How do you tell if you have a bad diskette?  Compare the symptoms to the ones
listed below to get some idea of what may be wrong with your diskette.

The disk drive may have problems or have failed if:
* The disk drive light does not come on when requested to read or write, or
  there is no whirring sound on these accesses.
* The disk drive cannot access two or more diskettes for read or write (also
  check the write protect notch on the side of the diskette).
* Two or more floppy diskettes have been corrupted in the same drive.
* The disk drive makes more noise than normal when reading or writing.

Diskette failures can show up in the following ways:
* A program you have not changed no longer runs.
* A file contains strange characters in the middle of it, or is missing some
  information.
* Files start disappearing from directories.
* The disk directory contains filenames you did not create.
* A file cannot be erased or written to that normally allows such accesses.
* File sizes or date stamps are displayed by the DIR command as unknown values.
* All file accesses on the diskette fail (if only write accesses fail check the
  write protect notch on the side of the diskette).


If your disk drive has problems, don't sacrifice any more diskettes.  Get
someone in to fix the drive.

If the diskette is corrupted, there are a variety of approaches that can be
taken depending upon whether or not the directory structure of the diskette is
still intact.

Before starting, take a new diskette and format it for use by DOS (see the help
file FORMAT for details).  This diskette will be used to store the recovered
files.

If the disk directory can be read, recovery is not all that difficult.  Use the
COPY command to copy as much of the corrupted diskette as possible onto the
scratch diskette (see the help file COPY for details).  All the files that
could not be copied must be recovered using the RECOVER command for individual
files (see the help file RECOVER for details).  Copy the files to the second
diskette as each file is recovered.  If a subdirectory could not be read, the
procedure for recovering a disk as outlined below will have to be followed
after all the individual files possible are saved.  Compare the recovered files
to the last backup version you have and keep the best copy.



If the disk directory cannot be read, the job of recovering the diskette is
more formidable.  Use the RECOVER command to recover all files possible on the
diskette.  You must then inspect the recovered files one at a time and copy
the files to the scratch diskette under the filenames they were before the
RECOVER operation.  Compare the recovered files to the last backup version you
have and keep the best copy.

Now make a second copy of the scratch diskette you have restored the files on
to (remember that we always want to have two current copies of any diskette).
Use the FORMAT command to reformat the diskette that had the bad file(s).  This
will map all the bad areas of the diskette so that they will not be allocated
to files.  Visually inspect the diskette for signs of wear and retire the
diskette if it is questionable (see the help file DISKS for guidelines).  Copy
one of your scratch diskettes back to the original and you are finally done!

NOTES **
* NEVER put a backup diskette in a disk drive you consider to be operating in
  a questionable manner.

* After recovering program files (those with .EXE and .COM filename
  extensions), do not try to run the program.  Instead, delete the recovered
  file and copy a good version of the program from one of your backup disks.

* It is not generally a good idea to erase the good files from a bad directory
  before doing the RECOVER operation.  Each file name is in a linked list of
  files, and if a good file is erased, the link to subsequent corrupted entries
  may be permanently lost before RECOVER has a chance to run.

* To get a permanent record of what files were recovered, etc., all output
  sent to the screen may be echoed to the printer using the Fn Echo key
  sequence (see the help file KEYS for information).

* If you have erratic disk problems which do not seem to match any of the
  symptoms mentioned above, you may be experiencing a more insidious problem.
  One of these could be periodic under-voltages (brownouts) in the power
  supplied to your computer or within the computer power supply itself.
  Brownouts can cause the disk rotational speed to vary, making the data
  unreadable when the disk is operating at the correct speed.  Another uncommon
  but possible problem is that of radio frequency (RF) interference caused by
  a nearby radio transmitter.  If your computer is located close to a street,
  CB radios in passing cars can cause problems.  Two-way radios used by
  security guards and even some personal paging devices (such as those worn by
  doctors) can mess up your computer.  Brownouts may be solved by repairing the
  power supply in the computer, using a different electrical circuit, or may
  require power conditioning equipment to solve the problem.  RF interference
  usually requires moving the computer to a better location.
