On Jun 3,  5:46pm, Andreas Gustafsson wrote:
} John Nemeth <jnemeth@victoria.tc.ca> wrote:
} >      This is wrong.  ESDI drives respond to the IDENTIFY command, and
} > possibly other "ATA" commands.  ESDI is a superset of the original
} > WD1003 command set, and ATA is a superset of that.
} 
} I thought ESDI was an electrical interface between controller and
} drive like ST506, not a controller command set like WD1003.

     It's both.  The WD1007 controller (and others) supported a command
set that was a superset of the WD1003 command set.  Later on, ATA came
along and extended the command set even more.

} If something in an ESDI system responds to an ATA IDENTIFY command, 
} it must be the controller, not the drive.

     Yes, but it gets the information needed to respond to the command
from the drive somehow.

}-- End of excerpt from Andreas Gustafsson