<s>
The	O
IBM	B-Device
2321	I-Device
Data	I-Device
Cell	I-Device
is	O
a	O
discontinued	O
direct	B-Application
access	I-Application
storage	I-Application
device	I-Application
(	O
DASD	B-Application
)	O
for	O
the	O
IBM	B-Application
System/360	I-Application
.	O
</s>
<s>
It	O
was	O
announced	O
with	O
System/360	B-Application
in	O
April	O
,	O
1964	O
.	O
</s>
<s>
It	O
holds	O
up	O
to	O
400	O
megabytes	O
of	O
data	O
,	O
with	O
an	O
access	O
time	O
of	O
95	O
milliseconds	O
to	O
600	O
milliseconds	O
,	O
depending	O
on	O
the	O
addressed	O
strip	O
position	O
and	O
data	O
arrangement	O
in	O
each	O
data	B-Device
cell	I-Device
.	O
</s>
<s>
The	O
2321	O
houses	O
up	O
to	O
ten	O
removable	O
and	O
interchangeable	O
data	B-Device
cells	I-Device
,	O
each	O
containing	O
40	O
megabytes	O
.	O
</s>
<s>
Each	O
data	B-Device
cell	I-Device
contains	O
200	O
strips	O
of	O
magnetic	O
tape	O
,	O
which	O
are	O
the	O
basic	O
recording	O
media	O
.	O
</s>
<s>
In	O
comparison	O
to	O
the	O
contemporary	O
IBM	O
2311	O
Disk	O
Device	O
,	O
the	O
IBM	B-Device
2321	I-Device
Data	I-Device
Cell	I-Device
Device	O
holds	O
55	O
times	O
more	O
data	O
,	O
while	O
being	O
only	O
seven	O
times	O
slower	O
(	O
85ms	O
and	O
600ms	O
access	O
times	O
respectively	O
)	O
.	O
</s>
<s>
One	O
fully	O
loaded	O
IBM	O
2841	O
Control	O
Unit	O
connected	O
with	O
eight	O
IBM	B-Device
2321	I-Device
Data	I-Device
Cell	I-Device
Devices	O
has	O
the	O
capacity	O
of	O
441	O
IBM	O
2311	O
Disk	O
Devices	O
,	O
which	O
would	O
need	O
to	O
be	O
connected	O
to	O
56	O
IBM	O
2841	O
Control	O
Units	O
,	O
which	O
would	O
require	O
seven	O
data	O
channels	O
.	O
</s>
<s>
The	O
Data	B-Device
Cell	I-Device
makes	O
use	O
of	O
three	O
concurrently	O
operating	O
separate	O
seeking	O
systems	O
:	O
a	O
servo-hydraulic	O
one	O
to	O
rotate	O
the	O
bins	O
to	O
select	O
the	O
proper	O
subcell	O
,	O
and	O
two	O
solenoid	B-Algorithm
driven	O
ones	O
:	O
one	O
to	O
select	O
the	O
correct	O
strip	O
tab	O
of	O
the	O
ten	O
in	O
the	O
subcell	O
,	O
and	O
the	O
other	O
to	O
select	O
one	O
of	O
the	O
five	O
head	O
positions	O
,	O
for	O
the	O
20	O
element	O
head	O
(	O
100	O
tracks	O
per	O
strip	O
)	O
.	O
</s>
<s>
The	O
hydraulic	O
fluid	O
,	O
Mobil	O
DTE	O
Light	O
,	O
a	O
machine	O
tool	O
circulating	O
oil	O
,	O
is	O
pressurized	O
at	O
1500	O
psi	O
and	O
despite	O
a	O
lot	O
of	O
folklore	B-Application
about	O
oil	O
leaks	O
,	O
they	O
were	O
very	O
rare	O
.	O
</s>
<s>
Although	O
its	O
storage	O
medium	O
is	O
tape	O
,	O
the	O
2321	O
is	O
classified	O
as	O
a	O
direct	B-Application
access	I-Application
storage	I-Application
device	I-Application
which	O
can	O
directly	O
access	O
a	O
record	O
rather	O
than	O
scan	O
all	O
the	O
tape	O
to	O
find	O
a	O
record	O
as	O
would	O
a	O
conventional	O
tape	O
drive	O
.	O
</s>
<s>
IBM	O
's	O
System/360	B-Application
channels	O
addressed	O
the	O
2321	O
as	O
a	O
direct	B-Application
access	I-Application
storage	I-Application
devices	I-Application
,	O
i.e.	O
,	O
a	O
disk	O
drive	O
,	O
with	O
a	O
6-byte	O
seek	O
address	O
of	O
the	O
form	O
ØBBSCH	O
(	O
hexadecimal	O
)	O
where	O
the	O
first	O
byte	O
is	O
zero	O
and	O
the	O
remaining	O
bytes	O
address	O
the	O
Bin	O
(	O
i.e.	O
,	O
cell	O
and	O
sub-cell	O
)	O
,	O
Strip	O
,	O
Cylinder	O
and	O
Head	O
.	O
</s>
