FLOST.DOC

 
    documentation for "flost.bin"  (should be renamed to "lost file")
 
what you need:
                download "flost.bin" from cbmprg
                download "flost.txt" from cbmprg
                download "flost.doc" (this file) from cbmprg
 
reading "flost.txt" will give you detailed information on the process
used in recovering files that have been lost not through the normal
scratching process, but with the save-and-replace command.  these will
usually be program files.
 
"flost.txt" should be read first, but if you are in a hurry, the most
important thing is to backup the diskette first with a "whole-disk" type
copier.  there are many available.  run "flost.bin" only on a backup, because
it will purposefully destroy the first file in the directory in the process
of recovering your lost file.
 
main menu options:
 
 
l--look for possible first blocks
 
this will ask you for a load address for the file.  this option only applies
to program files, not to sequential files.  (you can use it for any file, but
it will only help you for programs).  it will check the entire disk for sectors
which contain the proper load address for a program.  this means that any
sector having this load address could be the first sector of a program file.
 
k--display a chain of blocks
 
this will display and count the number of blocks in a chain.  on the diskette,
each 256-byte block is "chained" to the next in that particular file.  choosing
this option and entering the first block of your lost file will give you a
count of how many blocks long the file is.
 
a--ascii only scan
 
if you want to see what a block looks like in ascii (letters and numbers),
use this option.  it would be used when you were looking at a block you thought
might be the first block of your lost file.  if you saw something familiar
there, it might help you decide if that was the right one.  this will not look
at all like a program listing.  none of basic's keywords will print out, but
any letters or numbers in quotes or in rem lines will.  if you habitually
put the name of the program in a rem statement at or near the beginning of
the program, this would print out.
 
h--ascii and hex(adecimal) scan
 
in the c64 version of the program ("flost.bin") this will print to the
screen half of a sector at a time, showing on the left side of the screen
the actual contents in hex form, and the ascii to the right side of the
screen.  explaining the structure of data blocks or hexadecimal numbers
is beyond the scope of this document.
 
d--fix directory
 
this is actually the last option you will use.  after finding the starting
block and number of blocks for your lost file, this is where you will enter
them into the directory.  you will sacrifice the first file in the directory
for this purpose.  since this is only a backup diskette, it won't matter.
(the program could be modified to let you add the lost file as the last
directory entry, but it would lengthen the program and leave more room for
error.)
 
 
notes:
1.  this is clearly a "limited use" program as it stands.  this is inevitable,
since it was specifically written for a limited use.  the program, however, is
fairly logically designed, and can easily be changed to suit other uses.
 
2.  the 64 version was adapted from the original, which happened to be written
for a commodore b128.  the only changes necessary were for the smaller screen
of the 64 and the smaller capacity of the 1541 disk format.  although it has
not been tested, i'm sure it would run more or less unchanged on a c128 as
well.
 
3.  i would really like to hear of any bugs, preferably by e-mail.
 
rick joslin
72167,3312
december, 1988