<s>
The	O
IBM	B-Device
3090	I-Device
family	O
is	O
a	O
family	O
of	O
mainframe	B-Architecture
computers	I-Architecture
that	O
was	O
a	O
high-end	O
successor	O
to	O
the	O
IBM	B-Device
System/370	I-Device
series	O
,	O
and	O
thus	O
indirectly	O
the	O
successor	O
to	O
the	O
IBM	B-Application
System/360	I-Application
launched	O
25	O
years	O
earlier	O
.	O
</s>
<s>
Announced	O
on	O
12	O
February	O
1985	O
,	O
the	O
press	O
releases	O
did	O
not	O
explicitly	O
mention	O
that	O
the	O
two	O
models	O
,	O
Model	O
200	O
and	O
Model	O
400	O
,	O
were	O
backwardly	B-General_Concept
compatible	I-General_Concept
with	O
the	O
370	O
;	O
instead	O
,	O
they	O
were	O
simply	O
positioned	O
as	O
replacements	O
for	O
the	O
IBM	O
3033	O
.	O
</s>
<s>
By	O
the	O
late	O
1970s	O
and	O
early	O
1980s	O
,	O
patented	O
technology	O
allowed	O
Amdahl	O
mainframes	B-Architecture
of	O
this	O
era	O
to	O
be	O
completely	O
air-cooled	O
,	O
unlike	O
IBM	O
systems	O
that	O
required	O
chilled	O
water	O
and	O
its	O
supporting	O
infrastructure	O
.	O
</s>
<s>
The	O
eight	O
largest	O
of	O
the	O
18	O
models	O
of	O
the	O
ES/9000	B-Device
systems	O
introduced	O
in	O
1990	O
were	O
water-cooled	O
;	O
the	O
other	O
ten	O
were	O
air-cooled	O
.	O
</s>
<s>
In	O
additional	O
to	O
the	O
primary	O
and	O
secondary	O
addressing	O
modes	O
that	O
System/370	B-Device
Extended	O
Architecture	O
(	O
S/370	B-Device
-XA	I-Device
)	O
supports	O
,	O
ESA	O
has	O
an	O
AR	O
mode	O
in	O
which	O
each	O
use	O
of	O
general	O
register	O
1-15	O
as	O
a	O
base	O
register	O
uses	O
an	O
associated	O
access	O
register	O
to	O
select	O
an	O
address	O
space	O
.	O
</s>
<s>
In	O
addition	O
to	O
the	O
normal	O
address	O
spaces	O
that	O
S/370	B-Device
-XA	I-Device
supports	O
,	O
ESA	O
also	O
allows	O
data	O
spaces	O
,	O
which	O
contain	O
no	O
executable	O
code	O
.	O
</s>
<s>
Processor	B-Device
Resource/Systems	I-Device
Manager	I-Device
(	O
PR/SM	B-Device
)	O
for	O
3090	O
enhanced	O
(	O
"	O
E	O
"	O
)	O
models	O
This	O
feature	O
allows	O
the	O
operator	O
to	O
define	O
and	O
assign	O
resource	O
to	O
a	O
virtual	O
machine	O
known	O
as	O
a	O
logical	B-Device
partition	I-Device
(	O
LPAR	B-Device
)	O
.	O
</s>
<s>
Initially	O
there	O
was	O
a	O
4-LPAR	O
limit	O
for	O
uniprocessors	O
and	O
an	O
8-LPAR	O
limit	O
for	O
multiprocessors	O
,	O
but	O
newer	O
machines	O
support	O
more	O
.	O
</s>
<s>
On	O
October	O
1	O
,	O
1985	O
,	O
IBM	O
announced	O
an	O
optional	O
vector	B-Operating_System
facility	I-Operating_System
for	O
the	O
IBM	B-Device
3090	I-Device
;	O
such	O
a	O
facility	O
had	O
not	O
been	O
previously	O
available	O
in	O
the	O
System/370	B-Device
architecture	O
,	O
thus	O
bringing	O
integrated	O
supercomputer	B-Architecture
capabilities	O
to	O
the	O
mainframe	B-Architecture
line	O
.	O
</s>
<s>
Along	O
with	O
the	O
vector	O
unit	O
,	O
IBM	O
introduced	O
their	O
Engineering	O
and	O
Scientific	O
Subroutines	O
Library	O
and	O
a	O
facility	O
to	O
run	O
programs	O
written	O
for	O
the	O
discontinued	O
3838	O
array	B-Operating_System
processor	I-Operating_System
.	O
</s>
