<s>
Backward	B-General_Concept
compatibility	I-General_Concept
(	O
sometimes	O
known	O
as	O
backwards	B-General_Concept
compatibility	I-General_Concept
)	O
is	O
a	O
property	O
of	O
an	O
operating	B-General_Concept
system	I-General_Concept
,	O
product	O
,	O
or	O
technology	O
that	O
allows	O
for	O
interoperability	O
with	O
an	O
older	O
legacy	B-Device
system	I-Device
,	O
or	O
with	O
input	B-General_Concept
designed	O
for	O
such	O
a	O
system	O
,	O
especially	O
in	O
telecommunications	O
and	O
computing	O
.	O
</s>
<s>
Modifying	O
a	O
system	O
in	O
a	O
way	O
that	O
does	O
not	O
allow	O
backward	B-General_Concept
compatibility	I-General_Concept
is	O
sometimes	O
called	O
"	O
breaking	O
"	O
backward	B-General_Concept
compatibility	I-General_Concept
.	O
</s>
<s>
A	O
complementary	O
concept	O
is	O
forward	B-General_Concept
compatibility	I-General_Concept
.	O
</s>
<s>
A	O
design	O
that	O
is	O
forward-compatible	B-General_Concept
usually	O
has	O
a	O
roadmap	O
for	O
compatibility	B-Device
with	O
future	O
standards	O
and	O
products	O
.	O
</s>
<s>
A	O
simple	O
example	O
of	O
both	O
backward	O
and	O
forward	B-General_Concept
compatibility	I-General_Concept
is	O
the	O
introduction	O
of	O
FM	O
radio	O
in	O
stereo	O
.	O
</s>
<s>
Forward	B-General_Concept
compatibility	I-General_Concept
for	O
mono	O
receivers	O
with	O
stereo	O
signals	O
was	O
achieved	O
by	O
sending	O
the	O
sum	O
of	O
both	O
left	O
and	O
right	O
audio	O
channels	O
in	O
one	O
signal	O
and	O
the	O
difference	O
in	O
another	O
signal	O
.	O
</s>
<s>
Without	O
the	O
requirement	O
for	O
backward	B-General_Concept
compatibility	I-General_Concept
,	O
a	O
simpler	O
method	O
could	O
have	O
been	O
chosen	O
.	O
</s>
<s>
Full	O
backward	B-General_Concept
compatibility	I-General_Concept
is	O
particularly	O
important	O
in	O
computer	O
instruction	B-General_Concept
set	I-General_Concept
architectures	I-General_Concept
,	O
one	O
of	O
the	O
most	O
successful	O
being	O
the	O
x86	B-Operating_System
family	O
of	O
microprocessors	B-Architecture
.	O
</s>
<s>
Their	O
full	O
backward	B-General_Concept
compatibility	I-General_Concept
spans	O
back	O
to	O
the	O
16-bit	O
Intel	O
8086/8088	O
processors	O
introduced	O
in	O
1978	O
.	O
</s>
<s>
(	O
The	O
8086/8088	O
,	O
in	O
turn	O
,	O
were	O
designed	O
with	O
easy	O
machine-translatability	O
of	O
programs	O
written	O
for	O
its	O
predecessor	O
in	O
mind	O
,	O
although	O
they	O
were	O
not	O
instruction-set	O
compatible	O
with	O
the	O
8-bit	O
Intel	B-General_Concept
8080	I-General_Concept
processor	O
as	O
of	O
1974	O
.	O
</s>
<s>
The	O
Zilog	B-General_Concept
Z80	I-General_Concept
,	O
however	O
,	O
was	O
fully	O
backward	B-General_Concept
compatible	I-General_Concept
with	O
the	O
Intel	B-General_Concept
8080	I-General_Concept
.	O
)	O
</s>
<s>
Fully	O
backward	B-General_Concept
compatible	I-General_Concept
processors	O
can	O
process	O
the	O
same	O
binary	B-Application
executable	I-Application
software	I-Application
instructions	I-Application
as	O
their	O
predecessors	O
,	O
allowing	O
the	O
use	O
of	O
a	O
newer	O
processor	O
without	O
having	O
to	O
acquire	O
new	O
applications	B-Application
or	O
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
Similarly	O
,	O
the	O
success	O
of	O
the	O
Wi-Fi	O
digital	O
communication	O
standard	O
is	O
attributed	O
to	O
its	O
broad	O
forward	O
and	O
backward	B-General_Concept
compatibility	I-General_Concept
;	O
it	O
became	O
more	O
popular	O
than	O
other	O
standards	O
that	O
were	O
not	O
backward	B-General_Concept
compatible	I-General_Concept
.	O
</s>
<s>
Compiler	B-Language
backward	B-General_Concept
compatibility	I-General_Concept
may	O
refer	O
to	O
the	O
ability	O
of	O
a	O
compiler	B-Language
of	O
a	O
newer	O
version	O
of	O
the	O
language	O
to	O
accept	O
programs	O
or	O
data	O
that	O
worked	O
under	O
the	O
previous	O
version	O
.	O
</s>
<s>
A	O
data	O
format	O
is	O
said	O
to	O
be	O
backward	B-General_Concept
compatible	I-General_Concept
with	O
its	O
predecessor	O
if	O
every	O
message	O
or	O
file	O
that	O
is	O
valid	O
under	O
the	O
old	O
format	O
is	O
still	O
valid	O
,	O
retaining	O
its	O
meaning	O
,	O
under	O
the	O
new	O
format	O
.	O
</s>
<s>
There	O
are	O
several	O
incentives	O
for	O
a	O
company	O
to	O
implement	O
backward	B-General_Concept
compatibility	I-General_Concept
.	O
</s>
<s>
Backward	B-General_Concept
compatibility	I-General_Concept
can	O
be	O
used	O
to	O
preserve	O
older	O
software	O
that	O
would	O
have	O
otherwise	O
been	O
lost	O
when	O
a	O
manufacturer	O
decides	O
to	O
stop	O
supporting	O
older	O
hardware	O
.	O
</s>
<s>
The	O
cultural	O
impact	O
of	O
video	O
games	O
is	O
a	O
large	O
part	O
of	O
their	O
continued	O
success	O
,	O
and	O
some	O
believe	O
ignoring	O
backward	B-General_Concept
compatibility	I-General_Concept
would	O
cause	O
these	O
titles	O
to	O
disappear	O
.	O
</s>
<s>
Backward	B-General_Concept
compatibility	I-General_Concept
also	O
acts	O
as	O
a	O
selling	O
point	O
for	O
new	O
hardware	O
,	O
as	O
an	O
existing	O
player	O
base	O
can	O
more	O
affordably	O
upgrade	B-General_Concept
to	O
subsequent	O
generations	O
of	O
a	O
console	O
.	O
</s>
<s>
Moreover	O
,	O
studies	O
in	O
the	O
mid-1990s	O
found	O
that	O
even	O
consumers	O
who	O
never	O
play	O
older	O
games	O
after	O
purchasing	O
a	O
new	O
system	O
consider	O
backward	B-General_Concept
compatibility	I-General_Concept
a	O
highly	O
desirable	O
feature	O
,	O
valuing	O
the	O
mere	O
ability	O
to	O
continue	O
to	O
play	O
an	O
existing	O
collection	O
of	O
games	O
even	O
if	O
they	O
choose	O
never	O
to	O
do	O
so	O
.	O
</s>
<s>
Backward	B-General_Concept
compatibility	I-General_Concept
with	O
the	O
original	B-Device
PlayStation	I-Device
(	O
PS	O
)	O
software	O
discs	O
and	O
peripherals	O
is	O
considered	O
to	O
have	O
been	O
a	O
key	O
selling	O
point	O
for	O
the	O
PlayStation	B-Device
2	I-Device
(	O
PS2	B-Device
)	O
during	O
its	O
early	O
months	O
on	O
the	O
market	O
.	O
</s>
<s>
Despite	O
not	O
being	O
included	O
at	O
launch	O
,	O
Microsoft	O
slowly	O
incorporated	O
backward	B-General_Concept
compatibility	I-General_Concept
for	O
select	O
titles	O
on	O
the	O
Xbox	B-Device
One	O
several	O
years	O
into	O
its	O
product	O
life	O
cycle	O
.	O
</s>
<s>
Players	O
have	O
racked	O
up	O
over	O
a	O
billion	O
hours	O
with	O
backward-compatible	B-General_Concept
games	O
on	O
Xbox	B-Device
,	O
and	O
the	O
newest	O
generation	O
of	O
consoles	O
such	O
as	O
PlayStation	B-Device
5	I-Device
and	O
Xbox	B-Device
Series	I-Device
X/S	I-Device
also	O
support	O
this	O
feature	O
.	O
</s>
<s>
A	O
large	O
part	O
of	O
the	O
success	O
and	O
implementation	O
of	O
this	O
feature	O
is	O
that	O
the	O
hardware	O
within	O
newer	O
generation	O
consoles	O
is	O
both	O
powerful	O
and	O
similar	O
enough	O
to	O
legacy	B-Device
systems	I-Device
that	O
older	O
titles	O
can	O
be	O
broken	O
down	O
and	O
re-configured	O
to	O
run	O
on	O
the	O
Xbox	B-Device
One	O
.	O
</s>
<s>
This	O
program	O
has	O
proven	O
incredibly	O
popular	O
with	O
Xbox	B-Device
players	O
and	O
goes	O
against	O
the	O
recent	O
trend	O
of	O
studio	O
made	O
remasters	O
of	O
classic	O
titles	O
,	O
creating	O
what	O
some	O
believe	O
to	O
be	O
an	O
important	O
shift	O
in	O
console	O
maker	O
's	O
strategies	O
.	O
</s>
<s>
The	O
monetary	O
costs	O
of	O
supporting	O
old	O
software	O
is	O
considered	O
a	O
large	O
drawback	O
to	O
the	O
usage	O
of	O
backward	B-General_Concept
compatibility	I-General_Concept
.	O
</s>
<s>
The	O
associated	O
costs	O
of	O
backward	B-General_Concept
compatibility	I-General_Concept
are	O
a	O
larger	O
bill	O
of	O
materials	O
if	O
hardware	O
is	O
required	O
to	O
support	O
the	O
legacy	B-Device
systems	I-Device
;	O
increased	O
complexity	O
of	O
the	O
product	O
that	O
may	O
lead	O
to	O
longer	O
time	O
to	O
market	O
,	O
technological	O
hindrances	O
,	O
and	O
slowing	O
innovation	O
;	O
and	O
increased	O
expectations	O
from	O
users	O
in	O
terms	O
of	O
compatibility	B-Device
.	O
</s>
<s>
Because	O
of	O
this	O
,	O
several	O
console	O
manufacturers	O
phased	O
out	O
backward	B-General_Concept
compatibility	I-General_Concept
toward	O
the	O
end	O
of	O
the	O
console	O
generation	O
in	O
order	O
to	O
reduce	O
cost	O
and	O
briefly	O
reinvigorate	O
sales	O
before	O
the	O
arrival	O
of	O
newer	O
hardware	O
.	O
</s>
<s>
In	O
earlier	O
versions	O
of	O
the	O
PS2	B-Device
,	O
a	O
CPU	O
core	O
identical	O
to	O
that	O
of	O
the	O
PS	O
serves	O
a	O
dual	O
purpose	O
,	O
either	O
as	O
the	O
main	O
CPU	O
in	O
PS	O
mode	O
,	O
or	O
upclocking	O
itself	O
to	O
offload	O
I/O	B-General_Concept
in	O
PS2	B-Device
mode	O
.	O
</s>
<s>
Such	O
an	O
approach	O
can	O
backfire	O
,	O
however	O
,	O
as	O
in	O
the	O
case	O
of	O
the	O
Super	B-Application
Nintendo	I-Application
Entertainment	I-Application
System	I-Application
(	O
Super	B-Application
NES	I-Application
)	O
,	O
which	O
opted	O
for	O
the	O
peculiar	O
65C816	B-General_Concept
over	O
more	O
popular	O
16-bit	O
microprocessors	B-Architecture
on	O
the	O
basis	O
that	O
it	O
would	O
allow	O
easy	O
compatibility	B-Device
with	O
the	O
original	O
NES	O
,	O
but	O
NES	O
compatibility	B-Device
ultimately	O
did	O
not	O
prove	O
workable	O
once	O
the	O
rest	O
of	O
the	O
Super	B-Application
NES	I-Application
's	O
architecture	O
was	O
designed	O
.	O
</s>
<s>
Backward	B-General_Concept
compatibility	I-General_Concept
introduces	O
the	O
risk	O
that	O
developers	O
will	O
favor	O
developing	O
games	O
that	O
are	O
compatible	O
with	O
both	O
the	O
old	O
and	O
new	O
systems	O
,	O
since	O
this	O
gives	O
them	O
a	O
larger	O
base	O
of	O
potential	O
buyers	O
,	O
resulting	O
in	O
a	O
dearth	O
of	O
software	O
which	O
uses	O
the	O
advanced	O
features	O
of	O
the	O
new	O
system	O
.	O
</s>
<s>
With	O
the	O
decline	O
in	O
physical	O
game	O
sales	O
and	O
the	O
rise	O
of	O
digital	O
storefronts	O
and	O
downloads	O
,	O
some	O
believe	O
backward	B-General_Concept
compatibility	I-General_Concept
will	O
soon	O
be	O
obsolete	O
.	O
</s>
