They can be configured identically and the twist will swap the controlling input for them. This way, there is no need to "configure" the drives which drive (A or B) are they going to be and what they should listen to. The drive before the twist will be drive B while the one on the end will be A. While it might seem a little backward to have the drives respond to the drive B: wires in the absence of a twist, doing things that way makes it possible to use the full length of the cable when connecting a single drive A:, without requiring that the cable be twisted both before and after the middle connector. While it would have been possible to use jumpers on each drive to indicate whether it should respond to the first or second set of wires, standard practice has been to have all drives configured to respond to the drive-select and motor-start wires associated with drive B:, but then have a cable twisted between the two drive connectors so that the drive attached to the far-end connector will see the drive B: select wire when the controller is activating the drive A: wire. Additionally, one wire is activated when the drive A: motor should turn on, while the other does likewise for drive B: (obviously when code is going to want to access drive A: it's going to turn on the motor, but having separate motor-control wires will mean that code which wants to access drive A: now but will be wanting to access drive B: again can turn on both motors). On the PC floppy-drive cable, one of the wires is activated when a request is made to access drive A:, and another is activated when a request is made to access drive B.
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