<s>
A/ROSE	B-Application
(	O
the	O
Apple	O
Real-time	O
Operating	O
System	O
Environment	O
)	O
is	O
a	O
small	O
embedded	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
that	O
runs	O
on	O
Apple	O
Computer	O
's	O
"	O
Macintosh	B-Device
Coprocessor	O
Platform	O
"	O
,	O
an	O
expansion	B-Device
card	I-Device
for	O
the	O
Apple	B-Device
Macintosh	I-Device
.	O
</s>
<s>
The	O
idea	O
was	O
to	O
offer	O
a	O
single	O
"	O
overdesigned	O
"	O
hardware	O
platform	O
on	O
which	O
third	O
party	O
vendors	O
could	O
build	O
practically	O
any	O
product	O
,	O
reducing	O
the	O
otherwise	O
heavy	O
workload	O
of	O
developing	O
a	O
NuBus-based	O
expansion	B-Device
card	I-Device
.	O
</s>
<s>
A/ROSE	B-Application
saw	O
very	O
little	O
use	O
,	O
apparently	O
limited	O
solely	O
to	O
Apple	O
's	O
own	O
networking	O
cards	O
for	O
serial	O
I/O	O
,	O
Ethernet	O
,	O
Token	B-Device
Ring	I-Device
and	O
Twinax	O
.	O
</s>
<s>
GreenSpring	O
Computers	O
developed	O
the	O
RM1260	O
,	O
which	O
is	O
an	O
IndustryPack	O
(	O
IP	O
)	O
carrier	O
card	O
with	O
a	O
68000	B-Device
CPU	B-Device
running	O
A/ROSE	B-Application
and	O
is	O
intended	O
for	O
the	O
data	O
acquisition	O
market	O
.	O
</s>
<s>
A/ROSE	B-Application
and	O
the	O
MCP	O
originally	O
came	O
about	O
in	O
August	O
1987	O
during	O
the	O
development	O
of	O
the	O
Macintosh	B-Device
II	I-Device
.	O
</s>
<s>
While	O
working	O
on	O
various	O
networking	O
products	O
for	O
the	O
new	O
system	O
,	O
the	O
developers	O
realized	O
that	O
the	O
existing	O
classic	B-Application
Mac	I-Application
OS	I-Application
would	O
make	O
any	O
"	O
serious	O
"	O
card	O
difficult	O
to	O
create	O
,	O
due	O
to	O
large	O
latencies	O
and	O
the	O
difficulty	O
of	O
writing	O
complex	O
device	B-Application
drivers	I-Application
.	O
</s>
<s>
Their	O
solution	O
was	O
to	O
make	O
an	O
"	O
intelligent	O
"	O
NuBus	B-Device
card	O
that	O
was	O
essentially	O
an	O
entire	O
computer	O
on	O
a	O
card	O
,	O
containing	O
its	O
own	O
Motorola	B-Device
68000	I-Device
processor	I-Device
,	O
working	O
space	O
in	O
RAM	O
mirrored	O
in	O
the	O
main	O
system	O
,	O
and	O
its	O
own	O
basic	O
operating	O
system	O
.	O
</s>
<s>
A/ROSE	B-Application
was	O
internally	O
called	O
MR-DOS	O
(	O
Multitasking	O
Realtime	O
Distributed	O
Operating	O
System	O
)	O
,	O
but	O
Microsoft	O
(	O
developer	O
of	O
MS-DOS	B-Application
)	O
did	O
not	O
appreciate	O
the	O
name	O
and	O
put	O
pressure	O
on	O
Apple	O
to	O
change	O
its	O
name	O
.	O
</s>
<s>
Eric	O
M	O
.	O
Trehus	O
,	O
a	O
QA	O
engineer	O
on	O
the	O
Token	B-Device
Ring	I-Device
card	O
that	O
ran	O
A/ROSE	B-Application
reportedly	O
said	O
"	O
A/ROSE	B-Application
by	O
any	O
other	O
name	O
is	O
still	O
MR-DOS.	O
"	O
</s>
<s>
A/ROSE	B-Application
is	O
infamous	O
for	O
its	O
esoteric	O
purpose	O
,	O
which	O
is	O
generally	O
not	O
understood	O
by	O
Mac	O
end	O
users	O
,	O
as	O
well	O
as	O
for	O
causing	O
many	O
Mac	O
emulators	O
,	O
such	O
as	O
Basilisk	B-Application
II	I-Application
,	O
to	O
produce	O
a	O
system	O
error	O
at	O
boot	O
time	O
.	O
</s>
<s>
A/ROSE	B-Application
itself	O
is	O
very	O
small	O
,	O
the	O
kernel	O
using	O
only	O
6	O
KB	O
,	O
and	O
the	O
operating	O
system	O
as	O
a	O
whole	O
about	O
28	O
KB	O
.	O
</s>
<s>
A/ROSE	B-Application
supports	O
pre-emptive	O
multitasking	O
with	O
round-robin	B-Algorithm
task	I-Algorithm
scheduling	I-Algorithm
with	O
a	O
110	O
microsecond	O
context	B-Operating_System
switch	I-Operating_System
time	O
and	O
only	O
20	O
microseconds	O
of	O
latency	O
(	O
guaranteed	O
interrupt	O
response	O
time	O
)	O
.	O
</s>
<s>
The	O
system	O
's	O
task	O
is	O
primarily	O
to	O
move	O
data	O
around	O
and	O
start	O
and	O
stop	O
tasks	O
on	O
the	O
cards	O
,	O
and	O
the	O
entire	O
API	B-General_Concept
contains	O
only	O
ten	O
calls	O
.	O
</s>
<s>
A/ROSE	B-Application
is	O
a	O
message	B-Architecture
passing	I-Architecture
system	O
,	O
and	O
the	O
main	O
calls	O
made	O
by	O
programs	O
running	O
under	O
it	O
are	O
Send( )	O
and	O
Receive( )	O
.	O
</s>
<s>
To	O
find	O
the	O
appropriate	O
endpoint	O
,	O
A/ROSE	B-Application
includes	O
a	O
name	O
server	O
that	O
allows	O
the	O
applications	O
to	O
bind	O
their	O
names	O
to	O
their	O
task	O
IDs	O
,	O
allowing	O
them	O
to	O
move	O
in	O
the	O
system	O
and	O
be	O
found	O
dynamically	O
.	O
</s>
<s>
To	O
coordinate	O
communications	O
and	O
provide	O
a	O
mechanism	O
for	O
talking	O
with	O
the	O
host	O
's	O
CPU	B-Device
,	O
a	O
cut-down	O
copy	O
of	O
A/ROSE	B-Application
also	O
ran	O
inside	O
the	O
Mac	B-Application
OS	I-Application
in	O
the	O
form	O
of	O
a	O
system	B-Operating_System
extension	I-Operating_System
,	O
or	O
"	O
INIT	B-Operating_System
"	O
,	O
known	O
as	O
"	O
Prep	B-Device
"	O
(	O
which	O
should	O
not	O
be	O
confused	O
with	O
the	O
later	O
PReP	B-Device
hardware	O
standard	O
)	O
.	O
</s>
<s>
Device	B-Application
drivers	I-Application
for	O
A/ROSE	B-Application
cards	O
were	O
also	O
written	O
as	O
INITs	B-Operating_System
and	O
started	O
up	O
automatically	O
.	O
</s>
<s>
After	O
starting	O
,	O
they	O
find	O
the	O
Prep	B-Device
stub	O
and	O
use	O
the	O
normal	O
A/ROSE	B-Application
communications	O
channel	O
it	O
provides	O
to	O
communicate	O
with	O
the	O
cards	O
.	O
</s>
<s>
For	O
instance	O
,	O
the	O
Apple	O
TokenTalk	O
NB	B-Device
card	I-Device
installs	O
its	O
driver	O
as	O
an	O
INIT	B-Operating_System
,	O
and	O
optionally	O
installs	O
the	O
Prep	B-Device
stub	O
,	O
assuming	O
it	O
had	O
not	O
been	O
installed	O
before	O
.	O
</s>
<s>
On	O
startup	O
the	O
driver	O
finds	O
the	O
Prep	B-Device
stub	O
and	O
asks	O
it	O
to	O
enumerate	O
the	O
TokenTalk	O
cards	O
installed	O
in	O
the	O
machine	O
,	O
and	O
optionally	O
uploads	O
code	O
or	O
settings	O
to	O
them	O
.	O
</s>
<s>
From	O
that	O
point	O
on	O
,	O
Prep	B-Device
handles	O
the	O
communications	O
with	O
the	O
card	O
,	O
handing	O
off	O
the	O
results	O
to	O
the	O
TokenTalk	O
driver	O
.	O
</s>
