<s>
In	O
computer	O
hardware	O
,	O
a	O
caddy	B-Device
is	O
a	O
container	O
used	O
to	O
hold	O
some	O
medium	O
,	O
such	O
as	O
a	O
CD-ROM	B-Device
.	O
</s>
<s>
If	O
the	O
medium	O
is	O
a	O
hard	B-Device
disk	I-Device
drive	I-Device
,	O
the	O
caddy	B-Device
is	O
also	O
referred	O
to	O
as	O
a	O
disk	B-Device
enclosure	I-Device
.	O
</s>
<s>
Its	O
functionality	O
is	O
similar	O
to	O
that	O
of	O
the	O
3.5	B-Device
"	I-Device
floppy	I-Device
disk	I-Device
's	O
jacket	O
.	O
</s>
<s>
The	O
purpose	O
of	O
a	O
disk	O
caddy	B-Device
is	O
to	O
protect	O
the	O
disk	O
from	O
damage	O
when	O
handling	O
;	O
its	O
use	O
dates	O
back	O
to	O
at	O
least	O
the	O
Capacitance	O
Electronic	O
Disc	O
in	O
1976	O
,	O
and	O
they	O
were	O
used	O
in	O
initial	O
versions	O
of	O
Blu-ray	O
Discs	O
,	O
though	O
as	O
a	O
cost-saving	O
measure	O
newer	O
versions	O
use	O
hard-coating	O
technology	O
to	O
prevent	O
scratches	O
and	O
do	O
not	O
need	O
a	O
caddy	B-Device
.	O
</s>
<s>
Caddies	B-Device
may	O
be	O
an	O
integral	O
part	O
of	O
the	O
medium	O
,	O
as	O
in	O
some	O
DVD-RAM	O
discs	O
,	O
or	O
separately	O
attached	O
.	O
</s>
<s>
Caddies	B-Device
date	O
at	O
least	O
to	O
the	O
Capacitance	O
Electronic	O
Disc	O
,	O
which	O
used	O
a	O
caddy	B-Device
from	O
1976	O
to	O
protect	O
the	O
grooves	O
of	O
the	O
disc	O
.	O
</s>
<s>
While	O
caddies	B-Device
have	O
become	O
obsolete	O
,	O
some	O
websites	O
still	O
sell	O
them	O
,	O
although	O
they	O
have	O
become	O
quite	O
expensive	O
.	O
</s>
<s>
In	O
addition	O
to	O
caddies	B-Device
that	O
serve	O
purely	O
a	O
storage	O
purpose	O
,	O
there	O
are	O
also	O
ones	O
that	O
are	O
designed	O
to	O
be	O
loaded	O
directly	O
for	O
data	O
access	O
,	O
usually	O
via	O
a	O
shutter	O
.	O
</s>
<s>
Some	O
early	O
CD-ROM	B-Device
drives	O
used	O
a	O
mechanism	O
where	O
CDs	O
had	O
to	O
be	O
inserted	O
into	O
special	O
cartridges	O
,	O
somewhat	O
similar	O
in	O
appearance	O
to	O
a	O
jewel	O
case	O
.	O
</s>
<s>
Consumers	O
also	O
eschewed	O
the	O
intended	O
and	O
pricey	O
use	O
,	O
which	O
required	O
each	O
disc	O
to	O
be	O
protected	O
with	O
a	O
caddy	B-Device
for	O
its	O
full	O
useful	O
life	O
,	O
preferring	O
to	O
only	O
buy	O
one	O
caddy	B-Device
and	O
transfer	O
the	O
discs	O
between	O
their	O
traditional	O
storage	O
jewel	O
cases	O
and	O
the	O
caddy	B-Device
when	O
in	O
use	O
,	O
then	O
the	O
reverse	O
when	O
finished	O
.	O
</s>
<s>
Drives	O
that	O
used	O
the	O
caddy	B-Device
format	O
required	O
"	O
bare	O
"	O
discs	O
to	O
be	O
placed	O
into	O
a	O
caddy	B-Device
before	O
use	O
,	O
making	O
them	O
less	O
convenient	O
to	O
use	O
.	O
</s>
<s>
Drives	O
that	O
worked	O
this	O
way	O
were	O
referred	O
to	O
as	O
caddy	B-Device
drives	I-Device
or	O
caddy	O
load(ing )	O
,	O
but	O
from	O
about	O
1994	O
most	O
computer	O
manufacturers	O
moved	O
to	O
tray-loading	O
,	O
or	O
slot-loading	O
drives	O
.	O
</s>
<s>
The	O
PlayStation	B-Operating_System
Portable	I-Operating_System
,	O
UMD	O
disc	O
is	O
a	O
similar	O
concept	O
,	O
using	O
a	O
small	O
proprietary	O
DVD-type	O
disc	O
,	O
in	O
a	O
fixed	O
unopenable	O
caddy	B-Device
as	O
both	O
a	O
copy	O
protection	O
and	O
damage	O
prevention	O
measure	O
.	O
</s>
<s>
The	O
MiniDisc	O
is	O
a	O
similar	O
concept	O
again	O
,	O
using	O
a	O
small	O
proprietary	O
Magneto-optical	B-Device
type	O
disc	O
instead	O
,	O
also	O
in	O
a	O
fixed	O
unopenable	O
caddy	B-Device
.	O
</s>
