<s>
A	O
mainframe	B-Architecture
computer	I-Architecture
,	O
informally	O
called	O
a	O
mainframe	B-Architecture
or	O
big	B-Architecture
iron	I-Architecture
,	O
is	O
a	O
computer	O
used	O
primarily	O
by	O
large	O
organizations	O
for	O
critical	O
applications	O
like	O
bulk	O
data	B-General_Concept
processing	I-General_Concept
for	O
tasks	O
such	O
as	O
censuses	O
,	O
industry	O
and	O
consumer	O
statistics	O
,	O
enterprise	O
resource	O
planning	O
,	O
and	O
large-scale	O
transaction	B-General_Concept
processing	I-General_Concept
.	O
</s>
<s>
A	O
mainframe	B-Architecture
computer	I-Architecture
is	O
large	O
but	O
not	O
as	O
large	O
as	O
a	O
supercomputer	B-Architecture
and	O
has	O
more	O
processing	O
power	O
than	O
some	O
other	O
classes	B-Device
of	I-Device
computers	I-Device
,	O
such	O
as	O
minicomputers	B-Architecture
,	O
servers	B-Application
,	O
workstations	B-Device
,	O
and	O
personal	B-Device
computers	I-Device
.	O
</s>
<s>
Mainframe	B-Architecture
computers	I-Architecture
are	O
often	O
used	O
as	O
servers	B-Application
.	O
</s>
<s>
The	O
term	O
mainframe	B-Architecture
was	O
derived	O
from	O
the	O
large	O
cabinet	O
,	O
called	O
a	O
main	B-Architecture
frame	I-Architecture
,	O
that	O
housed	O
the	O
central	B-General_Concept
processing	I-General_Concept
unit	I-General_Concept
and	O
main	O
memory	B-General_Concept
of	O
early	O
computers	O
.	O
</s>
<s>
Later	O
,	O
the	O
term	O
mainframe	B-Architecture
was	O
used	O
to	O
distinguish	O
high-end	O
commercial	O
computers	O
from	O
less	O
powerful	O
machines	O
.	O
</s>
<s>
Modern	O
mainframe	B-Architecture
design	O
is	O
characterized	O
less	O
by	O
raw	O
computational	O
speed	O
and	O
more	O
by	O
:	O
</s>
<s>
High	O
hardware	O
and	O
computational	O
utilization	O
rates	O
through	O
virtualization	B-General_Concept
to	O
support	O
massive	O
throughput	O
.	O
</s>
<s>
Hot-swapping	B-Device
of	I-Device
hardware	I-Device
,	O
such	O
as	O
processors	O
and	O
memory	B-General_Concept
.	O
</s>
<s>
Mainframes	B-Architecture
have	O
high	O
availability	O
,	O
one	O
of	O
the	O
primary	O
reasons	O
for	O
their	O
longevity	O
,	O
since	O
they	O
are	O
typically	O
used	O
in	O
applications	O
where	O
downtime	O
would	O
be	O
costly	O
or	O
catastrophic	O
.	O
</s>
<s>
The	O
term	O
reliability	B-General_Concept
,	I-General_Concept
availability	I-General_Concept
and	I-General_Concept
serviceability	I-General_Concept
(	O
RAS	B-General_Concept
)	O
is	O
a	O
defining	O
characteristic	O
of	O
mainframe	B-Architecture
computers	I-Architecture
.	O
</s>
<s>
In	O
addition	O
,	O
mainframes	B-Architecture
are	O
more	O
secure	O
than	O
other	O
computer	B-Device
types	I-Device
:	O
the	O
NIST	O
vulnerabilities	O
database	O
,	O
US-CERT	O
,	O
rates	O
traditional	O
mainframes	B-Architecture
such	O
as	O
IBM	B-Device
Z	I-Device
(	O
previously	O
called	O
z	B-Device
Systems	I-Device
,	O
System	B-Device
z	I-Device
and	O
zSeries	O
)	O
,	O
Unisys	O
Dorado	O
and	O
Unisys	O
Libra	O
as	O
among	O
the	O
most	O
secure	O
with	O
vulnerabilities	O
in	O
the	O
low	O
single	O
digits	O
as	O
compared	O
with	O
thousands	O
for	O
Windows	O
,	O
UNIX	B-Application
,	O
and	O
Linux	B-Application
.	O
</s>
<s>
Software	O
upgrades	O
usually	O
require	O
setting	O
up	O
the	O
operating	B-General_Concept
system	I-General_Concept
or	O
portions	O
thereof	O
,	O
and	O
are	O
non-disruptive	O
only	O
when	O
using	O
virtualizing	B-General_Concept
facilities	O
such	O
as	O
IBM	B-Application
z/OS	I-Application
and	O
Parallel	B-Operating_System
Sysplex	I-Operating_System
,	O
or	O
Unisys	O
XPCL	O
,	O
which	O
support	O
workload	O
sharing	O
so	O
that	O
one	O
system	O
can	O
take	O
over	O
another	O
's	O
application	O
while	O
it	O
is	O
being	O
refreshed	O
.	O
</s>
<s>
In	O
the	O
late	O
1950s	O
,	O
mainframes	B-Architecture
had	O
only	O
a	O
rudimentary	O
interactive	O
interface	O
(	O
the	O
console	O
)	O
and	O
used	O
sets	O
of	O
punched	B-Architecture
cards	I-Architecture
,	O
paper	O
tape	O
,	O
or	O
magnetic	B-Architecture
tape	I-Architecture
to	O
transfer	O
data	O
and	O
programs	O
.	O
</s>
<s>
They	O
operated	O
in	O
batch	B-General_Concept
mode	I-General_Concept
to	O
support	O
back	O
office	O
functions	O
such	O
as	O
payroll	O
and	O
customer	O
billing	O
,	O
most	O
of	O
which	O
were	O
based	O
on	O
repeated	O
tape-based	O
sorting	B-Algorithm
and	I-Algorithm
merging	I-Algorithm
operations	O
followed	O
by	O
line	O
printing	O
to	O
preprinted	O
continuous	O
stationery	O
.	O
</s>
<s>
airline	B-Application
booking	I-Application
)	O
rather	O
than	O
program	O
development	O
.	O
</s>
<s>
However	O
,	O
in	O
1961	O
the	O
first	O
academic	O
,	O
general-purpose	O
timesharing	B-General_Concept
system	O
that	O
supported	O
software	O
development	O
,	O
CTSS	B-Operating_System
,	O
was	O
released	O
at	O
MIT	O
on	O
an	O
IBM	B-Device
709	I-Device
,	O
later	O
7090	O
and	O
7094	O
.	O
</s>
<s>
Typewriter	O
and	O
Teletype	O
devices	O
were	O
common	O
control	O
consoles	O
for	O
system	O
operators	O
through	O
the	O
early	O
1970s	O
,	O
although	O
ultimately	O
supplanted	O
by	O
keyboard/display	O
devices	O
.	O
</s>
<s>
By	O
the	O
early	O
1970s	O
,	O
many	O
mainframes	B-Architecture
acquired	O
interactive	O
user	O
terminals	O
operating	O
as	O
timesharing	B-General_Concept
computers	O
,	O
supporting	O
hundreds	O
of	O
users	O
simultaneously	O
along	O
with	O
batch	B-General_Concept
processing	I-General_Concept
.	O
</s>
<s>
Users	O
gained	O
access	O
through	O
keyboard/typewriter	O
terminals	O
and	O
later	O
character-mode	O
text	O
terminal	B-General_Concept
CRT	B-Device
displays	I-Device
with	O
integral	O
keyboards	B-Device
,	O
or	O
finally	O
from	O
personal	B-Device
computers	I-Device
equipped	O
with	O
terminal	B-Application
emulation	I-Application
software	O
.	O
</s>
<s>
By	O
the	O
1980s	O
,	O
many	O
mainframes	B-Architecture
supported	O
general	O
purpose	O
graphic	O
display	B-Device
terminals	I-Device
,	O
and	O
terminal	B-Application
emulation	I-Application
,	O
but	O
not	O
graphical	B-Application
user	I-Application
interfaces	I-Application
.	O
</s>
<s>
This	O
form	O
of	O
end-user	O
computing	O
became	O
obsolete	O
in	O
the	O
1990s	O
due	O
to	O
the	O
advent	O
of	O
personal	B-Device
computers	I-Device
provided	O
with	O
GUIs	B-Application
.	O
</s>
<s>
After	O
2000	O
,	O
modern	O
mainframes	B-Architecture
partially	O
or	O
entirely	O
phased	O
out	O
classic	O
"	O
green	B-Device
screen	I-Device
"	O
and	O
color	B-Device
display	I-Device
terminal	B-General_Concept
access	O
for	O
end-users	O
in	O
favour	O
of	O
Web-style	O
user	O
interfaces	O
.	O
</s>
<s>
The	O
infrastructure	O
requirements	O
were	O
drastically	O
reduced	O
during	O
the	O
mid-1990s	O
,	O
when	O
CMOS	B-Device
mainframe	B-Architecture
designs	O
replaced	O
the	O
older	O
bipolar	O
technology	O
.	O
</s>
<s>
IBM	O
claimed	O
that	O
its	O
newer	O
mainframes	B-Architecture
reduced	O
data	O
center	O
energy	O
costs	O
for	O
power	O
and	O
cooling	O
,	O
and	O
reduced	O
physical	O
space	O
requirements	O
compared	O
to	O
server	B-Operating_System
farms	I-Operating_System
.	O
</s>
<s>
Modern	O
mainframes	B-Architecture
can	O
run	O
multiple	O
different	O
instances	O
of	O
operating	B-General_Concept
systems	I-General_Concept
at	O
the	O
same	O
time	O
.	O
</s>
<s>
This	O
technique	O
of	O
virtual	B-Architecture
machines	I-Architecture
allows	O
applications	O
to	O
run	O
as	O
if	O
they	O
were	O
on	O
physically	O
distinct	O
computers	O
.	O
</s>
<s>
In	O
this	O
role	O
,	O
a	O
single	O
mainframe	B-Architecture
can	O
replace	O
higher-functioning	O
hardware	O
services	O
available	O
to	O
conventional	O
servers	B-Application
.	O
</s>
<s>
While	O
mainframes	B-Architecture
pioneered	O
this	O
capability	O
,	O
virtualization	B-General_Concept
is	O
now	O
available	O
on	O
most	O
families	O
of	O
computer	O
systems	O
,	O
though	O
not	O
always	O
to	O
the	O
same	O
degree	O
or	O
level	O
of	O
sophistication	O
.	O
</s>
<s>
Mainframes	B-Architecture
can	O
add	O
or	O
hot	B-Device
swap	I-Device
system	O
capacity	O
without	O
disrupting	O
system	O
function	O
,	O
with	O
specificity	O
and	O
granularity	O
to	O
a	O
level	O
of	O
sophistication	O
not	O
usually	O
available	O
with	O
most	O
server	B-Application
solutions	O
.	O
</s>
<s>
Modern	O
mainframes	B-Architecture
,	O
notably	O
the	O
IBM	B-Device
Z	I-Device
servers	B-Application
,	O
offer	O
two	O
levels	O
of	O
virtualization	B-General_Concept
:	O
logical	B-Device
partitions	I-Device
(	O
LPARs	B-Device
,	O
via	O
the	O
PR/SM	B-Device
facility	O
)	O
and	O
virtual	B-Architecture
machines	I-Architecture
(	O
via	O
the	O
z/VM	B-Application
operating	B-General_Concept
system	I-General_Concept
)	O
.	O
</s>
<s>
Many	O
mainframe	B-Architecture
customers	O
run	O
two	O
machines	O
:	O
one	O
in	O
their	O
primary	O
data	O
center	O
and	O
one	O
in	O
their	O
backup	B-General_Concept
data	I-General_Concept
center	I-General_Concept
—	O
fully	O
active	O
,	O
partially	O
active	O
,	O
or	O
on	O
standby	O
—	O
in	O
case	O
there	O
is	O
a	O
catastrophe	O
affecting	O
the	O
first	O
building	O
.	O
</s>
<s>
Such	O
a	O
two-mainframe	O
installation	O
can	O
support	O
continuous	O
business	O
service	O
,	O
avoiding	O
both	O
planned	O
and	O
unplanned	O
outages	O
.	O
</s>
<s>
In	O
practice	O
,	O
many	O
customers	O
use	O
multiple	O
mainframes	B-Architecture
linked	O
either	O
by	O
Parallel	B-Operating_System
Sysplex	I-Operating_System
and	O
shared	O
DASD	B-Application
(	O
in	O
IBM	O
's	O
case	O
)	O
,	O
or	O
with	O
shared	O
,	O
geographically	O
dispersed	O
storage	O
provided	O
by	O
EMC	O
or	O
Hitachi	O
.	O
</s>
<s>
Mainframes	B-Architecture
are	O
designed	O
to	O
handle	O
very	O
high	O
volume	O
input	B-General_Concept
and	I-General_Concept
output	I-General_Concept
(	O
I/O	B-General_Concept
)	O
and	O
emphasize	O
throughput	O
computing	O
.	O
</s>
<s>
Since	O
the	O
late	O
1950s	O
,	O
mainframe	B-Architecture
designs	O
have	O
included	O
subsidiary	O
hardware	O
(	O
called	O
channels	O
or	O
peripheral	O
processors	O
)	O
which	O
manage	O
the	O
I/O	B-General_Concept
devices	I-General_Concept
,	O
leaving	O
the	O
CPU	B-Device
free	O
to	O
deal	O
only	O
with	O
high-speed	O
memory	B-General_Concept
.	O
</s>
<s>
It	O
is	O
common	O
in	O
mainframe	B-Architecture
shops	O
to	O
deal	O
with	O
massive	O
databases	O
and	O
files	O
.	O
</s>
<s>
Compared	O
to	O
a	O
typical	O
PC	O
,	O
mainframes	B-Architecture
commonly	O
have	O
hundreds	O
to	O
thousands	O
of	O
times	O
as	O
much	O
data	B-General_Concept
storage	I-General_Concept
online	O
,	O
and	O
can	O
access	O
it	O
reasonably	O
quickly	O
.	O
</s>
<s>
Other	O
server	B-Application
families	O
also	O
offload	O
I/O	B-General_Concept
processing	O
and	O
emphasize	O
throughput	O
computing	O
.	O
</s>
<s>
Mainframe	B-Architecture
return	O
on	O
investment	O
(	O
ROI	O
)	O
,	O
like	O
any	O
other	O
computing	O
platform	O
,	O
is	O
dependent	O
on	O
its	O
ability	O
to	O
scale	O
,	O
support	O
mixed	O
workloads	O
,	O
reduce	O
labor	O
costs	O
,	O
deliver	O
uninterrupted	O
service	O
for	O
critical	O
business	O
applications	O
,	O
and	O
several	O
other	O
risk-adjusted	O
cost	O
factors	O
.	O
</s>
<s>
Mainframes	B-Architecture
also	O
have	O
execution	O
integrity	O
characteristics	O
for	O
fault	B-General_Concept
tolerant	I-General_Concept
computing	O
.	O
</s>
<s>
For	O
example	O
,	O
z900	O
,	O
z990	O
,	O
System	B-Device
z9	I-Device
,	O
and	O
System	B-Device
z10	I-Device
servers	B-Application
effectively	O
execute	O
result-oriented	O
instructions	O
twice	O
,	O
compare	O
results	O
,	O
arbitrate	O
between	O
any	O
differences	O
(	O
through	O
instruction	O
retry	O
and	O
failure	O
isolation	O
)	O
,	O
then	O
shift	O
workloads	O
"	O
in	O
flight	O
"	O
to	O
functioning	O
processors	O
,	O
including	O
spares	O
,	O
without	O
any	O
impact	O
to	O
operating	B-General_Concept
systems	I-General_Concept
,	O
applications	O
,	O
or	O
users	O
.	O
</s>
<s>
This	O
hardware-level	O
feature	O
,	O
also	O
found	O
in	O
HP	O
's	O
NonStop	B-Architecture
systems	O
,	O
is	O
known	O
as	O
lock-stepping	O
,	O
because	O
both	O
processors	O
take	O
their	O
"	O
steps	O
"	O
(	O
i.e.	O
</s>
<s>
Not	O
all	O
applications	O
absolutely	O
need	O
the	O
assured	O
integrity	O
that	O
these	O
systems	O
provide	O
,	O
but	O
many	O
do	O
,	O
such	O
as	O
financial	O
transaction	B-General_Concept
processing	I-General_Concept
.	O
</s>
<s>
IBM	O
,	O
with	O
the	O
IBM	B-Device
Z	I-Device
series	O
,	O
continues	O
to	O
be	O
a	O
major	O
manufacturer	O
in	O
the	O
mainframe	B-Architecture
market	O
.	O
</s>
<s>
Unisys	O
manufactures	O
ClearPath	B-Device
Libra	I-Device
mainframes	B-Architecture
,	O
based	O
on	O
earlier	O
Burroughs	B-Application
MCP	I-Application
products	O
and	O
ClearPath	O
Dorado	O
mainframes	B-Architecture
based	O
on	O
Sperry	O
Univac	O
OS	B-Operating_System
1100	I-Operating_System
product	O
lines	O
.	O
</s>
<s>
Hewlett	O
Packard	O
Enterprise	O
sells	O
its	O
unique	O
NonStop	B-Architecture
systems	O
,	O
which	O
it	O
acquired	O
with	O
Tandem	O
Computers	O
and	O
which	O
some	O
analysts	O
classify	O
as	O
mainframes	B-Architecture
.	O
</s>
<s>
Groupe	O
Bull	O
's	O
GCOS	B-Application
,	O
Stratus	B-General_Concept
OpenVOS	I-General_Concept
,	O
Fujitsu	O
(	O
formerly	O
Siemens	O
)	O
BS2000	B-Application
,	O
and	O
Fujitsu-ICL	O
VME	O
mainframes	B-Architecture
are	O
still	O
available	O
in	O
Europe	O
,	O
and	O
Fujitsu	O
(	O
formerly	O
Amdahl	O
)	O
GS21	O
mainframes	B-Architecture
globally	O
.	O
</s>
<s>
NEC	O
with	O
ACOS	B-Application
and	O
Hitachi	O
with	O
AP10000-VOS3	O
still	O
maintain	O
mainframe	B-Architecture
businesses	O
in	O
the	O
Japanese	O
market	O
.	O
</s>
<s>
The	O
amount	O
of	O
vendor	O
investment	O
in	O
mainframe	B-Architecture
development	O
varies	O
with	O
market	O
share	O
.	O
</s>
<s>
Fujitsu	O
and	O
Hitachi	O
both	O
continue	O
to	O
use	O
custom	O
S/390	O
-compatible	O
processors	O
,	O
as	O
well	O
as	O
other	O
CPUs	B-Device
(	O
including	O
POWER	O
and	O
Xeon	B-Device
)	O
for	O
lower-end	O
systems	O
.	O
</s>
<s>
Bull	O
uses	O
a	O
mixture	O
of	O
Itanium	B-General_Concept
and	O
Xeon	B-Device
processors	O
.	O
</s>
<s>
NEC	O
uses	O
Xeon	B-Device
processors	O
for	O
its	O
low-end	O
ACOS-2	O
line	O
,	O
but	O
develops	O
the	O
custom	O
NOAH-6	O
processor	O
for	O
its	O
high-end	O
ACOS-4	B-Application
series	O
.	O
</s>
<s>
IBM	O
also	O
develops	O
custom	O
processors	O
in-house	O
,	O
such	O
as	O
the	O
Telum	B-Device
.	O
</s>
<s>
Unisys	O
produces	O
code	O
compatible	O
mainframe	B-Architecture
systems	O
that	O
range	O
from	O
laptops	O
to	O
cabinet-sized	O
mainframes	B-Architecture
that	O
use	O
homegrown	O
CPUs	B-Device
as	O
well	O
as	O
Xeon	B-Device
processors	O
.	O
</s>
<s>
Furthermore	O
,	O
there	O
exists	O
a	O
market	O
for	O
software	O
applications	O
to	O
manage	O
the	O
performance	O
of	O
mainframe	B-Architecture
implementations	O
.	O
</s>
<s>
Starting	O
in	O
the	O
2010s	O
,	O
cloud	B-Architecture
computing	I-Architecture
is	O
now	O
a	O
less	O
expensive	O
,	O
more	O
scalable	O
alternative	O
.	O
</s>
<s>
Several	O
manufacturers	O
and	O
their	O
successors	O
produced	O
mainframe	B-Architecture
computers	I-Architecture
from	O
the	O
1950s	O
until	O
the	O
early	O
21st	O
century	O
,	O
with	O
gradually	O
decreasing	O
numbers	O
and	O
a	O
gradual	O
transition	O
to	O
simulation	O
on	O
Intel	O
chips	O
rather	O
than	O
proprietary	O
hardware	O
.	O
</s>
<s>
IBM	O
's	O
dominance	O
grew	O
out	O
of	O
their	O
700/7000	B-Device
series	I-Device
and	O
,	O
later	O
,	O
the	O
development	O
of	O
the	O
360	B-Application
series	I-Application
mainframes	B-Architecture
.	O
</s>
<s>
The	O
latter	O
architecture	O
has	O
continued	O
to	O
evolve	O
into	O
their	O
current	O
zSeries	O
mainframes	B-Architecture
which	O
,	O
along	O
with	O
the	O
then	O
Burroughs	O
and	O
Sperry	O
(	O
now	O
Unisys	O
)	O
MCP-based	O
and	O
OS1100	B-Operating_System
mainframes	B-Architecture
,	O
are	O
among	O
the	O
few	O
mainframe	B-Architecture
architectures	O
still	O
extant	O
that	O
can	O
trace	O
their	O
roots	O
to	O
this	O
early	O
period	O
.	O
</s>
<s>
While	O
IBM	O
's	O
zSeries	O
can	O
still	O
run	O
24-bit	O
System/360	B-Application
code	O
,	O
the	O
64-bit	O
IBM	B-Device
Z	I-Device
CMOS	B-Device
servers	B-Application
have	O
nothing	O
physically	O
in	O
common	O
with	O
the	O
older	O
systems	O
.	O
</s>
<s>
The	O
Soviet	O
Union	O
and	O
Warsaw	O
Pact	O
countries	O
manufactured	O
close	O
copies	O
of	O
IBM	O
mainframes	B-Architecture
during	O
the	O
Cold	B-Application
War	I-Application
;	O
the	O
BESM	B-Device
series	O
and	O
Strela	B-Device
are	O
examples	O
of	O
an	O
independently	O
designed	O
Soviet	O
computer	O
.	O
</s>
<s>
Other	O
Eastern	O
Block	O
manufacturer	O
is	O
Elwro	O
in	O
Poland	O
,	O
manufacturing	O
ODRA	B-Device
,	O
R-32	O
and	O
R-34	O
mainframes	B-Architecture
.	O
</s>
<s>
In	O
1984	O
estimated	O
sales	O
of	O
desktop	O
computers	O
(	O
$11.6	O
billion	O
)	O
exceeded	O
mainframe	B-Architecture
computers	I-Architecture
(	O
$11.4	O
billion	O
)	O
for	O
the	O
first	O
time	O
.	O
</s>
<s>
IBM	O
received	O
the	O
vast	O
majority	O
of	O
mainframe	B-Architecture
revenue	O
.	O
</s>
<s>
During	O
the	O
1980s	O
,	O
minicomputer-based	O
systems	O
grew	O
more	O
sophisticated	O
and	O
were	O
able	O
to	O
displace	O
the	O
lower	O
end	O
of	O
the	O
mainframes	B-Architecture
.	O
</s>
<s>
These	O
computers	O
,	O
sometimes	O
called	O
departmental	O
computers	O
,	O
were	O
typified	O
by	O
the	O
Digital	O
Equipment	O
Corporation	O
VAX	B-Device
series	O
.	O
</s>
<s>
During	O
the	O
same	O
period	O
,	O
companies	O
found	O
that	O
servers	B-Application
based	O
on	O
microcomputer	O
designs	O
could	O
be	O
deployed	O
at	O
a	O
fraction	O
of	O
the	O
acquisition	O
price	O
and	O
offer	O
local	O
users	O
much	O
greater	O
control	O
over	O
their	O
own	O
systems	O
given	O
the	O
IT	O
policies	O
and	O
practices	O
at	O
that	O
time	O
.	O
</s>
<s>
Terminals	O
used	O
for	O
interacting	O
with	O
mainframe	B-Architecture
systems	O
were	O
gradually	O
replaced	O
by	O
personal	B-Device
computers	I-Device
.	O
</s>
<s>
Consequently	O
,	O
demand	O
plummeted	O
and	O
new	O
mainframe	B-Architecture
installations	O
were	O
restricted	O
mainly	O
to	O
financial	O
services	O
and	O
government	O
.	O
</s>
<s>
In	O
the	O
early	O
1990s	O
,	O
there	O
was	O
a	O
rough	O
consensus	O
among	O
industry	O
analysts	O
that	O
the	O
mainframe	B-Architecture
was	O
a	O
dying	O
market	O
as	O
mainframe	B-Architecture
platforms	O
were	O
increasingly	O
replaced	O
by	O
personal	B-Device
computer	I-Device
networks	O
.	O
</s>
<s>
InfoWorld	O
's	O
Stewart	O
Alsop	O
infamously	O
predicted	O
that	O
the	O
last	O
mainframe	B-Architecture
would	O
be	O
unplugged	O
in	O
1996	O
;	O
in	O
1993	O
,	O
he	O
cited	O
Cheryl	O
Currid	O
,	O
a	O
computer	O
industry	O
analyst	O
as	O
saying	O
that	O
the	O
last	O
mainframe	B-Architecture
"	O
will	O
stop	O
working	O
on	O
December	O
31	O
,	O
1999	O
"	O
,	O
a	O
reference	O
to	O
the	O
anticipated	O
Year	B-Error_Name
2000	I-Error_Name
problem	I-Error_Name
(	O
Y2K	B-Error_Name
)	O
.	O
</s>
<s>
That	O
trend	O
started	O
to	O
turn	O
around	O
in	O
the	O
late	O
1990s	O
as	O
corporations	O
found	O
new	O
uses	O
for	O
their	O
existing	O
mainframes	B-Architecture
and	O
as	O
the	O
price	O
of	O
data	O
networking	O
collapsed	O
in	O
most	O
parts	O
of	O
the	O
world	O
,	O
encouraging	O
trends	O
toward	O
more	O
centralized	O
computing	O
.	O
</s>
<s>
The	O
growth	O
of	O
e-business	B-Application
also	O
dramatically	O
increased	O
the	O
number	O
of	O
back-end	O
transactions	O
processed	O
by	O
mainframe	B-Architecture
software	O
as	O
well	O
as	O
the	O
size	O
and	O
throughput	O
of	O
databases	O
.	O
</s>
<s>
Batch	B-General_Concept
processing	I-General_Concept
,	O
such	O
as	O
billing	O
,	O
became	O
even	O
more	O
important	O
(	O
and	O
larger	O
)	O
with	O
the	O
growth	O
of	O
e-business	B-Application
,	O
and	O
mainframes	B-Architecture
are	O
particularly	O
adept	O
at	O
large-scale	O
batch	B-General_Concept
computing	I-General_Concept
.	O
</s>
<s>
Another	O
factor	O
currently	O
increasing	O
mainframe	B-Architecture
use	O
is	O
the	O
development	O
of	O
the	O
Linux	B-Application
operating	I-Application
system	I-Application
,	O
which	O
arrived	B-Application
on	I-Application
IBM	I-Application
mainframe	I-Application
systems	I-Application
in	O
1999	O
and	O
is	O
typically	O
run	O
in	O
scores	O
or	O
up	O
to	O
c	O
.	O
8,000	O
virtual	B-Architecture
machines	I-Architecture
on	O
a	O
single	O
mainframe	B-Architecture
.	O
</s>
<s>
Linux	B-Application
allows	O
users	O
to	O
take	O
advantage	O
of	O
open	B-Application
source	I-Application
software	I-Application
combined	O
with	O
mainframe	B-Architecture
hardware	O
RAS	B-General_Concept
.	O
</s>
<s>
Rapid	O
expansion	O
and	O
development	O
in	O
emerging	O
markets	O
,	O
particularly	O
People	O
's	O
Republic	O
of	O
China	O
,	O
is	O
also	O
spurring	O
major	O
mainframe	B-Architecture
investments	O
to	O
solve	O
exceptionally	O
difficult	O
computing	O
problems	O
,	O
e.g.	O
</s>
<s>
providing	O
unified	O
,	O
extremely	O
high	O
volume	O
online	B-General_Concept
transaction	I-General_Concept
processing	I-General_Concept
databases	O
for	O
1	O
billion	O
consumers	O
across	O
multiple	O
industries	O
(	O
banking	O
,	O
insurance	O
,	O
credit	O
reporting	O
,	O
government	O
services	O
,	O
etc	O
.	O
)	O
</s>
<s>
In	O
late	O
2000	O
,	O
IBM	O
introduced	O
64-bit	O
z/Architecture	B-Device
,	O
acquired	O
numerous	O
software	O
companies	O
such	O
as	O
Cognos	O
and	O
introduced	O
those	O
software	O
products	O
to	O
the	O
mainframe	B-Architecture
.	O
</s>
<s>
IBM	O
's	O
quarterly	O
and	O
annual	O
reports	O
in	O
the	O
2000s	O
usually	O
reported	O
increasing	O
mainframe	B-Architecture
revenues	O
and	O
capacity	O
shipments	O
.	O
</s>
<s>
However	O
,	O
IBM	O
's	O
mainframe	B-Architecture
hardware	O
business	O
has	O
not	O
been	O
immune	O
to	O
the	O
recent	O
overall	O
downturn	O
in	O
the	O
server	B-Application
hardware	O
market	O
or	O
to	O
model	O
cycle	O
effects	O
.	O
</s>
<s>
For	O
example	O
,	O
in	O
the	O
4th	O
quarter	O
of	O
2009	O
,	O
IBM	O
's	O
System	B-Device
z	I-Device
hardware	O
revenues	O
decreased	O
by	O
27%	O
year	O
over	O
year	O
.	O
</s>
<s>
Alsop	O
had	O
himself	O
photographed	O
in	O
2000	O
,	O
symbolically	O
eating	O
his	O
own	O
words	O
(	O
"	O
death	O
of	O
the	O
mainframe	B-Architecture
"	O
)	O
.	O
</s>
<s>
In	O
2012	O
,	O
NASA	O
powered	O
down	O
its	O
last	O
mainframe	B-Architecture
,	O
an	O
IBM	B-Device
System	I-Device
z9	I-Device
.	O
</s>
<s>
However	O
,	O
IBM	O
's	O
successor	O
to	O
the	O
z9	O
,	O
the	O
z10	B-Device
,	O
led	O
a	O
New	O
York	O
Times	O
reporter	O
to	O
state	O
four	O
years	O
earlier	O
that	O
"	O
mainframe	B-Architecture
technology	O
—	O
hardware	O
,	O
software	O
and	O
services	O
—	O
remains	O
a	O
large	O
and	O
lucrative	O
business	O
for	O
I.B.M.	O
,	O
and	O
mainframes	B-Architecture
are	O
still	O
the	O
back-office	O
engines	O
behind	O
the	O
world	O
's	O
financial	O
markets	O
and	O
much	O
of	O
global	O
commerce	O
"	O
.	O
</s>
<s>
,	O
while	O
mainframe	B-Architecture
technology	O
represented	O
less	O
than	O
3%	O
of	O
IBM	O
's	O
revenues	O
,	O
it	O
"continue[d]	O
to	O
play	O
an	O
outsized	O
role	O
in	O
Big	O
Blue	O
's	O
results	O
"	O
.	O
</s>
<s>
In	O
2015	O
,	O
IBM	O
launched	O
the	O
IBM	B-Device
z13	I-Device
,	O
in	O
June	O
2017	O
the	O
IBM	B-Device
z14	I-Device
,	O
in	O
September	O
2019	O
the	O
IBM	B-Device
z15	I-Device
and	O
on	O
April	O
5	O
,	O
2022	O
,	O
they	O
announced	O
IBM	O
's	O
latest	O
mainframe	B-Architecture
system	O
,	O
the	O
IBM	O
z16	O
,	O
featuring	O
among	O
other	O
things	O
an	O
"	O
integrated	O
on-chip	O
AI	O
accelerator	O
"	O
and	O
the	O
new	O
Telum	B-Device
microprocessor	I-Device
.	O
</s>
<s>
A	O
supercomputer	B-Architecture
is	O
a	O
computer	O
at	O
the	O
leading	O
edge	O
of	O
data	B-General_Concept
processing	I-General_Concept
capability	O
,	O
with	O
respect	O
to	O
calculation	O
speed	O
.	O
</s>
<s>
Supercomputers	B-Architecture
are	O
used	O
for	O
scientific	O
and	O
engineering	O
problems	O
(	O
high-performance	B-Architecture
computing	I-Architecture
)	O
which	O
crunch	O
numbers	O
and	O
data	O
,	O
while	O
mainframes	B-Architecture
focus	O
on	O
transaction	B-General_Concept
processing	I-General_Concept
.	O
</s>
<s>
Mainframes	B-Architecture
are	O
built	O
to	O
be	O
reliable	O
for	O
transaction	B-General_Concept
processing	I-General_Concept
(	O
measured	O
by	O
TPC-metrics	O
;	O
not	O
used	O
or	O
helpful	O
for	O
most	O
supercomputing	B-Architecture
applications	O
)	O
as	O
it	O
is	O
commonly	O
understood	O
in	O
the	O
business	O
world	O
:	O
the	O
commercial	O
exchange	O
of	O
goods	O
,	O
services	O
,	O
or	O
money	O
.	O
</s>
<s>
A	O
typical	O
transaction	O
,	O
as	O
defined	O
by	O
the	O
Transaction	B-General_Concept
Processing	I-General_Concept
Performance	I-General_Concept
Council	I-General_Concept
,	O
updates	O
a	O
database	O
system	O
for	O
inventory	O
control	O
(	O
goods	O
)	O
,	O
airline	O
reservations	O
(	O
services	O
)	O
,	O
or	O
banking	O
(	O
money	O
)	O
by	O
adding	O
a	O
record	O
.	O
</s>
<s>
A	O
transaction	O
may	O
refer	O
to	O
a	O
set	O
of	O
operations	O
including	O
disk	O
read/writes	O
,	O
operating	B-General_Concept
system	I-General_Concept
calls	O
,	O
or	O
some	O
form	O
of	O
data	O
transfer	O
from	O
one	O
subsystem	O
to	O
another	O
which	O
is	O
not	O
measured	O
by	O
the	O
processing	O
speed	O
of	O
the	O
CPU	B-Device
.	O
</s>
<s>
Transaction	B-General_Concept
processing	I-General_Concept
is	O
not	O
exclusive	O
to	O
mainframes	B-Architecture
but	O
is	O
also	O
used	O
by	O
microprocessor-based	O
servers	B-Application
and	O
online	O
networks	O
.	O
</s>
<s>
Supercomputer	B-Architecture
performance	O
is	O
measured	O
in	O
floating	B-Algorithm
point	I-Algorithm
operations	O
per	O
second	O
(	O
FLOPS	O
)	O
or	O
in	O
traversed	B-Operating_System
edges	I-Operating_System
per	I-Operating_System
second	I-Operating_System
or	O
TEPS	O
,	O
metrics	O
that	O
are	O
not	O
very	O
meaningful	O
for	O
mainframe	B-Architecture
applications	O
,	O
while	O
mainframes	B-Architecture
are	O
sometimes	O
measured	O
in	O
millions	O
of	O
instructions	O
per	O
second	O
(	O
MIPS	O
)	O
,	O
although	O
the	O
definition	O
depends	O
on	O
the	O
instruction	O
mix	O
measured	O
.	O
</s>
<s>
Examples	O
of	O
integer	O
operations	O
measured	O
by	O
MIPS	O
include	O
adding	O
numbers	O
together	O
,	O
checking	O
values	O
or	O
moving	O
data	O
around	O
in	O
memory	B-General_Concept
(	O
while	O
moving	O
information	O
to	O
and	O
from	O
storage	O
,	O
so-called	O
I/O	B-General_Concept
is	O
most	O
helpful	O
for	O
mainframes	B-Architecture
;	O
and	O
within	O
memory	B-General_Concept
,	O
only	O
helping	O
indirectly	O
)	O
.	O
</s>
<s>
Floating	B-Algorithm
point	I-Algorithm
operations	O
are	O
mostly	O
addition	O
,	O
subtraction	O
,	O
and	O
multiplication	O
(	O
of	O
binary	B-Algorithm
floating	I-Algorithm
point	I-Algorithm
in	O
supercomputers	B-Architecture
;	O
measured	O
by	O
FLOPS	O
)	O
with	O
enough	O
digits	O
of	O
precision	O
to	O
model	O
continuous	O
phenomena	O
such	O
as	O
weather	O
prediction	O
and	O
nuclear	O
simulations	O
(	O
only	O
recently	O
standardized	O
decimal	O
floating	B-Algorithm
point	I-Algorithm
,	O
not	O
used	O
in	O
supercomputers	B-Architecture
,	O
are	O
appropriate	O
for	O
monetary	O
values	O
such	O
as	O
those	O
useful	O
for	O
mainframe	B-Architecture
applications	O
)	O
.	O
</s>
<s>
In	O
terms	O
of	O
computational	O
speed	O
,	O
supercomputers	B-Architecture
are	O
more	O
powerful	O
.	O
</s>
<s>
Mainframes	B-Architecture
and	O
supercomputers	B-Architecture
cannot	O
always	O
be	O
clearly	O
distinguished	O
;	O
up	O
until	O
the	O
early	O
1990s	O
,	O
many	O
supercomputers	B-Architecture
were	O
based	O
on	O
a	O
mainframe	B-Architecture
architecture	O
with	O
supercomputing	B-Architecture
extensions	O
.	O
</s>
<s>
An	O
example	O
of	O
such	O
a	O
system	O
is	O
the	O
HITAC	B-Device
S-3800	I-Device
,	O
which	O
was	O
instruction-set	O
compatible	O
with	O
IBM	B-Device
System/370	I-Device
mainframes	B-Architecture
,	O
and	O
could	O
run	O
the	O
Hitachi	O
VOS3	O
operating	B-General_Concept
system	I-General_Concept
(	O
a	O
fork	O
of	O
IBM	B-Application
MVS	I-Application
)	O
.	O
</s>
<s>
The	O
S-3800	O
therefore	O
can	O
be	O
seen	O
as	O
being	O
both	O
simultaneously	O
a	O
supercomputer	B-Architecture
and	O
also	O
an	O
IBM-compatible	O
mainframe	B-Architecture
.	O
</s>
<s>
In	O
2007	O
,	O
an	O
amalgamation	O
of	O
the	O
different	O
technologies	O
and	O
architectures	O
for	O
supercomputers	B-Architecture
and	O
mainframes	B-Architecture
has	O
led	O
to	O
a	O
so-called	O
gameframe	B-Protocol
.	O
</s>
