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Mac OS X Info

Why is Disk Charmer so cool? Erase disks quickly. Avoid the lengthy initialization process! You can erase any kind of disk, even using foreign formats such as MS-DOS (ugh!) Free trapped Megabytes! Set the minimum allocation block size with the Mac OS Extended format, a.k.a. HFS Plus; some companies charge thirty bucks just for this! Create oversize disks by reducing catalog space: you gain 9K on 800K disks, 19K on 1.4M disks, 1.5M on Zip disks, 2.1M on MO230 disks (storage gains for other popular removable media wanted) initialize floppy disks in the background! copy floppy disks verify floppy disk media create DiskCopy disk images from floppies recreate floppies from DiskCopy or DiskDup+ disk images Disk Charmer is easy and convenient to use: help balloons are everywhere it performs the job in the background; to access this feature, you need the Thread Manager extension from Apple, or System 7.5.x which incorporates it it supports drag&drop - even the new Drag Manager

MacUser's rating: four out of five mice. Disk Charmer in MacWEEK One of the MRP Essential Utilities. MacAddict, October 1997: one of the top 50 shareware programs. Chad Magendanz, author of the award-winning ShrinkWrap utility, praises Disk Charmer in TidBITS #339. MacWorld France, November 1996: Les 20 logiciels indispensables one of the 20 indispensable shareware/freeware programs. Rated as one of the top programs by the German magazine c't magazin für computertechnik. Was in The Mac Shareware Top 10. Monday's MacGadget on the MacObserver: ...those cool things that we all just have to have on our Macs.  macpool selected

Compatibility issues and known bugs

• Jon G. Stephenson reports that 3.1.3 might create HFS+ disks with an incorrect minimum allocation block size. I've also found out myself a related problem. This is fixed in 3.1.4.

• Robert H. Wilkinson and Chris Murphy report lingering problems with the Make disks larger option. Unfortunately the workaround introduced with 3.1.1 in order to avoid the Mac OS 8.1 corruption bug makes Disk Charmer unable to create "larger" Zip disks. (I should never fill up all my Zip disks! This is fixed in 3.1.3.)

• Thanks to François Grieu for the detailed report and the work-around suggestion.

  Mac OS 8.1 (even when starting up with extensions disabled) may corrupt disks created by Disk Charmer 3.1 and earlier with the Make disks larger option. Such disks work fine under System 8.0 and earlier. The problem is exacerbated by the fact that system extensions or newer versions of the Mac OS may silently create additional invisible files, potentially corrupting disks that are just inserted and then ejected.
  Disk Charmer 3.1.1 and later create "larger disks" that should be safe under all known versions of the Mac OS. The work-around is explained in the technical section later in this page.

  On a corrupted "larger disk", Disk First Aid will report the disk as irrecoverably damaged:

  Checking disk "1k btClpSize".
  Checking disk volume.
  Checking "HFS" volume structures.
  Problem: Invalid catalog PEOF, 4, 0
  Test done. Problems were found, but Disk First Aid cannot repair them.

  I wrote a small test program that creates empty files until a catalog expansion is triggered. So far I have found that normal HFS and HFS Plus disks are never corrupted.
  Everything works fine under System 8.0, 7.6.1, and 7.1.2, even if the disk is locked and checked by Disk First Aid 8.1 under System 8.1.

  Please note that using Disk Charmer is not the only way to create such disks. End users can obtain such disks in several other ways:

  • using the old freeware "1433K free 0.2a" by G&S Speranza (March 1992)
  • using the old Disklosure by Gabriele de Simone
  • from an acquaintance, backup software or software publisher who wanted to pack more data on the disk

  Technically inclined people, please read on

  "Larger disks" have shortened catalogs with a custom BTree clump size. The bug occurs when the BTree clump size is 1 KByte. Adding files triggers the expansion of the Catalog BTree. The first expansion goes fine: the Catalog BTree grows from 1K to 2K by addition of a 1K segment. Following the creation of the third Catalog BTree extent, the size of the Catalog BTree field is less than the sum of the size of the first three Catalog BTree extents. So far I did not have the patience to check if the additionally allocated blocks are reserved in the Volume Bitmap, and if these blocks are properly initialized. If not, this is bound to cause disasters later.

• Disk Charmer now attempts to work around the Apple Menu Options bug described below, which should be fixed in Mac OS 8.5 and later. Nevertheless, I still recommend to disable this control panel. Search the MacFixIt website to find relatively recent problem reports. There are other third party utilities implementing the hierarchical Apple menu just fine. (The detailed report is courtesy of Dave Wightman):

  Please note: it does not matter what selections you make in the Apple Menu Options control panel; the problem will persist until the panel is disabled completely by Extensions Manager or by moving it out of the System Folder.

  If the evil Apple Menu Options is installed, Disk Charmer may unleash an orgy of hard disk activity even though floppies are all that are being formatted. As soon as the Mac starts the initialization process on the floppy it would also start reading from the hard disk, a process which prevents any other activity from taking place. Then, when the floppy is ejected after the initialization, another hard disk scan may take place. Each of these scans might take a minute or more effectively locking up the Mac during the entire initialization process and a minute after. Apparently the feature which remembers the most recent applications, servers and documents requires requires heavy hard disk activity and is triggered somehow by Disk Charmer and Norton Backup (and who knows what else).

• The Quadra 840av has a peculiar floppy disk driver in that for some obscure reason asynchronous reads and writes are performed synchronously. This was first noted by Irene Bensinger and I'm now witnessing this on my Quadra 840av (darn!). There was already a workaround in Disk Charmer that I improved with 3.1; now that I can reproduce the problem I'll see to it that a better workaround (or a solution!) is found.

• SpeedEmulator (part of Connectix Corp.'s Speed Doubler) and/or RAM Doubler (also by Connectix) may be incompatible with Disk Charmer: your Mac may crash when erasing or verifying a floppy.
  • One report of crashes occurring on a PowerBook 5300cs, System 7.5.5, SpeedEmulator 1.3.1.
  • One report of cured crashes on a PowerMac 8500, by installing System 7.5.3 Revision 2 and SpeedEmulator 1.3. It still runs fine with System 7.5.5.
  • One report that on a Performa 6300 Disk Charmer will run correctly with Speed Doubler 1.3 or RAM Doubler 1.6.2 installed, but not both installed. With both installed, a request to initialize a disk terminates with an unimplemented trap error.
  • One report of crashes on a Performa 475, System 7.6.1, RAM Doubler 2.0.2.

  If you have a Mac with a PowerPC processor and either SpeedEmulator or RAMDoubler or both, please let me know whether it crashes or not.

  Update: Tech Note 1096 by Lenae Rowland reports a compatibility problem also mentioned on MacFixIt between Speed Doubler and System 7.6.1.

• System 7.5.5 fixes lots of bugs that may improve Disk Charmer's behavior on certain Mac models or in certain circumstances.

• Ontrack Disk Manager Mac 4.0, when installed on IDE drives, is incompatible with Disk Charmer: it makes your Mac hang when erasing or verifying a floppy if the "Can switch among applications..." option is active. The problem may or may not occur with SCSI drives. Use an Apple formatter, a different third party formatter or a later version of the abovementioned formatter.

  Update: The following appeared in MacInTouch on February 20, 1997:

  Craig DeRose reports that OnTrack's Disk Manager Mac is not certified for use with System 7.5.5 or later:

  I just got off the phone with OnTrack's Tech support for Disk Manager Mac. I was asking about the new disk formatting requirements needed with Mac OS 7.6. Tech Support stated that DMM 4.02c was tested and compatible with system 7.5.3. No testing or updates were planned for the product, and they could not recommend their product for use with System 7.6.

• Masatsugu Nagata long ago wrote me the following which may be of interest to some Mac Users:
  [I slightly edited his original message]

  Under the J2-7.5.2 system, Disk Charmer 3.0.2 complained: "An error occurred, could not read the disk into memory" after trying to read the disk, and the disk image was not created. Under the U.S.-7.5.3-Rev.2 system, the disk reading proceeded fine, and Disk Charmer worked fine, except for the (now familiar on the PB5300) message: "Although the disk has been correctly read, the presence of low-level errors indicates that this disk may fail in the future" was (still) shown. Back to the J2-7.5.2 System, Disk Charmer was still unable to read this 800K disk.
  
  So, 7.5.3-Rev.2 System handles things better than J2-7.5.2. I don't know what makes the difference, but perhaps the mention (in the TidBITS#332 article) of the changes in the Dynamic Recompiling emulator has something to do with it?
  
  Also, I noticed the Revision 2 Update resource files include a new '.Sony' DRVR resource. Maybe this has to do with it? Or, maybe this is just a fix concerning the following other paragraph in the Revision 2 Update readme doc:

  If you have a PowerBook 500 series or Duo series computer with the PowerPC Upgrade Card installed, PC-formatted floppy disks that were formatted on your computer may be unreadable in DOS or Windows computers. This software fixes this problem.

  In the end, I highly recommend to install Revision 2 (or, even better, System 7.5.5) if appropriate for your Mac model.

• On MFS disks Disk Charmer and Finder think the invisible SAM Quickscan File is open, and the disk cannot be charmed, erased, or even ejected. The workaround is turning off SAM for the duration of the erasure (SAM users already tell SAM to ignore Disk Charmer's formatting a volume). SAM is sold by Symantec.

• Do not try ejecting the disk with the Command-shift-number combination while Disk Charmer initializes or verifies the disk and the Thread Manager is installed: the Operating System crashes (not my fault).

• Thread Manager 2.0.1 is buggy. Install Thread Manager 2.1, or at least System 7.5 Update 1.0 (a.k.a. System 7.5.1) if you have System 7.5.

• Apple/Connectix Mode32 1.2 is incompatible with Thread Manager. Use Mode32 7.5 or later, freely available on most online services, such as the Info-Mac archive and its mirrors.