Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!rutgers!mcnc!rti!sunpix!matthew
From: matthew@sunpix.UUCP ( Sun NCAA)
Newsgroups: comp.sys.apple
Subject: Re: Usabale blocks on ProDOS data disk
Keywords: ProDOS
Message-ID: <394@greens.UUCP>
Date: 14 Feb 89 15:37:13 GMT
References: <7682@ihlpf.ATT.COM>
Organization: Sun Microsystems, Research Triangle Park, NC
Lines: 58

In article <7682@ihlpf.ATT.COM>, bird@ihlpf.ATT.COM (Walters) writes:

	[comments about files on AppleWorks program disk]

> 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.

	program files: 274
	boot block   :   1
	root directory:  2
	volume bitmap:   1
	------------------
	used           278
	free             2
	------------------
	total          280

> 2. How did Apple get one extra block on the disk? (274 when formatting a
> disk only leaves you with 273)
  
	The standard root directory is 4 blocks long. The shortened it to
	make room for the files (they only need room for 3 files, not 51)

> 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?

	No, the rules allow for changes like this. What was simply done, is 
	that the 'pointer to next directory block' in root directory block 2
	was zero'ed, and the bits for blocks 4 and 5 cleared in the volume 
	bitmap. 

	The most number of free blocks you can put on a 35 track - 5.25"
	floppy disk is 278. What you need to do is:

		1) Using your standard method, format a disk.
		2) Using a ProDOS block editor.
			A) Move block 6 to block 0.
			B) Edit block 0, byte 0 to $5f.
			C) Edit block 2, bytes 0 thru 3 are all zeros.
	
	Thats it, the only precautions is disk will crash your system if 
	booted (previously it only gave a warning). This disk only has 
	storage for 12 item in the root.
	
> 4. Do the answers to the above questions apply to 3.5 disks as well?

	Yes.


-- 
Matthew Lee Stier     (919) 469-8300|
Sun Microsystems ---  RTP, NC  27560|          "Wisconsin   Escapee"
uucp: {sun, rti}!sunpix!matthew     |