Re: Copying Mac MFS disks on an Apple II

["Bill Garber" <willy46pa@comcast.net>]

"Charlie" <charlied@NOSPAMbboard.com> wrote in message
bj6a9a0167q@enews3.newsguy.com">news:bj6a9a0167q@enews3.newsguy.com...
>
> "Bill Garber" <willy46pa@comcast.net> wrote in message
> u3mdnYVff7ZoAMuiXTWJjw@comcast.com">news:u3mdnYVff7ZoAMuiXTWJjw@comcast.com...
> >
> > "Charlie" <charlied@NOSPAMbboard.com> wrote in message
> > bj5u080m41@enews3.newsguy.com">news:bj5u080m41@enews3.newsguy.com...
> > >
> > > "Greg Buchner" <apple22@mn.rr.com> wrote in message
> > > apple22-A39589.22123102092003@apollo-ge0.rdc-kc.rr.com">news:apple22-A39589.22123102092003@apollo-ge0.rdc-kc.rr.com...
> > > > In article <acdalv4olv4h1ajrgdhr0njafd5gv2tum6@4ax.com>,
> > > >  Jeff Blakeney <CUTjblakeney@syndicomm.com> wrote:
> > > >
> > > > Actually it's slightly more complicated.  You have to deal with
physical
> > > > blocks (the actual blocks on the hard drive, which are almost always
512
> > > > bytes) and logical blocks, which can vary in multiples of 512 bytes
> > > > (unless the phsysical blocks on the HD are different).
> > > >
> > > > ProDOS supports only 512 byte logical blocks so they map 1:1 to the
HD,
> > > > 65536 blocks to the volume.
> > > >
> > >
> > > One minor quibble:
> > >
> > > I believe ProDOS supports 65535 blocks to the volume, not 65536.
> > >
> > > Charlie
> >
> > No charlie, 65536=0 thru 65535=32,768k=32mb
>
> Well, Bill, ProDOS volumes contain a word (two bytes) at a location in the
> Volume Directory Header ($29 byte offset from the beginning).  This word
> contains "the total number of blocks on the volume" (Apple's definition).
As
> you know the largest value you can fit into a word is $FFFF (65535).  A
quick
> check of a 5.25" ProDOS disk will show that word to contain $118 (280) so
the
> number is NOT zero based.
> I do admit that I have never actually created a 32 Mb volume on a real
Apple II
> to see what number is found in that location but I have always been to the
> understanding that the largest volume that can be created under ProDOS is
> 32Mb - 512 bytes.
>
> Charlie

Yes, I stand corrected, there is only 32,767.5 k per ProDOS HDD partition.
However, the blocks ARE numbered from 0 to 279 for 140k, 0 to 1599 for
800k, and so on until 0 to 65534 for 32mb ProDOS HDD partitions. So, in
actuality, a ProDOS partition will only be a max of 31.9995 mb. I did a very
extensive study to prove all this over a 2 hour period and it is true.

Bill @ GarberStreet Enterprizez };-)
Web Site - http://garberstreet.netfirms.com
Email - willy46pa@comcast.net



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