<s>
An	O
AV	B-Device
drive	I-Device
(	O
audio-visual	O
drive	O
)	O
is	O
a	O
hard	B-Device
disk	I-Device
drive	I-Device
that	O
is	O
designed	O
specifically	O
for	O
audio	O
and	O
video	O
purposes	O
.	O
</s>
<s>
AV	B-Device
drives	I-Device
were	O
also	O
popular	O
in	O
the	O
early	O
ages	O
of	O
CD	O
burning	O
;	O
early	O
CD	O
writers	O
ruined	O
the	O
disk	O
when	O
a	O
buffer	O
underrun	O
occurred	O
,	O
which	O
could	O
happen	O
during	O
the	O
hard	B-Device
drive	I-Device
's	O
automatic	O
calibration	O
.	O
</s>
<s>
They	O
are	O
now	O
obsolete	O
,	O
as	O
normal	O
hard	B-Device
drives	I-Device
are	O
designed	O
to	O
handle	O
realtime	O
media	O
through	O
servo	O
calibration	O
to	O
monitor	O
head	O
alignment	O
and	O
through	O
the	O
use	O
of	O
larger	O
memory	O
buffers	O
.	O
</s>
