Re: Apple II 3.5" Controller and SuperDrive problems...

[dempson@actrix.gen.nz (David Empson)]

<mkelsey@spam.eecs.wsu.edu> wrote:

> In article <19980307074501.CAA12289@ladder03.news.aol.com>,
>       supertimer@aol.com (Supertimer) writes:
> > CUTjefbla@bconnex.net (Jeff Blakeney) wrote:
> > 
> >>On 4 Mar 1998 05:08:35 GMT, supertimer@aol.com (Supertimer) wrote:
> >>
> >>[snip]
> > You are right that you can't erase a 720K MFM disk into an 800K
> > GCR disk.  You can, however, erase a 1.44MB MFM disk into a
> > 1.44MB MFM disk, which is what is happening with a ProDOS
> > erase of an MS-DOS disk.
> 
> Now this must be some characteristic of the Apple IIgs operating
> system.  If I attempt to erase (not format) an MS-DOS 1.44MB disk
> with Copy II+ it reports "not a ProDOS disk," and quits.

That would be a limitation of Copy II+, not the "IIgs operating system"
(which isn't even being used when Copy II+ goes to format a disk).  It
checks the volume, doesn't recognise the file system (and possibly the
volume size), and refuses to do anything with it.

ProDOS-8 provides no support for formatting disks - it is up to the
application to implement this.  It requires direct hardware access for
5.25" disks.  For other devices, the application must use the ProDOS
block driver (provided by the card firmware, or inside ProDOS itself in
the case of /RAM).

This assumes you want to do an actual format operation.  An "erase"
operation (writing boot blocks and an empty file system onto an already
formatted volume) can be done with ProDOS block-level calls, with some
assistance from the firmware driver to determine the size of the volume.
Even in this case, ProDOS-8 doesn't know what you are doing, and the
application must provide the code which goes in the boot blocks.

Under GS/OS, the operating system provides format and erase calls that
do all this, so it is not necessary for applications to provide special
code (except user interface support as required) if they want to format
or erase disks.

-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand