<s>
IBM	O
manufactured	O
magnetic	O
disk	B-Device
storage	I-Device
devices	O
from	O
1956	O
to	O
2003	O
,	O
when	O
it	O
sold	O
its	O
hard	B-Device
disk	I-Device
drive	I-Device
business	O
to	O
Hitachi	O
.	O
</s>
<s>
Both	O
the	O
hard	B-Device
disk	I-Device
drive	I-Device
(	O
HDD	O
)	O
and	O
floppy	B-Device
disk	I-Device
drive	I-Device
(	O
FDD	O
)	O
were	O
invented	O
by	O
IBM	O
and	O
as	O
such	O
IBM	O
's	O
employees	O
were	O
responsible	O
for	O
many	O
of	O
the	O
innovations	O
in	O
these	O
products	O
and	O
their	O
technologies	O
.	O
</s>
<s>
The	O
basic	O
mechanical	O
arrangement	O
of	O
hard	B-Device
disk	I-Device
drives	I-Device
has	O
not	O
changed	O
since	O
the	O
IBM	B-Device
1301	I-Device
.	O
</s>
<s>
Disk	B-Device
drive	I-Device
performance	O
and	O
characteristics	O
are	O
measured	O
by	O
the	O
same	O
standards	O
now	O
as	O
they	O
were	O
in	O
the	O
1950s	O
.	O
</s>
<s>
IBM	O
manufactured	O
8-inch	B-Device
floppy	B-Device
disk	I-Device
drives	I-Device
from	O
1969	O
until	O
the	O
mid-1980s	O
,	O
but	O
did	O
not	O
become	O
a	O
significant	O
manufacturer	O
of	O
smaller-sized	O
,	O
5.25	O
-	O
or	O
3.5-inch	O
floppy	B-Device
disk	I-Device
drives	I-Device
(	O
the	O
dimension	O
refers	O
to	O
the	O
diameter	O
of	O
the	O
floppy	B-Device
disk	I-Device
,	O
not	O
the	O
size	O
of	O
the	O
drive	O
)	O
.	O
</s>
<s>
IBM	O
always	O
offered	O
its	O
magnetic	O
disk	B-Device
drives	I-Device
for	O
sale	O
but	O
did	O
not	O
offer	O
them	O
with	O
original	O
equipment	O
manufacturer	O
(	O
OEM	O
)	O
terms	O
until	O
1981	O
.	O
</s>
<s>
By	O
1996	O
,	O
IBM	O
had	O
stopped	O
making	O
hard	B-Device
disk	I-Device
drives	I-Device
unique	O
to	O
its	O
systems	O
and	O
was	O
offering	O
all	O
its	O
HDDs	O
as	O
an	O
original	O
equipment	O
manufacturer	O
(	O
OEM	O
)	O
.	O
</s>
<s>
IBM	O
uses	O
many	O
terms	O
to	O
describe	O
its	O
various	O
magnetic	O
disk	B-Device
drives	I-Device
,	O
such	O
as	O
direct-access	B-Application
storage	I-Application
device	I-Application
(	O
DASD	B-Application
)	O
,	O
disk	B-Device
file	O
and	O
diskette	B-Device
file	O
.	O
</s>
<s>
Here	O
,	O
the	O
current	O
industry	O
standard	O
terms	O
,	O
hard	B-Device
disk	I-Device
drive	I-Device
(	O
HDD	O
)	O
and	O
floppy	B-Device
disk	I-Device
drive	I-Device
(	O
FDD	O
)	O
,	O
are	O
used	O
.	O
</s>
<s>
The	O
IBM	B-Device
350	I-Device
disk	B-Device
storage	I-Device
unit	O
,	O
the	O
first	O
disk	B-Device
drive	I-Device
,	O
was	O
announced	O
by	O
IBM	O
as	O
a	O
component	O
of	O
the	O
IBM	B-Device
305	I-Device
RAMAC	I-Device
computer	O
system	O
on	O
September	O
14	O
,	O
1956	O
.	O
</s>
<s>
Simultaneously	O
a	O
very	O
similar	O
product	O
,	O
the	O
IBM	B-Device
355	I-Device
,	O
was	O
announced	O
for	O
the	O
IBM	B-Device
650	I-Device
RAMAC	O
computer	O
system	O
.	O
</s>
<s>
The	O
first	O
engineering	O
prototype	O
350	O
disk	B-Device
storage	I-Device
shipped	O
to	O
Zellerbach	O
Paper	O
Company	O
,	O
San	O
Francisco	O
,	O
in	O
June	O
1956	O
,	O
with	O
production	O
shipment	O
beginning	O
in	O
November	O
1957	O
with	O
the	O
shipment	O
of	O
a	O
unit	O
to	O
United	O
Airlines	O
in	O
Denver	O
,	O
Colorado	O
.	O
</s>
<s>
It	O
has	O
fifty-two	O
diameter	O
disks	B-Device
of	O
which	O
100	O
recording	O
surfaces	O
are	O
used	O
,	O
omitting	O
the	O
top	O
surface	O
of	O
the	O
top	O
disk	B-Device
and	O
the	O
bottom	O
surface	O
of	O
the	O
bottom	O
disk	B-Device
.	O
</s>
<s>
The	O
disks	B-Device
spin	O
at	O
1200	O
rpm	O
.	O
</s>
<s>
An	O
access	O
mechanism	O
moves	O
a	O
pair	O
of	O
heads	O
up	O
and	O
down	O
to	O
select	O
a	O
disk	B-Device
pair	O
(	O
one	O
down	O
surface	O
and	O
one	O
up	O
surface	O
)	O
and	O
in	O
and	O
out	O
to	O
select	O
a	O
recording	O
track	O
of	O
a	O
surface	O
pair	O
.	O
</s>
<s>
The	O
IBM	B-Device
RAMAC	I-Device
305	I-Device
system	O
with	O
350	O
disk	B-Device
storage	I-Device
leased	O
for	O
$	O
3,200	O
per	O
month	O
.	O
</s>
<s>
from	O
the	O
RAMAC	O
program	O
is	O
generally	O
considered	O
to	O
be	O
the	O
fundamental	O
patent	O
for	O
disk	B-Device
drives	I-Device
.	O
</s>
<s>
This	O
first-ever	O
disk	B-Device
drive	I-Device
was	O
initially	O
cancelled	O
by	O
the	O
IBM	O
Board	O
of	O
Directors	O
because	O
of	O
its	O
threat	O
to	O
the	O
IBM	O
punch	O
card	O
business	O
but	O
the	O
IBM	O
San	O
Jose	O
laboratory	O
continued	O
development	O
until	O
the	O
project	O
was	O
approved	O
by	O
IBM	O
's	O
president	O
.	O
</s>
<s>
In	O
1984	O
,	O
the	O
RAMAC	O
350	O
Disk	B-Device
File	O
was	O
designated	O
an	O
International	O
Historic	O
Landmark	O
by	O
The	O
American	O
Society	O
of	O
Mechanical	O
Engineers	O
.	O
</s>
<s>
In	O
2002	O
at	O
the	O
Magnetic	O
Disk	B-Device
Heritage	O
Center	O
,	O
a	O
team	O
led	O
by	O
Al	O
Hoagland	O
began	O
restoration	O
of	O
an	O
IBM	B-Device
350	I-Device
RAMAC	O
in	O
collaboration	O
with	O
Santa	O
Clara	O
University	O
.	O
</s>
<s>
The	O
IBM	O
353	O
,	O
used	O
on	O
the	O
IBM	B-Device
7030	I-Device
,	O
was	O
similar	O
to	O
the	O
IBM	B-Device
1301	I-Device
,	O
but	O
with	O
a	O
faster	O
transfer	O
rate	O
.	O
</s>
<s>
A	O
prototype	O
unit	O
shipped	O
in	O
late	O
1960	O
was	O
the	O
first	O
disk	B-Device
drive	I-Device
to	O
use	O
one	O
head	B-Device
per	O
surface	O
flying	O
on	O
a	O
layer	O
of	O
compressed	O
air	O
as	O
in	O
the	O
older	O
head	B-Device
design	O
of	O
the	O
IBM	B-Device
350	I-Device
disk	B-Device
storage	I-Device
(	O
RAMAC	O
)	O
.	O
</s>
<s>
Production	O
353s	O
used	O
self-flying	O
heads	O
essentially	O
the	O
same	O
as	O
those	O
of	O
the	O
1301	B-Device
.	O
</s>
<s>
The	O
IBM	B-Device
355	I-Device
was	O
announced	O
on	O
September	O
14	O
,	O
1956	O
,	O
as	O
an	O
addition	O
to	O
the	O
popular	O
IBM	B-Device
650	I-Device
.	O
</s>
<s>
It	O
used	O
the	O
mechanism	O
of	O
the	O
IBM	B-Device
350	I-Device
with	O
up	O
to	O
three	O
access	B-Device
arms	I-Device
and	O
stored	O
6	O
million	O
decimal	O
digits	O
and	O
600,000	O
signs	O
.	O
</s>
<s>
It	O
transferred	O
a	O
full	O
track	O
to	O
and	O
from	O
the	O
IBM	O
653	O
magnetic	O
core	B-General_Concept
memory	I-General_Concept
,	O
an	O
IBM	B-Device
650	I-Device
option	O
that	O
stored	O
just	O
sixty	O
signed	O
10-digit	O
words	O
,	O
enough	O
for	O
a	O
single	O
track	O
of	O
disk	B-Device
or	O
a	O
tape	O
record	O
.	O
</s>
<s>
The	O
IBM	B-Device
1405	I-Device
Disk	B-Device
Storage	I-Device
Unit	O
was	O
announced	O
in	O
1961	O
and	O
was	O
designed	O
for	O
use	O
with	O
the	O
IBM	B-Device
1400	I-Device
series	I-Device
,	O
medium	O
scale	O
business	O
computers	O
.	O
</s>
<s>
The	O
1405	O
Model	O
1	O
has	O
a	O
storage	O
capacity	O
of	O
10	O
million	O
alphanumeric	O
characters	O
(	O
60,000,000	O
bits	O
)	O
on	O
25	O
disks	B-Device
.	O
</s>
<s>
Model	O
2	O
has	O
a	O
storage	O
capacity	O
of	O
20	O
million	O
alphanumeric	O
characters	O
(	O
120,000,000	O
bits	O
)	O
on	O
50	O
disks	B-Device
.	O
</s>
<s>
In	O
both	O
models	O
the	O
disks	B-Device
are	O
stacked	O
vertically	O
on	O
a	O
shaft	O
rotating	O
at	O
1200	O
rpm	O
.	O
</s>
<s>
Each	O
side	O
of	O
each	O
disk	B-Device
has	O
200	O
tracks	O
divided	O
into	O
5	O
sectors	O
.	O
</s>
<s>
One	O
to	O
three	O
forked-shaped	O
access	B-Device
arms	I-Device
each	O
contains	O
two	O
read/write	B-Device
heads	I-Device
,	O
one	O
for	O
the	O
top	O
of	O
the	O
disk	B-Device
and	O
the	O
other	O
for	O
the	O
bottom	O
of	O
the	O
same	O
disk	B-Device
.	O
</s>
<s>
The	O
access	B-Device
arms	I-Device
are	O
mounted	O
on	O
a	O
carriage	O
alongside	O
the	O
disk	B-Device
array	O
.	O
</s>
<s>
During	O
a	O
seek	O
operation	O
an	O
access	B-Device
arm	I-Device
moved	O
,	O
under	O
electronic	O
control	O
,	O
vertically	O
to	O
seek	O
a	O
disk	B-Device
0	O
–	O
49	O
and	O
then	O
horizontally	O
to	O
seek	O
a	O
track	O
0	O
–	O
199	O
.	O
</s>
<s>
The	O
1405	O
model	O
2	O
disk	B-Device
storage	I-Device
unit	O
has	O
100,000	O
sectors	O
containing	O
either	O
200	O
characters	O
in	O
move	O
mode	O
or	O
178	O
characters	O
in	O
load	O
mode	O
,	O
which	O
adds	O
a	O
word	B-Device
mark	I-Device
bit	O
to	O
each	O
character	O
.	O
</s>
<s>
The	O
IBM	O
7300	O
Disk	B-Device
Storage	I-Device
Unit	O
was	O
designed	O
for	O
use	O
with	O
the	O
IBM	B-Device
7070	I-Device
;	O
IBM	O
announced	O
a	O
model	O
2	O
in	O
1959	O
,	O
but	O
when	O
IBM	O
announced	O
the	O
1301	B-Device
on	O
June	O
5	O
,	O
1961	O
,	O
7070	O
and	O
7074	O
customers	O
found	O
it	O
to	O
be	O
more	O
attractive	O
than	O
the	O
7300	O
.	O
</s>
<s>
The	O
IBM	B-Device
1301	I-Device
Disk	B-Device
Storage	I-Device
Unit	O
was	O
announced	O
on	O
June	O
2	O
,	O
1961	O
with	O
two	O
models	O
.	O
</s>
<s>
It	O
was	O
designed	O
for	O
use	O
with	O
the	O
IBM	B-Device
7000	I-Device
series	I-Device
mainframe	B-Architecture
computers	I-Architecture
and	O
the	O
IBM	B-Device
1410	I-Device
.	O
</s>
<s>
The	O
1301	B-Device
stores	O
28	O
million	O
characters	O
(	O
168,000,000	O
bits	O
)	O
per	O
module	O
(	O
25	O
million	O
characters	O
with	O
the	O
1410	O
)	O
.	O
</s>
<s>
Each	O
module	O
has	O
25	O
large	O
disks	B-Device
and	O
40	O
user	O
recording	O
surfaces	O
,	O
with	O
250	O
tracks	O
per	O
surface	O
.	O
</s>
<s>
The	O
1301	B-Device
Model	O
1	O
has	O
one	O
module	O
,	O
the	O
Model	O
2	O
has	O
two	O
modules	O
,	O
stacked	O
vertically	O
.	O
</s>
<s>
The	O
disks	B-Device
spin	O
at	O
1800	O
rpm	O
.	O
</s>
<s>
A	O
major	O
advance	O
over	O
the	O
IBM	B-Device
350	I-Device
and	O
IBM	B-Device
1405	I-Device
is	O
the	O
use	O
of	O
a	O
separate	O
arm	O
and	O
head	B-Device
for	O
each	O
recording	O
surface	O
,	O
with	O
all	O
the	O
arms	O
moving	O
in	O
and	O
out	O
together	O
like	O
a	O
big	O
comb	O
.	O
</s>
<s>
This	O
eliminates	O
the	O
time	O
needed	O
for	O
the	O
arm	O
to	O
pull	O
the	O
head	B-Device
out	O
of	O
one	O
disk	B-Device
and	O
move	O
up	O
or	O
down	O
to	O
a	O
new	O
disk	B-Device
.	O
</s>
<s>
Seeking	O
the	O
desired	O
track	O
is	O
also	O
faster	O
since	O
,	O
with	O
the	O
new	O
design	O
,	O
the	O
head	B-Device
will	O
usually	O
be	O
somewhere	O
in	O
the	O
middle	O
of	O
the	O
disk	B-Device
,	O
not	O
starting	O
on	O
the	O
outer	O
edge	O
.	O
</s>
<s>
The	O
1301	B-Device
is	O
the	O
first	O
disk	B-Device
drive	I-Device
to	O
use	O
heads	O
that	O
are	O
aerodynamically	O
designed	O
to	O
fly	O
over	O
the	O
surface	O
of	O
the	O
disk	B-Device
on	O
a	O
thin	O
layer	O
of	O
air	O
.	O
</s>
<s>
The	O
1301	B-Device
connects	O
to	O
the	O
computer	O
via	O
the	O
IBM	O
7631	O
File	O
Control	O
.	O
</s>
<s>
Different	O
models	O
of	O
the	O
7631	O
allow	O
the	O
1301	B-Device
to	O
be	O
used	O
with	O
a	O
1410	O
or	O
7000	O
series	O
computer	O
,	O
or	O
shared	O
between	O
two	O
such	O
computers	O
.	O
</s>
<s>
The	O
IBM	B-Device
1301	I-Device
Model	O
1	O
leased	O
for	O
$	O
2,100	O
per	O
month	O
or	O
could	O
be	O
purchased	O
for	O
$	O
115,500	O
.	O
</s>
<s>
The	O
IBM	B-Device
1302	I-Device
Disk	B-Device
Storage	I-Device
Unit	O
was	O
introduced	O
in	O
September	O
1963	O
.	O
</s>
<s>
Improved	O
recording	O
quadrupled	O
its	O
capacity	O
over	O
that	O
of	O
the	O
1301	B-Device
,	O
to	O
117	O
million	O
6-bit	O
characters	O
per	O
module	O
.	O
</s>
<s>
Average	O
access	O
time	O
is	O
165ms	O
and	O
data	O
can	O
be	O
transferred	O
at	O
180	O
K	O
characters/second	O
,	O
more	O
than	O
double	O
the	O
speed	O
of	O
the	O
1301	B-Device
.	O
</s>
<s>
As	O
with	O
the	O
1301	B-Device
,	O
there	O
is	O
a	O
Model	O
2	O
which	O
doubles	O
the	O
capacity	O
by	O
stacking	O
two	O
modules	O
.	O
</s>
<s>
The	O
IBM	B-Device
1302	I-Device
Model	O
1	O
leased	O
for	O
$	O
5,600	O
per	O
month	O
or	O
could	O
be	O
purchased	O
for	O
$	O
252,000	O
.	O
</s>
<s>
The	O
1302	B-Device
was	O
withdrawn	O
in	O
February	O
1965	O
.	O
</s>
<s>
The	O
IBM	B-Device
1311	I-Device
Disk	B-Device
Storage	I-Device
Drive	O
was	O
announced	O
on	O
October	O
11	O
,	O
1962	O
,	O
and	O
was	O
designed	O
for	O
use	O
with	O
several	O
medium-scale	O
business	O
and	O
scientific	O
computers	O
.	O
</s>
<s>
The	O
1311	O
is	O
about	O
the	O
size	O
and	O
shape	O
of	O
a	O
top-loading	O
washing	O
machine	O
and	O
stores	O
2	O
million	O
characters	O
(	O
12,000,000	O
bits	O
)	O
(	O
or	O
,	O
in	O
so-called	O
"	O
Load	O
Mode	O
"	O
on	O
an	O
IBM	B-Device
1401	I-Device
,	O
a	O
sector	O
can	O
hold	O
90	O
7-bit	O
characters	O
,	O
or	O
12,600,000	O
bits	O
total	O
)	O
on	O
a	O
removable	O
IBM	B-Operating_System
1316	I-Operating_System
disk	I-Operating_System
pack	I-Operating_System
.	O
</s>
<s>
Each	O
IBM	B-Operating_System
1316	I-Operating_System
Disk	I-Operating_System
Pack	I-Operating_System
is	O
high	O
,	O
weighs	O
and	O
contains	O
six	O
diameter	O
disks	B-Device
,	O
yielding	O
10	O
recording	O
surfaces	O
(	O
the	O
outer	O
surfaces	O
are	O
not	O
used	O
)	O
.	O
</s>
<s>
The	O
10	O
individual	O
read/write	B-Device
heads	I-Device
are	O
mounted	O
on	O
a	O
common	O
actuator	O
within	O
the	O
disk	B-Device
drive	I-Device
which	O
moves	O
in	O
and	O
out	O
hydraulically	O
and	O
is	O
mechanically	O
detented	O
at	O
the	O
desired	O
track	O
before	O
reading	O
or	O
writing	O
occurs	O
.	O
</s>
<s>
The	O
disks	B-Device
spin	O
at	O
1500	O
rpm	O
.	O
</s>
<s>
The	O
disk	B-Operating_System
pack	I-Operating_System
is	O
covered	O
with	O
a	O
clear	O
plastic	O
shell	O
and	O
a	O
bottom	O
cover	O
when	O
not	O
in	O
use	O
.	O
</s>
<s>
Then	O
the	O
top	O
of	O
the	O
1311	O
drive	O
is	O
opened	O
and	O
the	O
plastic	O
shell	O
lowered	O
into	O
the	O
disk-drive	O
opening	O
(	O
assuming	O
it	O
is	O
empty	O
)	O
.	O
</s>
<s>
The	O
handle	O
is	O
turned	O
again	O
to	O
lock	O
the	O
disks	B-Device
in	O
place	O
and	O
release	O
the	O
plastic	O
shell	O
,	O
which	O
is	O
then	O
removed	O
and	O
the	O
drive	O
cover	O
closed	O
.	O
</s>
<s>
The	O
process	O
is	O
reversed	O
to	O
remove	O
a	O
disk	B-Operating_System
pack	I-Operating_System
.	O
</s>
<s>
The	O
same	O
methods	O
are	O
used	O
for	O
many	O
later	O
disk	B-Operating_System
packs	I-Operating_System
.	O
</s>
<s>
There	O
are	O
seven	O
models	O
of	O
the	O
1311	O
disk	B-Device
drive	I-Device
.	O
</s>
<s>
Master	O
drive	O
on	O
an	O
IBM	B-Device
1440	I-Device
,	O
IBM	B-Device
1460	I-Device
,	O
or	O
IBM	O
1240	O
system	O
and	O
can	O
control	O
up	O
to	O
four	O
Model	O
2	O
drives	O
.	O
</s>
<s>
Master	O
drive	O
on	O
IBM	B-Device
1620	I-Device
or	O
IBM	B-Device
1710	I-Device
system	O
and	O
can	O
control	O
up	O
to	O
three	O
Model	O
2	O
drives	O
.	O
</s>
<s>
Master	O
drive	O
on	O
an	O
IBM	B-Device
1401	I-Device
system	O
and	O
can	O
control	O
up	O
to	O
four	O
Model	O
2	O
drives	O
.	O
</s>
<s>
Master	O
drive	O
on	O
an	O
IBM	B-Device
1410	I-Device
,	O
IBM	B-Device
7010	I-Device
,	O
or	O
IBM	O
7740	O
system	O
and	O
can	O
control	O
up	O
to	O
four	O
Model	O
2	O
drives	O
.	O
</s>
<s>
Scan	O
Disk	B-Device
:	O
Automatic	O
rapid	O
search	O
for	O
identifier	O
or	O
condition	O
.	O
</s>
<s>
Track	O
Record	O
:	O
Increases	O
the	O
capacity	O
of	O
the	O
disk	B-Device
by	O
writing	O
a	O
single	O
large	O
record	O
per	O
track	O
instead	O
of	O
using	O
20	O
separate	O
sectors	O
.	O
</s>
<s>
The	O
IBM	O
2302	O
is	O
the	O
System/360	B-Application
version	O
of	O
the	O
1302	B-Device
,	O
with	O
track	O
formatting	O
in	O
accordance	O
with	O
S/360	B-Application
DASD	B-Application
architecture	O
rather	O
than	O
7000	O
series	O
architecture	O
.	O
</s>
<s>
The	O
access	O
mechanism	O
provides	O
one	O
read/write	B-Device
head	I-Device
per	O
track	O
.	O
</s>
<s>
The	O
2302	O
attaches	O
to	O
IBM	O
mainframes	B-Architecture
via	O
a	O
IBM	O
2841	O
Storage	O
Control	O
Unit	O
.	O
</s>
<s>
The	O
IBM	B-Device
2305	I-Device
fixed	O
head	B-Device
storage	O
(	O
a	O
fixed-head	O
disk	B-Device
drive	I-Device
sometimes	O
incorrectly	O
called	O
a	O
drum	B-General_Concept
)	O
and	O
associated	O
IBM	O
2835	O
Storage	O
Control	O
were	O
announced	O
in	O
1970	O
,	O
initially	O
to	O
connect	O
to	O
the	O
360/85	O
and	O
360/195	O
using	O
the	O
IBM	O
2880	O
Block	O
Multiplexor	O
Channel	O
.	O
</s>
<s>
The	O
2305	B-Device
Drive	O
was	O
in	O
much	O
demand	O
when	O
the	O
System	B-Device
370	I-Device
offered	O
Virtual	B-Application
Storage	I-Application
,	O
and	O
these	O
2305s	O
were	O
often	O
used	O
for	O
paging	O
devices	O
.	O
</s>
<s>
The	O
2305	B-Device
was	O
also	O
used	O
for	O
high	O
activity	O
small	O
data	O
sets	O
such	O
as	O
catalogs	O
and	O
job	O
queues	O
.	O
</s>
<s>
The	O
2305-1	O
runs	O
at	O
3.0MB/second	O
when	O
attached	O
using	O
the	O
2-byte	O
channel	O
interface	O
,	O
and	O
the	O
larger	O
2305-2	O
runs	O
at	O
1.5MB/second	O
.	O
</s>
<s>
The	O
2305	B-Device
provides	O
large-scale	O
IBM	O
computers	O
with	O
fast	O
,	O
continuous	O
access	O
to	O
small-sized	O
quantities	O
of	O
information	O
.	O
</s>
<s>
The	O
IBM	O
2311	O
Disk	B-Device
Storage	I-Device
Drive	O
was	O
introduced	O
with	O
the	O
2841	O
Control	O
Unit	O
in	O
1964	O
for	O
use	O
throughout	O
the	O
IBM	B-Application
System/360	I-Application
;	O
the	O
combination	O
was	O
also	O
available	O
on	O
the	O
IBM	B-Device
1130	I-Device
and	O
the	O
IBM	B-Device
1800	I-Device
.	O
</s>
<s>
The	O
drive	O
also	O
directly	O
attaches	O
to	O
the	O
IBM	B-Device
System/360	I-Device
Model	I-Device
20	I-Device
and	O
the	O
IBM	B-Device
System/360	I-Device
Model	I-Device
25	I-Device
.	O
</s>
<s>
All	O
drives	O
used	O
the	O
IBM	B-Operating_System
1316	I-Operating_System
Disk	I-Operating_System
Pack	I-Operating_System
introduced	O
with	O
the	O
IBM	B-Device
1311	I-Device
.	O
</s>
<s>
The	O
2311	O
Model	O
1	O
attaches	O
to	O
most	O
IBM	O
mainframes	B-Architecture
through	O
a	O
2841	O
Control	O
Unit	O
;	O
it	O
attaches	O
to	O
the	O
System/360	B-Application
Model	O
25	O
thru	O
a	O
Disk	B-Device
Attachment	O
Control	O
which	O
provides	O
the	O
function	O
of	O
the	O
control	O
unit	O
.	O
</s>
<s>
Disk	B-Operating_System
packs	I-Operating_System
are	O
written	O
in	O
these	O
attachments	O
in	O
IBM	O
's	O
count	B-Application
key	I-Application
data	I-Application
variable	O
record	O
length	O
format	O
.	O
</s>
<s>
The	O
2311	O
models	O
11	O
or	O
12	O
are	O
used	O
when	O
attached	O
to	O
an	O
integrated	O
control	O
of	O
the	O
System/360	B-Application
Model	O
20	O
and	O
the	O
disk	B-Operating_System
packs	I-Operating_System
are	O
written	O
with	O
a	O
fixed	O
sector	O
format	O
.	O
</s>
<s>
The	O
disk	B-Operating_System
packs	I-Operating_System
are	O
not	O
interchangeable	O
between	O
those	O
written	O
on	O
the	O
Model	O
1	O
and	O
those	O
written	O
on	O
the	O
Models	O
11	O
or	O
12	O
.	O
</s>
<s>
The	O
2311	O
stores	O
7.25megabytes	O
on	O
a	O
single	O
removable	O
IBM	B-Operating_System
1316	I-Operating_System
disk	I-Operating_System
pack	I-Operating_System
(	O
the	O
same	O
type	O
used	O
on	O
the	O
IBM	B-Device
1311	I-Device
)	O
consisting	O
of	O
six	O
platters	O
that	O
rotate	O
as	O
a	O
single	O
unit	O
.	O
</s>
<s>
This	O
created	O
an	O
opportunity	O
for	O
other	O
manufacturers	O
to	O
sell	O
plug	B-Device
compatible	I-Device
disk	B-Device
drives	I-Device
for	O
use	O
with	O
IBM	O
computers	O
and	O
an	O
entire	O
industry	O
was	O
born	O
.	O
</s>
<s>
The	O
IBM	O
2314	O
Disk	B-Device
Access	O
Storage	O
Facility	O
Model	O
1	O
was	O
introduced	O
on	O
April	O
22	O
,	O
1965	O
,	O
one	O
year	O
after	O
the	O
System/360	B-Application
introduction	O
.	O
</s>
<s>
It	O
was	O
used	O
with	O
the	O
System/360	B-Application
and	O
the	O
System/370	B-Device
lines	O
.	O
</s>
<s>
The	O
2314	O
Disk	B-Device
access	O
mechanism	O
was	O
similar	O
to	O
the	O
2311	O
,	O
but	O
further	O
recording	O
improvements	O
allowed	O
higher	O
data	O
density	O
.	O
</s>
<s>
The	O
2314	O
stored	O
29,176,000	O
characters	O
(	O
200×20×7294	O
bytes	O
per	O
track	O
)	O
on	O
a	O
single	O
removable	O
IBM	O
2316	O
disk	B-Operating_System
pack	I-Operating_System
which	O
was	O
similar	O
in	O
design	O
to	O
the	O
1316	O
but	O
was	O
taller	O
as	O
a	O
result	O
of	O
increasing	O
the	O
number	O
of	O
disks	B-Device
from	O
six	O
to	O
eleven	O
.	O
</s>
<s>
The	O
2316	O
disk	B-Operating_System
pack	I-Operating_System
containing	O
the	O
eleven	O
diameter	O
disks	B-Device
yielded	O
20	O
recording	O
surfaces	O
.	O
</s>
<s>
The	O
original	O
Model	O
1	O
consists	O
nine	O
disk	B-Device
drives	I-Device
bundled	O
together	O
with	O
one	O
price	O
;	O
separately	O
shipped	O
was	O
a	O
storage	O
control	O
unit	O
,	O
a	O
single	O
drive	O
module	O
,	O
and	O
two	O
four	O
drive	O
modules	O
for	O
a	O
total	O
of	O
nine	O
drives	O
.	O
</s>
<s>
The	O
drives	O
are	O
mounted	O
in	O
individual	O
drawers	O
that	O
are	O
unlatched	O
and	O
pulled	O
out	O
to	O
access	O
the	O
disk	B-Operating_System
pack	I-Operating_System
.	O
</s>
<s>
A	O
2844	O
Control	O
Unit	O
can	O
be	O
added	O
to	O
the	O
2314	O
Control	O
Unit	O
which	O
allows	O
two	O
S/360	B-Application
Channels	O
simultaneous	O
access	O
to	O
two	O
separate	O
disk	B-Device
drives	I-Device
in	O
the	O
Storage	O
Facility	O
.	O
</s>
<s>
2312	O
Disk	B-Device
Storage	I-Device
,	O
a	O
one	O
drive	O
module	O
.	O
</s>
<s>
2313	O
Disk	B-Device
Storage	I-Device
,	O
a	O
four	O
drive	O
module	O
.	O
</s>
<s>
2318	O
Disk	B-Device
Storage	I-Device
,	O
a	O
two	O
drive	O
module	O
.	O
</s>
<s>
In	O
a	O
response	O
to	O
competition	O
from	O
plug	B-Device
compatible	I-Device
manufacturers	I-Device
of	O
2314	O
equivalent	O
storage	O
subsystems	O
,	O
IBM	O
beginning	O
1970	O
introduced	O
a	O
series	O
of	O
low	O
priced	O
three	O
drive	O
module	O
2319s	O
which	O
were	O
manufactured	O
by	O
removing	O
one	O
module	O
from	O
the	O
four	O
drive	O
module	O
2313	O
,	O
rebranding	O
it	O
as	O
a	O
2319	O
A1	O
and	O
offering	O
it	O
at	O
a	O
substantially	O
reduced	O
rental	O
price	O
.	O
</s>
<s>
The	O
2319-A1	O
attaches	O
to	O
integrated	O
controllers	O
for	O
only	O
the	O
System/370	B-Device
Models	O
135	O
and	O
145	O
.	O
</s>
<s>
2319	O
B	O
series	O
of	O
three	O
disk	B-Device
drives	I-Device
modules	O
allow	O
three	O
,	O
six	O
or	O
nine	O
drive	O
attachment	O
to	O
a	O
new	O
2314	O
Model	O
B	O
Storage	O
Control	O
Unit	O
.	O
</s>
<s>
IBM	O
introduced	O
the	O
IBM	O
3310	O
Direct	B-Application
Access	I-Application
Storage	I-Application
Device	I-Application
on	O
January	O
30	O
,	O
1979	O
,	O
for	O
IBM	B-Device
4331	I-Device
midrange	B-Device
computers	I-Device
.	O
</s>
<s>
The	O
3310	O
was	O
a	O
fixed-block	B-Device
architecture	I-Device
device	O
,	O
used	O
on	O
DOS/VSE	B-Application
and	O
VM	B-Application
,	O
the	O
only	O
S/370	B-Device
operating	O
systems	O
that	O
supported	O
FBA	O
devices	O
.	O
</s>
<s>
The	O
IBM	O
3330	O
Direct	O
Access	O
Storage	O
Facility	O
,	O
code-named	O
Merlin	O
,	O
was	O
introduced	O
in	O
June	O
1970	O
for	O
use	O
with	O
the	O
IBM	B-Device
System/370	I-Device
and	O
the	O
IBM	O
System	O
360/195	O
.	O
</s>
<s>
Its	O
removable	O
disk	B-Operating_System
packs	I-Operating_System
hold	O
100MB	O
(	O
404×19×	O
13,030	O
bytes	O
)	O
.	O
</s>
<s>
A	O
major	O
advance	O
introduced	O
with	O
the	O
3330	O
was	O
the	O
use	O
of	O
error	B-Error_Name
correction	I-Error_Name
,	O
which	O
makes	O
the	O
drives	O
more	O
reliable	O
and	O
reduced	O
costs	O
because	O
small	O
imperfections	O
in	O
the	O
disk	B-Device
surface	O
can	O
be	O
tolerated	O
.	O
</s>
<s>
The	O
1973	O
3330	O
Model	O
11	O
features	O
IBM	O
3336-11	O
Disk	B-Operating_System
Packs	I-Operating_System
that	O
held	O
up	O
to	O
200MB	O
(	O
808x19x	O
13,030	O
bytes	O
)	O
.	O
</s>
<s>
Up	O
to	O
three	O
additional	O
3330	O
type	O
DASD	B-Application
(	O
six	O
drives	O
)	O
can	O
then	O
be	O
attached	O
to	O
a	O
3333	O
.	O
</s>
<s>
However	O
,	O
only	O
a	O
3340	O
can	O
serve	O
as	O
head	B-Device
of	O
string	O
;	O
there	O
are	O
no	O
A	O
model	O
3344	O
drives	O
,	O
and	O
a	O
3344	O
must	O
be	O
attached	O
to	O
a	O
3340	O
A	O
model	O
as	O
head	B-Device
of	O
string	O
.	O
</s>
<s>
The	O
IBM	O
3340	O
Direct	O
Access	O
Storage	O
Facility	O
,	O
code-named	O
Winchester	O
,	O
was	O
introduced	O
in	O
March	O
1973	O
for	O
use	O
with	O
IBM	B-Device
System/370	I-Device
.	O
</s>
<s>
It	O
uses	O
removable	O
data	O
modules	O
that	O
included	O
the	O
head	B-Device
and	O
arm	O
assembly	O
;	O
an	O
access	O
door	O
of	O
the	O
data	O
module	O
opens	O
or	O
closes	O
during	O
a	O
mechanical	O
load/unload	O
process	O
to	O
connect	O
the	O
data	O
module	O
to	O
the	O
drive	O
;	O
unlike	O
previous	O
disk	B-Operating_System
packs	I-Operating_System
and	O
cartridges	O
there	O
is	O
no	O
cover	O
to	O
remove	O
during	O
the	O
insertion	O
process	O
.	O
</s>
<s>
The	O
3340	O
also	O
uses	O
error	B-Error_Name
correction	I-Error_Name
.	O
</s>
<s>
One	O
significant	O
aspect	O
of	O
this	O
product	O
,	O
and	O
the	O
reason	O
that	O
disk	B-Device
drives	I-Device
in	O
general	O
became	O
known	O
as	O
"	O
Winchester	O
technology	O
"	O
,	O
was	O
that	O
this	O
head	B-Device
design	O
was	O
very	O
low	O
cost	O
and	O
did	O
not	O
require	O
the	O
heads	O
to	O
be	O
unloaded	O
from	O
the	O
media	O
.	O
</s>
<s>
Winchester	O
technology	O
allowed	O
the	O
head	B-Device
to	O
land	O
and	O
take	O
off	O
from	O
the	O
disk	B-Device
media	O
as	O
the	O
disk	B-Device
spun	O
up	O
and	O
down	O
.	O
</s>
<s>
This	O
resulted	O
in	O
very	O
significant	O
savings	O
and	O
a	O
large	O
reduction	O
of	O
complexity	O
of	O
the	O
head	B-Device
and	O
arm	O
actuating	O
mechanism	O
.	O
</s>
<s>
This	O
head	B-Device
design	O
rapidly	O
became	O
a	O
standard	O
design	O
within	O
the	O
disk	B-Device
drive	I-Device
manufacturing	O
community	O
.	O
</s>
<s>
Up	O
into	O
the	O
early	O
1990s	O
the	O
term	O
Winchester	O
or	O
Winnie	O
was	O
used	O
for	O
hard	B-Device
disk	I-Device
drives	I-Device
in	O
general	O
long	O
after	O
the	O
introduction	O
of	O
the	O
3340	O
,	O
but	O
is	O
no	O
longer	O
in	O
common	O
use	O
in	O
most	O
parts	O
of	O
the	O
world	O
.	O
</s>
<s>
The	O
IBM	O
3344	O
is	O
similar	O
to	O
the	O
3340	O
,	O
except	O
that	O
it	O
uses	O
fixed	O
media	O
rather	O
than	O
removable	O
3348	O
data	O
modules	O
,	O
each	O
spindle	O
has	O
4	O
logical	O
drives	O
each	O
with	O
the	O
capacity	O
of	O
a	O
3348	O
–	O
70	O
,	O
there	O
is	O
no	O
A	O
(	O
head	B-Device
of	O
string	O
)	O
model	O
and	O
it	O
is	O
only	O
available	O
in	O
dual	O
drive	O
models	O
.	O
</s>
<s>
Both	O
3344-B2	O
and	O
3344-B2F	O
require	O
a	O
3340-A2	O
or	O
3340-A2F	O
as	O
head	B-Device
of	O
string	O
.	O
</s>
<s>
The	O
IBM	O
3350	O
Direct	O
Access	O
Storage	O
Facility	O
,	O
code-named	O
Madrid	O
,	O
was	O
introduced	O
in	O
1975	O
for	O
use	O
with	O
IBM	B-Device
System/370	I-Device
.	O
</s>
<s>
Its	O
non-removable	O
head-disk	O
assemblies	O
(	O
HDAs	O
)	O
are	O
sealed	O
and	O
included	O
the	O
head	B-Device
and	O
arm	O
assembly	O
.	O
</s>
<s>
The	O
3350	O
disk	B-Device
geometry	O
is	O
555	O
cylinders	O
,	O
30	O
heads	O
,	O
and	O
19,069	O
bytes	O
per	O
track	O
,	O
which	O
give	O
each	O
HDA	O
a	O
storage	O
capacity	O
of	O
317,498,850	O
bytes	O
.	O
</s>
<s>
Sealed	O
HDAs	O
were	O
standard	O
practice	O
on	O
all	O
IBM	O
DASD	B-Application
hereafter	O
.	O
</s>
<s>
Disk	B-Device
units	O
are	O
identified	O
as	O
Models	O
A2	O
,	O
A2F	O
,	O
B2	O
,	O
B2F	O
,	O
C2	O
,	O
and	O
C2F	O
with	O
each	O
model	O
containing	O
two	O
HDAs	O
.	O
</s>
<s>
The	O
"	O
x2F	O
"	O
,	O
as	O
in	O
Model	O
A2F	O
,	O
unit	O
is	O
a	O
normal	O
x2	O
unit	O
,	O
but	O
its	O
two	O
HDAs	O
also	O
have	O
a	O
Fixed	O
Head	B-Device
area	O
over	O
the	O
first	O
five	O
cylinders	O
,	O
thereby	O
reducing	O
seek	O
time	O
to	O
zero	O
for	O
these	O
five	O
cylinders	O
.	O
</s>
<s>
This	O
fixed	O
head	B-Device
area	O
is	O
intended	O
to	O
be	O
allocated	O
to	O
the	O
frequently	O
accessed	O
HASP	B-Application
or	O
JES2	B-Application
checkpoint	O
area	O
and	O
thus	O
greatly	O
reduce	O
head	B-Device
motion	O
on	O
the	O
SPOOL	O
device	O
.	O
</s>
<s>
The	O
fixed	O
head	B-Device
area	O
can	O
also	O
be	O
utilized	O
for	O
TSO	B-Application
swap	O
data	O
(	O
MVT	O
and	O
SVS	B-Application
)	O
and	O
system	O
swap	O
data	O
(	O
MVS	B-Application
)	O
wherein	O
the	O
swap	O
data	O
for	O
SVS	B-Application
and	O
MVS	B-Application
consist	O
of	O
blocks	O
of	O
pages	O
that	O
have	O
been	O
in	O
memory	O
when	O
an	O
address	O
space	O
is	O
selected	O
for	O
swap-out	O
;	O
those	O
pages	O
need	O
not	O
be	O
contiguous	O
and	O
in	O
general	O
do	O
not	O
include	O
pages	O
that	O
have	O
not	O
been	O
modified	O
since	O
their	O
last	O
page-in	O
.	O
</s>
<s>
This	O
system	O
architecture	O
greatly	O
improves	O
context	O
switches	O
between	O
TSO	B-Application
users	O
or	O
batch	O
regions	O
.	O
</s>
<s>
IBM	O
introduced	O
the	O
IBM	O
3370	O
Direct	B-Application
Access	I-Application
Storage	I-Application
Device	I-Application
in	O
January	O
1979	O
for	O
IBM	B-Device
4331	I-Device
,	O
4341	O
,	O
and	O
System/38	B-Device
midrange	B-Device
computers	I-Device
.	O
</s>
<s>
It	O
has	O
seven	O
fixed	O
disks	B-Device
,	O
and	O
each	O
unit	O
has	O
a	O
capacity	O
of	O
571MB	O
.	O
</s>
<s>
It	O
was	O
the	O
first	O
HDD	O
to	O
use	O
thin-film	O
head	B-Device
technology	O
;	O
research	O
on	O
that	O
technology	O
started	O
at	O
Thomas	O
J	O
.	O
Watson	O
Research	O
Center	O
in	O
the	O
late	O
1960s	O
.	O
</s>
<s>
The	O
3370	O
was	O
a	O
fixed-block	B-Device
architecture	I-Device
device	O
,	O
used	O
on	O
DOS/VSE	B-Application
and	O
VM	B-Application
,	O
the	O
only	O
S/370	B-Device
operating	O
systems	O
that	O
supported	O
FBA	O
devices	O
.	O
</s>
<s>
The	O
sister	O
unit	O
was	O
called	O
the	O
IBM	O
3375	O
and	O
used	O
count	B-Application
key	I-Application
data	I-Application
architecture	O
,	O
which	O
was	O
required	O
for	O
OS/360	B-Application
and	I-Application
successor	I-Application
OSes	O
.	O
</s>
<s>
The	O
IBM	O
3380	O
Direct	B-Application
Access	I-Application
Storage	I-Application
Device	I-Application
was	O
introduced	O
in	O
June	O
1980	O
.	O
</s>
<s>
It	O
uses	O
film	O
head	B-Device
technology	O
and	O
has	O
a	O
unit	O
capacity	O
of	O
2.52	O
gigabytes	O
(	O
two	O
hard	B-Device
disk	I-Device
assemblies	O
each	O
with	O
two	O
independent	O
actuators	O
each	O
accessing	O
630MB	O
within	O
one	O
chassis	O
)	O
with	O
a	O
data	O
transfer	O
rate	O
of	O
3	O
megabytes	O
per	O
second	O
.	O
</s>
<s>
In	O
February	O
1985	O
,	O
IBM	O
announced	O
a	O
double	O
density	O
version	O
–	O
the	O
Extended	O
Capability	O
Models	O
of	O
the	O
3380	O
(	O
3380	O
E	O
)	O
having	O
5.04	O
gigabytes	O
per	O
chassis	O
,	O
that	O
is	O
,	O
two	O
1.26	O
gigabyte	O
actuators	O
on	O
two	O
hard	B-Device
disk	I-Device
assemblies	O
in	O
one	O
chassis	O
.	O
</s>
<s>
A	O
triple	O
capacity	O
version	O
,	O
the	O
3380	O
K	O
was	O
announced	O
in	O
August	O
1987	O
having	O
7.562	O
gigabytes	O
per	O
chassis	O
,	O
that	O
is	O
,	O
two	O
1.89	O
gigabyte	O
actuators	O
on	O
two	O
hard	B-Device
disk	I-Device
assemblies	O
in	O
one	O
chassis	O
.	O
</s>
<s>
The	O
IBM	O
3390	O
Direct	B-Application
Access	I-Application
Storage	I-Application
Device	I-Application
series	O
was	O
introduced	O
November	O
1989	O
,	O
offering	O
a	O
maximum	O
storage	O
of	O
up	O
to	O
22	O
gigabytes	O
in	O
a	O
string	O
of	O
multiple	O
drives	O
.	O
</s>
<s>
Packaged	O
in	O
Hard	B-Device
Disk	I-Device
Assemblies	O
with	O
2	O
actuator-head	O
units	O
and	O
one	O
set	O
of	O
platters	O
,	O
a	O
model	O
1	O
HDA	O
provides	O
1.89GB	O
before	O
formatting	O
and	O
a	O
model	O
2	O
provides	O
3.78GB/HDA	O
.	O
</s>
<s>
The	O
3390	O
Model	O
9	O
was	O
the	O
last	O
Single	O
Large	O
Expensive	O
Disk	B-Device
(	O
sometimes	O
called	O
SLEDs	O
)	O
drive	O
announced	O
by	O
IBM	O
.	O
</s>
<s>
It	O
was	O
an	O
up	O
to	O
1.5GB	O
full	O
height	O
5-inch	O
HDD	O
using	O
up	O
to	O
8	O
130mm	O
disks	B-Device
.	O
</s>
<s>
In	O
October	O
1991	O
the	O
9345	O
DASD	B-Application
was	O
announced	O
as	O
part	O
of	O
the	O
IBM	O
9340	O
channel-attached	O
,	O
count	B-Application
key	I-Application
data	I-Application
(	O
CKD	O
)	O
DASD	B-Application
subsystem	O
family	O
which	O
attached	O
to	O
IBM	O
mainframes	B-Architecture
including	O
the	O
ES/9000	O
processor	O
family	O
.	O
</s>
<s>
The	O
9345	O
DASD	B-Application
Model	O
1	O
had	O
two	O
1.0GB	O
HDDs	O
while	O
the	O
Model	O
2	O
had	O
two	O
1.5GB	O
HDDs	O
.	O
</s>
<s>
The	O
OS	O
's	O
IOS	B-Application
component	O
learned	O
of	O
this	O
device	O
's	O
characteristics	O
through	O
a	O
special	O
initializer	O
,	O
IECCINIT	O
,	O
which	O
also	O
serviced	O
other	O
DASD	B-Application
device	O
types	O
,	O
and	O
for	O
the	O
same	O
purpose	O
.	O
</s>
<s>
9331	O
Diskette	B-Device
Unit	O
models	O
1	O
and	O
11	O
contained	O
one	O
8-inch	O
FDD	O
while	O
the	O
models	O
2	O
and	O
12	O
contained	O
one	O
5-inch	O
FDD	O
.	O
</s>
<s>
9332	O
Direct	B-Application
Access	I-Application
Storage	I-Application
Device	I-Application
used	O
the	O
IBM	O
0667	O
HDD	O
.	O
</s>
<s>
9334	O
Disk	B-Device
Expansion	O
Unit	O
attaches	O
from	O
one	O
to	O
four	O
SCSI	O
HDDs	O
to	O
the	O
RS/6000	O
system	O
.	O
</s>
<s>
9335	O
Direct	O
Access	O
Storage	O
Subsystem	O
This	O
HDD	O
used	O
in	O
this	O
subsystem	O
was	O
developed	O
under	O
the	O
code	O
name	O
"	O
Kestrel	O
"	O
at	O
IBM	O
Hursley	O
,	O
UK	O
,	O
and	O
was	O
an	O
850MB	O
HDD	O
using	O
three	O
14-inch	O
disks	B-Device
with	O
dual	O
rotary	B-Algorithm
actuators	I-Algorithm
,	O
each	O
actuator	O
accessing	O
three	O
surfaces	O
with	O
two	O
heads	O
per	O
surface	O
.	O
</s>
<s>
The	O
HDD	O
was	O
in	O
the	O
rack	O
mountable	O
9335	O
announced	O
as	O
a	O
part	O
of	O
the	O
October	O
1986	O
IBM	B-Device
9370	I-Device
Information	O
System	O
announcement	O
.	O
</s>
<s>
9337	O
Disk	B-Device
Array	O
Subsystem	O
used	O
the	O
IBM	O
0662	O
(	O
Spitfire	O
)	O
or	O
0663	O
(	O
Corsair	O
)	O
HDDs	O
.	O
</s>
<s>
The	O
IBM	O
2310	O
Removable	O
Cartridge	O
Drive	O
was	O
announced	O
in	O
1964	O
with	O
the	O
IBM	B-Device
1800	I-Device
,	O
and	O
then	O
in	O
1965	O
with	O
the	O
IBM	B-Device
1130	I-Device
;	O
it	O
likely	O
first	O
shipped	O
with	O
the	O
1130	O
in	O
late	O
1965	O
.	O
</s>
<s>
A	O
single	O
oxide-coated	O
aluminum	O
disk	B-Device
spun	O
in	O
a	O
plastic	O
shell	O
with	O
openings	O
for	O
the	O
read/write	O
arm	O
and	O
two	O
heads	O
.	O
</s>
<s>
Developed	O
at	O
IBM	O
's	O
Hursley	O
,	O
England	O
,	O
laboratory	O
under	O
code	O
name	O
Dolphin	O
it	O
used	O
the	O
5440	O
disk	B-Device
cartridge	O
.	O
</s>
<s>
The	O
cartridge	O
in	O
turn	O
contained	O
one	O
14-inch	O
disk	B-Device
.	O
</s>
<s>
It	O
used	O
a	O
Swinging	O
Arm	O
actuator	O
with	O
one	O
14-inch	O
disk	B-Device
.	O
</s>
<s>
The	O
0680	O
first	O
shipped	O
in	O
1979	O
on	O
most	O
IBM	O
small	O
systems	O
and	O
the	O
low	O
end	O
of	O
the	O
System/370	B-Device
as	O
the	O
3310	O
direct	O
access	O
storage	O
.	O
</s>
<s>
Developed	O
at	O
IBM	O
's	O
Hursley	O
,	O
UK	O
,	O
laboratory	O
under	O
the	O
code	O
name	O
Piccolo	O
with	O
an	O
initial	O
capacity	O
of	O
up	O
to	O
65MB	O
,	O
it	O
used	O
six	O
8-inch	O
disks	B-Device
(	O
210mm	O
)	O
and	O
had	O
an	O
improved	O
rotary	B-Algorithm
actuator	I-Algorithm
.	O
</s>
<s>
The	O
0676	O
first	O
shipped	O
in	O
November	O
1982	O
as	O
a	O
5247	O
Disk	B-Device
Storage	I-Device
Unit	O
for	O
the	O
IBM	B-Device
System/23	I-Device
Datamaster	I-Device
.	O
</s>
<s>
Developed	O
at	O
the	O
IBM	O
Rochester	O
,	O
MN	O
,	O
laboratory	O
as	O
the	O
21ED	O
it	O
was	O
an	O
8-inch	O
HDD	O
with	O
an	O
initial	O
capacity	O
of	O
15	O
or	O
30MB	O
in	O
2	O
or	O
4	O
210mm	O
disks	B-Device
.	O
</s>
<s>
Developed	O
at	O
IBM	O
Rochester	O
,	O
MN	O
,	O
under	O
the	O
code	O
name	O
"	O
Grant	O
"	O
,	O
it	O
was	O
a	O
70MB	O
ESDI	O
full	O
height	O
5-inch	O
HDD	O
with	O
up	O
to	O
4	O
130mm	O
disks	B-Device
.	O
</s>
<s>
Developed	O
at	O
IBM	O
Rochester	O
,	O
MN	O
,	O
under	O
the	O
code	O
name	O
"	O
Grant-Prime	O
"	O
,	O
it	O
was	O
a	O
full-height	O
5-inch	O
HDD	O
with	O
a	O
capacity	O
of	O
up	O
to	O
115MB	O
on	O
up	O
to	O
4	O
130mm	O
disks	B-Device
.	O
</s>
<s>
Developed	O
under	O
the	O
code	O
name	O
"	O
Lee	O
"	O
at	O
IBM	O
Rochester	O
,	O
MN	O
,	O
it	O
was	O
an	O
up	O
to	O
316MB	O
ESDI	O
full	O
height	O
5-inch	O
HDD	O
with	O
up	O
to	O
8	O
130mm	O
disks	B-Device
depending	O
upon	O
model	O
.	O
</s>
<s>
This	O
was	O
IBM	O
's	O
first	O
usage	O
of	O
a	O
thin	O
metal	O
film	O
as	O
the	O
disk	B-Device
's	O
recording	O
surface	O
.	O
</s>
<s>
Developed	O
initially	O
under	O
the	O
code	O
name	O
"	O
Lightning	O
"	O
at	O
IBM	O
Rochester	O
MN	O
(	O
and	O
IBM	O
Hursley	O
,	O
UK	O
)	O
as	O
a	O
320MB	O
SCSI	O
HDD	O
with	O
up	O
to	O
eight	O
95mm	O
disks	B-Device
(	O
14heads	O
)	O
,	O
it	O
was	O
followed	O
in	O
1990	O
with	O
a	O
400MB	O
version	O
,	O
code	O
named	O
"	O
Turbo	O
"	O
.	O
</s>
<s>
It	O
was	O
an	O
up	O
to	O
857MB	O
full	O
height	O
5-inch	O
HDD	O
using	O
up	O
to	O
12	O
130mm	O
disks	B-Device
.	O
</s>
<s>
It	O
was	O
the	O
first	O
HDD	O
to	O
use	O
PRML	B-Device
decoding	O
of	O
data	O
.	O
</s>
<s>
It	O
was	O
the	O
drive	O
component	O
of	O
the	O
9333	O
Disk	B-Device
Drive	I-Device
Subsystem	O
which	O
first	O
shipped	O
in	O
early	O
1992	O
.	O
</s>
<s>
Developed	O
under	O
the	O
code	O
name	O
"	O
Corsair	O
"	O
,	O
it	O
was	O
a	O
3-inch	O
HDD	O
with	O
the	O
height	O
of	O
a	O
5-inch	O
half-height	O
device	O
(	O
1.6-inch	O
high	O
)	O
and	O
up	O
to	O
1GB	O
on	O
up	O
to	O
8	O
95mm	O
disks	B-Device
.	O
</s>
<s>
It	O
was	O
the	O
first	O
OEM	O
disk	B-Device
drive	I-Device
to	O
use	O
MR	O
Heads	O
.	O
</s>
<s>
Developed	O
under	O
the	O
code	O
name	O
"	O
Allicat	O
"	O
at	O
IBM	O
Rochester	O
,	O
MN	O
,	O
it	O
was	O
a	O
full-height	O
5-inch	O
HDD	O
(	O
3.25-inch	O
high	O
)	O
that	O
combined	O
two	O
3-inch	O
devices	O
in	O
one	O
,	O
with	O
up	O
to	O
2.013GB	O
capacity	O
on	O
up	O
to	O
8	O
95mm	O
disks	B-Device
.	O
</s>
<s>
Developed	O
under	O
the	O
code	O
name	O
"	O
Spitfire	O
"	O
at	O
IBM	O
Rochester	O
,	O
MN	O
,	O
it	O
was	O
a	O
full-height	O
(	O
1-inch	O
high	O
)	O
3-inch	O
HDD	O
with	O
1.05GB	O
on	O
3	O
disks	B-Device
or	O
5	O
disk	B-Device
surfaces	O
.	O
</s>
<s>
It	O
was	O
the	O
HDD	O
internal	O
to	O
the	O
9336	O
Disk	B-Device
Unit	O
and	O
the	O
9337	O
Disk	B-Device
Array	O
.	O
</s>
<s>
Another	O
important	O
IBM	O
innovation	O
is	O
the	O
floppy	B-Device
disk	I-Device
drive	I-Device
.	O
</s>
<s>
In	O
1973	O
IBM	O
shipped	O
its	O
first	O
read/write	O
floppy	B-Device
disk	I-Device
drive	I-Device
as	O
a	O
part	O
of	O
the	O
3740	O
Data	O
Entry	O
System	O
.	O
</s>
<s>
IBM	O
established	O
early	O
standards	O
in	O
8	B-Device
"	I-Device
FDDs	O
but	O
never	O
sold	O
such	O
products	O
separately	O
so	O
that	O
the	O
industry	O
then	O
developed	O
separate	O
from	O
IBM	O
.	O
</s>
<s>
On	O
October	O
17	O
,	O
1994	O
,	O
IBM	O
's	O
Storage	O
Systems	O
division	O
announced	O
three	O
new	O
families	O
of	O
hard	B-Device
disk	I-Device
drives	I-Device
,	O
the	O
Travelstar	B-Device
2-inch	O
family	O
for	O
notebooks	O
,	O
the	O
Deskstar	B-Device
3-inch	O
family	O
for	O
desktop	O
applications	O
and	O
the	O
Ultrastar	O
3-inch	O
family	O
for	O
high	O
performance	O
computer	O
system	O
applications	O
.	O
</s>
<s>
Parameter	O
(	O
units	O
)	O
RAMAC	O
350	O
Ultrastar	O
146Z10	O
Deskstar	B-Device
180GXP	O
Travelstar	B-Device
80GN	O
46-year	O
improvement	O
(	O
maximum	O
)	O
Announced	O
Sep	O
1956	O
Jul	O
2002	O
Oct	O
2002	O
Nov	O
2002	O
Capacity	O
(	O
gigabytes	O
)	O
0.004	O
146	O
180	O
80	O
48,000	O
Dimensions	O
(	O
inches	O
)	O
60×68×29	O
4×1×	O
5.75	O
4×1×	O
5.75	O
2.75	O
×	O
0.38	O
×	O
3.95	O
Dimensions	O
(	O
mm	O
)	O
1500×1700×700	O
102×25×146	O
102×25×146	O
70×	O
9.5	O
×100	O
Volume	O
(	O
in³	O
)	O
118,320	O
23	O
23	O
4	O
29,161	O
Volume	O
(	O
litres	O
)	O
1,939	O
0.4	O
0.4	O
0.1	O
Weight	O
(	O
lbs	O
)	O
2,140	O
1.7	O
1.4	O
0.2	O
1,244	O
Weight	O
(	O
kg	O
)	O
971	O
0.8	O
0.64	O
0.095	O
Power	O
(	O
watts	O
)	O
8100	O
BTUs/hour	O
(	O
i.e.	O
,	O
2374	O
watts	O
)	O
,	O
M.J.	O
Phister	O
,	O
Jr	O
,	O
Data	O
Process	O
–	O
Technology	O
and	O
Economics	O
2nd	O
Ed.	O
,	O
1979	O
,	O
Table	O
II.2.12.1	O
up	O
to	O
5500	O
VA	O
depending	O
upon	O
model	O
16	O
10.3	O
1.85	O
1,283	O
Power	O
density	O
(	O
megabytes/watt	O
)	O
0.0016	O
9,125	O
17,476	O
43,243	O
27,375,856	O
List	O
price	O
(	O
)	O
$	O
34,500	O
Ballistic	O
Research	O
Laboratories	O
"	O
A	O
Third	O
Survey	O
of	O
Domestic	O
Electronic	O
Digital	O
Computing	O
Systems	O
"	O
,	O
March	O
1961	O
,	O
section	O
on	O
IBM	B-Device
305	I-Device
RAMAC	I-Device
(	O
pp	O
.	O
</s>
<s>
IBM	O
in	O
some	O
of	O
its	O
operating	O
systems	O
classifies	O
HDDs	O
and	O
FDDs	O
as	O
DASDs	B-Application
,	O
direct	B-Application
access	I-Application
storage	I-Application
devices	I-Application
.	O
</s>
<s>
The	O
IBM	O
7320	O
is	O
a	O
magnetic	B-General_Concept
drum	I-General_Concept
storage	O
unit	O
announced	O
in	O
1962	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
introduced	O
in	O
1964	O
.	O
</s>
<s>
The	O
IBM	B-Device
2321	I-Device
Data	I-Device
Cell	I-Device
announced	O
in	O
1964	O
is	O
a	O
device	O
that	O
uses	O
short	O
strips	O
of	O
magnetic	O
tape	O
to	O
store	O
data	O
.	O
</s>
<s>
The	O
IBM	B-Device
3850	I-Device
Mass	I-Device
Storage	I-Device
System	I-Device
,	O
announced	O
in	O
1974	O
,	O
is	O
a	O
library	O
system	O
of	O
tape	O
cartridges	O
that	O
staged	O
data	O
from	O
the	O
cartridges	O
onto	O
physical	O
IBM	O
3330	O
or	O
3350	O
disk	B-Device
drives	I-Device
which	O
then	O
appeared	O
to	O
the	O
system	O
as	O
virtual	O
3330	O
drives	O
.	O
</s>
