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Night Owl's Shareware - PDSI-006 - Night Owl Corp (1990).iso
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README.DOC
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1991-06-10
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README.DOC File
Safe Erase Version 1.21
(C) Copyright by Tom Williams, 1990-1991
Safe Erase version 1.21 is a new software utility that offers a
preferred alternative to the MS-DOS ERASE and DEL commands. Safe Erase
provides a new erase command that enhances the erase procedure so that
erased files are 100% recoverable. Safe Erase is the only utility that
can ensure that any files that get erased can be retrieved at a 100%
success rate. This is no longer the case now that MS-DOS 5.0 offers its
new file-deletion tracking function which offers an approach to 100%
recoverability that is very similar to Safe Erase. Safe Erase, however,
is still very easily the preferred alternative to this new MS-DOS 5.0
function.
Safe Erase has many advantages over the MS-DOS file-deletion tracking
method. Both programs use a file to safely store the allocated clus-
ters of files just before they are erased. The problem with the MS-
DOS 5.0 method is that it can build a huge file to be prepared to store
the names and allocated clusters of files erased by the next ERASE or
DEL that takes place. Actually it builds three files, two of which are
quite large. Safe Erase builds only one file the same size as the File
Allocation Table for that particular disk or diskette, which takes up
much less disk space than the deletion-tracking file that MS-DOS 5.0
builds. Another big problem with the deletion-tracking method is that
MS-DOS requires you to tell it how many deleted files to be prepared
for, otherwise it defaults to a small number. If you tell it 100 and
then erase 125 files with a command such as ERASE *.*, the MS-DOS
UNDELETE program will only be able to retrieve the first 100 files.
This is how the deletion-tracking file gets so large, the more files you
tell it to be prepared for the larger the deletion-tracking file it
builds. Also, 999 files is the maximum number that the deletion-
tracking method can handle. Safe Erase is prepared for an erasure of
any number of files, even directories with thousands of files. Safe
Erase does not need to be given a number of deleted files to be prepared
for. It is prepared for any number of deleted files and its Safe File
Table will always stay the same small size as the File Allocation Table.
The third big problem with the deletion-tracking method is that when you
tell MS-DOS to build its deletion-tracking file, it builds it as a
hidden file and it makes you really unsure if the file was created or
not. Safe Erase builds its Safe File Table as a read-only file which is
visible with the DIR command so you know that you have successfully
created a Safe File Table. The fourth big advantage that Safe Erase has
over the DOS deletion-tracking method is that Safe Erase will
automatically build a Safe File Table on a disk that does not have one
before it erases any files. The fifth advantage of Safe Erase is that
it does not operate as a memory resident program like the deletion-
tracking method, so Safe Erase saves you valuable RAM. The sixth and
largest advantage of the Safe Erase method is that Safe Erase version
2.00 (available July 1, 1991) will offer the same protection for erased
subdirectories as it currently does for files. MS-DOS 5.0 does not
deliver this function with its deletion-tracking method.
Safe Erase will work fine on all systems with MS-DOS versions 2.10 and
higher.
(MS-DOS is a registered trademark of Microsoft Corporation.)
(UNDELETE Copyright (C) 1987-1991 Central Point Software, Inc.)
Other software utilities that recover erased files can usually retrieve
most files but many times there are files that cannot be retrieved even
when no new files have been put out on the disk after the erasure. The
new Safe File RETRIEVE program easily undeletes any files that have been
erased with the Safe Erase KILLF command. The KILLF.EXE file can be
renamed to anything you like such as killfile.exe, mydel.exe, but not
erase.exe or del.exe. MS-DOS will think you're trying to use its erase
and del and never call erase.exe or del.exe.
NOTE: If you're really addicted to typing erase or del when erasing
files request the Safe Erase Install program when registering for Safe
Erase version 2.00. The Safe Erase Install program will allow you to
use the Safe Erase programs erase.exe and del.exe. These programs work
exactly the same as killf.exe but are not shipped with Safe Erase
version 2.00 unless requested. The Safe Erase Install program works by
patching 4 bytes of your command.com file. The patch tells MS-DOS to
let you run programs called erase.exe, del.exe, rmdir.exe, and rd.exe.
Rmdir.exe and rd.exe work exactly like the killd.exe program that comes
with Safe Erase version 2.00. The Safe Erase Install program comes with
a companion program called De-install which will remove the patch from
your command.com file if you so desire. So using the Install patch
program is completely harmless. Once again, these programs are only
shipped with version 2.00 if requested.
The Safe Erase KILLF command is smart enough to know which version of
MS-DOS you are using and will work the same way erase and del have for
your version of DOS. KILLF can do everything functionally that the MS-
DOS erase and del commands can do. KILLF can be used at the command
prompt or in batch programs. Safe Erase works with disks of any size.
Files can be retrieved on disks with partitions greater than 32
megabytes. KILLF and RETRIEVE will work fine on RAM disks created with
VDISK.SYS and RAMDRIVE.SYS.
How Safe Erase Works
--------------------
Understanding how Safe Erase works is much easier after a quick
explanation of what the existing MS-DOS erase and del commands do to
erase a file. When the user erases a file MS-DOS changes the first
character of the file name to the "σ" character and then removes all of
the file's cluster numbers from the file allocation table. When
conventional file recovery programs attempt to recover a file, they
often must make a best guess as to which available clusters belong to
your file. This is why sometimes you think you have recovered a file
and then you find that it has some bad data in it. Safe Erase takes a
completely new approach to file recovery. Conventional file recovery
programs use a pound of cure in attempting to retrieve erased files.
Safe Erase uses an ounce of prevention when files are erased so that
they can easily and accurately be retrieved if needed.
It is a simple procedure to begin using the Safe Erase package. Please
read the file install.doc to learn how to begin using the Safe Erase
package.
Safe Erase works by building a small Safe File Table on your disk. This
is automatically done when the KILLF command is used for the first time
on a particular disk. Once the Safe File Table is built, the KILLF
command will recognize that it's there the next time it is used to erase
a file on that disk. The KILLF command will only build a new Safe File
Table on disks that don't have one already. The table is a read-only
file exactly the same size as the MS-DOS file allocation table. Now
when you erase a file using KILLF the first thing that gets done is that
the file's cluster numbers get stored in the Safe File Table. Then the
files cluster numbers are removed from the MS-DOS file allocation table.
Now the file is erased but its cluster numbers are safely stored in the
Safe File Table. The Safe File Table will always stay the same size.
Now if it is decided that the file is really needed or not the intended
file to be deleted, the user can simply retrieve the file by typing
RETRIEVE in the directory of the deleted file. Safe File Retrieve has a
simple task of retrieving the file since its cluster numbers are safely
stored in the Safe File Table.
The Safe Erase software package consists of the following files:
1) readme.doc - Introduction to Safe Erase and what it offers.
2) install.doc - Instructions for setting up Safe Erase and how to use
it.
3) killf.exe - Used to safely erase files instead of erase or del.
4) retrieve.exe - Safe File Retrieve program used to retrieve erased
files.
5) buildtab.exe - Puts a Safe File Table on a disk for safe file
erasing.
6) killtab.exe - Used to erase a read-only Safe File Table.
SHAREWARE NOTICE
----------------
Shareware: Please help distribute Safe Erase by sharing unmodified
copies of the software package. Please upload Safe Erase to computer
bulletin board systems.
Safe Erase Version 2.00 will be available on July 1, 1991. Version 2.00
will allow the user to remove a subdirectory with the Safe Erase command
KILLD and and have the directory's cluster numbers safely stored in the
Safe File Table in exactly the same way that Version 1.21 stores a
file's cluster numbers. This will give the user a 100% recovery success
rate if files or subdirectories are erased. If you use Safe Erase
version 1.21 please support it by becoming a registered user at a cost
of $15. A registered user is entitled to the following benefits:
o Safe Erase version 2.00 or later shipped by mail.
o A copy of Safe Erase with your own registration number. Let
anyone interested make a copy of your registered version and if
they register you get a $5 commission. Your registered copy of
Safe Erase could get passed around for years to come. Because of
the real need for Safe Erase and its popularity, registered users
who share the package could find commission checks trickling in
for years to come.
To register send a check to:
Tom Williams
P.O. Box 563
Fayetteville, New York 13066
Please include registration number 0008221 when sending the check to
credit the person that shared this copy of Safe Erase. Please also
specify 5.25 inch diskettes or 3.5 inch diskettes.