Re: [hatari-devel] Re: Hatari floppy drive detection with EmuTOS

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

Le 16/01/2014 01:05, David Savinkoff a écrit :
> ----- Nicolas Pomarède wrote:
> > ... the WD1772 doc
> > says it needs to count 6 revolutions (index hole) from the floppy drive
> > to determine when the spin up is good.
> >
> > But my understanding about this is that if the drive is disconnected,
> > you will never receive the index pulse, so the revolutions counter will
> > stay at "0", spin up will never complete, and restore will never
> > complete too, because it needs spin up to complete first.
>
> I just read parts of the WD1772 data sheet and noticed that the 6
> revolution spin-up is an optional flag that You set for some instructions.
>
> Thus, you must devise your own timeout for a non-existent drive.

Yes, that's why I think it would make more sense to test if a drive is 
avaible by just doing a "restore" command without spinup bit. This way, 
you just rely on moving the head and reading TR00 signal, no index hole 
involved.

> I read that an Atari ST floppy drive spins without stopping if the
> floppy index is not working. (search atari-forum for: magnetic switch)

As the counter will never reaches '6', this makes senses the motor never 
stops.

Nicolas