<s>
Idris	B-Operating_System
is	O
a	O
discontinued	O
multi-tasking	O
,	O
Unix-like	B-Operating_System
,	O
multi-user	O
,	O
real-time	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
released	O
by	O
Whitesmiths	O
,	O
of	O
Westford	O
,	O
Massachusetts	O
.	O
</s>
<s>
Idris	B-Operating_System
was	O
originally	O
written	O
for	O
the	O
PDP-11	B-Device
by	O
P	O
.	O
J	O
.	O
Plauger	O
,	O
who	O
started	O
working	O
on	O
Idris	B-Operating_System
in	O
August	O
1978	O
.	O
</s>
<s>
It	O
was	O
binary	B-General_Concept
compatible	I-General_Concept
with	O
Unix	B-Operating_System
V6	I-Operating_System
on	O
PDP-11	B-Device
,	O
but	O
it	O
could	O
run	O
on	O
non-memory	O
managed	O
systems	O
(	O
like	O
LSI-11	O
or	O
PDP-11/23	O
)	O
as	O
well	O
.	O
</s>
<s>
The	O
kernel	B-Operating_System
required	O
31KB	O
of	O
RAM	B-Architecture
,	O
and	O
the	O
C	O
compiler	O
(	O
provided	O
along	O
with	O
the	O
standard	O
V6	O
toolset	O
)	O
had	O
more	O
or	O
less	O
the	O
same	O
size	O
.	O
</s>
<s>
Although	O
Idris	B-Operating_System
was	O
initially	O
available	O
for	O
the	O
PDP-11	B-Device
,	O
it	O
was	O
later	O
ported	O
to	O
run	O
on	O
a	O
number	O
of	O
platforms	O
,	O
such	O
as	O
the	O
VAX	B-Device
,	O
Motorola	B-Device
68000	I-Device
,	O
System/370	B-Device
and	O
Intel	B-General_Concept
8086	I-General_Concept
.	O
</s>
<s>
There	O
was	O
also	O
a	O
version	O
that	O
used	O
bank-switching	O
for	O
memory	O
management	O
,	O
that	O
ran	O
on	O
the	O
Intel	B-General_Concept
8080	I-General_Concept
.	O
</s>
<s>
In	O
1986	O
,	O
David	O
M	O
.	O
Stanhope	O
at	O
Computer	O
Tools	O
International	O
ported	O
Idris	B-Operating_System
to	O
the	O
Atari	B-Device
ST	I-Device
and	O
developed	O
its	O
ROM	B-Device
boot	O
cartridge	B-Protocol
.	O
</s>
<s>
This	O
work	O
also	O
included	O
a	O
port	O
of	O
X	B-Operating_System
to	O
Idris	B-Operating_System
.	O
</s>
<s>
Computer	O
Tools	O
and	O
Whitesmiths	O
offered	O
it	O
to	O
Atari	O
as	O
a	O
replacement	O
for	O
Atari	B-Application
TOS	I-Application
,	I-Application
but	O
eventually	O
marketed	O
it	O
directly	O
to	O
ST	O
enthusiasts	O
.	O
</s>
<s>
A	O
specific	O
version	O
of	O
Idris	B-Operating_System
(	O
CoIdris	B-Operating_System
)	O
was	O
packaged	O
as	O
a	O
.COM	O
file	O
under	O
DOS	B-Device
and	O
used	O
it	O
for	O
low	O
level	O
I/O	B-General_Concept
services	O
.	O
</s>
<s>
Idris	B-Operating_System
was	O
ported	O
to	O
the	O
Apple	B-Device
Macintosh	I-Device
(	O
as	O
MacIdris	B-Operating_System
)	O
by	O
John	O
O'Brien	O
(	O
of	O
Whitesmiths	O
Australia	O
)	O
and	O
remained	O
available	O
until	O
the	O
early	O
1990s	O
.	O
</s>
<s>
MacIdris	B-Operating_System
ran	O
as	O
an	O
application	O
under	O
the	O
Finder	B-Application
or	O
MultiFinder	O
.	O
</s>
<s>
After	O
Whitesmiths	O
had	O
been	O
merged	O
with	O
Intermetrics	O
,	O
Idris	B-Operating_System
along	O
with	O
its	O
development	O
toolchain	B-General_Concept
was	O
ported	O
by	O
Real	O
Time	O
Systems	O
Ltd	O
to	O
the	O
INMOS	O
T800	O
transputer	B-General_Concept
architecture	O
for	O
the	O
Parsytec	B-Device
SN1000	O
multiprocessor	O
.	O
</s>
