<s>
Each	O
generation	O
of	O
floppy	B-Device
disk	I-Device
drive	I-Device
(	O
FDD	O
)	O
began	O
with	O
a	O
variety	O
of	O
incompatible	O
interfaces	B-Protocol
but	O
soon	O
evolved	O
into	O
one	O
de	O
facto	O
standard	O
interface	O
for	O
the	O
generations	O
of	O
8-inch	O
FDDs	O
,	O
5.25-inch	O
FDDs	O
and	O
3.5-inch	O
FDDs	O
.	O
</s>
<s>
3.5-inch	O
and	O
5.25-inch	O
drives	O
connect	O
to	O
the	O
floppy	B-Device
controller	I-Device
using	O
a	O
34-conductor	O
flat	O
ribbon	O
cable	O
for	O
signal	O
and	O
control	O
;	O
a	O
separate	O
cable	O
provides	O
d.c.	O
power	O
.	O
</s>
<s>
Most	O
controllers	O
support	O
two	O
floppy	B-Device
drives	I-Device
,	O
so	O
a	O
cable	O
could	O
have	O
5.25-inch	O
style	O
connectors	O
,	O
3.5-inch	O
style	O
connectors	O
,	O
or	O
a	O
combination	O
.	O
</s>
<s>
After	O
IBM	O
introduced	O
the	O
"	O
twist	O
"	O
to	O
floppy	B-Device
cables	O
,	O
and	O
when	O
both	O
5.25-inch	O
and	O
3.5-inch	O
drives	O
were	O
in	O
common	O
use	O
,	O
many	O
cables	O
had	O
four	O
connectors	O
:	O
one	O
of	O
each	O
type	O
before	O
the	O
twist	O
,	O
and	O
one	O
of	O
each	O
type	O
after	O
the	O
twist	O
.	O
</s>
<s>
When	O
multiple	O
floppy	B-Device
disks	I-Device
are	O
connected	O
,	O
many	O
pins	O
are	O
shared	O
,	O
including	O
the	O
read	O
and	O
write	O
data	O
pins	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
early	O
floppy	B-Device
drives	I-Device
required	O
jumpers	O
to	O
be	O
set	O
on	O
the	O
drive	O
to	O
tell	O
it	O
which	O
controller	O
commands	O
it	O
should	O
receive	O
.	O
</s>
<s>
This	O
eliminated	O
the	O
need	O
to	O
change	O
selection	O
jumpers	O
in	O
the	O
drive	O
,	O
and	O
eventually	O
many	O
floppy	B-Device
drives	I-Device
were	O
manufactured	O
without	O
jumpers	O
at	O
all	O
,	O
instead	O
being	O
hardwired	O
as	O
drive	O
"	O
B	O
"	O
.	O
</s>
<s>
+Floppy	O
drive	O
connector	O
pinout（host	O
controller	O
as	O
a	O
reference）Pin	O
numberAbbreviationDescriptionNotesType2DENSELDensity	O
Select	O
1	O
=	O
Low/0	O
=	O
HighThe	O
default	O
use	O
is	O
0Output4RSVDReservedNo	O
connection	O
or	O
connect	O
to	O
the	O
ground6RSVDReservedNo	O
connection	O
or	O
connect	O
to	O
the	O
ground8INDEX	O
#Index0	O
=	O
IndexInput10MOTEA	O
#Motor	O
A	O
Enable0	O
=	O
Motor	O
Enable	O
Drive	O
0Output12DRVSBDrive	O
Select	O
BOutput14DRVSADrive	O
Select	O
AOutput16MOTEB	O
#Motor	O
B	O
Enable	O
0	O
=	O
Motor	O
Enable	O
Drive	O
1Output18DIR	O
#Direction	O
SelectLow	O
Current/Direction	O
in	O
uPD765	O
controllerOutput20STEP	O
#Head	O
StepFault	O
Reset/Step	O
in	O
uPD765	O
controllerOutput22WDATAWrite	O
DataOutput24WGATE	O
#Floppy	O
Write	O
Enable0	O
=	O
Write	O
GateOutput26TRK0	O
#Track	O
0Fault/Track	O
0	O
in	O
uPD765	O
controllerInput28WPT	O
#Write	O
Protect0	O
=	O
Write	O
ProtectInput30RDATARead	O
DataInput32HDSEL#	O
/SIDEHead	O
Select	O
/	O
Side	O
selectTwo	O
uses	O
,	O
see	O
application	O
or	O
use	O
for	O
details	O
.	O
</s>
<s>
Since	O
floppy	B-Device
disks	I-Device
are	O
rarely	O
used	O
nowadays	O
,	O
"	O
MOTEB#	O
"	O
and	O
“	O
DRVSB	O
”	O
pins	O
are	O
not	O
connected	O
in	O
motherboards	O
designed	O
with	O
floppy	B-Device
disk	I-Device
data	O
interfaces	B-Protocol
,	O
and	O
only	O
one	O
floppy	B-Device
disk	I-Device
drive	I-Device
can	O
be	O
connected	O
.	O
</s>
