OK, so I finally bit the bullet and have the floppy drive under direct SX control.
I have my amiga power supply, which is a modified PC supply with harddrive leads powering the drive directly with +12v and +5v. I also have a number of leads running direct from the SX to the drive.
I am successfully stepping the drive, although I must admit the direction select is kind of wierd. I expected just to set the lead high or low, but it looks like it needs an edge to change. So HIGH to LOW causes it to step IN, increasing cylinder from 0 to 79, and LOW to HIGH causes it to step OUT, decreasing cylinder from 79 to 0.
I must admit my floppy drive is very cool with the cylinder number in an LED bar graph.
I’ve forgot to run a SIDE lead over, I’m doing that now.
It won’t be long until this is fully automated.