Floppy Drive Cable????

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I have an old machine with two floppy drives.
The twist in a floppy cable is between the two floppy drive
connectors. If the twist is necessary, why is it not necessary for the
first-in-line floppy drive?

Thanks
 
The twist was there so you didn't have to change any jumpers
on the drive to identify it. Both drives were strapped
as drive 0 and the twist took care of identifying
them by putting one drive on line 1 and the other on line 0.
 
The twist was there so you didn't have to change any jumpers
on the drive to identify it. Both drives were strapped
as drive 0 and the twist took care of identifying
them by putting one drive on line 1 and the other on line 0.
Click to expand...

Then why when you only have one FDD, it must be connected to the cable
AFTER the twist (I think so anyway).

Thanks
 
The twist in the cable can be done so that FDD 0 is at the end, and FDD 1 is
the next one. This has to do with how the cable was designed. If you don't
like it, then use a non-twisted cable, and start messing around to set the
jumpers.

--


Greetings,

Jerry G.
============
 
geezer said:
Then why when you only have one FDD, it must be connected to the cable
AFTER the twist (I think so anyway).
Click to expand...

The BIOS identifies the drive on the end, (after the twist), as "A". The
drive before the twist, if any, becomes "B". You can interchange "A"
and "B" with a BIOS setting.
 
The twist in the cable can be done so that FDD 0 is at the end, and FDD 1 is
the next one. This has to do with how the cable was designed. If you don't
like it, then use a non-twisted cable, and start messing around to set the
jumpers.
Click to expand...

Thanks.

You know - I had forgotten. Back in the days of the larger 5 1/4 FDD,
there were many times I had two FDDs installed. One on A: and one on
B:. You had to connect the two drives to the two connectors on the
FDD cable - I always connected the 3 1/2 as A: drive on the end of the
cable, after the twist, and the 5 1/4 as B: to the connector before
the twist. Of course, the BIOS had to be set to accept & recognize
both the FDDs. I used this configuration to copy disks. I see no
reason that two 3 1/2 FDDs couldn't be connected similarly. Haven't
tried it in years though.

Cya
 
[email protected] said:
The twist in a floppy cable is between the two floppy drive
connectors. If the twist is necessary, why is it not
necessary for the first-in-line floppy drive?
Click to expand...

It's not necessary for B: but is for A:.

Normally the floppy drives are numbered 0-3 (pins 10, 12, 14, and 6,
respectively) and connected to a straight-through cable and selected by
jumpers, making A: 0, B: 1, etc. But IBM decided to set all of them as
1 (the second drive) and use the twist in the cable to distinguish A:
from B:.
 
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