hp 9153 floppy & disk

I don;t think there ever were any technical manual for this drive :-(. Or at leasrt I've never seen one. There were never official schematics to my knowledge either .I have unofficial schematics, but they won't help you that much. It would be a lot less work to track down an HP9133 of some flavour. It would probaably be less work to recreate an HP9133... THe Nighthawk drive interface is strange. Very strange. it has the raw data signals of an ST412 drive (but on single-ended TTL lines, not differential pairs). It also hasa the strangest positioner interface you're likely to see. The positioner is a 2-winding stepper motor. You get (at the drive interface) to contrtoll the currents through the windings (there's a dual DAC in the drive).You also get soem kind of position feedback signal from the drive (there's an ADC in there too). There is no intellegence in the drive to control te DACs based on the output from the ADC, that is done in the controller (I assume in part by the 6809 firmware). Given there's an undocumented ASIC in the drive too, which has a register accessible over the interface, and for whaich I have no data, tryign to recreate the drive is going to be a big job. -tony