<s>
In	O
optical	B-General_Concept
storage	I-General_Concept
,	O
constant	B-Device
linear	I-Device
velocity	I-Device
(	O
CLV	O
)	O
is	O
a	O
qualifier	O
for	O
the	O
rated	O
speed	O
of	O
an	O
optical	B-Device
disc	I-Device
drive	O
,	O
and	O
may	O
also	O
be	O
applied	O
to	O
the	O
writing	O
speed	O
of	O
recordable	O
discs	B-Device
.	O
</s>
<s>
rpm	O
)	O
varies	O
during	O
an	O
operation	O
,	O
as	O
contrasted	O
with	O
CAV	B-Device
modes	O
.	O
</s>
<s>
The	O
concept	O
of	O
constant	B-Device
linear	I-Device
velocity	I-Device
was	O
patented	O
in	O
1886	O
by	O
phonograph	O
pioneers	O
Chichester	O
Bell	O
and	O
Charles	O
Tainter	O
.	O
</s>
<s>
Laserdiscs	O
,	O
the	O
first	O
consumer	O
optical	B-Device
discs	I-Device
,	O
used	O
constant	B-Device
linear	I-Device
velocity	I-Device
to	O
double	O
playback	O
time	O
(	O
CLV	O
/	O
"	O
extended	O
play	O
"	O
discs	B-Device
can	O
hold	O
1	O
hour	O
per	O
side	O
;	O
CAV	B-Device
/	O
"	O
standard	O
play	O
"	O
discs	B-Device
can	O
only	O
hold	O
30	O
minutes	O
)	O
.	O
</s>
<s>
To	O
accommodate	O
the	O
higher	O
data	O
transfer	O
rates	O
and	O
random	O
access	O
requirements	O
of	O
modern	O
CD-ROM	O
drives	O
,	O
CAV	B-Device
systems	O
are	O
used	O
.	O
</s>
<s>
For	O
a	O
miniature	O
disc	O
with	O
a	O
diameter	O
of	O
8cm	O
(	O
radius	O
of	O
4cm	O
)	O
,	O
the	O
angular	O
(	O
rotation	O
)	O
speed	O
ratio	O
of	O
outer	O
to	O
inner	O
data	O
edge	O
is	O
1.6	O
if	O
accessed	O
at	O
a	O
constant	B-Device
linear	I-Device
velocity	I-Device
.	O
</s>
<s>
Zoned	O
Constant	B-Device
Linear	I-Device
Velocity	I-Device
(	O
ZCLV	O
or	O
Z-CLV	O
)	O
is	O
a	O
modification	O
of	O
CLV	O
for	O
high	O
speed	O
CD	O
and	O
DVD	O
recorders	O
where	O
a	O
constant	B-Device
linear	I-Device
velocity	I-Device
is	O
maintained	O
until	O
the	O
next	O
zone	O
,	O
when	O
the	O
speed	O
is	O
stepped	O
up	O
.	O
</s>
<s>
Some	O
high-speed	O
recorders	O
use	O
the	O
zoned	B-Device
CLV	I-Device
method	O
(	O
ZCLV	O
)	O
,	O
which	O
divides	O
the	O
disc	O
into	O
stepped	O
zones	O
,	O
each	O
of	O
which	O
has	O
its	O
own	O
constant	B-Device
linear	I-Device
velocity	I-Device
.	O
</s>
<s>
At	O
higher	O
speeds	O
,	O
ZCLV	O
offers	O
a	O
compromise	O
between	O
CAV	B-Device
,	O
which	O
enables	O
faster	O
seek	O
times	O
,	O
and	O
CLV	O
,	O
which	O
enables	O
greater	O
writing	O
reliability	O
.	O
</s>
