<s>
The	O
original	O
IBM	B-Device
Personal	I-Device
Computer	I-Device
and	O
IBM	B-Device
PCjr	I-Device
included	O
support	O
for	O
storing	O
data	O
and	O
programs	O
on	O
compact	B-Device
cassette	I-Device
tape	I-Device
.	O
</s>
<s>
It	O
was	O
common	O
for	O
home	O
computers	O
of	O
the	O
time	O
,	O
such	O
as	O
the	O
Apple	B-Device
II	I-Device
,	O
Commodore	O
64	O
and	O
BBC	B-Device
Micro	I-Device
,	O
to	O
use	O
cassette	B-Device
tapes	I-Device
for	O
storage	O
due	O
to	O
the	O
lower	O
cost	O
of	O
hardware	O
and	O
media	O
compared	O
to	O
floppy	B-Device
disks	I-Device
.	O
</s>
<s>
The	O
IBM	B-Device
PC	I-Device
cassette	I-Device
format	O
did	O
not	O
experience	O
the	O
same	O
popularity	O
however	O
,	O
since	O
very	O
few	O
were	O
shipped	O
without	O
at	O
least	O
one	O
floppy	B-Device
disk	I-Device
drive	I-Device
,	O
and	O
apart	O
from	O
one	O
diagnostic	O
tape	O
available	O
from	O
IBM	O
,	O
there	O
seems	O
never	O
to	O
have	O
been	O
any	O
software	O
sold	O
on	O
tape	O
,	O
and	O
the	O
interface	O
was	O
not	O
included	O
on	O
the	O
followup	O
PC	B-Device
XT	I-Device
.	O
</s>
<s>
Despite	O
this	O
lack	O
of	O
popularity	O
,	O
up	O
until	O
the	O
original	O
PC	O
's	O
discontinuation	O
in	O
1987	O
,	O
IBM	O
continued	O
to	O
offer	O
a	O
Model	O
104	O
which	O
shipped	O
without	O
a	O
floppy	B-Device
disk	I-Device
drive	I-Device
.	O
</s>
<s>
The	O
IBM	B-Device
PCjr	I-Device
was	O
also	O
seldom	O
sold	O
without	O
a	O
floppy	B-Device
disk	I-Device
drive	I-Device
,	O
but	O
it	O
also	O
had	O
two	O
ROM	B-Protocol
cartridge	I-Protocol
slots	O
for	O
loading	O
commercial	O
software	O
,	O
which	O
offered	O
better	O
convenience	O
and	O
reliability	O
.	O
</s>
<s>
An	O
IBM	B-Device
PC	I-Device
with	O
just	O
an	O
external	O
cassette	O
recorder	O
for	O
storage	O
could	O
only	O
use	O
the	O
built-in	O
ROM	O
BASIC	O
as	O
its	O
operating	O
system	O
,	O
which	O
supported	O
cassette	O
operations	O
.	O
</s>
<s>
IBM	B-Operating_System
PC	I-Operating_System
DOS	I-Operating_System
had	O
no	O
support	O
for	O
cassette	B-Device
tape	I-Device
,	O
though	O
software	O
could	O
have	O
been	O
written	O
by	O
the	O
user	O
to	O
provide	O
support	O
.	O
</s>
<s>
BIOS	B-Device
interrupt	I-Device
call	I-Device
15h	O
routines	O
were	O
documented	O
in	O
the	O
technical	O
reference	O
manual	O
that	O
would	O
turn	O
the	O
cassette	O
motor	O
on	O
and	O
off	O
,	O
and	O
read	O
or	O
write	O
data	O
.	O
</s>
<s>
The	O
cassette	O
,	O
disk	O
,	O
advanced	O
,	O
and	O
cartridge	B-Protocol
versions	O
of	O
IBM	B-Language
BASIC	I-Language
included	O
statements	O
for	O
cassette	O
operations	O
,	O
but	O
these	O
features	O
only	O
worked	O
if	O
the	O
machine	O
had	O
a	O
cassette	O
port	O
.	O
</s>
<s>
The	O
IBM	B-Device
PC	I-Device
used	O
a	O
female	O
5-pin	O
DIN	B-Architecture
connector	I-Architecture
(	O
the	O
same	O
as	O
the	O
keyboard	O
connector	O
)	O
for	O
the	O
cassette	O
port	O
:	O
</s>
<s>
Motor	O
control	O
:	O
8255A	B-Device
port	O
,	O
bit	O
3	O
:	O
0	O
=	O
on	O
,	O
1	O
=	O
off	O
.	O
</s>
