On Thu, 14 Aug 2014, Antoine Vignau wrote:
> This is the IWM (or post-Disk II) which has integrated/modified the
> phase 0, not the IIgs (but, as the IWM is in the IIgs...)
> That thing was known to Apple for many years, read the IWM section at
>
http://www.brutaldeluxe.fr/documentation/iwm.html
Toto, what exactly do you mean by "IWM .. integrated the phase 0"?
Some of the differences between the discrete disk controller and the IWM
are listed here:
http://www.brutaldeluxe.fr/documentation/iwm/iwm_discussion_19820531.pdf
> Sirius Software, in the early 80's, turned off phase 0 for
> security/safety, as it was recommended by Apple.
The only two concerns I have seen about leaving PH0 (or any phase) on are:
1) degraded read data due to head oscillations. Practice shows this is no
concern and is probably offset by the wide enough head.
2) eventual stepper motor coil overheating. Haven't heard of such a case.
And maybe the very general screwing up the expectations of any RWTS if it
does not reset all phases first.
> I'm pretty sure this is the reason why the spiradisc floppies do not
> boot well on a IIgs with no Disk II controller card...
This is something interesting. Are you sure it is not because of using
parts of the $C6xx ROM?
Does it mean that they sometimes work and sometimes don't?