Re: Apple 3.5" drive questions

["Charlie" <charlied@NOSPAMbboard.com>]

"Eric Smith" <eric-no-spam-for-me@brouhaha.com> wrote in message
qhfzq3ak9b.fsf@ruckus.brouhaha.com">news:qhfzq3ak9b.fsf@ruckus.brouhaha.com...
> "Charlie" <charlied@NOSPAMbboard.com> writes:
> > This made me
> > wonder for the millionth time if software could solve the problem of
> > reading and writing MS-DOS with an 800k Apple 3.5" floppy drive
> > connected to an Apple II.
>
> > Yes, I know, this is supposed to be impossible.  The hardware is
> > supposed to be incompatible with writing MS-DOS.
> >
> > What I don't know is why.
>
> Because the Disk II controller (and all the other Apple II floppy
> controllers except the SuperDrive/FDHD controller) can only support GCR.
> They can't do MFM.  This has nothing to do with the drive.
>
> Actually the Disk II controller can sort of support FM (single density)
> since the data patterns are a subset of those used in GCR.  However, it
> can't really support the industry-standard IBM 3740 format.
>
> When Woz designed the Disk II controller, compatability with disks
> for other systems was not a major consideration.  He was mostly trying
> to make it simple and inexpensive, and succeeded admirably.  If you
> wanted compatability, there were third-party controller cards which
> could do that.

Eric,

Ok, I agree with what you have said.  I suppose I didn't make myself clear
though.  What I am getting at is the use of software to directly send the
signals (MFM) to the 3.5" drive through the smartport/IWM firmware and/or by
directly controlling the softswitches.

Charlie