Also, the 'miggy now waits quite a while for the IDE bus to answer, before giving up and moving on. Is there a jumper that tells the A4000 to ignore its IDE bus?
Hold down the escape key when booting. You'll get a menu with four options. Click System. If you have an A4000 Desktop, turn on SCSIPatch. If it's an A4000T (not a desktop in a tower) turn on NCR SCSIPatch.