This is a utility to bring back files which has previously been deleted. When a file is deleted, it is not really removed from the disk. The DOS (Disk Operating System) makes two changes which render the file as deleted: One, the file type flag is erased (set to 0), making the file unrecognizable to the DOS. Two, the space which the file used on the disk is made available to use as storage for other files. You should therefore restore scratched files before saving something new on the disk. It will work only with 1541, 1571, 1581 and compatible disk drives.
SPECIAL NOTE to GEOS users: You can unscratch GEOS files using this utility. However, you MUST validate the disk from the GEOS desktop before further saving anything to the disk. Furthermore, as an ounce of prevention if you suspect that the disk has been written to since the files were deleted, copy all the non-deleted files to another disk BEFORE attempting to restore lost GEOS files.
You will be asked to insert the target disk, the disk with the files you want to unscratch. The directory is then read into the computer's memory. If there are no deleted file entry in the disk's directory, the message "No valid files" appears, and the unscratch utility is aborted.
Move the cursor up and down using the cursor keys, the + and - keys to move one page up and down respectively, and HOME to go to the top of the directory.
All files will initially be marked as '*DEL'. To restore a file you must select a file type. Your choices are listed at the top of the screen. It is of the utmost importance that you select the right file type, as using the wrong file type will in most cases prohibit the correct function and use of the file. To undo the selection of a file, press D to make it a deleted file.
Some files may be marked as "Blocked". A blocked file is a file which is marked in the directory as deleted, but the block where the first part of the file should be is marked as used in the BAM. This would mean that the block is now occupied by a valid file. A blocked file is thereby unrecoverable since there is no way knowing where the rest of the file might be on the disk.
A file might be unrightfully "blocked" due to an error in the BAM. If you experience that the unscratch utility identifies that the file is blocked although you think it should be recoverable, validate the disk and attempt unscratching the file again.
PLEASE NOTE: A file name might appear more than once in the directory. You see two or more identical names, and you don't know which is the right one. A deleted file may also have the same name as a valid file. The solution: Restore both. Then rename the first one, the RENAME command will only affect the first file that match the command parameters. Repeat if more than two identical files. Try using the newly restored files to see which one(s) you would like to keep. Scratch the other ones and, IMPORTANT!, validate the disk to make sure the BAM is OK.
Since the disk space previously occupied by scratched files is left free for other files to overwrite, unscratching does imply some potential problems. To be absolutely sure that a file can be restored, it must be unscratched before something new is written to the disk. All might not be lost however, even if the disk has been written to. Each subsequent write to the disk reduce the odds that previously scratched files can be restored. If subsequent writes has occurred, or if you're in doubt, please read the following:
1) A scratched file might be partly overwritten. When you don't find the file contents you expect, the file is garbage, partly garbage, partly missing or has parts that repeat, you are probably dealing with a partly overwritten file. If a new file saved to the disk happens to claim even a single block of the scratched file, that block and the rest of the deleted file is lost. This is why: The two first bytes of each block in the file always points to the next block in the file (unless it's the last block). Now, if one block is overwritten, the pointers for the next block will obviously point towards the rest of the new file. At some point therefore, the two files will seem to have been spliced into one. The solution: If you want to try to recover as much as possible of the file in question, copy it. Either to another disk or by using the COPY command to make a copy under a new name. Scratch the original file and, IMPORTANT!, validate the disk to make sure the BAM is OK.
2) A file might be "looping". This is a phenomenon which is very rare, and equally difficult to recover from. It is related to the "partly overwritten file" problem. What happens is that, during the course of events, the pointers in one of the blocks are now, due to overwriting, pointing back to an earlier block in the same "file". The "file" will then repeat itself into infinity. We can't really call it a file, it's just a complete jumble. The unscratch utility will never be able to finish because it will never stop validating the file. The same goes for scratching, loading, reading or any other operation on the file; it just repeats forever! The Solution: Reset your system. The best solution is to clear the file's identifier in the directory using a sector editor, then validate the disk. If you don't have the means or knowledge to do that, copy all the other files to another disk using a FILE COPIER. If there is a boot sector on the original disk, do a "short new" (formatting the disk without specifying ID characters) on the original disk. Validate the new-ed disk to make sure that the boot sector(s), if present, are re-protected, and then file copy the files back.
3) The directory entry of the original file might have been overwritten. The place in the directory used by the scratched file has later been used by another file. Unless you know how to use a sector editor and are prepared to spend some time, the file is unrecoverable.
You may restore as many files as you wish. To start restoring the files, press F1. To be absolutely sure, you will be asked to confirm your action. Please note that unscratching may be a lengthy process as the disk has to be validated, reclaiming the space for the restored files. If you haven't selected any files, the message "No valid files" will appear, and the unscratch utility is aborted.
IMPORTANT NOTE: If a disk error message appears at this point, one of the restored files is probably malfunctioning. In any case, the disk hasn't been properly validated, and you should go about with great caution. Using the file copier, copy as many disks as possible to another disk. THE SERVANT file copier will identify the troublesome files. Then, you might want to try recovering those files. You need to read as much as you can from the original file and save it in a new file. Then, scratch the troublesome files and, IMPORTANT, validate the disk.
