<s>
The	O
IBM	B-Device
727	I-Device
Magnetic	O
Tape	O
Unit	O
was	O
announced	O
for	O
the	O
IBM	B-Device
701	I-Device
and	O
IBM	B-Device
702	I-Device
on	O
September	O
25	O
,	O
1953	O
.	O
</s>
<s>
Later	O
vacuum-tube	B-Device
machines	I-Device
and	O
first-generation	O
transistor	B-Device
computers	I-Device
used	O
the	O
IBM	O
729-series	O
tape	O
drive	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
</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>
