<s>
In	O
computer	B-General_Concept
programming	I-General_Concept
,	O
orthogonality	B-Application
means	O
that	O
operations	O
change	O
just	O
one	O
thing	O
without	O
affecting	O
others	O
.	O
</s>
<s>
The	O
term	O
is	O
most-frequently	O
used	O
regarding	O
assembly	O
instruction	O
sets	O
,	O
as	O
orthogonal	B-General_Concept
instruction	I-General_Concept
set	I-General_Concept
.	O
</s>
<s>
Orthogonality	B-Application
in	O
a	O
programming	O
language	O
means	O
that	O
a	O
relatively	O
small	O
set	O
of	O
primitive	O
constructs	O
can	O
be	O
combined	O
in	O
a	O
relatively	O
small	O
number	O
of	O
ways	O
to	O
build	O
the	O
control	O
and	O
data	O
structures	O
of	O
the	O
language	O
.	O
</s>
<s>
An	O
example	O
from	O
IBM	B-Application
Mainframe	O
and	O
VAX	B-Device
highlights	O
this	O
concept	O
.	O
</s>
<s>
An	O
IBM	B-Application
mainframe	O
has	O
two	O
different	O
instructions	O
for	O
adding	O
the	O
contents	O
of	O
a	O
register	B-General_Concept
to	O
a	O
memory	O
cell	O
(	O
or	O
another	O
register	B-General_Concept
)	O
.	O
</s>
<s>
In	O
the	O
second	O
case	O
,	O
the	O
contents	O
of	O
Reg1	O
are	O
added	O
to	O
the	O
contents	O
of	O
another	O
register	B-General_Concept
(	O
Reg2	O
)	O
and	O
the	O
result	O
is	O
stored	O
in	O
Reg1	O
.	O
</s>
<s>
In	O
contrast	O
to	O
the	O
above	O
set	O
of	O
statements	O
,	O
VAX	B-Device
has	O
only	O
one	O
statement	O
for	O
addition	O
:	O
</s>
<s>
VAX	B-Device
's	O
instruction	O
for	O
addition	O
is	O
more	O
orthogonal	O
than	O
the	O
instructions	O
provided	O
by	O
IBM	B-Application
;	O
hence	O
,	O
it	O
is	O
easier	O
for	O
the	O
programmer	O
to	O
remember	O
(	O
and	O
use	O
)	O
the	O
one	O
provided	O
by	O
VAX	B-Device
.	O
</s>
<s>
The	O
design	O
of	O
C	O
language	O
may	O
be	O
examined	O
from	O
the	O
perspective	O
of	O
orthogonality	B-Application
.	O
</s>
<s>
Though	O
this	O
concept	O
was	O
first	O
applied	O
to	O
programming	O
languages	O
,	O
orthogonality	B-Application
has	O
since	O
become	O
recognized	O
as	O
a	O
valuable	O
feature	O
in	O
the	O
design	O
of	O
APIs	O
and	O
even	O
user	O
interfaces	O
.	O
</s>
<s>
On	O
the	O
other	O
hand	O
,	O
orthogonality	B-Application
does	O
not	O
necessarily	O
result	O
in	O
simpler	O
systems	O
,	O
as	O
the	O
example	O
of	O
IBM	B-Application
and	O
VAX	B-Device
instructions	O
shows	O
—	O
in	O
the	O
end	O
,	O
the	O
less	O
orthogonal	O
RISC	B-Architecture
CPU	O
architectures	O
were	O
more	O
successful	O
than	O
the	O
CISC	B-Architecture
architectures	I-Architecture
.	O
</s>
