<s>
BootX	B-Operating_System
is	O
a	O
software-based	O
bootloader	B-Application
designed	O
and	O
developed	O
by	O
Apple	O
Inc	O
.	O
for	O
use	O
on	O
the	O
company	O
's	O
Macintosh	B-Device
computer	O
range	O
.	O
</s>
<s>
BootX	B-Operating_System
is	O
used	O
to	O
prepare	O
the	O
computer	O
for	O
use	O
,	O
by	O
loading	O
all	O
required	O
device	B-Application
drivers	I-Application
and	O
then	O
starting-up	O
Mac	B-Application
OS	I-Application
X	I-Application
by	O
booting	B-Operating_System
the	O
kernel	B-Operating_System
on	O
all	O
PowerPC	B-Architecture
Macintoshes	B-Device
running	O
the	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
10.2	I-Operating_System
operating	B-General_Concept
system	I-General_Concept
or	O
later	O
versions	O
.	O
</s>
<s>
Using	O
BootROM	O
,	O
a	O
read-only	B-Device
memory	I-Device
(	O
ROM	B-Device
)	O
computer	O
chip	O
containing	O
Open	B-Architecture
Firmware	I-Architecture
,	O
a	O
graphical	O
bootsplash	B-Operating_System
is	O
shown	O
briefly	O
on	O
all	O
compatible	O
Macintosh	B-Device
computers	O
as	O
a	O
grey	O
Apple	O
logo	O
with	O
a	O
spinning	O
cursor	O
that	O
appears	O
during	O
the	O
startup	B-Operating_System
sequence	O
.	O
</s>
<s>
The	O
program	O
is	O
freely	O
available	O
as	O
part	O
of	O
the	O
Darwin	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
under	O
the	O
open-source	O
Apple	B-License
Public	I-License
Source	I-License
License	I-License
.	O
</s>
<s>
BootX	B-Operating_System
was	O
superseded	O
by	O
another	O
nearly	O
identical	O
bootloader	B-Application
named	O
boot.efi	B-Operating_System
and	O
an	O
Extensible	B-Architecture
Firmware	I-Architecture
Interface	I-Architecture
ROM	B-Device
on	O
the	O
release	O
of	O
the	O
Intel-based	B-Device
Mac	I-Device
.	O
</s>
<s>
Older	O
Macintoshes	B-Device
dating	O
from	O
1983	O
until	O
1998	O
utilized	O
a	O
basic	O
bootloader	B-Application
;	O
the	O
bootloader	B-Application
was	O
solely	O
a	O
ROM	B-Device
chip	I-Device
varying	O
in	O
sizes	O
up	O
to	O
4megabytes	O
(	O
MB	O
)	O
,	O
which	O
contained	O
both	O
the	O
computer	B-Application
code	I-Application
to	O
boot	B-Operating_System
the	O
computer	O
and	O
to	O
run	O
the	O
Mac	B-Application
OS	I-Application
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
The	O
ROM-resident	O
portion	O
of	O
the	O
Mac	B-Application
OS	I-Application
is	O
the	O
Macintosh	B-Device
Toolbox	I-Device
and	O
the	O
boot-ROM	O
part	O
of	O
that	O
ROM	B-Device
was	O
retroactively	O
named	O
Old	B-Device
World	I-Device
ROM	I-Device
upon	O
the	O
release	O
of	O
the	O
New	B-Device
World	I-Device
ROM	I-Device
Macs	O
,	O
starting	O
with	O
the	O
first	O
iMac	B-Device
.	O
</s>
<s>
The	O
ROM-resident	O
Macintosh	B-Device
Toolbox	I-Device
differs	O
greatly	O
from	O
the	O
design	O
of	O
the	O
modern	O
Macintosh	B-Device
,	O
which	O
generally	O
use	O
a	O
hard	B-Device
drive	I-Device
of	O
large	O
capacity	O
to	O
store	O
the	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
This	O
bootloader	B-Application
was	O
used	O
in	O
all	O
Macintosh	B-Device
computers	O
until	O
mid-1998	O
.	O
</s>
<s>
With	O
the	O
advent	O
of	O
the	O
iMac	B-Device
series	O
of	O
Macintoshes	B-Device
,	O
the	O
firmware	O
was	O
updated	O
.	O
</s>
<s>
The	O
ROM	B-Device
was	O
reduced	O
in	O
size	O
to	O
1MB	O
,	O
called	O
BootROM	O
,	O
and	O
the	O
remainder	O
of	O
the	O
ROM	B-Device
was	O
moved	O
to	O
the	O
file	O
Mac	B-Application
OS	I-Application
ROM	B-Device
in	O
the	O
Mac	B-Application
OS	I-Application
System	B-Operating_System
Folder	I-Operating_System
,	O
stored	O
on	O
the	O
hard	B-Device
drive	I-Device
.	O
</s>
<s>
This	O
ROM	B-Device
used	O
a	O
full	O
implementation	O
of	O
the	O
Open	B-Architecture
Firmware	I-Architecture
standard	O
(	O
contained	O
in	O
BootROM	O
)	O
and	O
was	O
named	O
the	O
New	B-Device
World	I-Device
ROM	I-Device
.	O
</s>
<s>
In	O
2001	O
,	O
with	O
the	O
release	O
of	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
10.0	I-Operating_System
,	O
the	O
Mac	B-Application
OS	I-Application
ROM	B-Device
file	O
was	O
replaced	O
with	O
the	O
BootX	B-Operating_System
bootloader	B-Application
file	O
.	O
</s>
<s>
In	O
2002	O
,	O
with	O
the	O
release	O
of	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
10.2	I-Operating_System
,	O
the	O
historical	O
"	O
Happy	O
Mac	O
"	O
start-up	O
picture	O
was	O
replaced	O
with	O
a	O
grey	O
apple	O
logo	O
.	O
</s>
<s>
By	O
introducing	O
the	O
Intel	B-Device
Mac	I-Device
in	O
2006	O
,	O
BootROM	O
was	O
replaced	O
by	O
the	O
near	O
identical	O
Extensible	B-Architecture
Firmware	I-Architecture
Interface	I-Architecture
ROM	B-Device
(	O
although	O
Apple	O
still	O
calls	O
it	O
BootROM	O
)	O
and	O
the	O
boot.efi	B-Operating_System
file	O
.	O
</s>
<s>
To	O
make	O
the	O
boot	B-Application
loader	I-Application
appealing	O
to	O
other	O
operating	B-General_Concept
system	I-General_Concept
developers	O
,	O
Apple	O
added	O
features	O
to	O
allow	O
flexibility	O
in	O
the	O
booting	B-Operating_System
process	O
such	O
as	O
network	B-Device
boot	I-Device
using	O
TFTP	B-Device
and	O
load	O
Mach-O	B-Operating_System
and	O
ELF	O
formatted	O
kernels	B-Operating_System
.	O
</s>
<s>
BootX	B-Operating_System
can	O
also	O
boot	B-Operating_System
from	O
HFS	B-Application
,	O
HFS+	B-Application
,	O
UFS	B-Operating_System
and	O
ext2	B-Application
formatted	B-Application
volumes	I-Application
.	O
</s>
<s>
The	O
boot	B-Application
loader	I-Application
can	O
be	O
manipulated	O
at	O
startup	B-Operating_System
by	O
holding	O
down	O
various	O
key	O
combinations	O
to	O
alter	O
the	O
booting	B-Operating_System
process	O
.	O
</s>
<s>
Such	O
functions	O
include	O
Verbose	O
Mode	O
,	O
achieved	O
by	O
holding	O
down	O
the	O
Command	B-Device
and	O
V	B-Operating_System
key	O
at	O
startup	B-Operating_System
,	O
which	O
replaces	O
the	O
default	O
Apple	O
logo	O
with	O
text-based	O
information	O
on	O
the	O
boot	B-Operating_System
process	I-Operating_System
and	O
Single	B-Operating_System
User	I-Operating_System
Mode	I-Operating_System
,	O
achieved	O
by	O
holding	O
down	O
the	O
Command	B-Device
and	O
S	B-Language
,	O
which	O
,	O
depending	O
on	O
the	O
operating	B-General_Concept
system	I-General_Concept
,	O
may	O
boot	B-Operating_System
into	O
a	O
more	O
basic	O
command-line	B-Application
or	O
text-based	O
version	O
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
,	O
to	O
facilitate	O
maintenance	O
and	O
recovery	O
action	O
.	O
</s>
<s>
The	O
ROM	B-Device
can	O
also	O
be	O
set	O
to	O
require	O
a	O
password	O
to	O
access	O
these	O
technical	O
functions	O
using	O
the	O
OpenFirmware	B-Architecture
interface	O
.	O
</s>
<s>
In	O
PowerPC-based	O
Macintoshes	B-Device
,	O
the	O
boot	B-Operating_System
process	I-Operating_System
starts	O
with	O
the	O
activation	O
of	O
BootROM	O
,	O
the	O
basic	O
Macintosh	B-Device
ROM	B-Device
,	O
which	O
performs	O
a	O
Power	B-Device
On	I-Device
Self	I-Device
Test	I-Device
to	O
test	O
hardware	O
essential	O
to	O
startup	B-Operating_System
.	O
</s>
<s>
On	O
the	O
passing	O
of	O
this	O
test	O
,	O
the	O
startup	B-Operating_System
chime	O
is	O
played	O
and	O
control	O
of	O
the	O
computer	O
is	O
passed	O
to	O
OpenFirmware	B-Architecture
.	O
</s>
<s>
OpenFirmware	B-Architecture
initializes	O
the	O
Random	O
Access	O
Memory	O
,	O
Memory	B-General_Concept
Management	I-General_Concept
Unit	I-General_Concept
and	O
hardware	O
necessary	O
for	O
the	O
ROM	B-Device
's	O
operation	O
.	O
</s>
<s>
The	O
OpenFirmware	B-Architecture
then	O
checks	O
settings	O
,	O
stored	O
in	O
NVRAM	B-General_Concept
,	O
and	O
builds	O
a	O
list	O
of	O
all	O
devices	O
on	O
a	O
device	O
tree	O
by	O
gathering	O
their	O
stored	O
FCode	B-Architecture
information	O
.	O
</s>
<s>
On	O
the	O
completion	O
of	O
this	O
task	O
,	O
BootX	B-Operating_System
takes	O
over	O
the	O
startup	B-Operating_System
process	O
configuring	O
the	O
keyboard	O
and	O
display	O
,	O
claiming	O
and	O
reserving	O
memory	O
for	O
various	O
purposes	O
and	O
checking	O
to	O
see	O
if	O
various	O
key	O
combinations	O
are	O
being	O
pressed	O
.	O
</s>
<s>
After	O
this	O
process	O
has	O
been	O
completed	O
BootX	B-Operating_System
displays	O
the	O
grey	O
Apple	O
logo	O
,	O
spins	O
the	O
spinning	O
wait	O
cursor	O
,	O
and	O
proceeds	O
to	O
load	O
the	O
kernel	B-Operating_System
and	O
some	O
kernel	B-Application
extensions	I-Application
and	O
start	O
the	O
kernel	B-Operating_System
.	O
</s>
