<s>
z/Architecture	B-Device
,	O
initially	O
and	O
briefly	O
called	O
ESA	O
Modal	O
Extensions	O
(	O
ESAME	B-Device
)	O
,	O
is	O
IBM	O
's	O
64-bit	B-Device
complex	B-Architecture
instruction	I-Architecture
set	I-Architecture
computer	I-Architecture
(	O
CISC	O
)	O
instruction	B-General_Concept
set	I-General_Concept
architecture	I-General_Concept
,	O
implemented	O
by	O
its	O
mainframe	B-Architecture
computers	I-Architecture
.	O
</s>
<s>
IBM	O
introduced	O
its	O
first	O
z/Architecture	B-Device
-based	O
system	O
,	O
the	O
z900	O
,	O
in	O
late	O
2000	O
.	O
</s>
<s>
Later	O
z/Architecture	B-Device
systems	O
include	O
the	O
IBM	O
z800	O
,	O
z990	O
,	O
z890	O
,	O
System	B-Device
z9	I-Device
,	O
System	B-Device
z10	I-Device
,	O
zEnterprise	O
196	O
,	O
zEnterprise	O
114	O
,	O
zEC12	B-Device
,	O
zBC12	O
,	O
z13	B-Device
,	O
z14	B-Device
,	O
z15	B-Device
and	O
z16	O
.	O
</s>
<s>
z/Architecture	B-Device
retains	O
backward	B-General_Concept
compatibility	I-General_Concept
with	O
previous	O
32-bit-data/31	O
-bit-addressing	O
architecture	O
ESA/390	O
and	O
its	O
predecessors	O
all	O
the	O
way	O
back	O
to	O
the	O
32-bit-data/24	O
-bit-addressing	O
System/360	B-Application
.	O
</s>
<s>
The	O
IBM	B-Device
z13	I-Device
is	O
the	O
last	O
z	O
Systems	O
server	O
to	O
support	O
running	O
an	O
operating	B-General_Concept
system	I-General_Concept
in	O
ESA/390	O
architecture	O
mode	O
.	O
</s>
<s>
IBM	O
's	O
operating	B-General_Concept
systems	I-General_Concept
z/OS	B-Application
,	O
z/VSE	B-Application
,	O
z/TPF	B-Operating_System
,	O
and	O
z/VM	B-Application
are	O
versions	O
of	O
MVS	B-Application
,	O
VSE	B-Application
,	O
Transaction	B-Operating_System
Processing	I-Operating_System
Facility	I-Operating_System
(	O
TPF	O
)	O
,	O
and	O
VM	B-Application
that	O
support	O
z/Architecture	B-Device
.	O
</s>
<s>
Older	O
versions	O
of	O
z/OS	B-Application
,	O
z/VSE	B-Application
,	O
and	O
z/VM	B-Application
continued	O
to	O
support	O
32-bit	O
systems	O
;	O
z/OS	B-Application
version	O
1.6	O
and	O
later	O
,	O
z/VSE	B-Application
Version	O
4	O
and	O
later	O
,	O
and	O
z/VM	B-Application
Version	O
5	O
and	O
later	O
require	O
z/Architecture	B-Device
.	O
</s>
<s>
Linux	B-Application
also	O
supports	O
z/Architecture	B-Device
with	O
Linux	B-Application
on	I-Application
IBM	I-Application
Z	I-Application
.	O
</s>
<s>
z/Architecture	B-Device
supports	O
running	O
multiple	O
concurrent	O
operating	B-General_Concept
systems	I-General_Concept
and	O
applications	O
even	O
if	O
they	O
use	O
different	O
address	O
sizes	O
.	O
</s>
<s>
On	O
July	O
7	O
,	O
2009	O
,	O
IBM	O
on	O
occasion	O
of	O
announcing	O
a	O
new	O
version	O
of	O
one	O
of	O
its	O
operating	B-General_Concept
systems	I-General_Concept
implicitly	O
stated	O
that	O
Architecture	O
Level	O
Set	O
4	O
(	O
ALS	O
4	O
)	O
exists	O
,	O
and	O
is	O
implemented	O
on	O
the	O
System	B-Device
z10	I-Device
and	O
subsequent	O
machines	O
.	O
</s>
<s>
The	O
ALS	O
4	O
is	O
also	O
specified	O
in	O
LOADxx	O
as	O
ARCHLVL	O
3	O
,	O
whereas	O
the	O
earlier	O
z900	O
,	O
z800	O
,	O
z990	O
,	O
z890	O
,	O
System	B-Device
z9	I-Device
specified	O
ARCHLVL	O
2	O
.	O
</s>
<s>
Earlier	O
announcements	O
of	O
System	B-Device
z10	I-Device
simply	O
specified	O
that	O
it	O
implements	O
z/Architecture	B-Device
with	O
some	O
additions	O
:	O
50+	O
new	O
machine	O
instructions	O
,	O
1	O
MB	O
page	O
frames	O
,	O
and	O
hardware	O
decimal	O
floating	O
point	O
unit	O
(	O
HDFU	O
)	O
.	O
</s>
<s>
Most	O
operating	B-General_Concept
systems	I-General_Concept
for	O
the	O
z/Architecture	B-Device
,	O
including	O
z/OS	B-Application
,	O
generally	O
restrict	O
code	O
execution	O
to	O
the	O
first	O
2GB	O
(	O
31	O
address	O
bits	O
,	O
or	O
231	O
addressable	O
bytes	O
)	O
of	O
each	O
virtual	B-General_Concept
address	I-General_Concept
space	I-General_Concept
for	O
reasons	O
of	O
efficiency	O
and	O
compatibility	O
rather	O
than	O
because	O
of	O
architectural	O
limits	O
.	O
</s>
<s>
Linux	B-Application
on	I-Application
IBM	I-Application
Z	I-Application
allows	O
code	O
to	O
execute	O
within	O
64-bit	B-Device
address	O
ranges	O
.	O
</s>
<s>
Each	O
z/OS	B-Application
address	B-General_Concept
space	I-General_Concept
,	O
called	O
a	O
64-bit	B-Device
address	B-General_Concept
space	I-General_Concept
,	O
is	O
16	O
exabytes	O
in	O
size	O
.	O
</s>
<s>
The	O
z/OS	B-Application
implementation	O
of	O
the	O
Java	B-Language
programming	I-Language
language	I-Language
is	O
an	O
exception	O
.	O
</s>
<s>
The	O
z/OS	B-Application
virtual	B-Architecture
memory	I-Architecture
implementation	O
supports	O
multiple	O
2GB	O
address	O
spaces	O
,	O
permitting	O
more	O
than	O
2GB	O
of	O
concurrently	O
resident	O
program	O
code	O
.	O
</s>
<s>
(	O
Similar	O
to	O
the	O
NX	B-General_Concept
bit	I-General_Concept
on	O
other	O
modern	O
processors	O
.	O
)	O
</s>
<s>
By	O
default	O
,	O
the	O
z/Architecture	B-Device
memory	O
space	O
is	O
indexed	O
by	O
64-bit	B-Device
pointers	O
,	O
allowing	O
up	O
to	O
16	O
exabytes	O
of	O
memory	O
to	O
be	O
visible	O
to	O
an	O
executing	O
program	O
.	O
</s>
<s>
Applications	O
that	O
need	O
more	O
than	O
a	O
16exabyte	O
data	O
address	B-General_Concept
space	I-General_Concept
can	O
employ	O
extended	O
addressability	B-General_Concept
techniques	O
,	O
using	O
additional	O
address	O
spaces	O
or	O
data-only	O
spaces	O
.	O
</s>
<s>
These	O
spaces	O
are	O
similar	O
in	O
that	O
both	O
are	O
areas	O
of	O
virtual	B-Architecture
storage	I-Architecture
that	O
a	O
program	O
can	O
create	O
,	O
and	O
can	O
be	O
up	O
to	O
2gigabytes	O
.	O
</s>
<s>
Unlike	O
an	O
address	B-General_Concept
space	I-General_Concept
,	O
a	O
dataspace	O
or	O
hiperspace	O
contains	O
only	O
user	O
data	O
;	O
it	O
does	O
not	O
contain	O
system	O
control	O
blocks	O
or	O
common	O
areas	O
.	O
</s>
<s>
A	O
dataspace	O
differs	O
from	O
a	O
hiperspace	O
in	O
that	O
dataspaces	O
are	O
byte-addressable	B-General_Concept
,	O
whereas	O
hiperspaces	O
are	O
page-addressable	O
.	O
</s>
<s>
Traditionally	O
IBM	B-Architecture
Mainframe	I-Architecture
memory	O
has	O
been	O
byte-addressable	B-General_Concept
.	O
</s>
<s>
IBM	B-Architecture
Mainframe	I-Architecture
processors	O
through	O
much	O
of	O
the	O
1980s	O
and	O
1990s	O
supported	O
another	O
kind	O
of	O
memory	O
:	O
Expanded	O
Storage	O
.	O
</s>
<s>
The	O
MVPG	O
instruction	O
and	O
ADMF	O
are	O
explicitly	O
invoked	O
—	O
generally	O
by	O
middleware	O
in	O
z/OS	B-Application
or	O
z/VM	B-Application
(	O
and	O
ACP	O
?	O
</s>
<s>
Both	O
MVPG	O
and	O
ADMF	O
are	O
used	O
by	O
IBM	B-Application
Db2	I-Application
to	O
access	O
hiperpools	O
.	O
</s>
<s>
VM	B-Application
Minidisk	O
Caching	O
.	O
</s>
<s>
VM	B-Application
Minidisk	O
Caching	O
.	O
</s>
<s>
z/OS	B-Application
removed	O
the	O
support	O
for	O
Expanded	O
Storage	O
.	O
</s>
<s>
All	O
memory	O
in	O
z/OS	B-Application
is	O
now	O
Central	O
Storage	O
.	O
</s>
<s>
z/VM	B-Application
6.4	O
fulfills	O
Statement	O
of	O
Direction	O
to	O
drop	O
support	O
for	O
all	O
use	O
of	O
Expanded	O
Storage	O
.	O
</s>
<s>
The	O
MVPG	O
mainframe	B-Architecture
instruction	O
(	O
MoVe	O
PaGe	O
,	O
opcode	O
X'B254'	O
)	O
has	O
been	O
compared	O
to	O
the	O
MVCL	O
(	O
MoVe	O
Character	O
Long	O
)	O
instruction	O
,	O
both	O
of	O
which	O
can	O
move	O
more	O
than	O
256	O
bytes	O
within	O
main	O
memory	O
using	O
a	O
single	O
instruction	O
.	O
</s>
<s>
These	O
instructions	O
do	O
not	O
comply	O
with	O
definitions	O
for	O
atomicity	B-General_Concept
,	O
although	O
they	O
can	O
be	O
used	O
as	O
a	O
single	O
instruction	O
within	O
documented	O
timing	O
and	O
non-overlap	O
restrictions	O
.	O
</s>
<s>
The	O
need	O
to	O
move	O
more	O
than	O
256	O
bytes	O
within	O
main	O
memory	O
had	O
historically	O
been	O
addressed	O
with	O
software	O
(	O
MVC	O
loops	O
)	O
,	O
MVCL	O
,	O
which	O
was	O
introduced	O
with	O
the	O
1970	O
announcement	O
of	O
the	O
System/370	B-Device
,	O
and	O
MVPG	O
,	O
patented	O
and	O
announced	O
by	O
IBM	O
in	O
1989	O
,	O
each	O
have	O
advantages	O
.	O
</s>
<s>
A	O
macro	O
instruction	O
named	O
IOSADMF	O
,	O
which	O
has	O
been	O
described	O
as	O
an	O
API	B-Application
that	O
avoids	O
"	O
direct	O
,	O
low-level	O
use	O
of	O
ADMF	O
,	O
"	O
can	O
be	O
used	O
to	O
read	O
or	O
write	O
data	O
to	O
or	O
from	O
a	O
hiperspace	O
.	O
</s>
<s>
To	O
provide	O
reentrancy	B-Operating_System
,	O
IOSADMF	O
is	O
used	O
together	O
with	O
a	O
"	O
List	O
form	O
"	O
and	O
"	O
Execute	O
form.	O
"	O
</s>
<s>
Platform	O
Solutions	O
Inc	O
.	O
(	O
PSI	O
)	O
previously	O
marketed	O
Itanium-based	O
servers	O
which	O
were	O
compatible	O
with	O
z/Architecture	B-Device
.	O
</s>
<s>
FLEX-ES	O
,	O
zPDT	O
and	O
the	O
Hercules	B-Application
emulator	I-Application
also	O
implement	O
z/Architecture	B-Device
.	O
</s>
<s>
Hitachi	O
mainframes	B-Architecture
running	O
newer	O
releases	O
of	O
the	O
VOS3	O
operating	B-General_Concept
system	I-General_Concept
implement	O
ESA/390	O
plus	O
Hitachi-unique	O
CPU	O
instructions	O
,	O
including	O
a	O
few	O
64-bit	B-Device
instructions	O
.	O
</s>
<s>
While	O
Hitachi	O
formally	O
collaborated	O
with	O
IBM	O
on	O
the	O
z900-G2/z800	O
CPUs	O
introduced	O
in	O
2002	O
,	O
Hitachi	O
's	O
machines	O
are	O
not	O
z/Architecture	B-Device
-compatible	O
.	O
</s>
