I am trying to use some Tandy 1000 drives with a SuperCard Pro and have encountered some anomalies using them as "standard" floppy drives. It appears that with the original (or at least, working and as the machine came to me) jumper settings the motor of the 5.25" drive set as DS0 does not run while everything else does.
That is, when SCP tries to use it the LED of the drive comes on, and the head seeking steppers respond. But the spindle motor does not spin. Some further testing is a bit inclusive but it appears that with the default settings the first drive's motor only comes on when the second (DS1) drive is in use.
My question here is about the floppy drive controller (FDC) on the Tandy 1000 itself: does it have any special behaviors that are relevant to drive selection and the motor enable features? It uses a straight-through/non-twisted cable and so I sort of expected it to fully use the drive selection wires but it seems maybe the drive expects the motor controls to be a little different?