<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>
Part	O
of	O
the	O
IBM	B-Device
7-track	I-Device
family	O
of	O
tape	O
units	O
,	O
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>
Like	O
its	O
predecessor	O
,	O
the	O
IBM	B-Device
727	I-Device
and	O
many	O
successors	O
,	O
the	O
729	O
used	O
magnetic	O
tape	O
up	O
to	O
long	O
wound	O
on	O
reels	O
up	O
to	O
diameter	O
.	O
</s>
<s>
To	O
allow	O
rapid	O
tape	O
acceleration	O
(	O
and	O
thus	O
reduced	O
seek/access	O
times	O
)	O
,	O
long	O
vacuum	B-Device
columns	I-Device
were	O
placed	O
between	O
the	O
tape	O
reels	O
and	O
the	O
read/write	O
heads	O
to	O
absorb	O
sudden	O
increases	O
in	O
tape	O
tension	O
which	O
would	O
otherwise	O
break	O
the	O
tape	O
.	O
</s>
<s>
Write	B-Device
protection	I-Device
was	O
provided	O
by	O
a	O
removable	O
plastic	O
ring	O
in	O
the	O
back	O
of	O
the	O
tape	O
reel	O
.	O
</s>
<s>
The	O
tape	O
had	O
seven	B-Device
parallel	I-Device
tracks	I-Device
,	O
six	O
for	O
data	O
and	O
one	O
to	O
maintain	O
parity	B-Error_Name
.	O
</s>
<s>
Tapes	O
with	O
character	O
data	O
(	O
BCD	O
)	O
were	O
recorded	O
in	O
even	B-Error_Name
parity	I-Error_Name
.	O
</s>
<s>
Binary	O
tapes	O
used	O
odd	B-Error_Name
parity	I-Error_Name
(	O
709	O
manual	O
,	O
p.20	O
)	O
.	O
</s>
<s>
Write	B-Device
protection	I-Device
was	O
provided	O
by	O
a	O
removable	O
plastic	O
ring	O
in	O
the	O
back	O
of	O
the	O
tape	O
reel	O
.	O
</s>
<s>
Initial	O
tape	O
speed	O
was	O
75inches	O
per	O
second	O
(	O
2.95m/s	O
)	O
and	O
recording	O
density	O
was	O
200	O
characters	O
per	O
inch	O
,	O
giving	O
a	O
payload	O
transfer	O
speed	O
of	O
90	O
kbit/s	O
(	O
105	O
kbit/s	O
including	O
parity	B-Error_Name
bits	I-Error_Name
)	O
.	O
</s>
<s>
At	O
200	O
characters	O
per	O
inch	O
,	O
a	O
single	O
2400-foot	O
tape	O
could	O
store	O
the	O
equivalent	O
of	O
some	O
50,000	O
punched	B-Architecture
cards	I-Architecture
(	O
about	O
4,000,000	O
six-bit	O
bytes	O
,	O
a	O
data	O
quantity	O
equivalent	O
to	O
three	O
million	O
octets	O
)	O
.	O
</s>
<s>
The	O
729	O
series	O
was	O
superseded	O
by	O
9-track	B-Device
tape	I-Device
drives	O
introduced	O
with	O
the	O
IBM	B-Application
System/360	I-Application
.	O
</s>
<s>
The	O
IBM	B-Device
729	I-Device
I	O
was	O
introduced	O
for	O
the	O
IBM	B-Device
709	I-Device
and	O
IBM	B-Device
705	I-Device
III	I-Device
computers	O
,	O
looked	O
identical	O
to	O
the	O
IBM	B-Device
727	I-Device
,	O
and	O
used	O
vacuum	O
tubes	O
.	O
</s>
<s>
The	O
IBM	B-Device
729	I-Device
II	O
was	O
introduced	O
for	O
the	O
IBM	B-Device
7000	I-Device
series	I-Device
computers	O
,	O
introducing	O
a	O
new	O
cabinet	O
style	O
and	O
transistorized	O
circuitry	O
.	O
</s>
