Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!HUB.UCSB.EDU!bfox%vision
From: bfox%vision@HUB.UCSB.EDU (Brian Fox)
Newsgroups: comp.sys.apple
Subject: Usabale blocks on ProDOS data disk
Message-ID: <8902131751.AA19999@hub.ucsb.edu>
Date: 13 Feb 89 17:51:25 GMT
References: <7682@ihlpf.ATT.COM>
Sender: daemon@ucbvax.BERKELEY.EDU
Reply-To: bfox@wheaties.ai.mit.edu
Organization: The Internet
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   From: Walters <att!ihlpf!bird@ucbvax.berkeley.edu>

   Continuing, if you format a ProDOS disk and then CATALOG it you are told:

   Blocks Total   Blocks Free   Blocks Used
	280           273           7

   If you catalog the program disk for Appleworks version 2.1 you are told:

   Blocks Total   Blocks Free   Blocks Used
       280            2            278

   There are thee files on the disk and their size is:

   SEG.MO  SEG.M1  SEG.PR
     46      219     9

   As expected, the disk total is still 280, however, the three files total
   274. Add blocks free to this you get 276. This leads to a number of
   questions:

   1. What happened to the missing 4 blocks (280-276)? Or 278-274 if you
   look at blocks used and the total file sizes.

   2. How did Apple get one extra block on the disk? (274 when formatting a
   disk only leaves you with 273)

   3. Are they somehow breaking their own rules on disk usage? If not, how
   can I "break" the same rules and gain some additional storage on my
   disks?


On a "normally" formatted disk, (e.g. one formatted from FILER) blocks 0
through 7 are marked in use, where blocks 2 through 7 contain the volume
directory.   Without looking at the disk, I suspect that the people who made
Appleworks only used 1 directory block for directory information, since they
knew that there would only be three files on the disk, and that the directory
information for those three files could be kept in one block.  That would
allow them to free the 4 remaining blocks in the volume directory for the
storage of file data.

Using a program such as BLOCK.WARDEN from Glenn Bredon would allow you to do
the same thing.  But first, you should read _Beneath Apple ProDOS_, which can
be found at any reasonable store which sells Apple // hardware.

Brian Fox