<s>
Thoth	B-Operating_System
is	O
a	O
real-time	B-General_Concept
,	O
message	B-Architecture
passing	I-Architecture
operating	B-General_Concept
system	I-General_Concept
(	O
OS	O
)	O
developed	O
at	O
the	O
University	O
of	O
Waterloo	O
in	O
Waterloo	O
,	O
Ontario	O
Canada	O
.	O
</s>
<s>
Thoth	B-Operating_System
was	O
developed	O
at	O
the	O
University	O
of	O
Waterloo	O
in	O
Waterloo	O
,	O
Ontario	O
,	O
Canada	O
.	O
</s>
<s>
The	O
curriculum	O
at	O
Waterloo	O
includes	O
a	O
Real	B-Operating_System
Time	I-Operating_System
Operating	I-Operating_System
Systems	I-Operating_System
course	O
and	O
an	O
associated	O
"	O
Train	O
lab	O
"	O
,	O
where	O
students	O
must	O
develop	O
a	O
real-time	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
(	O
RTOS	B-Operating_System
)	O
to	O
control	O
a	O
model	O
track	O
with	O
multiple	O
trains	O
.	O
</s>
<s>
In	O
1972	O
,	O
the	O
B	B-Language
programming	I-Language
language	I-Language
,	O
a	O
derivative	O
of	O
BCPL	B-Language
,	O
was	O
brought	O
to	O
Waterloo	O
by	O
Stephen	O
C	O
.	O
Johnson	O
while	O
on	O
sabbatical	O
from	O
Bell	O
Labs	O
.	O
</s>
<s>
A	O
new	O
language	O
derived	O
from	O
B	B-Language
,	O
named	O
Eh	O
,	O
was	O
developed	O
at	O
Waterloo	O
.	O
</s>
<s>
Thoth	B-Operating_System
was	O
written	O
originally	O
in	O
Eh	O
with	O
some	O
assembly	B-Language
language	I-Language
.	O
</s>
<s>
Initial	O
development	O
of	O
Thoth	B-Operating_System
occurred	O
on	O
a	O
Honeywell	B-Device
6050	I-Device
computer	O
.	O
</s>
<s>
In	O
October	O
1976	O
,	O
the	O
University	O
of	O
Waterloo	O
published	O
Laurence	O
S	O
.	O
Melen	O
's	O
Master	O
's	O
Thesis	O
,	O
titled	O
"	O
A	O
Portable	O
Real-Time	B-General_Concept
Executive	O
,	O
Thoth	B-Operating_System
"	O
.	O
</s>
<s>
Thoth	B-Operating_System
was	O
then	O
rewritten	O
in	O
Zed	O
.	O
</s>
<s>
One	O
of	O
the	O
early	O
principal	O
developers	O
of	O
Thoth	B-Operating_System
was	O
David	O
Cheriton	O
.	O
</s>
<s>
Cheriton	O
would	O
go	O
on	O
to	O
develop	O
the	O
Verex	O
kernel	B-Operating_System
,	O
and	O
the	O
V-System	B-Operating_System
OS	O
;	O
both	O
influenced	O
by	O
Thoth	B-Operating_System
.	O
</s>
<s>
Another	O
early	O
developer	O
was	O
Michael	O
Malcolm	O
,	O
who	O
would	O
later	O
found	O
Waterloo	O
Microsystems	O
,	O
Network	O
Appliances	O
,	O
Inc.	O
,	O
Blue	O
Coat	O
Systems	O
,	O
and	O
Kaliedescape	O
,	O
several	O
of	O
whose	O
operating	B-General_Concept
systems	I-General_Concept
are	O
believed	O
to	O
have	O
been	O
derived	O
from	O
or	O
influenced	O
by	O
Thoth	B-Operating_System
.	O
</s>
<s>
Certain	O
papers	O
describe	O
DEMOS	O
as	O
the	O
inspiration	O
for	O
Thoth	B-Operating_System
.	O
</s>
<s>
As	O
prior	O
art	O
Cheriton	O
cited	O
Per	O
Brinch	O
Hansen	O
's	O
RC	B-Operating_System
4000	I-Operating_System
,	O
then	O
listed	O
Thoth	B-Operating_System
,	O
DEMOS	O
,	O
and	O
Accent	O
together	O
as	O
later	O
developments	O
.	O
</s>
<s>
Other	O
influences	O
on	O
the	O
development	O
of	O
Thoth	B-Operating_System
included	O
Multics	B-Application
,	O
Data	O
General	O
's	O
RTOS	B-Operating_System
,	O
Honeywell	O
GCLS	O
,	O
and	O
Unix	B-Application
.	O
</s>
<s>
Later	O
references	O
cite	O
Thoth	B-Operating_System
as	O
the	O
original	O
implementation	O
of	O
its	O
particular	O
use	O
of	O
synchronous	O
message	B-Architecture
passing	I-Architecture
and	O
multiprocess	O
program	O
structure	O
,	O
which	O
were	O
subsequently	O
applied	O
by	O
other	O
projects	O
.	O
</s>
<s>
Work	O
on	O
Thoth	B-Operating_System
ended	O
around	O
1982	O
.	O
</s>
<s>
Thoth	B-Operating_System
was	O
developed	O
to	O
meet	O
four	O
goals	O
:	O
</s>
<s>
Thoth	B-Operating_System
exposes	O
the	O
same	O
abstract	B-Application
machine	I-Application
to	O
application	B-Application
software	I-Application
,	O
regardless	O
of	O
the	O
underlying	O
physical	B-Architecture
machine	I-Architecture
.	O
</s>
<s>
This	O
abstract	B-Application
machine	I-Application
was	O
defined	O
with	O
certain	O
minimal	O
requirements	O
,	O
such	O
that	O
meeting	O
these	O
requirements	O
allowed	O
a	O
given	O
computer	O
to	O
be	O
included	O
in	O
the	O
Thoth	B-Operating_System
Domain	O
of	O
potential	O
Thoth	B-Operating_System
port	O
targets	O
.	O
</s>
<s>
Processes	O
running	O
under	O
Thoth	B-Operating_System
can	O
be	O
grouped	O
into	O
"	O
Teams	O
"	O
.	O
</s>
<s>
Processes	O
not	O
members	O
of	O
the	O
same	O
team	O
communicate	O
using	O
Thoth	B-Operating_System
's	O
IPC	O
.	O
</s>
<s>
Inter	B-Operating_System
Process	I-Operating_System
Communication	I-Operating_System
in	O
Thoth	B-Operating_System
is	O
primarily	O
accomplished	O
by	O
means	O
of	O
synchronous	O
message	B-Architecture
passing	I-Architecture
.	O
</s>
<s>
Although	O
the	O
term	O
was	O
not	O
current	O
when	O
the	O
original	O
papers	O
were	O
written	O
,	O
Thoth	B-Operating_System
has	O
been	O
called	O
a	O
microkernel	B-Operating_System
.	O
</s>
<s>
Thoth	B-Operating_System
's	O
synchronous	O
message	B-Architecture
passing	I-Architecture
IPC	O
lent	O
itself	O
to	O
the	O
application	O
of	O
an	O
anthropomorphic	O
programming	O
model	O
,	O
building	O
on	O
the	O
work	O
of	O
Carl	O
Hewitt	O
's	O
actor	B-Application
model	I-Application
,	O
and	O
of	O
Smalltalk	B-Application
.	O
</s>
<s>
The	O
Thoth	B-Operating_System
operating	B-General_Concept
system	I-General_Concept
provided	O
either	O
the	O
basis	O
or	O
the	O
inspiration	O
for	O
several	O
later	O
projects	O
,	O
some	O
of	O
which	O
are	O
listed	O
below	O
.	O
</s>
<s>
The	O
microNet	O
distributed	O
file	B-Application
server	I-Application
system	O
at	O
the	O
University	O
of	O
Waterloo	O
ran	O
on	O
an	O
operating	B-General_Concept
system	I-General_Concept
named	O
WatSys	O
that	O
was	O
similar	O
to	O
Thoth	B-Operating_System
,	O
and	O
Port	O
.	O
</s>
<s>
The	O
National	O
Research	O
Council	O
of	O
Canada	O
was	O
the	O
development	O
home	O
of	O
the	O
Harmony	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
,	O
a	O
derivative	O
of	O
Thoth	B-Operating_System
oriented	O
towards	O
real-time	B-General_Concept
robot	O
control	O
.	O
</s>
<s>
Cheriton	O
took	O
a	O
position	O
at	O
the	O
University	O
of	O
British	O
Columbia	O
,	O
where	O
he	O
was	O
involved	O
in	O
developing	O
Verex	O
,	O
and	O
Distributed	O
Verex	O
,	O
using	O
many	O
of	O
the	O
ideas	O
he	O
had	O
earlier	O
explored	O
in	O
Thoth	B-Operating_System
.	O
</s>
<s>
Cheriton	O
later	O
moved	O
to	O
Stanford	O
University	O
in	O
the	O
US	O
,	O
where	O
he	O
developed	O
the	O
V-System	B-Operating_System
,	O
which	O
continued	O
to	O
build	O
on	O
earlier	O
work	O
with	O
Thoth	B-Operating_System
.	O
</s>
<s>
The	O
Sylvan	O
Multiprocessing	O
system	O
's	O
architecture	O
included	O
a	O
coprocessor	O
that	O
implemented	O
Thoth	B-Operating_System
's	O
synchronous	O
message	B-Architecture
passing	I-Architecture
primitives	O
(	O
and	O
Ada	O
's	O
extended	O
rendezvous	O
)	O
in	O
hardware	B-Architecture
.	O
</s>
<s>
Thoth	B-Operating_System
and	O
its	O
message	B-Architecture
passing	I-Architecture
IPC	O
were	O
used	O
to	O
underpin	O
a	O
multi-process	O
paint	O
program	O
that	O
employed	O
the	O
anthropomorphic	O
programming	O
model	O
.	O
</s>
<s>
Thoth	B-Operating_System
's	O
message	B-Architecture
passing	I-Architecture
semantics	O
were	O
part	O
of	O
an	O
experimental	O
parallel-processing	O
version	O
of	O
the	O
computer	B-General_Concept
algebra	I-General_Concept
system	I-General_Concept
(	O
CAS	O
)	O
Maple	B-Language
.	O
</s>
<s>
The	O
paper	O
cites	O
Thoth	B-Operating_System
as	O
a	O
"	O
major	O
foundation	O
"	O
for	O
the	O
project	O
.	O
</s>
<s>
Thoth	B-Operating_System
provided	O
the	O
inspiration	O
for	O
the	O
design	O
of	O
the	O
EMPS	O
kernel	B-Operating_System
.	O
</s>
<s>
An	O
experimental	O
human-computer	O
interface	O
environment	O
named	O
the	O
Room	O
system	O
was	O
built	O
on	O
Waterloo	O
Port	O
,	O
which	O
was	O
derived	O
from	O
Thoth	B-Operating_System
and	O
which	O
used	O
its	O
IPC	O
techniques	O
.	O
</s>
<s>
The	O
Room	O
paper	O
references	O
earlier	O
Thoth	B-Operating_System
papers	O
.	O
</s>
<s>
The	O
Flash	O
web	O
server	O
,	O
a	O
research	O
project	O
with	O
an	O
emphasis	O
on	O
efficiency	O
and	O
portability	O
,	O
was	O
said	O
to	O
resemble	O
Thoth	B-Operating_System
in	O
its	O
method	O
of	O
multi-process	O
structuring	O
and	O
concept	O
of	O
process	O
teams	O
communicating	O
via	O
message	B-Architecture
passing	I-Architecture
.	O
</s>
<s>
Gordon	O
Bell	O
and	O
Dan	O
Dodge	O
,	O
developers	O
of	O
the	O
QNX	B-Operating_System
message	B-Architecture
passing	I-Architecture
realtime	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
,	O
both	O
worked	O
with	O
Thoth	B-Operating_System
while	O
they	O
were	O
students	O
at	O
Waterloo	O
.	O
</s>
<s>
T	O
's	O
System	O
75	O
Office	O
Communication	O
System	O
was	O
controlled	O
by	O
the	O
Oryx	O
kernel	B-Operating_System
and	O
the	O
Pecos	O
set	O
of	O
essential	O
system	O
processes	O
,	O
jointly	O
referred	O
to	O
as	O
Oryx/Pecos	O
.	O
</s>
<s>
It	O
used	O
ideas	O
from	O
Thoth	B-Operating_System
,	O
DEMOS	O
,	O
and	O
an	O
internal	O
AT&T	O
project	O
.	O
</s>
<s>
The	O
commercial	O
Waterloo	O
Port	O
network	O
operating	B-General_Concept
system	I-General_Concept
was	O
derived	O
from	O
Thoth	B-Operating_System
.	O
</s>
<s>
The	O
Auspex	O
storage	O
company	O
produced	O
the	O
Functional	O
Multiprocessing	O
Kernel	B-Operating_System
(	O
FMK	O
)	O
,	O
which	O
employed	O
concepts	O
identified	O
as	O
having	O
been	O
first	O
developed	O
in	O
Thoth	B-Operating_System
.	O
</s>
<s>
Unlike	O
the	O
V-System	B-Operating_System
and	O
Waterloo	O
Port	O
,	O
FMK	O
had	O
no	O
memory	O
management	O
.	O
</s>
<s>
Early	O
versions	O
of	O
Network	O
Appliance	O
,	O
Inc.	O
'	O
s	O
storage	O
appliance	O
operating	B-General_Concept
system	I-General_Concept
have	O
been	O
described	O
as	O
being	O
very	O
similar	O
to	O
Thoth	B-Operating_System
.	O
</s>
<s>
In	O
1996	O
the	O
CacheFlow	O
web	O
acceleration	O
appliance	O
company	O
released	O
their	O
CacheOS	O
,	O
which	O
was	O
based	O
on	O
Thoth	B-Operating_System
.	O
</s>
<s>
In	O
2001	O
CacheFlow	O
was	O
renamed	O
Blue	O
Coat	O
Systems	O
and	O
,	O
with	O
the	O
addition	O
of	O
a	O
policy	O
engine	O
,	O
CacheOS	O
became	O
the	O
Secure	O
Gateway	O
Operating	B-General_Concept
System	I-General_Concept
(	O
SGOS	O
)	O
.	O
</s>
