<s>
OS	B-Operating_System
2200	I-Operating_System
is	O
the	O
operating	B-General_Concept
system	I-General_Concept
for	O
the	O
Unisys	O
ClearPath	O
Dorado	O
family	O
of	O
mainframe	O
systems	O
.	O
</s>
<s>
The	O
operating	B-General_Concept
system	I-General_Concept
kernel	O
of	O
OS	B-Operating_System
2200	I-Operating_System
is	O
a	O
lineal	O
descendant	O
of	O
Exec	O
8	O
for	O
the	B-Operating_System
UNIVAC	I-Operating_System
1108	O
.	O
</s>
<s>
See	O
Unisys	B-Architecture
2200	I-Architecture
Series	I-Architecture
system	I-Architecture
architecture	I-Architecture
for	O
a	O
description	O
of	O
the	O
machine	O
architecture	O
and	O
its	O
relationship	O
to	O
the	O
OS	B-Operating_System
2200	I-Operating_System
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
Unisys	O
stopped	O
producing	O
ClearPath	O
Dorado	O
hardware	O
in	O
the	O
early	O
2010s	O
,	O
and	O
the	O
operating	B-General_Concept
system	I-General_Concept
is	O
now	O
run	O
under	O
emulation	O
.	O
</s>
<s>
There	O
were	O
earlier	O
1100	O
systems	O
going	O
back	O
to	O
the	O
1101	B-Device
in	O
1951	O
,	O
but	O
the	O
1108	O
was	O
the	O
first	O
1100	B-Device
Series	I-Device
computer	O
designed	O
for	O
efficient	O
support	O
of	O
multiprogramming	O
and	O
multiprocessing	B-Operating_System
.	O
</s>
<s>
Along	O
with	O
this	O
new	O
hardware	O
came	O
the	O
operating	B-General_Concept
system	I-General_Concept
Exec	O
8	O
(	O
Executive	O
System	O
for	O
the	O
1108	O
)	O
.	O
</s>
<s>
The	B-Operating_System
UNIVAC	I-Operating_System
1108	O
computer	O
was	O
announced	O
in	O
1964	O
and	O
delivered	O
in	O
late	O
1965	O
.	O
</s>
<s>
The	O
first	O
1108	O
computers	O
used	O
Exec	B-Application
I	I-Application
and	O
Exec	B-Application
II	I-Application
,	O
which	O
had	O
been	O
developed	O
for	O
the	B-Operating_System
UNIVAC	I-Operating_System
1107	O
.	O
</s>
<s>
However	O
,	O
UNIVAC	B-Operating_System
planned	O
to	O
offer	O
symmetric	B-Operating_System
multiprocessor	I-Operating_System
versions	O
of	O
the	O
1108	O
with	O
up	O
to	O
4	O
processors	O
and	O
the	O
earlier	O
operating	B-General_Concept
systems	I-General_Concept
(	O
really	O
basic	O
monitor	O
programs	O
)	O
were	O
n't	O
designed	O
for	O
that	O
,	O
even	O
though	O
they	O
supported	O
limited	O
multiprogramming	O
.	O
</s>
<s>
When	O
the	B-Operating_System
UNIVAC	I-Operating_System
1110	O
was	O
introduced	O
in	O
1972	O
,	O
the	O
operating	B-General_Concept
system	I-General_Concept
name	O
was	O
changed	O
to	O
OS	O
1100	O
to	O
reflect	O
its	O
support	O
for	O
the	O
wider	O
range	O
of	O
systems	O
.	O
</s>
<s>
The	O
name	O
OS	O
1100	O
was	O
retained	O
until	O
1988	O
with	O
the	O
introduction	O
of	O
the	O
Sperry	O
2200	B-Device
Series	I-Device
as	O
a	O
follow	O
on	O
to	O
the	O
1100	B-Device
Series	I-Device
when	O
its	O
name	O
was	O
changed	O
to	O
OS	B-Operating_System
2200	I-Operating_System
.	O
</s>
<s>
Since	O
that	O
time	O
,	O
the	O
2200	B-Device
Series	I-Device
became	O
the	O
Unisys	O
ClearPath	O
IX	O
Series	O
and	O
then	O
the	O
Unisys	O
ClearPath	O
Dorado	O
Series	O
,	O
but	O
the	O
operating	B-General_Concept
system	I-General_Concept
retained	O
the	O
OS	B-Operating_System
2200	I-Operating_System
name	O
.	O
</s>
<s>
Remington	O
Rand	O
also	O
acquired	O
the	O
Eckert	O
–	O
Mauchly	O
Computer	O
Corporation	O
of	O
Philadelphia	O
which	O
was	O
then	O
building	O
the	B-Operating_System
UNIVAC	I-Operating_System
computer	O
.	O
</s>
<s>
The	O
two	O
were	O
combined	O
into	O
the	B-Operating_System
UNIVAC	I-Operating_System
division	O
of	O
Remington	O
Rand	O
under	O
the	O
direction	O
of	O
William	O
Norris	O
.	O
</s>
<s>
The	B-Operating_System
UNIVAC	I-Operating_System
division	O
of	O
Remington	O
Rand	O
Corporation	O
became	O
the	B-Operating_System
UNIVAC	I-Operating_System
division	O
of	O
Sperry	O
Rand	O
Corporation	O
after	O
Remington	O
Rand	O
merged	O
with	O
Sperry	O
Corporation	O
.	O
</s>
<s>
In	O
the	O
1970s	O
Sperry	O
Rand	O
began	O
a	O
corporate	O
identity	O
program	O
that	O
changed	O
its	O
name	O
to	O
Sperry	O
Corporation	O
and	O
all	O
the	O
division	O
names	O
to	O
begin	O
with	O
Sperry	O
,	O
so	O
the	O
computer	O
systems	O
division	O
became	O
Sperry	O
UNIVAC	B-Operating_System
.	O
</s>
<s>
The	O
operating	B-General_Concept
system	I-General_Concept
kernel	O
is	O
still	O
referred	O
to	O
as	O
"	O
the	O
Exec	O
"	O
by	O
most	O
Unisys	O
and	O
customer	O
personnel	O
.	O
</s>
<s>
However	O
,	O
when	O
Unisys	O
began	O
releasing	O
suites	O
of	O
products	O
tested	O
together	O
as	O
system	O
base	O
releases	O
,	O
later	O
called	O
"	O
ClearPath	O
OS	B-Operating_System
2200	I-Operating_System
Release	O
n	O
"	O
,	O
the	O
term	O
OS	B-Operating_System
2200	I-Operating_System
changed	O
to	O
refer	O
to	O
the	O
entire	O
suite	O
of	O
products	O
in	O
the	O
system	O
release	O
and	O
others	O
,	O
such	O
as	O
BIS	B-Language
,	O
released	O
asynchronously	O
for	O
the	O
Dorado	O
hardware	O
platforms	O
.	O
</s>
<s>
In	O
1986	O
Burroughs	O
and	O
Sperry	O
corporations	O
merged	O
to	O
become	O
Unisys	O
(	O
which	O
some	O
long	O
time	O
2200	B-Device
Series	I-Device
clients	O
say	O
stands	O
for	O
"	O
UNIVAC	B-Operating_System
Is	I-Operating_System
Still	O
Your	O
Supplier	O
"	O
)	O
.	O
</s>
<s>
The	O
major	O
mainframe	O
product	O
lines	O
of	O
both	O
companies	O
have	O
continued	O
in	O
development	O
including	O
the	O
MCP	B-Application
Operating	I-Application
System	I-Application
from	O
Burroughs	O
and	O
OS	B-Operating_System
2200	I-Operating_System
from	O
Sperry	O
.	O
</s>
<s>
In	O
2016	O
Unisys	O
made	O
a	O
virtual	O
Microsoft	B-Application
Windows	I-Application
version	O
of	O
OS2200	O
available	O
at	O
no	O
cost	O
for	O
educational	O
and	O
leisure	O
purposes	O
.	O
</s>
<s>
EXEC	O
8	O
(	O
sometimes	O
referred	O
to	O
as	O
EXEC	O
VIII	O
)	O
was	O
UNIVAC	B-Operating_System
's	O
operating	B-General_Concept
system	I-General_Concept
developed	O
for	O
the	B-Operating_System
UNIVAC	I-Operating_System
1108	O
in	O
1964	O
.	O
</s>
<s>
It	O
combined	O
the	O
best	O
features	O
of	O
the	O
earlier	O
operating	B-General_Concept
systems	I-General_Concept
,	O
EXEC	B-Application
I	I-Application
and	O
EXEC	B-Application
II	I-Application
,	O
which	O
were	O
used	O
on	O
the	B-Operating_System
UNIVAC	I-Operating_System
1107	O
.	O
</s>
<s>
EXEC	O
8	O
was	O
one	O
of	O
the	O
first	O
commercially	O
successful	O
multiprocessing	B-Operating_System
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
It	O
supported	O
simultaneous	O
mixed	O
workloads	O
comprising	O
batch	B-General_Concept
,	O
time-sharing	B-General_Concept
and	O
real-time	B-General_Concept
.	O
</s>
<s>
Its	O
one	O
file	B-Application
system	I-Application
had	O
a	O
flat	O
naming	O
structure	O
across	O
many	O
drums	B-General_Concept
and	O
spindles	O
.	O
</s>
<s>
It	O
also	O
supported	O
a	O
well-received	O
transaction	B-Application
processing	I-Application
system	I-Application
.	O
</s>
<s>
Previous	O
systems	O
were	O
all	O
real-mode	O
systems	O
with	O
no	O
hardware	O
support	O
for	O
protection	O
and	O
separation	O
of	O
programs	O
and	O
the	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
While	O
there	O
had	O
been	O
support	O
for	O
multiprogramming	O
in	O
previous	O
systems	O
,	O
it	O
was	O
limited	O
to	O
running	O
one	O
user	O
job	O
concurrently	O
with	O
multiple	O
supporting	O
functions	O
known	O
to	O
be	O
well-behaved	O
,	O
such	O
as	O
the	O
card	O
reader	O
,	O
printer	O
,	O
and	O
card	O
punch	O
spoolers	B-Device
.	O
</s>
<s>
The	O
Exec	O
8	O
operating	B-General_Concept
system	I-General_Concept
was	O
designed	O
from	O
the	O
very	O
beginning	O
to	O
be	O
a	O
multiprogramming	O
and	O
multiprocessing	B-Operating_System
operating	B-General_Concept
system	I-General_Concept
because	O
the	O
1108	O
was	O
designed	O
to	O
have	O
up	O
to	O
four	O
CPUs	O
.	O
</s>
<s>
While	O
the	O
1100	B-Device
Series	I-Device
was	O
envisioned	O
as	O
targeting	O
a	O
more	O
general	O
market	O
,	O
extreme	O
real	B-General_Concept
time	I-General_Concept
processing	I-General_Concept
was	O
a	O
primary	O
requirement	O
.	O
</s>
<s>
Exec	O
8	O
began	O
as	O
a	O
real	B-General_Concept
time	I-General_Concept
operating	B-General_Concept
system	I-General_Concept
with	O
early	O
use	O
mostly	O
in	O
general	O
scientific	O
and	O
engineering	O
work	O
,	O
but	O
it	O
was	O
also	O
used	O
in	O
message	O
switching	O
,	O
process	O
control	O
,	O
simulation	O
,	O
and	O
missile	O
firing	O
control	O
.	O
</s>
<s>
It	O
was	O
designed	O
to	O
run	O
on	O
systems	O
that	O
often	O
had	O
only	O
128K	O
words	O
(	O
576	O
K	O
bytes	O
—	O
less	O
than	O
the	O
maximum	O
memory	O
size	O
for	O
the	O
IBM	B-Device
PC	I-Device
XT	I-Device
)	O
,	O
and	O
was	O
focused	O
on	O
real	B-General_Concept
time	I-General_Concept
and	O
batch	B-General_Concept
processing	I-General_Concept
.	O
</s>
<s>
Mass	O
storage	O
consisted	O
of	O
6-foot	O
long	O
rotating	O
drums	B-General_Concept
that	O
held	O
256KW	O
(	O
in	O
the	O
FH-432	O
)	O
to	O
2MW	O
(	O
in	O
the	O
FH-1782	O
)	O
.	O
</s>
<s>
The	O
highest	O
capacity	O
mass	O
storage	O
was	O
the	O
FASTRAND	B-Device
drum	O
,	O
which	O
held	O
22	O
MW	O
(	O
99	O
MB	O
)	O
.	O
</s>
<s>
It	O
involved	O
rolling	O
all	O
files	O
out	O
to	O
tape	O
,	O
reinitializing	O
the	O
drum	O
file	B-Application
system	I-Application
,	O
then	O
reading	O
the	O
files	O
back	O
in	O
.	O
</s>
<s>
With	O
severe	O
memory	O
constraints	O
and	O
real	B-General_Concept
time	I-General_Concept
use	O
,	O
keeping	O
only	O
a	O
single	O
copy	O
of	O
code	O
loaded	O
into	O
core	O
was	O
a	O
requirement	O
.	O
</s>
<s>
Since	O
the	O
1108	O
was	O
designed	O
for	O
multitasking	O
,	O
the	O
system	O
was	O
fully	O
"	O
reentrant	O
"	O
(	O
thread	B-Operating_System
safe	I-Operating_System
)	O
.	O
</s>
<s>
Reentrant	O
code	O
had	O
to	O
be	O
thread	B-Operating_System
safe	I-Operating_System
(	O
execute	O
only	O
)	O
;	O
self-modifying	O
code	O
was	O
not	O
allowed	O
.	O
</s>
<s>
Exec	O
8	O
was	O
primarily	O
a	O
batch	B-General_Concept
processing	I-General_Concept
system	O
that	O
gave	O
applications	O
(	O
called	O
"	O
tasks	O
"	O
)	O
very	O
fine	O
control	O
of	O
CPU	O
scheduling	O
priority	O
for	O
its	O
threads	O
(	O
called	O
"	O
activities	O
"	O
)	O
.	O
</s>
<s>
Except	O
in	O
realtime	B-General_Concept
systems	I-General_Concept
,	O
even	O
the	O
lowest	O
priority	O
tasks	O
got	O
some	O
processor	O
time	O
.	O
</s>
<s>
It	O
was	O
a	O
multiprogramming	O
and	O
multiprocessing	B-Operating_System
operating	B-General_Concept
system	I-General_Concept
with	O
fully	O
symmetric	O
processor	O
management	O
.	O
</s>
<s>
In	O
Exec	O
8	O
,	O
work	O
is	O
organized	O
into	O
jobs	O
,	O
called	O
"	O
runs	O
,	O
"	O
which	O
are	O
scheduled	O
based	O
on	O
their	O
priority	O
and	O
need	O
for	O
lockable	O
resources	O
such	O
as	O
Uniservo	O
tape	O
drives	O
or	O
Fastrand	B-Device
drum	O
files	O
.	O
</s>
<s>
The	O
control	O
language	O
syntax	O
uses	O
the	O
"	O
@	O
"	O
symbol	O
(	O
which	O
Univac	B-Operating_System
called	O
"	O
the	O
master	O
space	O
"	O
)	O
as	O
the	O
control	O
statement	O
recognition	O
symbol	O
.	O
</s>
<s>
In	O
1968	O
,	O
work	O
began	O
on	O
adding	O
time-sharing	B-General_Concept
capability	O
to	O
Exec	O
8	O
.	O
</s>
<s>
Time	B-General_Concept
sharing	I-General_Concept
(	O
called	O
demand	O
mode	O
)	O
had	O
the	O
same	O
capabilities	O
as	O
batch	B-General_Concept
and	O
real	B-General_Concept
time	I-General_Concept
processes	O
.	O
</s>
<s>
Everything	O
that	O
could	O
be	O
done	O
in	O
batch	B-General_Concept
could	O
be	O
done	O
from	O
an	O
ASCII	O
terminal	O
.	O
</s>
<s>
In	O
demand	O
mode	O
,	O
job	O
stream	O
I/O	O
was	O
attached	O
to	O
a	O
terminal	O
handler	O
rather	O
than	O
card	O
image	O
(	O
input	O
)	O
and	O
spool	B-Device
(	O
output	O
)	O
files	O
.	O
</s>
<s>
A	O
few	O
years	O
later	O
,	O
more	O
specific	O
time	B-General_Concept
sharing	I-General_Concept
commands	O
were	O
added	O
,	O
and	O
some	O
control	O
statements	O
could	O
be	O
issued	O
asynchronously	O
for	O
immediate	O
processing	O
,	O
even	O
when	O
neither	O
the	O
executive	O
or	O
the	O
running	O
program	O
were	O
expecting	O
data	O
.	O
</s>
<s>
Both	O
batch	B-General_Concept
and	O
demand	O
runs	O
terminate	O
with	O
an	O
@FIN	O
statement	O
,	O
and	O
if	O
a	O
demand	O
user	O
terminates	O
his	O
session	O
while	O
his	O
run	O
is	O
active	O
,	O
the	O
Exec	O
automatically	O
terminates	O
the	O
run	O
without	O
requiring	O
@FIN	O
.	O
</s>
<s>
A	O
transaction	B-General_Concept
processing	I-General_Concept
capability	O
was	O
developed	O
in	O
the	O
late	O
1960s	O
as	O
a	O
joint	O
project	O
with	O
United	O
Airlines	O
and	O
later	O
refined	O
in	O
another	O
joint	O
project	O
with	O
Air	O
Canada	O
.	O
</s>
<s>
This	O
capability	O
was	O
fully	O
integrated	O
into	O
the	O
operating	B-General_Concept
system	I-General_Concept
in	O
1972	O
and	O
became	O
the	O
basis	O
of	O
much	O
of	O
the	O
future	O
growth	O
of	O
the	O
1100	B-Device
Series	I-Device
.	O
</s>
<s>
Early	O
users	O
controlled	O
communication	O
lines	O
directly	O
from	O
within	O
their	O
real	B-General_Concept
time	I-General_Concept
programs	O
.	O
</s>
<s>
Part	O
of	O
the	O
development	O
of	O
transaction	B-General_Concept
processing	I-General_Concept
included	O
a	O
communication	O
message	O
system	O
that	O
managed	O
the	O
communication	O
lines	O
and	O
presented	O
messages	O
to	O
Exec	O
8	O
to	O
be	O
scheduled	O
as	O
transactions	O
.	O
</s>
<s>
CMS	O
1100	O
itself	O
ran	O
as	O
a	O
real	B-General_Concept
time	I-General_Concept
multi-threaded	O
program	O
with	O
the	O
privilege	O
of	O
acquiring	O
control	O
of	O
communication	O
lines	O
and	O
submitting	O
transaction	O
messages	O
for	O
scheduling	O
.	O
</s>
<s>
The	O
system	O
was	O
still	O
primarily	O
batch	B-General_Concept
and	O
transaction	B-General_Concept
processing	I-General_Concept
and	O
there	O
was	O
little	O
chance	O
that	O
anyone	O
could	O
install	O
unauthorized	O
code	O
on	O
the	O
system	O
.	O
</s>
<s>
For	O
the	O
Intel-based	O
Dorado	O
server	O
models	O
,	O
the	O
lower	O
level	O
communications	O
were	O
moved	O
to	O
firmware	B-Application
,	O
with	O
the	O
upper	O
levels	O
handled	O
by	O
SILAS	O
and	O
CPCommOS	O
(	O
ClearPath	O
Enterprise	O
Servers	O
Communications	O
Platform	O
for	O
Open	O
Systems	O
)	O
.	O
</s>
<s>
The	O
Exec	B-Application
is	I-Application
responsible	O
for	O
managing	O
the	O
system	O
hardware	O
,	O
scheduling	O
and	O
managing	O
work	O
,	O
and	O
communicating	O
with	O
operators	O
and	O
administrators	O
.	O
</s>
<s>
In	O
Release	O
16.0	O
,	O
the	O
Exec	B-Application
is	I-Application
level	O
49R2	O
(	O
49.70.5	O
)	O
.	O
</s>
<s>
The	O
Exec	B-Application
is	I-Application
at	O
heart	O
a	O
real	B-General_Concept
time	I-General_Concept
,	O
multi-threaded	O
batch	B-General_Concept
processing	I-General_Concept
system	O
.	O
</s>
<s>
The	O
Exec	O
itself	O
is	O
largely	O
structured	O
as	O
a	O
real	B-General_Concept
time	I-General_Concept
program	O
.	O
</s>
<s>
Functions	O
that	O
are	O
performed	O
as	O
Services	O
in	O
Windows	O
or	O
Daemons	B-Operating_System
in	O
Linux	O
and	O
UNIX	O
are	O
implemented	O
as	O
either	O
activities	O
within	O
the	O
Exec	O
or	O
as	O
batch	B-General_Concept
programs	I-General_Concept
that	O
are	O
always	O
running	O
in	O
the	O
background	O
.	O
</s>
<s>
Time-sharing	B-General_Concept
(	O
known	O
as	O
demand	O
mode	O
)	O
and	O
transaction	B-General_Concept
processing	I-General_Concept
are	O
implemented	O
as	O
special	O
cases	O
of	O
batch	B-General_Concept
.	O
</s>
<s>
One	O
result	O
is	O
that	O
there	O
are	O
few	O
restrictions	O
on	O
what	O
a	O
time-sharing	B-General_Concept
user	O
or	O
transaction	O
program	O
can	O
do	O
.	O
</s>
<s>
A	O
batch	B-General_Concept
Run	O
is	O
typically	O
stored	O
as	O
a	O
file	O
and	O
is	O
scheduled	O
by	O
a	O
"	O
Start	O
"	O
command	O
from	O
within	O
another	O
Run	O
or	O
by	O
the	O
operator	O
.	O
</s>
<s>
A	O
time	B-General_Concept
sharing	I-General_Concept
Run	O
is	O
initiated	O
by	O
logging	O
in	O
from	O
a	O
time-sharing	B-General_Concept
terminal	O
and	O
inputting	O
the	O
@RUN	O
command	O
.	O
</s>
<s>
Batch	B-General_Concept
jobs	I-General_Concept
(	O
Runs	O
)	O
are	O
characterized	O
by	O
having	O
a	O
runstream	O
(	O
job	O
control	O
language	O
statements	O
)	O
stored	O
in	O
a	O
file	O
.	O
</s>
<s>
A	O
batch	B-General_Concept
job	I-General_Concept
always	O
contains	O
an	O
@RUN	O
statement	O
as	O
the	O
first	O
record	O
in	O
the	O
file	O
.	O
</s>
<s>
The	O
Exec	O
has	O
a	O
configured	O
maximum	O
number	O
of	O
open	O
batch	B-General_Concept
runs	O
.	O
</s>
<s>
When	O
that	O
level	O
is	O
reached	O
,	O
jobs	O
are	O
then	O
selected	O
from	O
the	O
backlog	O
queues	B-Device
in	O
priority	O
order	O
.	O
</s>
<s>
While	O
the	O
OS	B-Operating_System
2200	I-Operating_System
job	O
control	O
language	O
does	O
not	O
support	O
full	O
programmability	O
,	O
it	O
does	O
allow	O
dynamic	O
additions	O
of	O
sequences	O
of	O
control	O
language	O
through	O
an	O
@ADD	O
control	O
statement	O
.	O
</s>
<s>
Additional	O
programmability	O
is	O
available	O
indirectly	O
through	O
the	O
use	O
of	O
the	O
Symbolic	B-Language
Stream	I-Language
Generator	I-Language
(	O
SSG	O
)	O
.	O
</s>
<s>
It	O
is	O
used	O
heavily	O
for	O
configuration	O
management	O
(	O
make	B-Application
)	O
processing	O
and	O
other	O
functions	O
where	O
text	O
images	O
need	O
to	O
be	O
created	O
programmatically	O
.	O
</s>
<s>
Deadline	O
is	O
a	O
special	O
case	O
of	O
batch	B-General_Concept
.	O
</s>
<s>
A	O
deadline	O
run	O
looks	O
just	O
like	O
any	O
other	O
batch	B-General_Concept
run	O
except	O
that	O
a	O
deadline	O
time	O
is	O
specified	O
on	O
the	O
@RUN	O
or	O
@START	O
control	O
statement	O
.	O
</s>
<s>
A	O
deadline	O
job	O
runs	O
at	O
normal	O
batch	B-General_Concept
priorities	O
unless	O
or	O
until	O
it	O
appears	O
that	O
it	O
could	O
miss	O
its	O
deadline	O
time	O
.	O
</s>
<s>
While	O
deadline	O
ca	O
n’t	O
totally	O
shut	O
off	O
transactions	O
and	O
has	O
no	O
effect	O
on	O
real	B-General_Concept
time	I-General_Concept
,	O
it	O
can	O
effectively	O
shut	O
off	O
most	O
other	O
processing	O
in	O
the	O
system	O
if	O
necessary	O
to	O
achieve	O
its	O
goal	O
.	O
</s>
<s>
OS	B-Operating_System
2200	I-Operating_System
time-sharing	B-General_Concept
sessions	O
are	O
called	O
demand	O
(	O
from	O
"	O
on	O
demand	O
"	O
)	O
runs	O
.	O
</s>
<s>
They	O
use	O
the	O
same	O
control	O
language	O
as	O
batch	B-General_Concept
runs	O
with	O
a	O
few	O
additions	O
known	O
as	O
"	O
immediate	O
"	O
control	O
statements	O
.	O
</s>
<s>
Instead	O
when	O
a	O
message	O
is	O
received	O
from	O
a	O
session	O
defined	O
as	O
a	O
transaction	O
session	O
,	O
it	O
is	O
scanned	O
to	O
determine	O
the	O
transaction	O
queue	B-Device
on	O
which	O
it	O
is	O
to	O
be	O
placed	O
.	O
</s>
<s>
A	O
call	O
is	O
made	O
to	O
the	O
Transaction	O
Interface	O
Package	O
(	O
TIP	O
)	O
APIs	O
in	O
the	O
operating	B-General_Concept
system	I-General_Concept
to	O
queue	B-Device
the	O
transaction	O
on	O
the	O
appropriate	O
queuing	O
point	O
.	O
</s>
<s>
Real	B-General_Concept
time	I-General_Concept
is	O
not	O
another	O
type	O
of	O
run	O
.	O
</s>
<s>
Real	B-General_Concept
time	I-General_Concept
is	O
most	O
typically	O
used	O
by	O
long	O
running	O
batch	B-General_Concept
programs	I-General_Concept
,	O
like	O
the	O
OS	B-Operating_System
2200	I-Operating_System
communications	O
manager	O
CPComm	O
,	O
but	O
is	O
not	O
restricted	O
to	O
such	O
.	O
</s>
<s>
There	O
are	O
36	O
real	B-General_Concept
time	I-General_Concept
priority	O
levels	O
available	O
by	O
API	O
for	O
applications	O
to	O
use	O
.	O
</s>
<s>
The	O
user	O
and	O
account	O
must	O
have	O
the	O
privilege	O
to	O
use	O
real	B-General_Concept
time	I-General_Concept
priorities	O
.	O
</s>
<s>
Real	B-General_Concept
time	I-General_Concept
priorities	O
totally	O
dominate	O
all	O
lower	O
priorities	O
so	O
it	O
's	O
quite	O
possible	O
for	O
a	O
misbehaved	O
real	B-General_Concept
time	I-General_Concept
program	O
to	O
tie	O
up	O
one	O
or	O
more	O
processors	O
.	O
</s>
<s>
The	O
real	B-General_Concept
time	I-General_Concept
priority	O
applies	O
to	O
an	O
individual	O
activity	O
(	O
thread	O
)	O
so	O
a	O
program	O
may	O
have	O
both	O
real	B-General_Concept
time	I-General_Concept
and	O
non-real	O
time	O
threads	O
executing	O
at	O
the	O
same	O
time	O
.	O
</s>
<s>
The	O
heart	O
of	O
the	O
Exec	B-Application
is	I-Application
the	O
Dispatcher	B-Operating_System
which	O
manages	O
all	O
the	O
processors	O
.	O
</s>
<s>
The	O
Dispatcher	B-Operating_System
,	O
I/O	O
completions	O
,	O
and	O
I/O	O
initiation	O
are	O
some	O
examples	O
.	O
</s>
<s>
High	O
Exec	O
priority	O
is	O
used	O
by	O
the	O
operator	O
command	O
handler	O
and	O
some	O
other	O
functions	O
that	O
may	O
have	O
to	O
run	O
even	O
when	O
a	O
real	B-General_Concept
time	I-General_Concept
program	O
has	O
control	O
.	O
</s>
<s>
If	O
they	O
need	O
more	O
time	O
,	O
they	O
should	O
queue	B-Device
the	O
work	O
to	O
be	O
processed	O
by	O
a	O
Low	O
Exec	O
activity	O
.	O
</s>
<s>
Real	B-General_Concept
time	I-General_Concept
activities	O
have	O
an	O
unlimited	O
processor	O
quantum	O
and	O
run	O
without	O
switching	O
unless	O
interrupted	O
by	O
a	O
higher	O
priority	O
real	B-General_Concept
time	I-General_Concept
activity	O
or	O
High	O
Exec	O
activity	O
.	O
</s>
<s>
Real	B-General_Concept
Time	I-General_Concept
activities	O
are	O
given	O
control	O
of	O
any	O
available	O
processor	O
that	O
is	O
running	O
something	O
of	O
lower	O
priority	O
.	O
</s>
<s>
Real	B-General_Concept
time	I-General_Concept
is	O
used	O
by	O
customers	O
to	O
fly	O
missiles	O
,	O
run	O
simulators	O
,	O
and	O
other	O
functions	O
that	O
require	O
immediate	O
response	O
.	O
</s>
<s>
They	O
may	O
be	O
a	O
sort	O
of	O
lower	O
priority	O
real	B-General_Concept
time	I-General_Concept
in	O
that	O
only	O
the	O
priority	O
matters	O
and	O
the	O
quantum	O
size	O
is	O
essentially	O
infinite	O
.	O
</s>
<s>
Batch	B-General_Concept
and	O
demand	O
always	O
use	O
dynamically	O
adjusted	O
priorities	O
.	O
</s>
<s>
Programs	O
that	O
are	O
I/O	O
limited	O
or	O
are	O
in	O
a	O
conversation	O
with	O
a	O
time-sharing	B-General_Concept
user	O
get	O
higher	O
priorities	O
but	O
short	O
time	O
slices	O
.	O
</s>
<s>
The	O
site	O
can	O
define	O
the	O
relative	O
percentage	O
of	O
resources	O
to	O
be	O
allocated	O
to	O
each	O
of	O
transactions	O
,	O
demand	O
and	O
batch	B-General_Concept
.	O
</s>
<s>
Within	O
transactions	O
and	O
batch	B-General_Concept
there	O
are	O
priority	O
groupings	O
that	O
can	O
further	O
indicate	O
what	O
percentage	O
of	O
their	O
group	O
's	O
time	O
is	O
to	O
be	O
allocated	O
to	O
the	O
priority	O
.	O
</s>
<s>
This	O
ensures	O
that	O
transactions	O
cannot	O
so	O
dominate	O
the	O
system	O
that	O
no	O
batch	B-General_Concept
work	O
gets	O
done	O
.	O
</s>
<s>
These	O
"	O
fairness	O
"	O
algorithms	O
only	O
come	O
into	O
play	O
when	O
the	O
processors	O
are	O
very	O
busy	O
,	O
but	O
OS	B-Operating_System
2200	I-Operating_System
systems	O
often	O
run	O
with	O
all	O
processors	O
at	O
near	O
100%	O
utilized	O
.	O
</s>
<s>
OS	B-Operating_System
2200	I-Operating_System
supports	O
several	O
models	O
for	O
system	O
performance	O
management	O
.	O
</s>
<s>
OS	B-Operating_System
2200	I-Operating_System
does	O
not	O
have	O
a	O
hierarchical	B-Application
file	I-Application
system	I-Application
as	O
do	O
most	O
other	O
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
Files	O
in	O
OS	B-Operating_System
2200	I-Operating_System
are	O
simply	O
containers	O
that	O
may	O
be	O
addressed	O
either	O
by	O
word	O
offset	O
in	O
the	O
file	O
or	O
by	O
sector	O
(	O
28-word	O
unit	O
)	O
offset	O
in	O
the	O
file	O
.	O
</s>
<s>
The	O
28	O
words	O
is	O
a	O
historical	O
unit	O
from	O
an	O
early	O
mass	O
storage	O
device	O
(	O
the	O
FASTRAND	B-Device
drum	O
)	O
that	O
could	O
hold	O
64	O
such	O
units	O
per	O
physical	O
track	O
.	O
</s>
<s>
With	O
today	O
's	O
mass	O
storage	O
devices	O
all	O
using	O
512-byte	O
physical	O
records	O
,	O
OS	B-Operating_System
2200	I-Operating_System
clients	O
have	O
almost	O
all	O
adopted	O
some	O
multiple	O
of	O
112	O
words	O
as	O
their	O
physical	O
record	O
size	O
and	O
database	O
page	O
size	O
.	O
</s>
<s>
OS	B-Operating_System
2200	I-Operating_System
handles	O
applications	O
that	O
use	O
sizes	O
other	O
than	O
multiples	O
of	O
112	O
words	O
by	O
indivisibly	O
reading	O
the	O
containing	O
physical	O
records	O
and	O
writing	O
back	O
out	O
the	O
unchanged	O
and	O
changed	O
portions	O
with	O
data	O
chaining	O
.	O
</s>
<s>
Batch	B-General_Concept
production	O
runs	O
that	O
create	O
new	O
generations	O
of	O
files	O
use	O
this	O
approach	O
.	O
</s>
<s>
OS	B-Operating_System
2200	I-Operating_System
implements	O
a	O
fully	O
virtual	O
file	B-Application
system	I-Application
.	O
</s>
<s>
In	O
general	O
,	O
the	O
Exec	O
does	O
not	O
provide	O
access	B-Application
methods	I-Application
.	O
</s>
<s>
Access	B-Application
methods	I-Application
are	O
provided	O
by	O
the	O
language	O
run	O
time	O
systems	O
and	O
the	O
database	O
manager	O
.	O
</s>
<s>
The	O
one	O
exception	O
is	O
a	O
fixed-block	O
access	B-Application
method	I-Application
provided	O
for	O
high-volume	O
transaction	B-General_Concept
processing	I-General_Concept
.	O
</s>
<s>
At	O
one	O
time	O
these	O
truly	O
represented	O
physically	O
removable	O
disk	O
packs	O
,	O
and	O
the	O
operating	B-General_Concept
system	I-General_Concept
would	O
automatically	O
generate	O
pack	O
mount	O
requests	O
to	O
operators	O
as	O
needed	O
.	O
</s>
<s>
OS	B-Operating_System
2200	I-Operating_System
also	O
provides	O
a	O
full	O
implementation	O
of	O
the	O
Common	B-Operating_System
Internet	I-Operating_System
File	I-Operating_System
System	I-Operating_System
(	O
CIFS	B-Operating_System
)	O
.	O
</s>
<s>
CIFS	B-Operating_System
implements	O
the	O
SMB	B-Operating_System
protocol	I-Operating_System
used	O
by	O
Microsoft	O
servers	O
and	O
the	O
UNIX/Linux	O
Samba	B-Language
software	I-Language
.	O
</s>
<s>
CIFS	B-Operating_System
for	O
ClearPath	O
OS	B-Operating_System
2200	I-Operating_System
is	O
both	O
a	O
file	O
server	O
and	O
file	O
client	O
to	O
other	O
CIFS-compliant	O
systems	O
.	O
</s>
<s>
CIFS	B-Operating_System
supports	O
SMB	O
message	O
signing	O
.	O
</s>
<s>
To	O
maintain	O
OS	B-Operating_System
2200	I-Operating_System
security	O
,	O
CIFS	B-Operating_System
for	O
ClearPath	O
OS	B-Operating_System
2200	I-Operating_System
provides	O
two	O
levels	O
of	O
protection	O
.	O
</s>
<s>
First	O
,	O
OS	B-Operating_System
2200	I-Operating_System
files	O
are	O
not	O
visible	O
to	O
the	O
network	O
until	O
they	O
have	O
been	O
declared	O
as	O
"	O
shares	O
"	O
with	O
a	O
CIFS	B-Operating_System
command	O
.	O
</s>
<s>
The	O
second	O
level	O
of	O
control	O
is	O
that	O
all	O
access	O
is	O
still	O
protected	O
by	O
OS	B-Operating_System
2200	I-Operating_System
security	O
.	O
</s>
<s>
Clients	O
accessing	O
OS	B-Operating_System
2200	I-Operating_System
via	O
CIFS	B-Operating_System
will	O
either	O
have	O
to	O
be	O
automatically	O
identified	O
via	O
NTLM	O
or	O
Kerberos	B-Protocol
or	O
they	O
will	O
be	O
presented	O
with	O
a	O
query	O
for	O
their	O
OS	B-Operating_System
2200	I-Operating_System
user	O
id	O
and	O
password	O
.	O
</s>
<s>
CIFS	B-Operating_System
allows	O
OS	B-Operating_System
2200	I-Operating_System
files	O
to	O
be	O
presented	O
in	O
a	O
hierarchical	O
view	O
.	O
</s>
<s>
In	O
addition	O
,	O
files	O
may	O
be	O
stored	O
on	O
OS	B-Operating_System
2200	I-Operating_System
servers	O
using	O
the	O
full	O
Windows	O
filename	O
format	O
.	O
</s>
<s>
Windows	B-Application
applications	I-Application
will	O
see	O
OS	B-Operating_System
2200	I-Operating_System
as	O
another	O
file	O
server	O
.	O
</s>
<s>
OS	B-Operating_System
2200	I-Operating_System
applications	O
have	O
APIs	O
available	O
to	O
read	O
and	O
write	O
files	O
existing	O
on	O
other	O
CIFS-compliant	O
servers	O
,	O
such	O
as	O
Windows	O
file	O
servers	O
,	O
in	O
the	O
network	O
.	O
</s>
<s>
Text	O
files	O
are	O
automatically	O
converted	O
to	O
and	O
from	O
OS	B-Operating_System
2200	I-Operating_System
internal	O
formats	O
.	O
</s>
<s>
The	O
CIFSUT	O
utility	O
running	O
under	O
OS	B-Operating_System
2200	I-Operating_System
can	O
exchange	O
encrypted	O
compressed	O
files	O
with	O
other	O
software	O
,	O
such	O
as	O
WinZip	O
.	O
</s>
<s>
The	O
concept	O
of	O
subsystems	O
and	O
protected	O
subsystems	O
are	O
central	O
to	O
the	O
design	O
of	O
OS	B-Operating_System
2200	I-Operating_System
.	O
</s>
<s>
In	O
OS	B-Operating_System
2200	I-Operating_System
each	O
subsystem	O
has	O
its	O
own	O
set	O
of	O
banks	O
that	O
reside	O
in	O
a	O
separate	O
part	O
of	O
the	O
address	O
space	O
that	O
cannot	O
be	O
directly	O
accessed	O
by	O
any	O
user	O
program	O
.	O
</s>
<s>
See	O
Unisys	B-Architecture
2200	I-Architecture
Series	I-Architecture
system	I-Architecture
architecture	I-Architecture
for	O
more	O
information	O
.	O
</s>
<s>
The	O
OS	B-Operating_System
2200	I-Operating_System
security	O
system	O
is	O
designed	O
to	O
protect	O
data	O
from	O
unauthorized	O
access	O
,	O
modification	O
,	O
or	O
exposure	O
.	O
</s>
<s>
OS	B-Operating_System
2200	I-Operating_System
first	O
obtained	O
a	O
successful	O
B1	O
evaluation	O
in	O
September	O
,	O
1989	O
.	O
</s>
<s>
After	O
that	O
point	O
,	O
OS	B-Operating_System
2200	I-Operating_System
developers	O
continued	O
to	O
follow	O
development	O
and	O
documentation	O
practices	O
required	O
by	O
the	O
B1	O
evaluation	O
.	O
</s>
<s>
Objects	O
in	O
OS	B-Operating_System
2200	I-Operating_System
consist	O
of	O
files	O
,	O
protected	O
subsystems	O
,	O
devices	O
,	O
and	O
tape	O
reels	O
.	O
</s>
<s>
OS	B-Operating_System
2200	I-Operating_System
implements	O
both	O
Mandatory	O
Access	O
Control	O
(	O
MAC	O
)	O
and	O
Discretionary	O
Access	O
Control	O
(	O
DAC	O
)	O
based	O
on	O
the	O
Bell-La	O
Padula	O
model	O
for	O
confidentiality	O
(	O
no	O
read	O
up	O
,	O
no	O
write	O
down	O
)	O
and	O
the	O
Biba	O
integrity	O
model	O
(	O
no	O
read	O
down	O
,	O
no	O
write	O
up	O
)	O
.	O
</s>
<s>
Because	O
OS	B-Operating_System
2200	I-Operating_System
combines	O
the	O
Bell-La	O
Padula	O
and	O
Biba	O
model	O
requirements	O
,	O
a	O
run	O
's	O
executing	O
clearance	O
level	O
and	O
compartment	O
set	O
must	O
exactly	O
match	O
those	O
of	O
a	O
file	O
to	O
permit	O
writing	O
to	O
the	O
file	O
or	O
deleting	O
it	O
.	O
</s>
<s>
Every	O
OS	B-Operating_System
2200	I-Operating_System
system	O
has	O
one	O
user	O
designated	O
as	O
the	O
security	O
officer	O
.	O
</s>
<s>
OS	B-Operating_System
2200	I-Operating_System
provides	O
a	O
fine-grained	O
security	O
mechanism	O
based	O
on	O
the	O
principle	O
of	O
least	O
privilege	O
.	O
</s>
<s>
Thus	O
,	O
OS	B-Operating_System
2200	I-Operating_System
has	O
no	O
concept	O
of	O
a	O
"	O
Super	O
User	O
"	O
role	O
that	O
can	O
be	O
assumed	O
by	O
any	O
user	O
.	O
</s>
<s>
OS	B-Operating_System
2200	I-Operating_System
offers	O
a	O
flexible	O
authentication	O
system	O
.	O
</s>
<s>
OS	B-Operating_System
2200	I-Operating_System
provides	O
encryption	O
for	O
data	O
at	O
rest	O
through	O
Cipher	O
API	O
,	O
a	O
software	O
subsystem	O
that	O
encrypts	O
and	O
decrypts	O
caller	O
data	O
.	O
</s>
<s>
For	O
CMOS-based	O
Dorado	O
servers	O
,	O
CPComm	O
provides	O
SSL/TLS	B-Protocol
encryption	O
for	O
data	B-General_Concept
in	I-General_Concept
transit	I-General_Concept
.	O
</s>
<s>
For	O
Intel-based	O
Dorado	O
servers	O
,	O
SSL	O
and	O
TLS	O
are	O
provided	O
by	O
openSSL	B-Language
,	O
which	O
is	O
included	O
in	O
the	O
Dorado	O
firmware	B-Application
.	O
</s>
<s>
The	O
AES	B-Algorithm
and	O
Triple	B-Algorithm
DES	I-Algorithm
algorithms	O
are	O
among	O
the	O
algorithms	O
implemented	O
in	O
CryptoLib	O
.	O
</s>
<s>
OS	B-Operating_System
2200	I-Operating_System
also	O
supports	O
encrypting	O
tape	O
drives	O
,	O
which	O
provide	O
encryption	O
for	O
archive	O
data	O
.	O
</s>
<s>
OS	B-Operating_System
2200	I-Operating_System
systems	O
may	O
be	O
clustered	B-Architecture
to	O
achieve	O
greater	O
performance	O
and	O
availability	O
than	O
a	O
single	O
system	O
.	O
</s>
<s>
A	O
hardware	O
device	O
,	O
the	O
XPC-L	O
,	O
provides	O
coordination	O
among	O
the	O
systems	O
by	O
providing	O
a	O
high-speed	O
lock	O
manager	O
for	O
database	O
and	O
file	B-Application
access	I-Application
.	O
</s>
<s>
A	O
clustered	B-Architecture
environment	O
allows	O
each	O
system	O
to	O
have	O
its	O
own	O
local	O
files	O
,	O
databases	O
,	O
and	O
application	O
groups	O
along	O
with	O
shared	O
files	O
and	O
one	O
or	O
more	O
shared	O
application	O
groups	O
.	O
</s>
<s>
Maintenance	O
,	O
including	O
loading	O
new	O
versions	O
of	O
the	O
XPC-L	O
firmware	B-Application
,	O
may	O
be	O
performed	O
on	O
one	O
of	O
the	O
servers	O
while	O
the	O
other	O
continues	O
to	O
run	O
.	O
</s>
<s>
OS	B-Operating_System
2200	I-Operating_System
operations	O
is	O
built	O
around	O
active	O
operators	O
and	O
one	O
or	O
more	O
consoles	O
.	O
</s>
<s>
Operations	O
Sentinel	O
is	O
used	O
for	O
all	O
OS	B-Operating_System
2200	I-Operating_System
operations	O
.	O
</s>
<s>
OS	B-Operating_System
2200	I-Operating_System
consoles	O
are	O
simply	O
windows	O
within	O
an	O
Operations	O
Sentinel	O
display	O
.	O
</s>
<s>
Administration	O
of	O
OS	B-Operating_System
2200	I-Operating_System
systems	O
is	O
performed	O
using	O
a	O
wide	O
variety	O
of	O
tools	O
,	O
each	O
specialized	O
to	O
a	O
particular	O
area	O
of	O
the	O
system	O
.	O
</s>
<s>
All	O
provide	O
a	O
batch	B-General_Concept
stored	O
file	O
interface	O
where	O
all	O
actions	O
are	O
specified	O
in	O
the	O
control	O
stream	O
.	O
</s>
<s>
Application	O
groups	O
are	O
a	O
logical	O
construct	O
consisting	O
of	O
an	O
instance	O
of	O
the	O
Universal	O
Data	O
System	O
(	O
UDS	O
)	O
,	O
an	O
instance	O
of	O
the	O
message	O
queue	B-Device
subsystem	O
,	O
and	O
some	O
set	O
of	O
transactions	O
.	O
</s>
<s>
OS	B-Operating_System
2200	I-Operating_System
supports	O
a	O
maximum	O
of	O
16	O
application	O
groups	O
in	O
a	O
system	O
.	O
</s>
