<s>
In	O
addition	O
to	O
the	O
drums	O
used	O
as	O
main	O
memory	O
by	O
IBM	O
,	O
e.g.	O
,	O
IBM	B-Device
305	I-Device
,	O
IBM	B-Device
650	I-Device
,	O
IBM	O
offered	O
drum	B-General_Concept
devices	I-General_Concept
as	O
secondary	O
storage	O
for	O
the	O
700/7000	B-Device
series	I-Device
and	O
System/360	B-Application
series	I-Application
of	O
computers	O
.	O
</s>
<s>
The	O
IBM	O
731	O
is	O
a	O
discontinued	O
storage	O
unit	O
used	O
on	O
the	O
IBM	B-Device
701	I-Device
.	O
</s>
<s>
The	O
IBM	O
732	O
is	O
a	O
discontinued	O
storage	O
unit	O
used	O
on	O
the	O
IBM	B-Device
702	I-Device
.	O
</s>
<s>
The	O
IBM	O
733	O
is	O
a	O
discontinued	O
storage	O
unit	O
used	O
on	O
the	O
IBM	B-Device
704	I-Device
and	O
IBM	B-Device
709	I-Device
.	O
</s>
<s>
The	O
IBM	O
734	O
is	O
a	O
discontinued	O
storage	O
unit	O
used	O
on	O
the	O
IBM	B-Device
705	I-Device
It	O
has	O
a	O
storage	O
capacity	O
of	O
60,000	O
6-bit	O
characters	O
(	O
45,000	O
8-bit	O
bytes	O
)	O
.	O
</s>
<s>
The	O
IBM	O
7320	O
is	O
a	O
discontinued	O
storage	O
unit	O
manufactured	O
by	O
IBM	O
announced	O
on	O
December	O
10	O
,	O
1962	O
for	O
the	O
IBM	B-Device
7090	I-Device
and	O
7094	O
computer	O
systems	O
,	O
was	O
retained	O
for	O
the	O
earliest	O
System/360	B-Application
systems	I-Application
as	O
a	O
count	B-Application
key	I-Application
data	I-Application
device	O
,	O
and	O
was	O
discontinued	O
in	O
1965	O
.	O
</s>
<s>
Attachment	O
to	O
a	O
709x	O
system	O
is	O
through	O
an	O
IBM	O
7909	O
Data	O
Channel	O
and	O
an	O
IBM	O
7631	O
File	O
Control	O
unit	O
,	O
which	O
can	O
attach	O
up	O
to	O
five	O
random-access	O
storage	O
units	O
,	O
a	O
mix	O
of	O
7320	O
and	O
1301	B-Device
DASD	O
.	O
</s>
<s>
The	O
7320	O
attaches	O
to	O
a	O
System/360	B-Application
through	O
a	O
channel	O
and	O
an	O
2841	O
Storage	O
Control	O
unit	O
.	O
</s>
<s>
When	O
used	O
with	O
System/360	B-Application
,	O
a	O
track	O
holds	O
2081	O
eight-bit	O
bytes	O
,	O
and	O
a	O
7320	O
unit	O
holds	O
878,000	O
bytes	O
.	O
</s>
<s>
The	O
IBM	O
2301	O
is	O
a	O
magnetic	B-General_Concept
drum	I-General_Concept
storage	O
device	O
introduced	O
in	O
the	O
late	O
1960s	O
to	O
"	O
provide	O
large	O
capacity	O
,	O
direct	O
access	O
storage	O
for	O
IBM	B-Application
System/360	I-Application
Models	O
65	O
,	O
67	O
,	O
75	O
,	O
or	O
85.	O
"	O
</s>
<s>
The	O
2301	O
attaches	O
to	O
a	O
System/360	B-Application
via	O
a	O
selector	O
channel	O
and	O
an	O
IBM	O
2820	O
Storage	O
Control	O
Unit	O
,	O
which	O
can	O
control	O
up	O
to	O
four	O
2301	O
units	O
.	O
</s>
<s>
The	O
IBM	O
2303	O
is	O
a	O
magnetic	B-General_Concept
drum	I-General_Concept
storage	O
device	O
with	O
the	O
same	O
physical	O
specifications	O
as	O
the	O
IBM	O
2301	O
.	O
</s>
<s>
The	O
2303	O
attaches	O
to	O
System/360	B-Application
through	O
a	O
channel	O
and	O
an	O
IBM	O
2841	O
Storage	O
Control	O
Unit	O
,	O
which	O
can	O
attach	O
up	O
to	O
two	O
2303	O
units	O
.	O
</s>
