READ/WRITE ERRORS.

   I thought I had it under control, there was no way I'd lose any 
   work to disk errors, always had a backup. So there I was, 90%
   through MD5 when a "Read/Write" error was announced. So without
   really thinking I did a diskcopy to my backup disk - big mistake!
   It stopped halfway but not before having formatted the disk. And
   it copied about 10% of the original...So there I was with no 
   backup, and with all that work on a very dicky disk. Consulted with
   the DiskDoctor (Megadisc's resident problem-solver) to make sure
   that nothing else stupid was done, and eventually recovered all 
   the contents of the disk except...Hints&Tips. Ah, the irony. So in 
   this revamped, rewritten, remembered column, the first tip goes as
        follows:
   When you have a read/write error on an important disk, follow these
   steps - 1. Write-protect the offending disk before you do anything.
           2. Make a copy of the disk immediately via HACK, or any 
                   copier program which can place formatted tracks instead 
                   of errored tracks from the source disk - see DUTILS in
         UTILITIES for an excellent utility for these purposes.
         If using Hack, select the VALIDATE DISABLE
         option from the menu. Note that HACK is available from
         COMPUMED in the USA (Address: PO Box 6939, Salinas,
         CA 93912  TEL: (408) 7582436). 
       3. From the CLI do a DISKCOPY of the dumb copy you just
         made, to be used for retrieving data.
           4. Use DISKSALV (or perhaps RECOVERALL) to retrieve the
         data on the disk. You'll find DISKSALV on Fish 20, 
         though I believe there's another more recent version.
         DiskSalv will do a better job than DISKDOCTOR, although
         the system tells you to try that. In fact, I tried 
         Diskdoctor before I wised up - at the end it still
         couldn't "validate" the disk, so I couldn't do as it
         recommended and copy all the retrieved files to another
         formatted disk.
      5. You should now have a reasonable retrieved copy of your
         original. If you want to investigate further, you can
         can use FM off Fish 36 to have a look at where the
         various files and their directory tracks are on the
         disk, and how much of the damaged files still remain.
                   (That is, number of blocks indicated multiplied by 512
         bytes to give approximate size in Kilobytes, as compared 
                   to the original file.)
         With an "executable binary file" any little problem
         of scrambling/deletion or whatever will render it 
         useless since it's all of a piece; but with a text file
         you might have lost a bit here and there. If you want
         to look a bit further into the disk structure, get the
         program HACK, or a variety of other PD sector editors
         such as SECTORAMA on Fish 102. 
   ## Anyone who has more to add to this topic is asked to share his/
      her wisdom with all of us. Any hints along this line are most
      welcome. EVEN BETTER - would some advanced hacker send us a
      tutorial covering use of sector editors in general and how best
      to use them. 


 CONTROL KEY COMBINATIONS IN THE CLI

   LEFT-AMIGA N : Workbench window to back - works with most programs
   LEFT-AMIGA M : Reverse the above        - works with most programs
   CTRL-D       : Abort a command sequence file/batch file, such as
             the startup-sequence, say to get straight into
             the CLI rather than loading Workbench.
   CTRL-C       : Stop any CLI operation
   CTRL-X       : Erase an entire line in the CLI
   STOP-SCROLL  : Press any character key once to stop a file scrolling
                       (which you've TYPEd)
        CONTINUE-SCROLL: BACKSPACE KEY or RETURN. (BACK-SLASH '\' and 
                  BACKSPACE is a good combination to start and stop,
                       since they're beside each other on the keyboard)  
   CTRL-O       : Enable the Alternate Character Set - try it, and 
             press a few keys!
   CTRL-N       : To undo the above situation, ie get the normal 
             character set back.
   ESC-C        : Clear the screen and display normal text.
        CTRL-L       : Clear the screen, cursor to top (form-feed)
        CTRL-J       : Linefeed, ie one line down
        CTRL-K       : Up one line
        CTRL-H       : Delete a character under cursor (ie backspace)
        CTRL-G       : BELL character - flashes screen on the Amiga
        CTRL-M       : Carriage return 
   CTRL-\       : End of file indicator - ie if you enter a command
             such as  > copy * to prt: all keyboard input goes
             to the printer. To stop this process use CTRL-\
             and you'll be back in the normal CLI.


   If you ever have to copy something to, say, your C directory, or
   mention it in any way in a CLI command, rather than refer to it
   as    df0:c   or   sys:c you can simply refer to it as  c:  ,
   because the C directory of your boot disk is a "logical device",
   recognised as such by AmigaDOS, just as your external disk drive
   is recognised as a "physical device", DF1: . The same comment
   goes for any of the other logical devices - DEVS:, LIBS:, etc.
   To see what are the logical and physical devices recognised by
   the system, simply type   > assign  in the CLI. And of course
   you can ASSIGN whatever you like, so if you often refer to, say,
        the directory  MYLETTERS:LOVELETTERS/ANNA, you could simply type
   this:   > assign A: myletters:loveletters/anna   and in future
   just type  a: when you would normally have typed the whole thing.
   In fact, if you have a regular pattern in this way, you could set
   up an ASSIGN_TABLE in your favourite text editor of all the ASSIGNS
   you want to make each session, and then insert in your startup-
   sequence the command    EXECUTE ASSIGN_TABLE  .