Floppy cable pinout

34 pin IDC female connector layout
34 pin IDC female connector at the Controller


34 pin IDC female connector layout
34 pin IDC female connector

The original floppy cable required that each drive was jumpered to
the right ID. But IBM come up with an idea to avoid jumpering the
floppies.
If wire 10-16 are twisted before the last connector the
jumpering is avoided. Each drive should be jumpered to act as Drive 2.
If only one drive is used then leave the middle connector free.
The IDC could also be an edge connector on some old drives.

Controller           Drive 2   Twist   Drive 1
+--+                   +--+            +--+
|::|===================|  |============|  |  <-Pin 1
|::|===================|  |=====/=====|  |
|::|===================|  |=====/=====|  |
|::|===================|  |============|  |
|::|===================|  |============|  |
|::|===================|  |============|  |
|::|===================|  |============|  |
+--+                   +--+            +--+

Controller Drive 1 Drive 2
Wire 1-9 1-9 1-9 1-9
Wire 10 10 16 10
Wire 11 11 15 11
Wire 12 12 14 12
Wire 13 13 13 13
Wire 14 14 12 14
Wire 15 15 11 15
Wire 16 16 10 16
Wire 17-34 17-34 17-34 17-34