
"	O
subfolder	B-Application
of	O
the	O
System	B-Operating_System
Folder	I-Operating_System
.	O
</s>
<s>
System	B-Operating_System
7	I-Operating_System
also	O
introduced	O
the	O
following	O
:	O
AppleScript	B-Application
,	O
a	O
scripting	B-Language
language	I-Language
for	O
automating	O
tasks	O
;	O
32-bit	O
QuickDraw	B-Operating_System
,	O
supporting	O
so-called	O
"	O
true	O
color	O
"	O
imaging	O
,	O
previously	O
available	O
as	O
a	O
system	O
extension	O
;	O
and	O
TrueType	O
,	O
an	O
outline	O
font	O
standard	O
.	O
</s>
<s>
The	O
Trash	O
,	O
under	O
System	O
6	O
and	O
earlier	O
,	O
empties	O
itself	O
automatically	O
when	O
shutting	O
down	O
the	O
computer	O
—	O
or	O
,	O
if	O
MultiFinder	O
is	O
not	O
running	O
,	O
when	O
launching	O
an	O
application	B-Application
.	O
</s>
<s>
System	B-Operating_System
7	I-Operating_System
reimplements	O
the	O
Trash	O
as	O
a	O
special	O
hidden	O
folder	O
,	O
allowing	O
files	O
to	O
remain	O
in	O
it	O
across	O
reboots	O
until	O
the	O
user	O
deliberately	O
chose	O
the	O
"	O
Empty	O
Trash	O
"	O
command	O
.	O
</s>
<s>
One	O
of	O
the	O
major	O
new	O
features	O
of	O
System	O
7.1	O
was	O
moving	O
fonts	O
out	O
of	O
the	O
System	O
file	O
into	O
the	O
Fonts	O
folder	O
in	O
the	O
System	B-Operating_System
Folder	I-Operating_System
.	O
</s>
<s>
System	O
7.1	O
is	O
not	O
only	O
the	O
first	O
Macintosh	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
to	O
cost	O
money	O
(	O
all	O
previous	O
versions	O
were	O
free	O
or	O
sold	O
at	O
the	O
cost	O
of	O
the	O
floppies	O
)	O
,	O
but	O
also	O
received	O
a	O
"	O
Pro	O
"	O
sibling	O
(	O
version	O
7.1.1	O
)	O
with	O
extra	O
features	O
.	O
</s>
<s>
System	B-Operating_System
7.1.2	I-Operating_System
was	O
the	O
first	O
version	O
to	O
support	O
PowerPC-based	O
Macs	O
.	O
</s>
<s>
This	O
leads	O
to	O
extra	O
files	O
inside	O
the	O
system	B-Operating_System
folder	I-Operating_System
(	O
one	O
per	O
new	O
model	O
supported	O
)	O
.	O
</s>
<s>
On	O
the	O
newer	O
PowerPC	B-Architecture
machines	O
,	O
System	O
7.5	O
may	O
have	O
stability	O
problems	O
partly	O
due	O
to	O
a	O
new	O
memory	O
manager	O
(	O
which	O
can	O
be	O
turned	O
off	O
)	O
,	O
and	O
issues	O
with	O
the	O
handling	O
of	O
errors	O
in	O
the	O
PowerPC	B-Architecture
code	O
(	O
all	O
PowerPC	B-Architecture
exceptions	O
map	O
to	O
Type	O
11	O
)	O
.	O
</s>
<s>
These	O
issues	O
do	O
not	O
affect	O
68k-architecture	O
machines	O
.	O
</s>
<s>
System	O
7.5	O
is	O
contemporary	O
with	O
Apple	O
's	O
failed	O
Copland	B-Application
effort	O
as	O
well	O
as	O
the	O
release	O
of	O
Windows	B-Application
95	I-Application
.	O
</s>
<s>
Stability	O
improved	O
in	O
PowerPC-based	O
Macs	O
with	O
Mac	O
OS	O
7.6	O
,	O
which	O
dropped	O
the	O
"	O
System	O
"	O
moniker	O
as	O
a	O
more	O
trademarkable	O
name	O
was	O
needed	O
in	O
order	O
to	O
license	O
the	O
OS	O
to	O
the	O
growing	O
market	O
of	O
third-party	O
Macintosh	B-Device
clone	I-Device
manufacturers	O
.	O
</s>
<s>
Mac	O
OS	O
7.6	O
required	O
32-bit-clean	O
ROMs	O
,	O
and	O
so	O
it	O
dropped	O
support	O
for	O
every	O
Mac	O
with	O
a	O
68000	B-Device
processor	O
,	O
as	O
well	O
as	O
the	O
Mac	B-Device
II	I-Device
,	O
Mac	B-Device
IIx	I-Device
,	O
Mac	B-Device
IIcx	I-Device
,	O
and	O
Mac	B-Device
SE/30	I-Device
.	O
</s>
<s>
Mac	B-Operating_System
OS	I-Operating_System
8	I-Operating_System
was	O
released	O
on	O
July	O
26	O
,	O
1997	O
,	O
the	O
same	O
month	O
Steve	O
Jobs	O
became	O
the	O
de	O
facto	O
CEO	O
of	O
Apple	O
.	O
</s>
<s>
It	O
was	O
mainly	O
released	O
to	O
keep	O
the	O
Mac	B-Application
OS	I-Application
moving	O
forward	O
during	O
a	O
difficult	O
time	O
for	O
Apple	O
.	O
</s>
<s>
Initially	O
planned	O
as	O
Mac	O
OS	O
7.7	O
,	O
it	O
was	O
renumbered	O
"	O
8	O
"	O
to	O
exploit	O
a	O
legal	O
loophole	O
and	O
accomplish	O
Jobs	O
's	O
goal	O
of	O
terminating	O
third-party	O
manufacturers	O
 '	O
licenses	O
to	O
System	B-Operating_System
7	I-Operating_System
and	O
shutting	O
down	O
the	O
Macintosh	B-Device
clone	I-Device
market	O
.	O
</s>
<s>
Mac	B-Operating_System
OS	I-Operating_System
8	I-Operating_System
added	O
a	O
number	O
of	O
features	O
from	O
the	O
abandoned	O
Copland	B-Application
project	O
,	O
while	O
leaving	O
the	O
underlying	O
operating	B-General_Concept
system	I-General_Concept
unchanged	O
.	O
</s>
<s>
A	O
multi-threaded	B-Operating_System
Finder	B-Application
was	O
included	O
;	O
files	O
could	O
now	O
be	O
copied	O
in	O
the	O
background	O
.	O
</s>
<s>
The	O
GUI	B-Application
was	O
changed	O
in	O
appearance	O
to	O
a	O
new	O
shaded	O
greyscale	O
look	O
named	O
Platinum	O
,	O
and	O
the	O
ability	O
to	O
change	O
the	O
appearance	O
themes	O
(	O
also	O
known	O
as	O
skins	B-Application
)	O
was	O
added	O
with	O
a	O
new	O
control	B-Operating_System
panel	I-Operating_System
(	O
though	O
Platinum	O
was	O
the	O
only	O
one	O
shipped	O
)	O
.	O
</s>
<s>
Apple	O
sold	O
1.2	O
million	O
copies	O
of	O
Mac	B-Operating_System
OS	I-Operating_System
8	I-Operating_System
in	O
its	O
first	O
two	O
weeks	O
of	O
availability	O
and	O
3million	O
within	O
six	O
months	O
.	O
</s>
<s>
Mac	O
OS	O
8.1	O
introduced	O
an	O
updated	O
version	O
of	O
the	O
Hierarchical	B-Application
File	I-Application
System	I-Application
named	O
HFS+	B-Application
,	O
which	O
fixed	O
many	O
of	O
the	O
limitations	O
of	O
the	O
earlier	O
system	O
and	O
continued	O
to	O
be	O
used	O
in	O
macOS	B-Application
up	O
until	O
macOS	B-Operating_System
High	I-Operating_System
Sierra	I-Operating_System
,	O
when	O
it	O
was	O
replaced	O
with	O
the	O
Apple	B-Application
File	I-Application
System	I-Application
.	O
</s>
<s>
There	O
are	O
some	O
other	O
interface	O
changes	O
such	O
as	O
separating	O
network	O
features	O
from	O
printing	O
,	O
and	O
some	O
improvements	O
to	O
application	B-Application
switching	O
.	O
</s>
<s>
However	O
,	O
in	O
underlying	O
technical	O
respects	O
,	O
Mac	B-Operating_System
OS	I-Operating_System
8	I-Operating_System
is	O
not	O
very	O
different	O
from	O
System	B-Operating_System
7	I-Operating_System
.	O
</s>
<s>
Mac	O
OS	O
8.5	O
focuses	O
on	O
speed	O
and	O
stability	O
,	O
with	O
most	O
68k	B-Device
code	O
replaced	O
by	O
modern	O
code	O
native	O
to	O
the	O
PowerPC	B-Architecture
.	O
</s>
<s>
It	O
also	O
improved	O
the	O
appearance	O
of	O
the	O
user	B-Application
interface	I-Application
,	O
although	O
the	O
theming	O
feature	O
was	O
cut	O
late	O
in	O
development	O
.	O
</s>
<s>
System	O
VersionRelease	O
InformationMac	O
OS	O
8.0first	O
version	O
to	O
require	O
a	O
68040	B-Device
processor	O
,	O
dropping	O
support	O
for	O
the	O
remainder	O
of	O
the	O
Macintosh	B-Device
II	I-Device
series	I-Device
and	O
other	O
68030	B-Device
Macs	O
.	O
</s>
<s>
It	O
also	O
added	O
support	O
for	O
the	O
PowerPC	B-Device
G3	I-Device
processorMac	O
OS	O
8.1last	O
Mac	B-Application
OS	I-Application
release	O
to	O
run	O
on	O
a	O
68k	B-Device
processor	O
,	O
and	O
it	O
added	O
support	O
for	O
USB	B-Protocol
on	O
the	O
iMac	B-Device
and	O
added	O
support	O
for	O
the	O
HFS+	B-Application
filesystem	B-Application
,	O
also	O
called	O
Mac	B-Application
OS	I-Application
ExtendedMac	O
OS	O
8.5first	O
version	O
to	O
run	O
solely	O
on	O
a	O
PowerPC	B-Architecture
processor	I-Architecture
,	O
and	O
it	O
added	O
built-in	O
support	O
for	O
FireWire	B-Protocol
.	O
</s>
<s>
Mac	B-Operating_System
OS	I-Operating_System
9	I-Operating_System
,	O
the	O
last	O
major	O
revision	O
of	O
the	O
Classic	B-Application
Mac	I-Application
OS	I-Application
,	O
was	O
released	O
on	O
October	O
23	O
,	O
1999	O
.	O
</s>
<s>
It	O
is	O
generally	O
a	O
steady	O
evolution	O
from	O
Mac	B-Operating_System
OS	I-Operating_System
8	I-Operating_System
.	O
</s>
<s>
Early	O
development	O
releases	O
of	O
Mac	B-Operating_System
OS	I-Operating_System
9	I-Operating_System
were	O
numbered	O
8.7	O
.	O
</s>
<s>
Mac	B-Operating_System
OS	I-Operating_System
9	I-Operating_System
added	O
improved	O
support	O
for	O
AirPort	O
wireless	B-General_Concept
networking	I-General_Concept
.	O
</s>
<s>
Though	O
not	O
a	O
true	O
multi-user	O
operating	B-General_Concept
system	I-General_Concept
,	O
Mac	B-Operating_System
OS	I-Operating_System
9	I-Operating_System
does	O
allow	O
multiple	O
desktop	B-Application
users	O
to	O
have	O
their	O
own	O
data	O
and	O
system	B-Operating_System
settings	I-Operating_System
.	O
</s>
<s>
An	O
improved	O
Sherlock	B-Operating_System
search	O
engine	O
added	O
several	O
new	O
search	O
plug-ins	O
.	O
</s>
<s>
Mac	B-Operating_System
OS	I-Operating_System
9	I-Operating_System
also	O
provides	O
a	O
much	O
improved	O
memory	O
implementation	O
and	O
management	O
.	O
</s>
<s>
AppleScript	B-Application
was	O
improved	O
to	O
allow	O
TCP/IP	B-Protocol
and	O
networking	O
control	O
.	O
</s>
<s>
Mac	B-Operating_System
OS	I-Operating_System
9	I-Operating_System
also	O
makes	O
the	O
first	O
use	O
of	O
the	O
centralized	O
Apple	O
Software	O
Update	O
to	O
find	O
and	O
install	O
OS	O
and	O
hardware	O
updates	O
.	O
</s>
<s>
Other	O
new	O
features	O
included	O
its	O
on-the-fly	O
file	O
encryption	O
software	O
with	O
code	O
signing	O
and	O
Keychain	B-Application
technologies	O
,	O
Remote	O
Networking	O
and	O
File	B-Application
Server	I-Application
packages	O
,	O
and	O
much	O
improved	O
list	O
of	O
USB	B-Protocol
drivers	B-Application
.	O
</s>
<s>
Mac	B-Operating_System
OS	I-Operating_System
9	I-Operating_System
also	O
added	O
some	O
transitional	O
technologies	O
to	O
help	O
application	B-Application
developers	O
adopt	O
some	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
features	O
before	O
the	O
introduction	O
of	O
the	O
new	O
OS	O
to	O
the	O
public	O
,	O
to	O
help	O
ease	O
the	O
transition	O
.	O
</s>
<s>
These	O
included	O
new	O
APIs	O
for	O
the	O
file	B-Application
system	I-Application
and	O
the	O
bundling	O
of	O
the	O
Carbon	B-Operating_System
library	O
that	O
apps	O
could	O
link	O
against	O
instead	O
of	O
the	O
traditional	O
API	O
libraries	O
—	O
apps	O
that	O
were	O
adapted	O
to	O
do	O
this	O
could	O
be	O
run	O
natively	O
on	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
as	O
well	O
.	O
</s>
<s>
Other	O
changes	O
were	O
made	O
beginning	O
with	O
the	O
Mac	B-Operating_System
OS	I-Operating_System
9.1	I-Operating_System
update	O
to	O
allow	O
it	O
to	O
be	O
launched	O
in	O
the	O
Classic	B-Device
Environment	O
within	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
.	O
</s>
<s>
The	O
final	O
update	O
to	O
the	O
Classic	B-Application
Mac	I-Application
OS	I-Application
was	O
version	O
9.2.2	B-Operating_System
,	O
released	O
on	O
December	O
5	O
,	O
2001	O
.	O
</s>
<s>
macOS	B-Application
(	O
originally	O
named	O
"	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
"	O
until	O
2011	O
and	O
then	O
"	O
OS	B-Operating_System
X	I-Operating_System
"	O
until	O
2016	O
)	O
is	O
Apple	O
's	O
current	O
Mac	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
that	O
officially	O
succeeded	O
the	O
Classic	B-Application
Mac	I-Application
OS	I-Application
in	O
2001	O
.	O
</s>
<s>
Although	O
it	O
was	O
originally	O
marketed	O
as	O
simply	O
"	O
version	O
10	O
"	O
of	O
Mac	B-Application
OS	I-Application
,	O
it	O
has	O
a	B-Operating_System
history	I-Operating_System
that	O
is	O
largely	O
independent	O
of	O
the	O
earlier	O
Mac	B-Application
OS	I-Application
releases	O
.	O
</s>
<s>
The	O
macOS	B-Application
architectural	O
legacy	O
is	O
the	O
successor	O
to	O
Mac	B-Operating_System
OS	I-Operating_System
9	I-Operating_System
and	O
the	O
Classic	B-Application
Mac	I-Application
OS	I-Application
legacy	O
.	O
</s>
<s>
However	O
,	O
unlike	O
the	O
Classic	B-Application
Mac	I-Application
OS	I-Application
,	O
it	O
is	O
a	O
Unix-based	O
operating	B-General_Concept
system	I-General_Concept
built	O
on	O
NeXTSTEP	B-Application
and	O
technology	O
developed	O
at	O
NeXT	O
from	O
the	O
late	O
1980s	O
until	O
early	O
1997	O
,	O
when	O
Apple	O
purchased	O
the	O
company	O
,	O
and	O
its	O
CEO	O
Steve	O
Jobs	O
returned	O
to	O
Apple	O
.	O
</s>
<s>
macOS	B-Application
also	O
makes	O
use	O
of	O
the	O
BSD	B-Operating_System
codebase	O
and	O
the	O
XNU	B-Operating_System
kernel	I-Operating_System
,	O
and	O
its	O
core	O
set	O
of	O
components	O
is	O
based	O
upon	O
Apple	O
's	O
open	B-Application
source	I-Application
Darwin	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
.	O
</s>
<s>
An	O
early	O
version	O
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
,	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
Server	I-Operating_System
1.0	I-Operating_System
,	O
was	O
released	O
in	O
1999	O
.	O
</s>
<s>
It	O
retains	O
the	O
"	O
Platinum	O
"	O
appearance	O
from	O
the	O
Classic	B-Application
Mac	I-Application
OS	I-Application
and	O
even	O
resembles	O
OPENSTEP	B-Operating_System
in	O
places	O
,	O
with	O
the	O
first	O
version	O
to	O
arrive	O
with	O
the	O
new	O
Aqua	B-Application
user	I-Application
interface	I-Application
.	O
</s>
<s>
The	O
desktop	B-Application
version	O
,	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
10.0	I-Operating_System
,	O
followed	O
on	O
March	O
24	O
,	O
2001	O
,	O
supporting	O
the	O
new	O
Aqua	B-Application
user	I-Application
interface	I-Application
.	O
</s>
<s>
Since	O
then	O
,	O
several	B-Operating_System
more	I-Operating_System
versions	I-Operating_System
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
have	O
been	O
released	O
.	O
</s>
<s>
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
was	O
renamed	O
"	O
OS	B-Operating_System
X	I-Operating_System
"	O
in	O
2011	O
and	O
"	O
macOS	B-Application
"	O
in	O
2016	O
.	O
</s>
<s>
Users	O
of	O
the	O
Classic	B-Application
Mac	I-Application
OS	I-Application
generally	O
upgraded	O
to	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
,	O
but	O
it	O
was	O
criticized	O
in	O
its	O
early	O
years	O
as	O
more	O
difficult	O
and	O
less	O
user-friendly	O
than	O
the	O
original	O
Mac	B-Application
OS	I-Application
,	O
for	O
the	O
lack	O
of	O
certain	O
features	O
that	O
had	O
not	O
yet	O
been	O
reimplemented	O
in	O
the	O
new	O
OS	O
,	O
for	O
being	O
slower	O
on	O
the	O
same	O
hardware	O
(	O
especially	O
older	O
hardware	O
)	O
,	O
and	O
for	O
incompatibilities	O
with	O
the	O
older	O
OS	O
.	O
</s>
<s>
Because	O
drivers	B-Application
(	O
for	O
printers	O
,	O
scanners	O
,	O
tablets	O
,	O
etc	O
.	O
)	O
</s>
<s>
written	O
for	O
the	O
older	O
Mac	B-Application
OS	I-Application
were	O
not	O
compatible	O
with	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
,	O
inconsistent	O
program	O
support	O
with	O
the	O
Classic	B-Device
Environment	O
program	O
used	O
to	O
run	O
the	O
older	O
operating	B-General_Concept
system	I-General_Concept
's	O
programs	O
on	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
,	O
and	O
the	O
lack	O
of	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
support	O
for	O
older	O
Apple	O
computers	O
before	O
late	O
1997	O
;	O
some	O
Macintosh	B-Device
users	O
continued	O
using	O
the	O
older	O
Classic	B-Application
Mac	I-Application
OS	I-Application
for	O
a	O
few	O
years	O
after	O
the	O
original	O
release	O
of	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
.	O
Steve	O
Jobs	O
encouraged	O
people	O
to	O
upgrade	O
to	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
by	O
staging	O
a	O
mock	O
funeral	O
for	O
Mac	B-Operating_System
OS	I-Operating_System
9	I-Operating_System
at	O
WWDC	O
2002	O
.	O
</s>
<s>
PowerPC	B-Architecture
versions	O
of	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
up	O
to	O
and	O
including	O
Mac	B-Application
OS	I-Application
X	I-Application
10.4	I-Application
Tiger	I-Application
include	O
a	O
compatibility	B-General_Concept
layer	I-General_Concept
for	O
running	O
older	O
Mac	O
applications	O
,	O
the	O
Classic	B-Device
Environment	O
.	O
</s>
<s>
Originally	O
codenamed	O
the	O
"	O
blue	O
box	O
"	O
,	O
the	O
environment	O
runs	O
a	O
nearly	O
complete	O
Mac	B-Operating_System
OS	I-Operating_System
9	I-Operating_System
operating	B-General_Concept
system	I-General_Concept
,	O
version	O
9.1	O
or	O
later	O
,	O
as	O
a	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
application	B-Application
.	O
</s>
<s>
This	O
allows	O
applications	O
that	O
have	O
not	O
been	O
ported	O
to	O
the	O
Carbon	B-Operating_System
API	I-Operating_System
to	O
run	O
on	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
.	O
</s>
<s>
This	O
is	O
reasonably	O
seamless	O
,	O
though	O
"	O
classic	B-Device
"	O
applications	O
retain	O
their	O
original	O
Mac	B-Operating_System
OS	I-Operating_System
9	I-Operating_System
appearance	O
and	O
do	O
not	O
gain	O
the	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
"	O
Aqua	B-Application
"	O
appearance	O
.	O
</s>
<s>
Early	O
New	B-Device
World	I-Device
ROM	I-Device
PowerPC-based	O
Macs	O
shipped	O
with	O
Mac	B-Operating_System
OS	I-Operating_System
9.2	I-Operating_System
as	O
well	O
as	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
.	O
Mac	B-Operating_System
OS	I-Operating_System
9.2	I-Operating_System
had	O
to	O
be	O
installed	O
by	O
the	O
user	O
—	O
it	O
was	O
not	O
installed	O
by	O
default	O
on	O
hardware	O
revisions	O
released	O
after	O
Mac	B-Application
OS	I-Application
X	I-Application
10.4	I-Application
.	O
</s>
<s>
Most	O
well-written	O
"	B-Application
classic	I-Application
"	I-Application
Mac	I-Application
OS	I-Application
applications	O
function	O
properly	O
under	O
this	O
environment	O
,	O
but	O
compatibility	O
is	O
assured	O
only	O
if	O
the	O
software	O
was	O
written	O
to	O
be	O
unaware	O
of	O
the	O
actual	O
hardware	O
and	O
to	O
interact	O
solely	O
with	O
the	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
The	O
Classic	B-Device
Environment	O
is	O
not	O
available	O
on	O
Intel-based	B-Device
Mac	I-Device
systems	I-Device
or	O
the	O
latest	O
Apple	B-Device
silicon	I-Device
Macs	I-Device
due	O
to	O
the	O
incompatibility	O
of	O
Mac	B-Operating_System
OS	I-Operating_System
9	I-Operating_System
with	O
both	O
the	O
x86	B-Operating_System
and	O
ARM	B-Architecture
hardware	O
.	O
</s>
<s>
Third-party	O
Macintosh	B-Device
emulators	B-Application
,	O
such	O
as	O
vMac	B-Application
,	O
Basilisk	B-Application
II	I-Application
,	O
and	O
Executor	B-Operating_System
,	O
eventually	O
made	O
it	O
possible	O
to	O
run	O
the	O
Classic	B-Application
Mac	I-Application
OS	I-Application
on	O
Intel-based	O
PCs	B-Device
.	O
</s>
<s>
These	O
emulators	B-Application
were	O
restricted	O
to	O
emulating	B-Application
the	O
68k	B-Device
series	O
of	O
processors	O
,	O
and	O
as	O
such	O
most	O
could	O
n't	O
run	O
versions	O
of	O
the	O
Mac	B-Application
OS	I-Application
that	O
succeeded	O
8.1	B-Operating_System
,	O
which	O
required	O
PowerPC	B-Architecture
processors	I-Architecture
.	O
</s>
<s>
Most	O
also	O
required	O
a	O
Mac	O
ROM	B-Device
image	O
or	O
a	O
hardware	O
interface	O
supporting	O
a	O
real	O
Mac	O
ROM	B-Device
chip	I-Device
;	O
those	O
requiring	O
an	O
image	O
are	O
of	O
dubious	O
legal	O
standing	O
as	O
the	O
ROM	B-Device
image	O
may	O
infringe	O
on	O
Apple	O
's	O
intellectual	O
property	O
.	O
</s>
<s>
A	O
notable	O
exception	O
was	O
the	O
Executor	B-Operating_System
commercial	B-Application
software	I-Application
product	O
from	O
Abacus	O
Research	O
&	O
Development	O
,	O
the	O
only	O
product	O
that	O
used	O
100%	O
reverse-engineered	O
code	O
without	O
the	O
use	O
of	O
Apple	O
technology	O
.	O
</s>
<s>
Executor	B-Operating_System
filled	O
a	O
niche	O
market	O
for	O
porting	O
68k	B-Device
Mac	O
applications	O
to	O
x86	B-Operating_System
platforms	O
;	O
development	O
ceased	O
in	O
2002	O
and	O
the	O
source	O
code	O
was	O
released	O
by	O
the	O
author	O
in	O
late	O
2008	O
.	O
</s>
<s>
Emulators	B-Application
using	O
Mac	O
ROM	B-Device
images	O
offered	O
near	O
complete	O
Mac	B-Application
OS	I-Application
compatibility	O
,	O
and	O
later	O
versions	O
offered	O
excellent	O
performance	O
as	O
modern	O
x86	B-Operating_System
processor	O
performance	O
increased	O
exponentially	O
.	O
</s>
<s>
Apple	O
included	O
its	O
own	O
Mac	B-Device
68k	I-Device
emulator	I-Device
that	O
ran	O
seamlessly	O
on	O
all	O
PowerPC-based	O
versions	O
of	O
the	O
Classic	B-Application
Mac	I-Application
OS	I-Application
.	O
</s>
<s>
In	O
comparison	O
with	O
68k-emulator	O
development	O
,	O
PowerPC	B-Architecture
emulation	B-Application
is	O
more	O
complex	O
and	O
requires	O
more	O
CPU	O
power	O
.	O
</s>
<s>
The	O
emulator	B-Application
is	O
capable	O
of	O
running	O
Classic	B-Application
Mac	I-Application
OS	I-Application
and	O
OS	B-Operating_System
X	I-Operating_System
at	O
full	O
speed	O
with	O
networking	O
and	O
sound	O
in	O
most	O
cases	O
.	O
</s>
<s>
QEMU	B-Application
has	O
official	O
support	O
for	O
Classic	B-Application
Mac	I-Application
OS	I-Application
version	O
9.0	O
through	O
9.2	O
and	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
10.0	I-Operating_System
up	O
to	O
and	O
including	O
10.5	O
.	O
</s>
<s>
QEMU	B-Application
has	O
several	O
advantages	O
over	O
other	O
PowerPC	B-Architecture
emulators	B-Application
namely	O
supporting	O
a	O
wide	O
range	O
of	O
platforms	O
from	O
Linux	O
to	O
Mac	O
and	O
Windows	O
on	O
current	O
CPU	O
architectures	O
.	O
</s>
<s>
Another	O
PowerPC	B-Architecture
emulator	B-Application
is	O
SheepShaver	B-Application
,	O
which	O
has	O
been	O
around	O
since	O
1998	O
for	O
BeOS	B-Application
on	O
the	O
PowerPC	B-Architecture
platform	I-Architecture
,	O
but	O
in	O
2002	O
was	O
open-sourced	B-Application
,	O
and	O
efforts	O
began	O
to	O
port	O
it	O
to	O
other	O
platforms	O
.	O
</s>
<s>
Originally	O
it	O
was	O
not	O
designed	O
for	O
use	O
on	O
x86	B-Operating_System
platforms	O
and	O
required	O
an	O
actual	O
PowerPC	B-Architecture
processor	I-Architecture
present	O
in	O
the	O
machine	O
it	O
was	O
running	O
on	O
similar	O
to	O
a	O
hypervisor	B-Operating_System
.	O
</s>
<s>
Although	O
it	O
provides	O
PowerPC	B-Architecture
processor	I-Architecture
support	O
,	O
it	O
can	O
run	O
only	O
up	O
to	O
Mac	B-Operating_System
OS	I-Operating_System
9.0.4	I-Operating_System
because	O
it	O
does	O
not	O
emulate	O
a	O
memory	B-General_Concept
management	I-General_Concept
unit	I-General_Concept
.	O
</s>
<s>
Other	O
examples	O
include	O
ShapeShifter	O
(	O
by	O
the	O
same	O
developer	O
that	O
created	O
SheepShaver	B-Application
)	O
,	O
Fusion	O
,	O
PearPC	O
and	O
.	O
</s>
<s>
The	O
latter	O
ran	O
Classic	B-Application
Mac	I-Application
OS	I-Application
with	O
a	O
PowerPC	B-Architecture
"	O
coprocessor	O
"	O
accelerator	O
card	O
.	O
</s>
<s>
Using	O
this	O
method	O
has	O
been	O
said	O
to	O
equal	O
or	O
better	O
the	O
speed	O
of	O
a	O
Macintosh	B-Device
with	O
the	O
same	O
processor	O
,	O
especially	O
with	O
respect	O
to	O
the	O
68k	B-Device
series	O
due	O
to	O
real	O
Macs	O
running	O
in	O
MMU	B-General_Concept
trap	O
mode	O
,	O
hampering	O
performance	O
.	O
</s>
<s>
Apple	O
's	O
Rosetta	B-Operating_System
was	O
a	O
PowerPC	B-Architecture
emulator	B-Application
allowing	O
Intel-based	B-Device
Macs	I-Device
to	O
run	O
PowerPC	B-Architecture
MacOS	B-Operating_System
X	I-Operating_System
applications	O
,	O
but	O
it	O
did	O
not	O
support	O
Classic	B-Application
Mac	I-Application
OS	I-Application
(	O
9.2.2	B-Operating_System
or	O
earlier	O
)	O
applications	O
.	O
</s>
