<s>
OS-9	B-Operating_System
is	O
a	O
family	O
of	O
real-time	B-General_Concept
,	O
process-based	B-Operating_System
,	O
multitasking	B-Operating_System
,	O
multi-user	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
,	O
developed	O
in	O
the	O
1980s	O
,	O
originally	O
by	O
Microware	B-Operating_System
Systems	I-Operating_System
Corporation	I-Operating_System
for	O
the	O
Motorola	B-Device
6809	I-Device
microprocessor	B-Architecture
.	O
</s>
<s>
It	O
was	O
purchased	O
by	O
Radisys	O
Corp	O
in	O
2001	O
,	O
and	O
was	O
purchased	O
again	O
in	O
2013	O
by	O
its	O
current	O
owner	O
Microware	B-Operating_System
LP	O
.	O
</s>
<s>
The	O
OS-9	B-Operating_System
family	O
was	O
popular	O
for	O
general-purpose	O
computing	O
and	O
remains	O
in	O
use	O
in	O
commercial	O
embedded	B-Architecture
systems	I-Architecture
and	O
amongst	O
hobbyists	O
.	O
</s>
<s>
Today	O
,	O
OS-9	B-Operating_System
is	O
a	O
product	O
name	O
used	O
by	O
both	O
a	O
Motorola	O
68000-series	O
machine	B-Language
language	I-Language
OS	O
and	O
a	O
portable	O
(	O
PowerPC	B-Architecture
,	O
x86	B-Operating_System
,	O
ARM	B-Architecture
,	O
MIPS	B-Device
,	O
SH4	O
,	O
etc	O
.	O
)	O
</s>
<s>
version	O
written	O
in	O
C	B-Language
,	O
originally	O
known	O
as	O
OS-9000	B-Operating_System
.	O
</s>
<s>
The	O
first	O
version	O
(	O
"	O
OS-9	B-Operating_System
Level	O
One	O
"	O
)	O
,	O
which	O
dates	O
back	O
to	O
1979	O
–	O
1980	O
,	O
was	O
written	O
in	O
assembly	B-Language
language	I-Language
for	O
the	O
Motorola	B-Device
6809	I-Device
CPU	O
,	O
and	O
all	O
of	O
its	O
processes	O
ran	O
within	O
the	O
64KB	O
address	O
space	O
of	O
the	O
CPU	O
without	O
a	O
memory	B-General_Concept
management	I-General_Concept
unit	I-General_Concept
.	O
</s>
<s>
It	O
was	O
developed	O
as	O
a	O
supporting	O
operating	B-General_Concept
system	I-General_Concept
for	O
the	O
BASIC09	B-Language
project	O
,	O
contracted	O
for	O
by	O
Motorola	O
as	O
part	O
of	O
the	O
6809	B-Device
development	O
.	O
</s>
<s>
A	O
later	O
6809	B-Device
version	O
(	O
"	O
Level	O
Two	O
"	O
)	O
takes	O
advantage	O
of	O
memory	B-General_Concept
mapping	I-General_Concept
hardware	O
,	O
supported	O
up	O
to	O
2	O
MB	O
of	O
memory	O
(	O
ca	O
.	O
</s>
<s>
1980	O
)	O
in	O
most	O
implementations	O
,	O
and	O
included	O
a	O
GUI	B-Application
on	O
some	O
platforms	O
.	O
</s>
<s>
In	O
1983	O
,	O
OS-9/6809	O
was	O
ported	O
to	O
Motorola	B-Device
68000	I-Device
assembly	B-Language
language	I-Language
and	O
extended	O
(	O
called	O
OS-9/68K	O
)	O
;	O
and	O
a	O
still	O
later	O
(	O
1989	O
)	O
version	O
was	O
rewritten	O
mostly	O
in	O
C	B-Language
for	O
further	O
portability	O
.	O
</s>
<s>
The	O
portable	O
version	O
was	O
initially	O
called	O
OS-9000	B-Operating_System
and	O
was	O
released	O
for	O
80386	B-General_Concept
PC	O
systems	O
around	O
1989	O
,	O
then	O
ported	O
to	O
PowerPC	B-Architecture
around	O
1995	O
.	O
</s>
<s>
These	O
later	O
versions	O
lack	O
the	O
memory	B-General_Concept
mapping	I-General_Concept
facilities	O
of	O
OS-9/6809	O
Level	O
Two	O
simply	O
because	O
they	O
do	O
not	O
need	O
them	O
.	O
</s>
<s>
They	O
used	O
a	O
single	O
flat	O
address	O
space	O
that	O
all	O
processes	O
share	O
;	O
memory	B-General_Concept
mapping	I-General_Concept
hardware	O
,	O
if	O
present	O
,	O
is	O
mostly	O
used	O
to	O
ensure	O
that	O
processes	O
access	O
only	O
memory	O
they	O
have	O
the	O
right	O
to	O
access	O
.	O
</s>
<s>
The	O
680x0	B-Device
and	O
80386	B-General_Concept
(	O
and	O
later	O
)	O
MPUs	B-Architecture
all	O
directly	O
support	O
far	O
more	O
than	O
of	O
memory	O
in	O
any	O
case	O
.	O
</s>
<s>
As	O
a	O
consequence	O
of	O
early	O
pervasive	O
design	O
decisions	O
taking	O
advantage	O
of	O
the	O
easily	O
used	O
reentrant	B-Operating_System
object	O
code	O
capabilities	O
of	O
the	O
6809	B-Device
processor	O
,	O
programs	O
intended	O
for	O
OS-9	B-Operating_System
are	O
required	O
to	O
be	O
reentrant	B-Operating_System
;	O
compilers	O
produce	O
reentrant	B-Operating_System
code	I-Operating_System
automatically	O
and	O
assemblers	B-Language
for	O
OS-9	B-Operating_System
offer	O
considerable	O
support	O
for	O
it	O
.	O
</s>
<s>
OS-9	B-Operating_System
also	O
uses	O
position-independent	B-Operating_System
code	I-Operating_System
and	O
data	O
because	O
the	O
6809	B-Device
also	O
supports	O
it	O
directly	O
;	O
compilers	O
and	O
assemblers	B-Language
support	O
position	O
independence	O
.	O
</s>
<s>
The	O
OS-9	B-Operating_System
kernel	O
loads	O
programs	O
(	O
including	O
shared	O
code	O
)	O
,	O
and	O
allocates	O
data	O
,	O
wherever	O
sufficient	O
free	O
space	O
is	O
available	O
in	O
the	O
memory	O
map	O
.	O
</s>
<s>
This	O
allows	O
the	O
entire	O
OS	O
and	O
all	O
applications	O
to	O
be	O
placed	O
in	O
ROM	O
or	O
Flash	O
memory	O
,	O
and	O
eases	O
memory	B-General_Concept
management	I-General_Concept
requirements	O
when	O
programs	O
are	O
loaded	O
into	O
RAM	O
and	O
run	O
.	O
</s>
<s>
Programs	O
,	O
device	B-Application
drivers	I-Application
,	O
and	O
I/O	O
managers	O
under	O
OS-9	B-Operating_System
are	O
all	O
'	O
modules	B-Application
 '	O
and	O
can	O
be	O
dynamically	O
loaded	O
and	O
unloaded	O
(	O
subject	O
to	O
link	O
counts	O
)	O
as	O
needed	O
.	O
</s>
<s>
OS-9/6809	O
runs	O
on	O
Motorola	O
EXORbus	O
systems	O
using	O
the	O
Motorola	B-Device
6809	I-Device
,	O
SS-50	B-Architecture
Bus	I-Architecture
and	O
SS-50C	O
bus	O
systems	O
from	O
companies	O
such	O
as	O
SWTPC	O
,	O
Tano	O
,	O
Gimix	O
,	O
Midwest	O
Scientific	O
,	O
and	O
Smoke	O
Signal	O
Broadcasting	O
,	O
STD-bus	O
6809	B-Device
systems	O
from	O
several	O
suppliers	O
,	O
personal	O
computers	O
such	O
as	O
the	O
Fujitsu	O
FM-11	B-Device
,	O
FM-8	B-Device
,	O
FM-7	B-Device
and	O
FM-77	O
,	O
Hitachi	O
MB-S1	O
,	O
and	O
many	O
others	O
.	O
</s>
<s>
System	O
Industries	O
,	O
a	O
third-party	O
provider	O
of	O
DEC	O
compatible	O
equipment	O
,	O
used	O
a	O
68B09E	B-Device
processor	O
running	O
OS9	O
in	O
its	O
QIC	O
(	O
quarter-inch	B-Device
cartridge	I-Device
)	O
tape	O
backup	B-Protocol
controllers	O
in	O
VAX	B-Device
installations	O
.	O
</s>
<s>
The	O
best	O
known	O
hardware	O
(	O
due	O
to	O
its	O
low	O
price	O
and	O
broad	O
distribution	O
)	O
was	O
the	O
TRS-80	B-Device
Color	I-Device
Computer	I-Device
(	O
CoCo	O
)	O
and	O
the	O
similar	O
Dragon	B-Device
series	O
.	O
</s>
<s>
Even	O
on	O
the	O
CoCo	O
,	O
a	O
quite	O
minimalist	O
hardware	O
platform	O
,	O
it	O
was	O
possible	O
under	O
OS-9/6809	O
Level	O
One	O
to	O
have	O
more	O
than	O
one	O
interactive	O
user	O
running	O
concurrently	O
(	O
for	O
example	O
,	O
one	O
on	O
the	O
console	O
keyboard	O
,	O
another	O
in	O
the	O
background	O
,	O
and	O
perhaps	O
a	O
third	O
interactively	O
via	O
a	O
serial	O
connection	O
)	O
as	O
well	O
as	O
several	O
other	O
non-interactive	O
processes	O
.	O
</s>
<s>
A	O
second	O
processor	O
implementation	O
for	O
the	O
BBC	B-Device
Micro	I-Device
was	O
produced	O
by	O
Cumana	O
.	O
</s>
<s>
It	O
included	O
on-board	O
RAM	O
,	O
SCSI	O
hard	O
disk	O
interface	O
and	O
a	O
MC68008	B-Device
processor	O
.	O
</s>
<s>
OS-9	B-Operating_System
was	O
also	O
ported	O
to	O
the	O
Commodore	O
SP-9000	O
or	O
SuperPET	O
,	O
which	O
had	O
a	O
6809	B-Device
in	O
addition	O
to	O
the	O
6502	O
of	O
the	O
base	O
8032	O
model	O
,	O
as	O
well	O
as	O
64	O
KB	O
more	O
.	O
</s>
<s>
The	O
Toronto	O
PET	O
Users	O
Group	O
sponsored	O
a	O
HW/SW	O
project	O
which	O
included	O
a	O
daughter	O
board	O
with	O
an	O
MMU	O
as	O
well	O
as	O
the	O
OS-9	B-Operating_System
distribution	O
disks	O
.	O
</s>
<s>
With	O
two	O
processors	O
,	O
96	O
KB	O
,	O
a	O
25×80	O
screen	O
and	O
serial	O
,	O
parallel	O
and	O
IEEE-488	O
ports	O
and	O
many	O
peripherals	O
this	O
was	O
one	O
of	O
the	O
most	O
capable	O
OS-9	B-Operating_System
systems	O
available	O
.	O
</s>
<s>
OS-9	B-Operating_System
'	O
s	O
multi-user	B-Operating_System
and	O
multi-tasking	O
capabilities	O
make	B-Application
it	O
usable	O
as	O
a	O
general-purpose	O
interactive	O
computer	O
system	O
.	O
</s>
<s>
Many	O
third-party	O
interactive	O
applications	O
have	O
been	O
written	O
for	O
it	O
,	O
such	O
as	O
the	O
Dynacalc	O
spreadsheet	B-Application
,	O
the	O
VED	O
text	B-General_Concept
formatter	I-General_Concept
,	O
and	O
the	O
Stylograph	O
and	O
Screditor-3	O
WYSIWYG	B-Application
word	B-General_Concept
processors	I-General_Concept
.	O
</s>
<s>
TSC	O
's	O
nroff	B-Device
emulating	O
formatter	O
was	O
ported	O
to	O
OS-9	B-Operating_System
by	O
MicroWay	O
,	O
as	O
well	O
.	O
</s>
<s>
In	O
mid	O
1980s	O
,	O
OS-9	B-Operating_System
was	O
selected	O
for	O
the	O
CD-i	B-Device
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
Around	O
the	O
same	O
time	O
,	O
Microsoft	O
approached	O
Microware	B-Operating_System
for	O
acquisition	O
of	O
the	O
company	O
primarily	O
because	O
it	O
was	O
attracted	O
by	O
CD-RTOS	B-Operating_System
,	O
the	O
CD-i	B-Device
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
The	O
negotiation	O
failed	O
and	O
no	O
deal	O
was	O
made	O
;	O
Microware	B-Operating_System
decided	O
to	O
remain	O
independent	O
.	O
</s>
<s>
In	O
late	O
1980s	O
,	O
Microware	B-Operating_System
released	O
OS-9000	B-Operating_System
,	O
a	O
more	O
portable	O
version	O
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
The	O
vast	O
majority	O
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
kernel	O
was	O
rewritten	O
in	O
C	B-Language
leaving	O
a	O
handful	O
of	O
hardware-dependent	O
parts	O
in	O
assembly	B-Language
language	I-Language
.	O
</s>
<s>
A	O
few	O
"	O
more	O
advanced	O
features	O
"	O
were	O
added	O
such	O
as	O
tree-like	O
kernel	B-Application
module	I-Application
name	O
space	O
.	O
</s>
<s>
OS-9000	B-Operating_System
was	O
initially	O
ported	O
to	O
the	O
Motorola	B-Device
680x0	I-Device
family	O
CPUs	O
,	O
Intel	B-General_Concept
80386	I-General_Concept
,	O
and	O
PowerPC	B-Architecture
.	O
</s>
<s>
The	O
OS-9000/680x0	O
was	O
a	O
marketing	O
failure	O
and	O
withdrawn	O
very	O
quickly	O
,	O
probably	O
because	O
few	O
customers	O
wanted	O
to	O
try	O
the	O
fatter	O
and	O
slower	O
operating	B-General_Concept
system	I-General_Concept
over	O
the	O
existing	O
OS-9/680x0	O
proven	O
record	O
of	O
stability	O
.	O
</s>
<s>
That	O
the	O
Motorola	B-Device
680x0	I-Device
family	O
and	O
VME	B-Architecture
board	I-Architecture
computer	O
system	O
vendors	O
were	O
nearing	O
their	O
end	O
of	O
life	O
might	O
have	O
affected	O
the	O
unpopularity	O
of	O
OS-9000/680x0	O
.	O
</s>
<s>
Microware	B-Operating_System
later	O
started	O
calling	O
all	O
of	O
its	O
operating	B-General_Concept
systems	I-General_Concept
—	O
including	O
what	O
had	O
been	O
originally	O
called	O
OS-9000	B-Operating_System
—	O
simply	O
OS-9	B-Operating_System
,	O
and	O
started	O
shifting	O
its	O
business	O
interest	O
towards	O
portable	O
consumer	O
device	O
markets	O
such	O
as	O
cellphones	O
,	O
car	O
navigation	O
,	O
and	O
multimedia	O
.	O
</s>
<s>
In	O
late	O
1980s	O
and	O
early	O
1990s	O
,	O
the	O
Character	O
Generators	O
computers	O
used	O
in	O
Broadcast	O
Systems	O
used	O
OS-9	B-Operating_System
and	O
OS-9000	B-Operating_System
extensively	O
.	O
</s>
<s>
The	O
now	O
defunct	O
Pesa	O
Electronica	O
used	O
OS-9	B-Operating_System
on	O
their	O
CGs	O
such	O
as	O
CG	O
4722	O
and	O
CG4733	O
.	O
</s>
<s>
In	O
1999	O
,	O
nineteen	O
years	O
after	O
the	O
first	O
release	O
of	O
OS-9	B-Operating_System
,	O
Apple	O
Computer	O
released	O
Mac	B-Operating_System
OS	I-Operating_System
9	I-Operating_System
.	O
</s>
<s>
Microware	B-Operating_System
sued	O
Apple	O
that	O
year	O
for	O
trademark	O
infringement	O
,	O
although	O
a	O
judge	O
ruled	O
that	O
there	O
would	O
be	O
little	O
chance	O
for	O
confusion	O
between	O
the	O
two	O
.	O
</s>
<s>
Some	O
Macintosh	B-Device
users	O
who	O
are	O
unaware	O
of	O
Microware	B-Operating_System
's	O
lesser	O
known	O
OS-9	B-Operating_System
have	O
posted	O
to	O
the	O
comp.os.os9	O
newsgroup	O
not	O
realizing	O
what	O
OS-9	B-Operating_System
is	O
.	O
</s>
<s>
In	O
2001	O
,	O
RadiSys	O
purchased	O
Microware	B-Operating_System
to	O
acquire	O
the	O
Intel	O
IXP-1200	B-Device
network	O
processor	O
resources	O
.	O
</s>
<s>
This	O
acquisition	O
infused	O
Microware	B-Operating_System
with	O
capital	O
and	O
allowed	O
Microware	B-Operating_System
to	O
continue	O
OS-9	B-Operating_System
development	O
and	O
support	O
.	O
</s>
<s>
On	O
February	O
21	O
,	O
2013	O
,	O
Microware	B-Operating_System
LP	O
(	O
a	O
partnership	O
formed	O
by	O
Freestation	O
of	O
Japan	O
,	O
Microsys	O
Electronics	O
of	O
Germany	O
and	O
RTSI	O
LLC	O
of	O
the	O
USA	O
)	O
announced	O
that	O
they	O
signed	O
an	O
Asset	O
Purchase	O
Agreement	O
to	O
buy	O
the	O
rights	O
to	O
the	O
names	O
Microware	B-Operating_System
,	O
OS-9	B-Operating_System
and	O
all	O
assets	O
from	O
RadiSys	O
.	O
</s>
<s>
OS-9	B-Operating_System
(	O
especially	O
the	O
68k	B-Device
version	O
and	O
thereafter	O
)	O
clearly	O
distinguishes	O
itself	O
from	O
the	O
prior	O
generation	O
of	O
embedded	O
operating	B-General_Concept
systems	I-General_Concept
in	O
many	O
aspects	O
.	O
</s>
<s>
Clear	O
separation	O
between	O
user	B-Operating_System
mode	I-Operating_System
and	O
supervisor	O
(	O
kernel	O
)	O
mode	O
.	O
</s>
<s>
Dynamic	O
use	O
of	O
individually	O
and	O
separately	O
built	O
software	O
components	O
(	O
executable	O
program	O
images	O
and	O
kernel	B-Application
modules	I-Application
)	O
rather	O
than	O
a	O
statically	B-Library
linked	I-Library
single	O
monolithic	O
image	O
.	O
</s>
<s>
Unix-like	O
process	O
name-space	O
model	O
(	O
not	O
memory	B-General_Concept
model	I-General_Concept
)	O
and	O
user	O
shell	B-Application
program	O
.	O
</s>
<s>
device	B-Application
drivers	I-Application
)	O
layers	O
.	O
</s>
<s>
When	O
compared	O
with	O
more	O
modern	O
operating	B-General_Concept
systems	I-General_Concept
:	O
</s>
<s>
The	O
kernel	O
is	O
written	O
entirely	O
in	O
assembly	B-Language
language	I-Language
(	O
OS-9/68K	O
version	O
only	O
)	O
and	O
C	B-Language
(	O
portable	O
version	O
to	O
other	O
architectures	O
)	O
using	O
simple	O
internal	O
data	O
structures	O
,	O
reducing	O
flexibility	O
and	O
improvement	O
scope	O
while	O
improving	O
determinability	O
required	O
for	O
real-time	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
.	O
</s>
<s>
Performance	O
was	O
also	O
affected	O
for	O
some	O
operations	O
,	O
but	O
assembly	B-Language
language	I-Language
helped	O
with	O
the	O
speed	O
issue	O
.	O
</s>
<s>
Systems	O
without	O
a	O
memory	B-General_Concept
management	I-General_Concept
unit	I-General_Concept
(	O
MMU	O
)	O
have	O
no	O
memory	O
protection	O
against	O
illegal	O
access	O
,	O
nor	O
per-process	O
memory	O
protection	O
,	O
while	O
systems	O
with	O
an	O
MMU	O
can	O
have	O
memory	O
protection	O
enabled	O
.	O
</s>
<s>
The	O
module	B-Application
controlling	O
the	O
MMU	O
can	O
be	O
included	O
or	O
omitted	O
by	O
the	O
system	O
integrator	O
to	O
enable	O
or	O
disable	O
memory	O
protection	O
.	O
</s>
<s>
This	O
allows	O
OS-9	B-Operating_System
to	O
run	O
on	O
older	O
systems	O
which	O
do	O
not	O
include	O
an	O
MMU	O
.	O
</s>
<s>
Older	O
versions	O
of	O
OS-9	B-Operating_System
do	O
not	O
support	O
POSIX	B-Operating_System
threads	I-Operating_System
,	O
while	O
all	O
OS-9	B-Operating_System
supported	O
processors	O
support	O
POSIX	B-Operating_System
threads	I-Operating_System
.	O
</s>
<s>
No	O
SMP	B-Operating_System
support	O
for	O
multiple	O
sockets	O
,	O
cores	O
,	O
or	O
hardware	O
threads	O
in	O
the	O
same	O
OS-9	B-Operating_System
instance	O
(	O
can	O
run	O
as	O
a	O
RTOS	B-Operating_System
on	O
one	O
of	O
the	O
cores	O
of	O
dual	O
core	O
processors	O
like	O
Core	O
Duo	O
and	O
Core	O
2	O
Duo	O
,	O
when	O
Linux	B-Application
is	O
running	O
on	O
the	O
other	O
core	O
doing	O
general	O
purpose	O
tasks	O
)	O
.	O
</s>
<s>
OS-9	B-Operating_System
'	O
s	O
real-time	B-General_Concept
kernel	I-General_Concept
allows	O
multiple	O
independent	O
applications	O
to	O
execute	O
simultaneously	O
through	O
task	O
switching	O
and	O
inter-process	O
communication	O
facilities	O
.	O
</s>
<s>
All	O
OS-9	B-Operating_System
programs	O
run	O
as	O
processes	O
containing	O
at	O
least	O
one	O
lightweight	O
process	O
(	O
thread	O
)	O
but	O
may	O
contain	O
an	O
effectively	O
unlimited	O
number	O
of	O
threads	O
.	O
</s>
<s>
Within	O
a	O
process	O
,	O
these	O
lightweight	O
processes	O
share	O
memory	O
,	O
I/O	O
paths	O
,	O
and	O
other	O
resources	O
in	O
accordance	O
with	O
the	O
POSIX	B-Operating_System
threads	I-Operating_System
specification	O
and	O
API	O
.	O
</s>
<s>
OS-9	B-Operating_System
schedules	O
the	O
threads	O
using	O
a	O
fixed-priority	O
preemptive	O
scheduling	O
algorithm	O
with	O
round-robin	O
scheduling	O
within	O
each	O
priority	O
.	O
</s>
<s>
The	O
priority	O
levels	O
can	O
be	O
divided	O
into	O
a	O
range	O
that	O
supports	O
aging	B-Operating_System
and	O
a	O
higher-priority	O
range	O
that	O
uses	O
strict	O
priority	O
scheduling	O
.	O
</s>
<s>
Each	O
process	O
can	O
access	O
any	O
system	O
resource	O
by	O
issuing	O
the	O
appropriate	O
OS-9	B-Operating_System
service	O
request	O
.	O
</s>
<s>
At	O
every	O
scheduling	O
point	O
,	O
OS-9	B-Operating_System
compares	O
the	O
priority	O
of	O
the	O
thread	O
at	O
the	O
head	O
of	O
the	O
active	O
queue	O
to	O
the	O
priority	O
of	O
the	O
current	O
thread	O
.	O
</s>
<s>
Aging	B-Operating_System
artificially	O
increases	O
the	O
effective	O
priority	O
of	O
threads	O
in	O
the	O
active	O
queue	O
as	O
time	O
passes	O
.	O
</s>
<s>
The	O
following	O
list	O
of	O
commands	B-Application
is	O
supported	O
by	O
the	O
OS-9	B-Operating_System
shell	B-Application
.	O
</s>
<s>
OS-9	B-Operating_System
'	O
s	O
notion	O
of	O
processes	O
and	O
I/O	O
paths	O
is	O
quite	O
similar	O
to	O
that	O
of	O
Unix	O
in	O
nearly	O
all	O
respects	O
,	O
but	O
there	O
are	O
some	O
significant	O
differences	O
.	O
</s>
<s>
Firstly	O
,	O
the	O
file	B-Application
system	I-Application
is	O
not	O
a	O
single	O
tree	O
,	O
but	O
instead	O
is	O
a	O
forest	O
with	O
each	O
tree	O
corresponding	O
to	O
a	O
device	O
.	O
</s>
<s>
Second	O
,	O
OS-9	B-Operating_System
does	O
not	O
have	O
a	O
Unix-style	O
fork( )	O
system	O
call	O
—	O
instead	O
it	O
has	O
a	O
system	O
call	O
which	O
creates	O
a	O
process	O
running	O
a	O
specified	O
program	O
,	O
performing	O
much	O
the	O
same	O
function	O
as	O
a	O
fork-exec	B-Operating_System
or	O
a	O
spawn	B-Language
.	O
</s>
<s>
Additionally	O
,	O
OS-9	B-Operating_System
processes	O
keep	O
track	O
of	O
two	O
"	O
current	O
directories	O
"	O
rather	O
than	O
just	O
one	O
;	O
the	O
"	O
current	O
execution	O
directory	O
"	O
is	O
where	O
it	O
will	O
by	O
default	O
look	O
first	O
to	O
load	O
programs	O
to	O
run	O
(	O
which	O
is	O
similar	O
to	O
the	O
use	O
of	O
PATH	O
environment	O
variable	O
under	O
UNIX	O
)	O
.	O
</s>
<s>
Another	O
difference	O
is	O
that	O
in	O
OS-9	B-Operating_System
,	O
grandparent	O
directories	O
can	O
be	O
indicated	O
by	O
repeating	O
periods	O
three	O
or	O
more	O
times	O
,	O
without	O
any	O
intervening	O
slashes	O
(	O
a	O
feature	O
also	O
found	O
in	O
4DOS/4OS2/4NT/TC	O
)	O
.	O
</s>
<s>
For	O
example	O
,	O
..../file	O
in	O
OS-9	B-Operating_System
,	O
is	O
similar	O
to	O
../../../file	O
in	O
Unix	O
.	O
</s>
<s>
and	O
..	O
,	O
with	O
just	O
one	O
or	O
two	O
periods	O
,	O
each	O
work	O
the	O
same	O
in	O
both	O
OS-9	B-Operating_System
and	O
Unix	O
.	O
</s>
<s>
OS-9	B-Operating_System
has	O
had	O
a	O
modular	O
design	O
from	O
the	O
beginning	O
,	O
influenced	O
by	O
notions	O
of	O
the	O
designers	O
of	O
the	O
6809	B-Device
and	O
how	O
they	O
expected	O
software	O
would	O
be	O
distributed	O
in	O
the	O
future	O
(	O
see	O
the	O
three-part	O
series	O
of	O
articles	O
in	O
January-March	O
1979	O
Byte	O
by	O
Terry	O
Ritter	O
,	O
et	O
al	O
.	O
</s>
<s>
The	O
module	B-Application
structure	O
requires	O
more	O
explanation	O
:	O
OS-9	B-Operating_System
keeps	O
a	O
"	O
module	B-Application
directory	O
"	O
,	O
a	O
memory-resident	O
list	O
of	O
all	O
modules	B-Application
that	O
are	O
in	O
memory	O
either	O
by	O
having	O
been	O
loaded	O
,	O
or	O
by	O
having	O
been	O
found	O
in	O
ROM	O
during	O
an	O
initial	O
scan	O
at	O
boot	O
time	O
.	O
</s>
<s>
When	O
one	O
types	O
a	O
command	O
to	O
the	O
OS-9	B-Operating_System
shell	B-Application
,	O
it	O
will	O
look	O
first	O
in	O
the	O
current	O
module	B-Application
directory	O
for	O
a	O
module	B-Application
of	O
the	O
specified	O
name	O
and	O
will	O
use	O
it	O
(	O
and	O
increase	O
its	O
link	O
count	O
)	O
if	O
found	O
,	O
or	O
it	O
will	O
look	O
on	O
disk	O
for	O
an	O
appropriately	O
named	O
file	O
if	O
not	O
.	O
</s>
<s>
In	O
OS-9/6809	O
and	O
OS-9/68000	O
,	O
the	O
module	B-Application
directory	O
is	O
flat	O
,	O
but	O
OS-9000	B-Operating_System
made	O
the	O
module	B-Application
directory	O
tree-structured	O
.	O
</s>
<s>
The	O
OS-9000	B-Operating_System
shell	B-Application
looks	O
in	O
one	O
's	O
alternative	O
module	B-Application
directory	O
for	O
a	O
MODPATH	O
environment	O
variable	O
,	O
analogous	O
to	O
the	O
PATH	O
variable	O
in	O
all	O
versions	O
,	O
indicating	O
the	O
sequence	O
of	O
module	B-Application
directories	O
in	O
which	O
to	O
look	O
for	O
pre-loaded	O
modules	B-Application
.	O
</s>
<s>
Modules	B-Application
are	O
not	O
only	O
used	O
to	O
hold	O
programs	O
,	O
but	O
can	O
also	O
be	O
created	O
on	O
the	O
fly	O
to	O
hold	O
data	O
,	O
and	O
are	O
the	O
way	O
in	O
which	O
OS-9	B-Operating_System
supports	O
shared	O
memory	O
.	O
</s>
<s>
OS-9/non	O
-68000	O
supports	O
POSIX	B-Operating_System
threads	I-Operating_System
.	O
</s>
<s>
OS-9	B-Operating_System
has	O
faded	O
from	O
popular	O
use	O
,	O
though	O
Microware	B-Operating_System
LP	O
does	O
still	O
support	O
it	O
and	O
it	O
does	O
run	O
on	O
modern	O
architectures	O
such	O
as	O
ARM	B-Architecture
and	O
x86	B-Operating_System
.	O
</s>
<s>
The	O
compiler	O
provided	O
,	O
Ultra	O
C/C	O
++	O
,	O
supports	O
C89	O
,	O
but	O
supports	O
neither	O
C99	B-Language
nor	O
C++98	O
.	O
</s>
<s>
Ultra	O
C++	O
does	O
provide	O
limited	O
support	O
for	O
C++	O
templates	O
.	O
</s>
<s>
It	O
is	O
also	O
supported	O
by	O
popular	O
SSL/TLS	B-Protocol
libraries	O
such	O
as	O
wolfSSL	B-Protocol
.	O
</s>
<s>
A	O
Version	O
of	O
OS-9	B-Operating_System
running	O
Steve	O
Adams	O
 '	O
G-Windows	O
is	O
present	O
on	O
semiconductor	O
wafer	O
scrubbers	O
manufactured	O
by	O
Ontrak	O
Systems	O
/	O
Lam	O
Research	O
.	O
</s>
<s>
Versions	O
of	O
OS-9/68K	O
ran	O
on	O
a	O
wide	O
variety	O
of	O
68000	B-Device
family	I-Device
platforms	O
,	O
including	O
the	O
Sharp	B-Device
X68000	I-Device
in	O
Japan	O
,	O
some	O
personal	O
computers	O
intended	O
by	O
their	O
designers	O
as	O
upgrades	O
from	O
the	O
Color	B-Device
Computer	I-Device
(	O
e.g.	O
,	O
the	O
68070	O
and	O
68340-based	O
MM/1	O
,	O
and	O
on	O
other	O
computers	O
from	O
Frank	O
Hogg	O
Laboratories	O
,	O
PEP	O
Modular	O
Computers	O
,	O
and	O
Delmar	O
Co	O
.	O
)	O
It	O
was	O
also	O
ported	O
to	O
the	O
Atari	B-Device
ST	I-Device
by	O
Recc-o-ware	O
in	O
the	O
early	O
1990s	O
,	O
and	O
was	O
distributed	O
by	O
Cumana	O
in	O
Europe	O
.	O
</s>
<s>
A	O
port	O
for	O
68000-based	O
Apple	B-Device
Macintoshes	I-Device
distributed	O
by	O
Ultrascience	O
exists	O
.	O
</s>
<s>
A	O
port	O
to	O
the	O
Amiga	B-Device
by	O
Digby	O
Tarvin	O
is	O
also	O
purported	O
to	O
exist	O
.	O
</s>
<s>
OS-9/68K	O
is	O
mandated	O
by	O
Caltrans	O
to	O
be	O
used	O
in	O
the	O
2070-1B	O
and	O
2070-1E	O
controller	O
cards	O
,	O
and	O
so	O
ends	O
up	O
being	O
used	O
to	O
run	O
many	O
North	O
American	O
traffic	O
signal	O
control	O
systems	O
.	O
</s>
<s>
OS-9/68K	O
is	O
also	O
found	O
in	O
some	O
other	O
embedded	O
applications	O
,	O
including	O
the	O
Quanta	O
Delta	O
television	O
broadcast	O
character	O
generator	O
,	O
still	O
in	O
production	O
by	O
ScanLine	O
Technologies	O
in	O
Utah	O
.	O
</s>
<s>
While	O
the	O
user-level	B-Operating_System
interface	O
code	O
on	O
this	O
system	O
started	O
at	O
boot	O
time	O
,	O
there	O
was	O
a	O
hidden	O
,	O
undocumented	O
keyboard	O
sequence	O
that	O
would	O
provide	O
a	O
user	O
with	O
a	O
root	O
shell	B-Application
prompt	O
in	O
a	O
scroll	O
window	O
on	O
the	O
device	O
's	O
edit-channel	O
monitor	O
.	O
</s>
<s>
In	O
the	O
embedded	O
market	O
,	O
where	O
OS-9	B-Operating_System
has	O
found	O
application	O
in	O
such	O
devices	O
as	O
the	O
Fairlight	O
CMI	O
synthesizers	O
,	O
robotics	O
,	O
in-car	O
navigation	O
systems	O
,	O
and	O
Philips	O
 '	O
Compact	O
Disc-Interactive	O
(	O
CD-i	B-Device
)	O
industry	O
standard	O
.	O
</s>
<s>
The	O
TRS-80	B-Device
Color	I-Device
Computer	I-Device
(	O
and	O
clones	O
)	O
still	O
has	O
users	O
and	O
an	O
annual	O
conference	O
in	O
Chicago	O
;	O
as	O
of	O
2018	O
the	O
27th	O
Annual	O
"	O
Last	O
"	O
Chicago	O
CoCoFEST	O
was	O
scheduled	O
for	O
April	O
21-22	O
,	O
2018	O
.	O
</s>
<s>
A	O
group	O
of	O
Canadian	O
programmers	O
rewrote	O
OS-9/6809	O
Level	O
II	O
for	O
the	O
CoCo	O
3	O
(	O
w/	O
address	O
translation	O
hardware	O
)	O
for	O
efficiency	O
,	O
and	O
to	O
take	O
advantage	O
of	O
the	O
native	B-Language
mode	I-Language
of	O
the	O
Hitachi	B-General_Concept
6309	I-General_Concept
.	O
</s>
<s>
Today	O
's	O
serious	O
CoCo	O
users	O
now	O
typically	O
have	O
replaced	O
the	O
68B09E	B-Device
in	O
the	O
CoCo	O
3	O
with	O
an	O
Hitachi	O
63B09E	O
and	O
run	O
the	O
rewrite	O
,	O
called	O
NitrOS-9	O
.	O
</s>
<s>
Gary	O
Becker	O
's	O
CoCo3	O
FPGA	O
is	O
a	O
synthesized	O
TRS-80	B-Device
Color	I-Device
Computer	I-Device
which	O
runs	O
NitrOS-9	O
on	O
an	O
Altera	O
DE-1	O
development	O
board	O
.	O
</s>
<s>
The	O
core	O
6809	B-Device
CPU	O
was	O
designed	O
by	O
John	O
Kent	O
and	O
is	O
currently	O
running	O
at	O
25MHz	O
.	O
</s>
<s>
OS-9000/80x86	O
can	O
be	O
run	O
on	O
PC-type	O
machines	O
built	O
around	O
the	O
Intel	B-Operating_System
x86	I-Operating_System
CPUs	O
.	O
</s>
<s>
OS-9000	B-Operating_System
has	O
also	O
been	O
ported	O
to	O
the	O
PowerPC	B-Architecture
,	O
MIPS	B-Device
,	O
some	O
versions	O
of	O
Advanced	B-Architecture
RISC	I-Architecture
Machines	I-Architecture
 '	O
ARM	B-Architecture
processor	I-Architecture
,	O
and	O
some	O
of	O
the	O
Hitachi	O
SH	O
family	O
of	O
processors	O
.	O
</s>
<s>
The	O
audio	O
playback	O
unit	O
runs	O
OS-9/68K	O
.	O
</s>
<s>
German	O
electronics	O
manufacturer	O
Eltec	O
has	O
been	O
manufacturing	O
the	O
Eurocom-model	O
CPU	O
boards	O
for	O
industrial	O
purposes	O
since	O
the	O
late	O
1970s	O
,	O
starting	O
with	O
the	O
6802	O
and	O
6809	B-Device
Eurocom-1	O
and	O
Eurocom-2	O
,	O
and	O
onwards	O
with	O
68K	B-Device
,	O
and	O
derivative	O
,	O
CPU	O
boards	O
up	O
to	O
today	O
.	O
</s>
<s>
The	O
modern	O
boards	O
can	O
be	O
delivered	O
with	O
a	O
range	O
of	O
operating	B-General_Concept
systems	I-General_Concept
,	O
amongst	O
which	O
is	O
OS-9	B-Operating_System
.	O
</s>
<s>
Omron	O
used	O
OS-9	B-Operating_System
in	O
their	O
NS	O
series	O
HMI	O
panels	O
.	O
</s>
<s>
However	O
,	O
for	O
their	O
new	O
NA	O
series	O
,	O
Omron	O
selected	O
Windows	B-Device
Embedded	I-Device
Compact	I-Device
7	I-Device
.	O
</s>
<s>
Omron	O
indicated	O
that	O
with	O
OS-9	B-Operating_System
nearly	O
all	O
the	O
drivers	O
,	O
for	O
example	O
for	O
a	O
USB	O
stick	O
,	O
had	O
to	O
be	O
written	O
by	O
Omron	O
.	O
</s>
<s>
OS-9000/SH4	O
can	O
be	O
found	O
in	O
loader	O
(	O
inside	O
KIWI-format	O
container	O
LOADING.KWI	O
)	O
on	O
Map	O
CD/DVD	O
for	O
old	O
automotive	O
GPS	O
navigation	O
systems	O
made	O
by	O
Matsushita	O
for	O
Japan	O
domestical	O
market	O
.	O
</s>
