Re: 3.5" Disk archiving

[Jeff Blakeney <CUTjblakeney@sentex.net>]

On Tue, 11 Feb 2003 22:34:57 GMT, "Phil Abel"
<phil_nospam_abel@prodigy.nospam.net> wrote:

>I think GSHK gives you a "warning" when attempting to do a 3.5" disk shk
>that it is an obsolete method and recommends you do it by file instead.

I've never understood why that warning is there.  There are many
instances when having a disk archive is preferable, if not necessary,
to make things work.  For instance, if there is an installer program
on the disk you are archiving and that program looks for its files on
a disk with a specific volume number or name.  It is easier for users
to just unpack a disk archive which will create the disk the way they
need it than it is for them to unpack the files to a disk and then
have to read a text file to find out what the volume number or name of
the disk needs to be and then set it.  Under DOS 3.3 this would mean
either sector editting the disk or having to INIT a new disk and then
copy the files again.

>But
>for games, etc. that aren't in prodos file format, it is the only way
>(doesn't always work on copy protected ones tho).

Personally, I think it would be more accurate to say that it almost
never works for copy protected disks.

>The common notation for a
>shrunk DISK is to save the file as *.SDK versus *.SHK for file archives.

This is very true.  I have often had to change the suffix on files
I've downloaded so that when I go through my own archives, I can tell
the file archives from the disk archives.

However, if either of these type of files are in a Binary II wrapper,
I believe they both usually get a suffix of .BXY which can make it
harder to tell them apart when you are going to download them.

>I
>think even if there is only 100k on the disk and 700k of zero blocks it
>still builds the *.SDK archive as if it were a full 800k disk (ditto for
>archiving 140k floppies).  So the archive wastes some space, but of course
>extra disk space is not an issue today like it was 10+ years ago.

GSHK compresses the entire 140 KB or 800 KB disk so yes, it puts all
of the sectors/blocks from the disk into the image but it does
compress all the zero sectors/blocks down to practically nothing.

However, if files have been written to the disk and then deleted,
there can be a lot of sectors/blocks on the disk that are no longer
zero but are also not in use by any file.  These won't compress as
well as if they were all zeros.  This is why, when making a disk
image, I recommend that you do a file copy of the contents of the disk
onto a freshly formatted disk (a RAM disk of the same size as your
floppy is a great thing to use here) and then make the disk image out
of the new disk you just created.  That way you will be sure that all
the unused sectors/blocks will be zeros and will compress better.

-- 
 Jeff Blakeney - Dean of the Apple II University in the
                 Apple II Community on Syndicomm.com
 CUT the obvious from my address if you want to e-mail me