ST506/412 cable

The ST506/412 interface requires two cables, one for control and one for data. The control cable is shared between the two drives. But each drive has each own data cable. By twisting some wires on the control cable it won"t be necessary to set the ID for each drive, since the twist will do the job. Wires 25 to 29 should be twisted between drive 1 & drive 2.

Controller           Drive 2   Twist   Drive 1

+--+                   +--+            +--+

|::|===================|  |============|  |  <-Pin 1
|::|===================| |============| |
|::|===================| |============| |
|::|===================| |============| |
|::|===================| |=====\/=====| |
|::|===================| |=====/\=====| |
|::|===================| |============| |
+--+ +--+ +--+

Control cable

Data cable

(To the Controller)
(To the Drive)

20 PIN IDC FEMALE to the Controller.
20 PIN IDC FEMALE to the Drive.