Is this a floppy drive cable?

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M

mm

OT floppy drive cable?
IN my box of miscellaneous parts, I have two flat cables, probably
that a friend gave me, that look like floppy drive cables. They have
the right connector on each end.

But they only have connectors on each end, none in the middle. And
yet 7 of the wires in the middle flip over, like they flip over some
wires for the second floppy drive on one cable.

What are these cables for? Why the flipped wires?


I don't know what brand these cables were made for.

Thanks)

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for some reason, remove NOPSAM :-)
 
mm said:
OT floppy drive cable?
IN my box of miscellaneous parts, I have two flat cables, probably
that a friend gave me, that look like floppy drive cables. They have
the right connector on each end.

But they only have connectors on each end, none in the middle. And
yet 7 of the wires in the middle flip over, like they flip over some
wires for the second floppy drive on one cable.

What are these cables for? Why the flipped wires?


I don't know what brand these cables were made for.

Thanks)

If you are inclined to email me
for some reason, remove NOPSAM :-)
Click to expand...

If you only have one floppy drive, you don't need a middle connector.
 
If you only have one floppy drive, you don't need a middle connector.
Click to expand...

Sure but why do there need to be the flipped wires?

If you are inclined to email me
for some reason, remove NOPSAM :-)
 
mm said:
But they only have connectors on each end, none in the middle. And
yet 7 of the wires in the middle flip over, like they flip over some
wires for the second floppy drive on one cable.

What are these cables for? Why the flipped wires?
Click to expand...

Sounds like a floppy cable for some machine set up to have a single
floppy drive. If it was a mass market computer they saved a few cents
on each unit by not bothering to install the second connector. It's
been a long time but I sort of remember that drive A was the one at
the end of the cable, i.e. with the flipped wires. So you'd use a
cable like that for a machine with just an A drive and no B drive.
 
Its not off topic.

Thats pretty common with new systems now, because hardly
anyone has more than one floppy drive anymore and some
chipsets dont even support more than one anymore now.

No choice on that if you only have one drive connector.

Systems which will only have one floppy drive.

No choice on that if you only have one drive connector.

It isnt brand specific, its the most common type of floppy cable now.
Sure but why do there need to be the flipped wires?
Click to expand...

Because that is the way that the drive letters evolved over time,
the single drive goes on the end of the cable, and so needs to
be after the flip, even if there isnt a middle connector because
there's only one floppy drive.
 
Because that is the way that the drive letters evolved over time,
the single drive goes on the end of the cable, and so needs to
be after the flip, even if there isnt a middle connector because
there's only one floppy drive.
Click to expand...

It took a while, but I get it now. Thanks Rod and Paul and CJ.

If you are inclined to email me
for some reason, remove NOPSAM :-)
 
mm said:
Sure but why do there need to be the flipped wires?
Click to expand...

Interesting question!...

The Shugart floppy standard (that IBM adapted for the original PC)
allowed four drives to be controlled with a single 34 pin cable with no
twists.

There was a separate "device select" line for each of the four drives,
and each drive had to be set (with jumpers) to respond to only one of
the device select lines. You could have Drive 0,1,2, and 3.

Although some early PC's could actually run three or four floppies, by
the time the AT was released (1984) most controllers only supported
lines 0 and 1.

The "twist" appeared as a lazy way to simplify drive installation. Each
drive is set as 1, and then the twist moves the drive 0 control lines
into the drive 1 pins for the drive at the end of the cable.

Dave
 
David Flory said:
Interesting question!...

The Shugart floppy standard (that IBM adapted for the original PC)
allowed four drives to be controlled with a single 34 pin cable with no
twists.

There was a separate "device select" line for each of the four drives,
and each drive had to be set (with jumpers) to respond to only one of
the device select lines. You could have Drive 0,1,2, and 3.

Although some early PC's could actually run three or four floppies, by
the time the AT was released (1984) most controllers only supported
lines 0 and 1.
Click to expand...

Actually the controllers supported a Drive Select for each of 2 drives
AND a Motor On for each of 2 drives.
The PC floppy drives will have only 1 drive select line and 1 Motor On
signal line on the original Drive Select 1 and Drive Select 0 respectively.
The other original drive selects are not connected on a PC drive.
The "twist" appeared as a lazy way to simplify drive installation.
Click to expand...

Similar to cable select with IDE drives.
Each drive is set as 1, and then the twist moves the drive 0 control
lines into the drive 1 pins for the drive at the end of the cable.
Click to expand...

If you used a standard switchable (ie non PC drive) floppy drive. There is
no '0' and '1' Drive Select on PC drives, just Drive Select and Motor On.
 
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