<s>
IBM	O
's	O
first	O
magnetic-tape	B-Architecture
data	I-Architecture
storage	I-Architecture
devices	O
,	O
introduced	O
in	O
1952	O
,	O
use	O
what	O
is	O
now	O
generally	O
known	O
as	O
7-track	B-Device
tape	I-Device
.	O
</s>
<s>
These	O
tape	O
drives	O
were	O
mechanically	O
sophisticated	O
floor-standing	O
drives	O
that	O
used	O
vacuum	B-Device
columns	I-Device
to	O
buffer	O
long	O
U-shaped	O
loops	O
of	O
tape	O
.	O
</s>
<s>
When	O
active	O
,	O
the	O
two	O
tape	O
reels	O
thus	O
fed	O
tape	O
into	O
or	O
pulled	O
tape	O
out	O
of	O
the	O
vacuum	B-Device
columns	I-Device
,	O
intermittently	O
spinning	O
in	O
rapid	O
,	O
unsynchronized	O
bursts	O
resulting	O
in	O
visually	O
striking	O
action	O
.	O
</s>
<s>
Write	B-Device
protection	I-Device
A	O
removable	O
plastic	O
ring	O
in	O
the	O
back	O
of	O
the	O
tape	O
reel	O
was	O
inserted	O
to	O
indicate	O
that	O
writing	O
should	O
be	O
permitted	O
.	O
</s>
<s>
The	O
IBM	B-Device
726	I-Device
dual	O
magnetic	O
tape	O
reader/recorder	O
for	O
the	O
IBM	O
701	O
was	O
announced	O
on	O
May	O
21	O
,	O
1952	O
.	O
</s>
<s>
The	O
IBM	B-Device
727	I-Device
Magnetic	O
Tape	O
Unit	O
was	O
announced	O
for	O
the	O
IBM	O
701	O
and	O
IBM	O
702	O
on	O
September25	O
,	O
1953	O
.	O
</s>
<s>
The	O
IBM	B-Device
728	I-Device
magnetic	O
tape	O
drive	O
was	O
used	O
on	O
the	O
SAGE	O
AN/FSQ	B-Device
-7	I-Device
computer	O
.	O
</s>
<s>
The	O
IBM	B-Device
729	I-Device
Magnetic	O
Tape	O
Unit	O
was	O
IBM	O
's	O
iconic	O
tape	O
mass	O
storage	O
system	O
from	O
the	O
late	O
1950s	O
through	O
the	O
mid-1960s	O
.	O
</s>
<s>
It	O
was	O
used	O
on	O
late	B-Device
700	I-Device
,	I-Device
most	I-Device
7000	I-Device
and	O
many	O
1400	B-Device
series	O
computers	O
.	O
</s>
<s>
The	O
IBM	B-Device
7330	I-Device
Magnetic	O
Tape	O
Unit	O
was	O
a	O
low	O
cost	O
slower	O
tape	O
system	O
.	O
</s>
<s>
It	O
was	O
common	O
on	O
1400	B-Device
series	O
computers	O
.	O
</s>
<s>
The	O
2400	O
Series	O
Magnetic	O
Tape	O
Units	O
were	O
introduced	O
with	O
the	O
System/360	B-Application
.	O
</s>
<s>
Most	O
were	O
IBM	B-Device
9	I-Device
Track	I-Device
format	O
drives	O
,	O
but	O
they	O
could	O
be	O
ordered	O
with	O
seven-track	O
read/write	O
heads	O
,	O
allowing	O
them	O
to	O
read	O
and	O
write	O
seven-track	O
tapes	O
.	O
</s>
<s>
As	O
of	O
2020	O
,	O
IBM	O
still	O
sells	O
magnetic	O
tape	O
cartridge	O
drives	O
using	O
half-inch	O
wide	O
tape	O
in	O
the	O
Linear	B-Operating_System
Tape-Open	I-Operating_System
and	O
3592	B-Device
formats	O
.	O
</s>
