So how does it do this when the disk is yet to be formatted? In other words,
when it formats the disk how does it know what size the disk is?
Some (all?) ST412-interfaced drives report 'iilegal' head selections and
seeks by asserting the WrtieFault/ line. The ST412 diagram I've jsut
looked at suggests it will assert said line if either more than one head
is selected (indicating a fault i nthe selection circuitry) or if no
heads are selected (possibly due to the head selection lines tryign to
select mroe heads than the drive has). There's a link on the ST412 PCB
shich is removed if the board is used in an ST406 (I do not mena an
ST506!) which has fewer heads, so as to cause this error if heads only
present in the ST412 are selected
The microcotnrolelr which cotnrosl the head posiitoner stepper motor i
nthe ST412 can also assert WriteFault/ My guess (and I do not have the
firmware source) is that it does this if you try to step in too far.
If other drives behave in this way, its' farily easy to find out how many
cylinders and heads they have.
-tony