<s>
ProDOS	B-Operating_System
is	O
the	O
name	O
of	O
two	O
similar	O
operating	B-General_Concept
systems	I-General_Concept
for	O
the	O
Apple	B-Device
II	I-Device
series	I-Device
of	O
personal	B-Device
computers	I-Device
.	O
</s>
<s>
The	O
original	O
ProDOS	B-Operating_System
,	O
renamed	O
ProDOS	B-Operating_System
8	I-Operating_System
in	O
version	O
1.2	O
,	O
is	O
the	O
last	O
official	O
operating	B-General_Concept
system	I-General_Concept
usable	O
by	O
all	O
8-bit	O
Apple	B-Device
II	I-Device
series	I-Device
computers	B-Device
,	O
and	O
was	O
distributed	O
from	O
1983	O
to	O
1993	O
.	O
</s>
<s>
The	O
other	O
,	O
ProDOS	B-Operating_System
16	I-Operating_System
,	O
was	O
a	O
stop-gap	O
solution	O
for	O
the	O
16-bit	B-Device
Apple	B-Device
II	I-Device
that	O
was	O
replaced	O
by	O
GS/OS	B-Application
within	O
two	O
years	O
.	O
</s>
<s>
ProDOS	B-Operating_System
was	O
marketed	O
by	O
Apple	O
as	O
meaning	O
Professional	O
Disk	O
Operating	B-General_Concept
System	I-General_Concept
,	O
and	O
became	O
the	O
most	O
popular	O
operating	B-General_Concept
system	I-General_Concept
for	O
the	O
Apple	B-Device
II	I-Device
series	I-Device
of	O
computers	B-Device
10	O
months	O
after	O
its	O
release	O
in	O
January	O
1983	O
.	O
</s>
<s>
ProDOS	B-Operating_System
was	O
released	O
to	O
address	O
shortcomings	O
in	O
the	O
earlier	O
Apple	O
operating	B-General_Concept
system	I-General_Concept
(	O
called	O
simply	O
DOS	B-Operating_System
)	O
,	O
which	O
was	O
beginning	O
to	O
show	O
its	O
age	O
.	O
</s>
<s>
Apple	B-Operating_System
DOS	I-Operating_System
only	O
has	O
built-in	O
support	O
for	O
5.25	B-Device
"	I-Device
floppy	B-Device
disks	I-Device
and	O
requires	O
patches	O
to	O
use	O
peripheral	O
devices	O
such	O
as	O
hard	O
disk	O
drives	O
and	O
non-Disk-II	O
floppy	B-Device
disk	I-Device
drives	I-Device
,	O
including	O
3.5	B-Device
"	I-Device
floppy	B-Device
drives	I-Device
.	O
</s>
<s>
ProDOS	B-Operating_System
adds	O
a	O
standard	O
method	O
of	O
accessing	O
ROM-based	O
drivers	O
on	O
expansion	O
cards	O
for	O
disk	O
devices	O
,	O
expands	O
the	O
maximum	O
volume	O
size	O
from	O
about	O
400	O
kilobytes	O
to	O
32	O
megabytes	O
,	O
introduces	O
support	O
for	O
hierarchical	O
subdirectories	B-Application
(	O
a	O
vital	O
feature	O
for	O
organizing	O
a	O
hard	O
disk	O
's	O
storage	O
space	O
)	O
,	O
and	O
supports	O
RAM	B-Application
disks	I-Application
on	O
machines	O
with	O
128	O
KB	O
or	O
more	O
of	O
memory	O
.	O
</s>
<s>
ProDOS	B-Operating_System
addresses	O
problems	O
with	O
handling	O
hardware	O
interrupts	B-Application
,	O
and	O
includes	O
a	O
well-defined	O
and	O
documented	O
programming	O
and	O
expansion	O
interface	O
,	O
which	O
Apple	B-Operating_System
DOS	I-Operating_System
had	O
always	O
lacked	O
.	O
</s>
<s>
Although	O
ProDOS	B-Operating_System
also	O
includes	O
support	O
for	O
a	O
real-time	O
clock	O
(	O
RTC	O
)	O
,	O
this	O
support	O
went	O
largely	O
unused	O
until	O
the	O
release	O
of	O
the	O
Apple	B-Device
II	I-Device
,	O
the	O
first	O
in	O
the	O
Apple	B-Device
II	I-Device
series	I-Device
to	O
include	O
an	O
RTC	O
on	O
board	O
.	O
</s>
<s>
Third-party	O
clocks	O
were	O
available	O
for	O
the	O
II	O
Plus	O
,	O
IIe	B-Device
,	O
and	O
IIc	O
,	O
however	O
.	O
</s>
<s>
ProDOS	B-Operating_System
,	O
unlike	O
earlier	O
Apple	B-Operating_System
DOS	I-Operating_System
versions	O
,	O
has	O
its	O
developmental	O
roots	O
in	O
SOS	B-Operating_System
,	O
the	O
operating	B-General_Concept
system	I-General_Concept
for	O
the	O
ill-fated	O
Apple	B-Device
III	I-Device
computer	O
released	O
in	O
1980	O
.	O
</s>
<s>
Pre-release	O
documentation	O
for	O
ProDOS	B-Operating_System
(	O
including	O
early	O
editions	O
of	O
Beneath	O
Apple	B-Operating_System
ProDOS	I-Operating_System
)	O
documented	O
SOS	B-Operating_System
error	O
codes	O
,	O
notably	O
one	O
for	O
switched	O
disks	O
,	O
that	O
ProDOS	B-Operating_System
itself	O
could	O
never	O
generate	O
.	O
</s>
<s>
Its	O
disk	O
format	O
and	O
programming	O
interface	O
are	O
completely	O
different	O
from	O
those	O
of	O
Apple	B-Operating_System
DOS	I-Operating_System
,	O
and	O
ProDOS	B-Operating_System
cannot	O
read	O
or	O
write	O
DOS	B-Operating_System
3.3	O
disks	O
except	O
by	O
means	O
of	O
a	O
conversion	O
utility	O
;	O
while	O
the	O
low-level	O
track-and-sector	O
format	O
of	O
DOS	B-Operating_System
3.3	O
disks	O
was	O
retained	O
for	O
5.25-inch	O
disks	O
,	O
the	O
high-level	O
arrangement	O
of	O
files	O
and	O
directories	B-Application
is	O
completely	O
different	O
.	O
</s>
<s>
For	O
this	O
reason	O
,	O
most	O
machine-language	O
programs	O
that	O
run	O
under	O
Apple	B-Operating_System
DOS	I-Operating_System
will	O
not	O
work	O
under	O
ProDOS	B-Operating_System
.	O
</s>
<s>
A	O
third-party	O
program	O
called	O
DOS.MASTER	O
enables	O
users	O
to	O
have	O
multiple	O
virtual	O
DOS	B-Operating_System
3.3	O
partitions	O
on	O
a	O
larger	O
ProDOS	B-Operating_System
volume	O
.	O
</s>
<s>
With	O
the	O
release	O
of	O
ProDOS	B-Operating_System
came	O
the	O
end	O
of	O
support	O
for	O
Integer	B-Language
BASIC	I-Language
and	O
the	O
original	O
Apple	B-Device
II	I-Device
model	O
,	O
which	O
had	O
long	O
since	O
been	O
effectively	O
supplanted	O
by	O
Applesoft	B-Language
BASIC	I-Language
and	O
the	O
Apple	B-Device
II	I-Device
Plus	O
.	O
</s>
<s>
Whereas	O
DOS	B-Operating_System
3.3	O
always	O
loads	O
built-in	O
support	O
for	O
BASIC	O
programming	O
,	O
under	O
ProDOS	B-Operating_System
this	O
job	O
is	O
given	O
to	O
a	O
separate	O
system	O
program	O
called	O
,	O
which	O
one	O
launches	O
to	O
run	O
and	O
write	O
Applesoft	B-Language
BASIC	I-Language
programs	O
.	O
</s>
<s>
BASIC	O
itself	O
continued	O
to	O
be	O
built	O
into	O
the	O
Apple	O
ROMs	O
;	O
is	O
merely	O
a	O
command	O
interpreter	O
enhancement	O
that	O
allows	O
BASIC	O
programs	O
to	O
access	O
ProDOS	B-Operating_System
by	O
means	O
of	O
the	O
same	O
"	O
Control-D	O
"	O
text	O
output	O
they	O
had	O
used	O
under	O
DOS	B-Operating_System
3.3	O
.	O
alone	O
requires	O
about	O
as	O
much	O
memory	O
as	O
the	O
whole	O
of	O
DOS	B-Operating_System
3.3	O
.	O
</s>
<s>
Since	O
the	O
ProDOS	B-Operating_System
kernel	O
itself	O
is	O
stowed	O
away	O
in	O
the	O
"	O
Language	O
Card	O
"	O
RAM	O
,	O
the	O
usable	O
amount	O
of	O
RAM	O
for	O
BASIC	O
programmers	O
remains	O
the	O
same	O
under	O
ProDOS	B-Operating_System
as	O
it	O
had	O
been	O
under	O
DOS	B-Operating_System
3.3	O
.	O
</s>
<s>
Despite	O
ProDOS	B-Operating_System
's	O
many	O
advantages	O
,	O
many	O
users	O
and	O
programmers	O
resisted	O
it	O
for	O
a	O
time	O
because	O
of	O
their	O
investment	O
in	O
learning	O
the	O
ins	O
and	O
outs	O
of	O
Apple	B-Operating_System
DOS	I-Operating_System
and	O
in	O
Apple-DOS-based	O
software	O
and	O
data	O
formats	O
.	O
</s>
<s>
A	O
contributing	O
reason	O
was	O
that	O
ProDOS	B-Operating_System
allows	O
only	O
15	O
characters	O
in	O
a	O
filename	B-Device
compared	O
to	O
Apple	B-Operating_System
DOS	I-Operating_System
's	O
30	O
.	O
</s>
<s>
But	O
Apple	O
's	O
integrated	B-Application
software	I-Application
package	O
AppleWorks	B-Device
,	O
released	O
in	O
1984	O
,	O
proved	O
a	O
compelling	O
reason	O
to	O
switch	O
,	O
and	O
by	O
the	O
end	O
of	O
1985	O
few	O
new	O
software	O
products	O
were	O
being	O
released	O
for	O
the	O
older	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
Apple	O
IIs	O
continued	O
to	O
be	O
able	O
to	O
boot	O
the	O
older	O
DOS	B-Operating_System
(	O
even	O
the	O
Apple	B-Device
IIGS	I-Device
can	O
boot	O
the	O
older	O
DOS	B-Operating_System
floppies	B-Device
)	O
but	O
as	O
3.5	B-Device
"	I-Device
floppies	B-Device
and	O
hard	O
disks	O
became	O
more	O
prevalent	O
,	O
most	O
users	O
spent	O
the	O
bulk	O
of	O
their	O
time	O
in	O
ProDOS	B-Operating_System
.	O
</s>
<s>
The	O
Apple	B-Device
IIe	I-Device
,	O
also	O
released	O
in	O
1983	O
,	O
was	O
the	O
first	O
Apple	B-Device
II	I-Device
computer	I-Device
to	O
have	O
64	O
KB	O
of	O
memory	O
built	O
in	O
.	O
</s>
<s>
For	O
a	O
while	O
,	O
Apple	O
shipped	O
both	O
DOS	B-Operating_System
3.3	O
and	O
ProDOS	B-Operating_System
with	O
new	O
computers	B-Device
.	O
</s>
<s>
The	O
original	O
ProDOS	B-Operating_System
was	O
renamed	O
ProDOS	B-Operating_System
8	I-Operating_System
when	O
ProDOS	B-Operating_System
16	I-Operating_System
was	O
released	O
to	O
support	O
the	O
16-bit	B-Device
Apple	B-Device
II	I-Device
computer	I-Device
,	O
although	O
ProDOS	B-Operating_System
16	I-Operating_System
(	O
which	O
was	O
8-bit	O
at	O
its	O
core	O
)	O
was	O
soon	O
replaced	O
by	O
GS/OS	B-Application
.	O
</s>
<s>
All	O
editions	O
of	O
ProDOS	B-Operating_System
require	O
an	O
Apple	B-Device
II	I-Device
series	I-Device
computer	O
or	O
compatible	O
.	O
</s>
<s>
ProDOS	B-Operating_System
8	I-Operating_System
requires	O
64	O
KB	O
of	O
memory	O
to	O
run	O
.	O
</s>
<s>
The	O
original	O
ProDOS	B-Operating_System
(	O
8	O
)	O
1.0	O
through	O
1.0.2	O
requires	O
only	O
48	O
KB	O
for	O
the	O
kernel	O
,	O
but	O
nearly	O
all	O
programs	O
,	O
including	O
the	O
needed	O
to	O
use	O
Applesoft	B-Language
BASIC	I-Language
,	O
require	O
64	O
KB	O
,	O
making	O
a	O
48	O
KB	O
system	O
useless	O
for	O
ProDOS	B-Operating_System
as	O
a	O
practical	O
matter	O
,	O
and	O
support	O
for	O
48	O
KB	O
machines	O
was	O
removed	O
in	O
version	O
1.1	O
.	O
</s>
<s>
ProDOS	B-Operating_System
8	I-Operating_System
version	O
2.x	O
requires	O
a	O
65C02	B-General_Concept
or	O
later	O
(	O
65802	O
,	O
65816	O
)	O
CPU	B-General_Concept
.	O
</s>
<s>
ProDOS	B-Operating_System
8	I-Operating_System
2.x	O
runs	O
in	O
64	O
KB	O
,	O
but	O
the	O
utility	O
programs	O
on	O
the	O
system	O
disk	O
require	O
128	O
KB	O
.	O
</s>
<s>
Systems	O
with	O
a	O
6502	O
CPU	B-General_Concept
instead	O
of	O
a	O
65C02	B-General_Concept
must	O
use	O
ProDOS	B-Operating_System
8	I-Operating_System
versions	O
prior	O
to	O
version	O
2.0	O
.	O
</s>
<s>
ProDOS	B-Operating_System
16	I-Operating_System
requires	O
an	O
Apple	B-Device
IIGS	I-Device
.	O
</s>
<s>
With	O
the	O
release	O
of	O
ProDOS	B-Operating_System
version	O
1.01	O
and	O
higher	O
,	O
a	O
check	O
was	O
added	O
to	O
see	O
if	O
it	O
was	O
running	O
on	O
an	O
official	O
Apple-manufactured	O
computer	O
.	O
</s>
<s>
If	O
the	O
word	O
"	O
Apple	O
"	O
is	O
found	O
in	O
the	O
computer	O
's	O
ROM	O
firmware	O
,	O
ProDOS	B-Operating_System
will	O
load	O
up	O
as	O
normal	O
.	O
</s>
<s>
"	O
Golden	O
"	O
,	O
"	O
Franklin	O
"	O
,	O
"	O
Elite	O
"	O
)	O
ProDOS	B-Operating_System
refuses	O
to	O
run	O
,	O
locking	O
up	O
at	O
the	O
boot	O
splash	O
screen	O
.	O
</s>
<s>
This	O
measure	O
was	O
taken	O
by	O
Apple	O
Computer	O
to	O
discourage	O
use	O
of	O
unlicensed	O
Apple	B-Device
II	I-Device
clones	O
.	O
</s>
<s>
It	O
is	O
still	O
possible	O
to	O
run	O
newer	O
versions	O
of	O
ProDOS	B-Operating_System
on	O
clones	O
;	O
however	O
,	O
users	O
have	O
to	O
apply	O
a	O
small	O
byte	O
patch	O
to	O
every	O
successive	O
version	O
of	O
ProDOS	B-Operating_System
.	O
</s>
<s>
ProDOS	B-Operating_System
8	I-Operating_System
natively	O
supports	O
Disk	O
II-compatible	O
floppy	B-Device
drives	I-Device
,	O
a	O
RAM	B-Application
drive	I-Application
of	O
approximately	O
59	O
KB	O
on	O
computers	B-Device
having	O
128	O
KB	O
or	O
more	O
RAM	O
,	O
and	O
block	O
devices	O
whose	O
controllers	O
support	O
the	O
Pascal	O
firmware	O
protocol	O
,	O
a	O
standardized	O
method	O
of	O
accepting	O
block	O
reads	O
and	O
writes	O
originally	O
introduced	O
for	O
use	O
with	O
the	O
UCSD	B-Language
p-System	I-Language
.	O
</s>
<s>
This	O
latter	O
category	O
includes	O
3.5	B-Device
"	I-Device
floppy	B-Device
drives	I-Device
and	O
hard	O
drives	O
.	O
</s>
<s>
ProDOS	B-Operating_System
uses	O
the	O
same	O
file	B-Application
system	I-Application
as	O
the	O
earlier	O
Apple	B-Operating_System
SOS	I-Operating_System
for	O
the	O
Apple	B-Device
III	I-Device
.	O
</s>
<s>
The	O
SOS/ProDOS	O
file	B-Application
system	I-Application
is	O
native	O
to	O
Apple	B-Operating_System
SOS	I-Operating_System
,	O
ProDOS	B-Operating_System
8	I-Operating_System
,	O
ProDOS	B-Operating_System
16	I-Operating_System
,	O
and	O
GS/OS	B-Application
.	O
</s>
<s>
Some	O
classic	B-Application
Mac	I-Application
OS	I-Application
versions	O
also	O
come	O
with	O
a	O
file	B-Application
system	I-Application
translator	I-Application
to	O
handle	O
this	O
file	B-Application
system	I-Application
.	O
</s>
<s>
(	O
5.25	B-Device
"	I-Device
floppy	B-Device
disks	I-Device
are	O
still	O
formatted	O
using	O
256-byte	O
sectors	O
,	O
as	O
this	O
is	O
the	O
format	O
required	O
by	O
the	O
controller	O
ROM	O
to	O
boot	O
the	O
disk	O
.	O
</s>
<s>
ProDOS	B-Operating_System
simply	O
treats	O
pairs	O
of	O
256-byte	O
sectors	O
as	O
a	O
single	O
block	O
on	O
such	O
drives	O
.	O
)	O
</s>
<s>
Each	O
volume	O
(	O
floppy	B-Device
disk	I-Device
or	O
hard	O
drive	O
partition	O
)	O
has	O
a	O
"	O
volume	O
name	O
"	O
,	O
a	O
filename	B-Device
which	O
is	O
used	O
as	O
the	O
base	O
directory	B-Application
name	O
;	O
having	O
two	O
volumes	O
with	O
the	O
same	O
volume	O
name	O
can	O
result	O
in	O
conflicts	O
.	O
</s>
<s>
If	O
necessary	O
,	O
ProDOS	B-Operating_System
searches	O
all	O
available	O
drives	O
to	O
find	O
a	O
named	O
volume	O
.	O
</s>
<s>
Subdirectories	B-Application
are	O
supported	O
,	O
and	O
the	O
concept	O
of	O
a	O
"	O
prefix	O
"	O
(	O
working	O
directory	B-Application
or	O
current	O
path	O
)	O
was	O
provided	O
to	O
make	O
working	O
with	O
subdirectories	B-Application
easier	O
.	O
</s>
<s>
File	O
,	O
directory	B-Application
,	O
and	O
volume	O
names	O
can	O
be	O
1	O
to	O
15	O
characters	O
,	O
starting	O
with	O
a	O
letter	O
,	O
then	O
containing	O
more	O
letters	O
,	O
digits	O
or	O
periods	O
.	O
</s>
<s>
Each	O
file	O
entry	O
also	O
contains	O
the	O
16-bit	B-Device
(	O
2-byte	O
)	O
pointer	O
to	O
the	O
block	O
containing	O
the	O
beginning	O
of	O
the	O
file	O
(	O
or	O
its	O
block	O
index	O
)	O
;	O
a	O
16-bit	B-Device
block	O
count	O
;	O
a	O
24-bit	O
(	O
3-byte	O
)	O
file	O
size	O
;	O
an	O
8-bit	O
(	O
1-byte	O
)	O
filetype	O
;	O
a	O
16-bit	B-Device
auxiliary	O
type	O
(	O
the	O
meaning	O
of	O
which	O
depends	O
upon	O
the	O
filetype	O
)	O
;	O
creation	O
and	O
modification	O
timestamps	O
;	O
and	O
data	O
related	O
to	O
how	O
the	O
file	O
is	O
stored	O
on	O
the	O
volume	O
.	O
</s>
<s>
Sparse	B-General_Concept
files	I-General_Concept
are	O
supported	O
,	O
but	O
files	O
are	O
never	O
"	O
sparsified	O
"	O
by	O
removing	O
zero-filled	O
blocks	O
.	O
</s>
<s>
Directories	B-Application
(	O
including	O
the	O
root	O
directory	B-Application
)	O
are	O
sequentially	O
indexed	O
,	O
with	O
each	O
block	O
starting	O
with	O
the	O
address	O
of	O
the	O
previous	O
block	O
(	O
or	O
zero	O
if	O
none	O
)	O
and	O
the	O
subsequent	O
block	O
(	O
or	O
zero	O
if	O
none	O
)	O
.	O
</s>
<s>
The	O
root	O
directory	B-Application
on	O
most	O
disks	O
is	O
initialized	O
to	O
4	O
blocks	O
,	O
allowing	O
51	O
entries	O
(	O
excluding	O
the	O
volume	O
header	O
)	O
.	O
</s>
<s>
Subdirectories	B-Application
begin	O
at	O
one	O
block	O
,	O
and	O
grow	O
automatically	O
as	O
needed	O
.	O
</s>
<s>
Single-block	O
files	O
(	O
under	O
513	O
bytes	O
)	O
have	O
no	O
index	O
block	O
;	O
the	O
directory	B-Application
entry	O
points	O
directly	O
to	O
the	O
block	O
of	O
file	O
data	O
.	O
</s>
<s>
Files	O
with	O
between	O
2	O
and	O
256	O
blocks	O
(	O
513	O
bytes	O
to	O
128	O
KB	O
)	O
of	O
data	O
have	O
a	O
single	O
index	O
block	O
,	O
to	O
which	O
the	O
directory	B-Application
entry	O
points	O
,	O
which	O
contains	O
a	O
list	O
of	O
up	O
to	O
256	O
data	O
block	O
addresses	O
.	O
</s>
<s>
When	O
the	O
Apple	B-Device
IIGS	I-Device
was	O
introduced	O
,	O
a	O
new	O
storage	O
format	O
was	O
introduced	O
for	O
files	O
with	O
two	O
forks	O
,	O
as	O
was	O
typical	O
for	O
IIGS	B-Device
system	O
and	O
program	O
files	O
;	O
the	O
directory	B-Application
entry	O
points	O
to	O
an	O
informational	O
block	O
that	O
tells	O
the	O
computer	O
the	O
storage	O
format	O
of	O
the	O
two	O
forks	O
.	O
</s>
<s>
These	O
files	O
cannot	O
be	O
read	O
or	O
written	O
natively	O
by	O
ProDOS	B-Operating_System
8	I-Operating_System
,	O
though	O
the	O
volume	O
itself	O
remains	O
compatible	O
.	O
</s>
<s>
Other	O
than	O
this	O
,	O
there	O
is	O
no	O
central	O
file	B-Application
allocation	I-Application
table	I-Application
.	O
</s>
<s>
A	O
ProDOS	B-Operating_System
8	I-Operating_System
volume	O
formatted	O
by	O
Apple	O
's	O
tools	O
has	O
a	O
boot	B-Device
sector	I-Device
that	O
supports	O
booting	O
both	O
ProDOS	B-Operating_System
and	O
SOS	B-Operating_System
depending	O
on	O
what	O
computer	O
it	O
is	O
booted	O
on	O
.	O
</s>
<s>
Block	O
0	O
is	O
the	O
Apple	B-Device
II	I-Device
boot	B-Device
block	I-Device
and	O
block	O
1	O
boots	O
SOS	B-Operating_System
.	O
</s>
<s>
This	O
allows	O
a	O
disk	O
to	O
be	O
used	O
to	O
boot	O
on	O
either	O
Apple	B-Device
II	I-Device
or	O
Apple	B-Device
III	I-Device
computers	B-Device
by	O
putting	O
both	O
operating	B-General_Concept
system	I-General_Concept
kernels	O
in	O
the	O
top	O
directory	B-Application
:	O
the	O
Apple	B-Device
II	I-Device
boot	B-Device
sector	I-Device
looks	O
for	O
the	O
file	O
and	O
the	O
Apple	B-Device
III	I-Device
boot	B-Device
sector	I-Device
looks	O
for	O
the	O
file	O
.	O
</s>
<s>
Third-party	O
formatting	O
utilities	O
often	O
did	O
not	O
provide	O
the	O
SOS	B-Operating_System
boot	B-Device
block	I-Device
,	O
and	O
some	O
would	O
even	O
mark	O
block	O
1	O
available	O
for	O
user	O
data	O
.	O
</s>
<s>
ProDOS	B-Operating_System
has	O
no	O
kernel	O
support	O
for	O
other	O
file	B-Application
systems	I-Application
.	O
</s>
<s>
If	O
necessary	O
,	O
a	O
conversion	O
utility	O
on	O
the	O
main	O
system	O
disk	O
is	O
used	O
to	O
transfer	O
files	O
individually	O
between	O
ProDOS	B-Operating_System
and	O
older	O
Apple	B-Operating_System
DOS	I-Operating_System
3.3	O
disks	O
.	O
</s>
<s>
Because	O
they	O
use	O
a	O
different	O
low-level	O
disk	O
format	O
than	O
DOS	B-Operating_System
3.3	O
and	O
ProDOS	B-Operating_System
,	O
transferring	O
data	O
from	O
DOS	B-Operating_System
3.2	O
disks	O
to	O
ProDOS	B-Operating_System
is	O
a	O
two-step	O
process	O
using	O
a	O
DOS	B-Operating_System
3.3	O
disk	O
as	O
an	O
intermediary	O
(	O
utilizing	O
the	O
DOS	B-Operating_System
3.3	O
utility	O
MUFFIN	O
or	O
similar	O
)	O
.	O
</s>
