Floppy Fixer is a utility for recovering files from damaged Macintosh diskettes. It works by using 12 bytes of data called file tags attached to each data block on the disk to determine which file the data belongs to, and its correct logical position within the file. These file tags allow Floppy Fixer to reconstruct files which are inaccessible to the Macintosh file system, provided that the actual data in the file and the file tags themselves remain intact. In addition, Floppy Fixer provides easy-to-use tools for identifying and correcting errors in file tags which would cause other file recovery utilities to fail.
SYSTEM REQUIREMENTS
Floppy Fixer will run on a Macintosh 512, 512E, Plus, SE, or II. At least two disk drives are required, one of which may be a hard disk.
INSTALLATION
To install Floppy Fixer on a hard disk system, simply copy the program to your hard disk. On a floppy disk system, copy Floppy Fixer to a diskette which contains a current system folder. To avoid excessive disk swapping, it is recommended that you avoid running Floppy Fixer from a disk which does not contain a system folder.
USING FLOPPY FIXER
To use Floppy Fixer, launch the program by double-clicking its icon, and then select “Open Volume” from the “File” menu. Click the appropriate buttons to indicate whether your source disk is single or double sided, in MFS or HFS format, and select the drive that you will use for reading the source disk. When all the information is correct, click the “OK” button. You will then be prompted to insert the source disk in the appropriate drive. After you do this, you will have to wait a couple of minutes for the program to read in all the file tags on the disk and sort them into logical order. (The program will try to access each data block on the disk. If the disk is in extremely bad shape, e.g. if it's unformatted, this could take a long time. If you get tired of waiting, hold down the command key and press “.” to cancel.)
After the file tags are read in and sorted, you will see two windows. The top window has the name of the bad disk in its title bar, and displays a scrolling list of all files and file fragments that were found on the disk, along with some descriptive information about each file. We will call this window the File List Window. A file may be selected by clicking on its entry in the File List Window with the mouse. The second window has the name or file number of the selected file in its title bar, and it displays the contents of the selected file in ASCII and Hexadecimal. We will call this window the File Scan Window. The data is displayed in 512 byte blocks. The vertical scroll bar scrolls the data within a single block, and the horizontal scroll bar scrolls among blocks.
The three buttons at the bottom of the File List Window perform various operations on the currently selected file. Clicking the button labeled “Get Info…” invokes a dialog that displays some additional information about the selected file, and allows you to edit some of the information. (Editing information may be necessary since, presumably, the information on the source disk is corrupted in some way.) The button labeled “Repair” is only functional when Floppy Fixer detects some inconsistency in the file tags for the currently selected file. In this case, clicking the “Repair” button will cause Floppy Fixer to attempt to resolve these inconsistencies. (It should be noted here that repairs to the file map are made only in memory, and are not written to the disk.) Finally, the most important button is the one labeled “Recover…”. Clicking on this button will cause Floppy Fixer to attempt to reconstruct the currently selected file on another disk. Floppy Fixer will display a standard “Save As…” dialog for you to specify the destination for the recovered file, and the name under which it is to be saved. It may be necessary for you to supply the file type and creator if Floppy Fixer was unable to scavenge this information from the disk. If you are not sure of the correct values of these parameters, click the “Help” button to display a scrolling list of document types. If you find the document type for your document in the list, select it and click “OK”. Floppy Fixer will automatically fill in the type and creator fields for you. When everything looks right, click “Save”. Repeat this procedure for every file you wish to recover.
LOGICAL END OF FILE
The correct logical length of a file cannot be determined from the file tags. This means that many reconstructed files will have a few extra bytes of garbage at the very end. For documents created by most Macintosh applications, this is of no consequence since most applications can read their files correctly without knowing the correct logical length. (Text files are an exception, but it's a simple matter to remove the garbage from the end of a text file with your favorite text editor.) However, if you wish to set the logical end of file marker, you may do so with the “Set File” command under the “File” menu. The correct logical length for a file will be displayed in the File List Window if Floppy Fixer is able to find this information in the disk directory. Also, if you know the structure of the file you are trying to recover, you may be able to determine the correct logical length by examining the file's data in the File Scan Window.
In case you’re wondering, Floppy Fixer does not automatically set the logical length to the value found in the disk directory since that value may be incorrect.
FINDING YOUR FILE
On a disk containing fragments of many files, you may have trouble finding the file you're looking for. In this case, you can use the search commands under the “Search” menu to locate your data. Select the first file in the File List Window (so that the search begins at the beginning), click in the File Scan Window, and select “Ascii Search…” or “Hex Search…” from the “Search” menu. Enter the search string and click “OK”. The program will search all files on the disk until it finds the search string. Additional occurrences of the same string can be found by choosing “Repeat Search” from the “Search” menu.
Searching an entire volume may take a few minutes. If you get tired of waiting, hold down the command key and press “.” to cancel the search.
NUMERIC INPUT
Several Floppy Fixer dialogs require numeric input. Entries may be made in either hex or decimal. Numbers preceded by the symbol “$” are interpreted as hex, and all other numbers are interpreted as decimal. This same convention is used for displaying numbers in the file list and File Scan Windows.
RESOLVING PROBLEMS
Files which are listed as “Bad” in the File List Window can often be repaired by simply selecting the file and clicking on the repair button. However, it is possible that Floppy Fixer will be unable to complete the repair even though all of your data is intact. In this case, it will be necessary to effect repairs manually.
There are essentially two types of problems that can arise while trying to recover a file: gaps in the file caused by missing data blocks, and duplicate blocks. The appearance of either problem for a particular file will be indicated in the descriptive information displayed in the File List Window. Duplicate blocks appear when the file tags of two or more data blocks place them in the same logical position in the same file. Missing blocks occur when there is no data block having file tags indicating that it belongs in some vacant position. The logical position of the missing or duplicated data can be found by using the “Find Gaps” and “Find Duplicate Blocks” commands in the “Search” menu.
Duplicate blocks are usually easy to deal with, and are usually resolved by using the “Repair” button. To deal with them manually, use the File List Window to select the file with the duplicate blocks. Click in the File Scan Window, and scroll through the data blocks until you find two with the same logical position. (The logical position is displayed at the top of the window.) Alternatively, you can locate duplicate blocks in the selected file by clicking in the File List Window and then selecting “Find Duplicate Blocks” from the “Search” menu. By examining the data in the duplicate blocks, decide which block is misplaced. With the misplaced block visible in the File Scan Window, select “Remove Block” from the “Edit” menu. Repeat the performance until all duplicate blocks have been removed. If you cannot tell from the data itself which duplicate block does not belong, you might try two other criteria: First, blocks which are logically adjacent are often physically adjacent on the disk, so you may be able to determine which of a pair of duplicate blocks is correct by examining logical and physical positions of logically adjacent blocks. (Logical and physical positions of each data block are displayed at the top of the File Scan Window.) Second, you may be able to determine which block is correct by examining the date that each block was written, which appears at the top of the File Scan Window. You should be forewarned, however, that the date field of the file tags is usually incorrect on HFS volumes.
If your file has missing blocks, you may just be out of luck. In most cases, the missing blocks are caused by part of the file being overwritten, which permanently deletes any data that was there previously. You may still use the “Reconstruct…” button to put the pieces that remain in their correct logical position. To make the gaps in the reconstructed file easy to locate, they are filled with the character “*”, repeated 512 times for each missing block. You may thus be able to retrieve a great deal of the data by setting the file type to TEXT and using your favorite text editor to clean up the resulting file. On the other hand, it occasionally happens that the data in a missing block is completely intact, but the file system has written the file tags of the block incorrectly. In this case, if you can find the missing block, then you can move it to its correct logical position by using the “Move Block” command under the “Edit” menu: With the misplaced block visible in the File Scan Window, select “Move Block”, enter its correct position in the resulting dialog, and click “Move”. Often, a misplaced block will have only one incorrect field in its file tags. Thus, in addition to the ASCII and hex search commands, the “Tag Search” command under the “Search” menu can be useful for locating misplaced blocks. Also, blocks which are logically adjacent in a particular file are often physically adjacent on the disk. The physical position of a block displayed in the File Scan Window is shown at the top of the window. Physically adjacent blocks can be located using the “Find Physical Block…” command in the “Search” menu.
SAVING THE FILE MAP
Changes made to the file map and to the file and volume information using Floppy Fixer's “Edit” menu are not written to the source disk. This design decision was made to prevent you from inadvertently making permanent changes that make a bad situation even worse. However, it is possible to save your changes in a Floppy Fixer document by using the “Save File Map As…” or “Save File Map” command in the “File” menu. The first of these commands creates a new document and saves the file map in it, while the second saves the file map in the the currently open Floppy Fixer document. The saved information can be restored at a later time by either selecting “Reopen Volume…” from the “File” menu or by double clicking a Floppy Fixer document icon from the Finder. In either case, you will be prompted to insert the appropriate source disk, after which the state of Floppy Fixer at the time the document was saved will be restored.
It's generally a good idea to save the file map even if you have not made changes, since restoring the file map later using the “Reopen Volume…” command is much faster than repeating the “Open Volume…” command. Of course, if you make changes to the source disk after saving the file map, then the saved file map will become invalid, and should not be used.
USE AND DISTRIBUTION
Floppy Fixer and this document are copyrighted material. You have permission to use them non-commercially, but you may not sell them or use them to perform a service for which you charge a fee. Copies of the program may be freely distributed, provided that the program is in no way altered and that this documentation accompanies the program. In exchange for these privileges, I request that you send a contribution of $20, or whatever you can afford, to
Lupus Foundation of America, Inc.
1717 Massachusetts Avenue N.W.
Suite 203
Washington, D.C. 20036
If you have any comments or suggestions concerning the program, you may contact me electronically at beatrous@pittvms.bitnet, or by paper mail at
309 Barnes Street
Pittsburgh, PA 15221
ACKNOWLEDGEMENT
Floppy Fixer is written in MacForth, Copyright (c) 1986 Creative Solutions, Inc.
