1(4), August 1984, page 3

[conclusion of Cramer article at top of this page]

Saving Grace:
Recovering & Preserving Files and Data

Dr. Roger C. Schlobin
802 North Calumet Road, Chesterton, IN 46304 (219)-926-7368

There are two kinds of computer users: those who have lost data and programs and those who will. That's one of the great truisms of modern computer technology. In the past, the major way to deal with this problem was by making many backup copies. It seems that every software manual offers the dread warning: "Copy the original and work from the copy. Put the original in a safe place." There is even one manual that recommends storing originals in a separate building. This wise admonition has been the inspiration for uncountable executions throughout the world of manufacturer-supplied copy and file-transfer programs. It has also given birth to numerous specialized disk-and file-duplication programs for both hard and floppy disks, such as BACKUP/RESTORE, COPY II PC, FIVE-STAR BACKUP, PC DUPLICATOR, and the much-heralded QBAX with its added feature of only copying new or altered files (as well as entire disks).

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However, even a multitude of backups will not protect against the loss of data due to hard errors (physical damage), soft errors (magnetic damage), or accidental erasing of files. For these problems, some software manufacturers have dipped into that vast well of public-domain software to refine and improve various data- and file-salvage programs. The value and importance of these programs appears in that they were originally developed by users who could not wait for manufacturers and professionals to catch up with their needs and problems. Too many people were being far too frustrated by that infuriating "BDOS ERROR ON B: BAD SECTOR." Thus, disk-protection and data-recovery software is truly of and for the people, and such programs stand beyond advertising, hype, applications, and uses. Simply, they should be among the essential tools that any responsible computer user should have. Since these programs were initially developed by users, for a long time they were available only for the CP/M operating system. CP/M has been around longer than most other operating systems, and its advocates have been an energetic and creative bunch. Now, however, as MS-DOS, PC-DOS, and CP/M-86 are becoming more popular due to the increasing sales of the pseudo-16-bit (like the IBM-PC) and real 16-bit microcomputers, disk-protection and data-recovery software is quickly being converted to these operating systems.

At this moment, there are a significant number of products for a variety of operating systems that will insure disk integrity, recover accidentally erased files, and recover at least the remaining good data on physically or magnetically damaged disks.


Prior to the existence of Colorado Online's DATACURE the best before-the-fact measures for hard and soft errors anyone could take were bad-sector, lockout programs. These lockout programs at least insured that a disk didn't have any bad sectors that had slipped by the too-often-inadequate initialization (format) routines supplied by manufacturers (which sometimes did not even verify the sectors). DATACURE has changed all this and is the first of a new generation of disk-protection software that uses methods that were once only available on mainframe computers. Through its various subroutines, DATACURE can rebuild damaged directories and protect against loss of files due to a single bad sector, destruction of sector tracks due to power loss, and destruction of data due to physical damage (nicks or scratches). There is an unbelievable claim in the DATACURE manual that you can stick a pin through a protected disk and still recover the data. While I wouldn't recommend doing it because of the potential damage to the disk drives, it was so much of a challenge that I couldn't resist, and I sacrificed a disk on the altar of journalistic integrity. You can believe it! Pin hole and all, DATACURE worked! The most recent DATACURE manual recommends a less dramatic but saner and safer way of testing this with a pointed magnet.

DATACURE's data protection is accomplished through a set of error-correction algorithms that reside on user level 15. They use about five percent of any disk's space, but that's a small price to pay. In fact, given the opportunity to use those multiple backup disks for other things will more than compensate for the missing five percent. These algorithms and DATACURE's subroutines allow the user of a protected disk to rewrite bad sectors, replace lost data, and/or transfer the information from a damaged disk to a good one.

The only drawbacks to DATACURE are that it's only available for CP/M-80 and floppy disks at the moment, and someone with a large disk library is going to have to spend a considerable amount of time transferring to DATACURE -protected disks. However, a hard-disk version and other operating-system versions are in the works, and the time to redo backups is minor compared to the benefit. Also, it's only a matter of time until versions for other operating systems are available from Colorado Online. Finally, DATACURE operates in a way unlike any other program I've ever seen. Even with its automated installation, you should read the clearly-written manual carefully. Also, DATACURE is perhaps the best supported program I've ever seen, and users will find Colorado Online very helpful. In fact, various users have already been helped with instructions and free public-domain programs (which Colorado Online will supply with a purchase) to recover disks that had crashed before they purchased DATACURE.

The conclusion here should be obvious. No responsible users, no responsible businesses should be without DATACURE if it will work on their systems. This is simply too critical a program to be without!


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Even with the existence of DATACURE, bad-sector lockout programs are still useful, especially considering their relative inexpensiveness ($29.95 for Quest SUPER RX with Super Unerase and $79 for Blat's BADLIM). These programs are the magicians among utilities in that they fool the operating system. Like their public-domain ancestor, FINDBAD, once they find a bad sector, they write a shadow file on it and allocate the bad sector to user 15. The operating system then sees that the sector is allocated and won't try to write on it. This means that the disk is usable again. For example, DATACURE cannot make an out-of-the-carton, uninitialized, flawed disk usable, but SUPER RX and BADLIM can (as can a disk-examination program like DPATCH). In addition, by blocking out damaged areas, these programs are among the easiest ways to save a disk with data already on it. Both SUPER RX and BADLIM are very easy to use, requiring no installation and only the naming of the drive with the "patient disk" in it. SUPER RX is available for floppy disks only; BADLIM is available for floppy and hard disks.


Another way of handling bad sectors is to use a program that will copy the good sectors onto a new disk and leave the old ones behind. One of the least expensive and lesser known of these is DSAVE. In addition to the good-sector recovery, it can also be used as a very fast disk-copy program.

However, one of the limitations of bad-sector lockout programs and DSAVE is that they cannot save even a portion of the bad sectors. For this problem, you either need DISK DOCTOR or one of the data-manipulation programs listed below. DISK DOCTOR has for years been one of the more valuable programs around. However, its popularity has been hindered by a difficult install program and manual. Now, there's an automatic install, but the manual still is troublesome, even though DISK DOCTOR is menu driven. One of DISK DOCTOR 's features is that it has a very sloppy and very slow (ten minutes to an hour) copy program, and this can be used sometimes to recover a disk with bad sectors. Other features include eliminating bad sectors like SUPER RX and BADLIM do, recovering any sector or file from a disk with a damaged directory, de-erasing accidentally erased files, and listing all recovered files. Given the difficulty of DISK DOCTOR, however, the learning time might be better spent with one of the more powerful data-manipulation programs.


So far, we've covered bad disks produced by quirky drives, mishandling, or poor manufacturing. We shouldn't forget that old favorite, "user error," or as it usually feels at the time, "deep dumbness." The oft-repeated anecdote about this is the person who types ERA *.BAS instead of ERA *.BAK. Suddenly, all those carefully constructed BASIC files are gone, seemingly forever. And it's amazing how many computer owners think that the files are really gone. They're not! What the vast majority of operating systems do when a file is erased is mark its space as available. The file is still there. CP/M, for example, does this by putting an E5 at the beginning of the file-control block. By running an de-erase program as soon as possible after the error, this overwrite indicator is changed to 00. Lo and behold, as if by magic, the file is there again. It's necessary to do it before any further operations to eliminate the chance that the file be partially overwritten with a new one.

Unerase software has been available in the public domain for some time as UNERA. However, it has been enhanced, adapted to particular microcomputers, and documented by a number of software vendors. The latest development is that most new unerase programs--such as UNERA (Compu-Draw), SUPER UNERASE (Quest), UNE/CON (Elliam), and UNERASE (Norton Utilities)--will do multiple file recovery either through wildcards or lists of "erased" files. In addition, UNE/CON borrows a feature from the data-manipulation software and includes a program (CONFLICT) that will recover a partially overwritten file. Again, unless you're sophisticated enough to use a data-manipulation program, one of the unerase programs is a necessary purchase.


Frequently data-manipulation utilities are simply referred to as "disk fixers." However, given the power of these programs, that's like calling a raging bull a moving mammal. These programs were well described in Alan R. Miller's review of DISK FIX (IA, Dec., 1982), but for convenience here is an overview. Like their public-domain ancestor, DUU (written by Ward Christensen and Ron Fowler), these programs allow access to any byte on a hard or floppy disk and can correct soft (not hard) errors. With an understanding of the operating system, the user can

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then effectively change anything! "With an understanding of the operating system" is, of course, the problem. These programs demand a greater understanding than any of the other types mentioned here. Even the menu driven, user-friendly ones--like CP/M.D., DISK FIX, DISK MECHANIC, DISKMAP PC, DPATCH, and MASTER SERIES UTILITIES--are not simple. However, once they are mastered, they offer extraordinary features that exceed all the programs mentioned here with the exception of DATACURE.

For more specifics, consider CP/M.D., one of the better buys ($52.95). It will do all of the following: display and access any sector, change or rewrite any ASCII or HEX character, display all the information in the disk directory (thus making it possible to repair a damaged one), recover any erased file, retrieve files from disks with damaged directories, retrieve and rewrite files from bad sectors, lockout bad sectors (DPATCH has two methods for this), move data from disk to memory and memory to disk, and install automatic disk call-up programs ("boots," submit routines, etc.). Those are only a few of the features. The uses of a data-manipulation program are limited only by the user's imagination. Remember, however, that they can be as difficult as they are powerful. They are not for the novice.


What programs a user selects for data recovery and protection are, of course, limited by availability and cost. Many of the programs listed here have limited application to certain operating systems and computers, with the CP/M user having the greatest access. Cost can be something of a factor, but notice that programs recommended here are much less expensive than others of the same type. This again proves the old adage that good software is not necessarily expensive software.

However, setting these limitations aside, everyone who needs to protect data should have DATACURE and one of the unerase programs. For the novice, a bad-sector lockout program can also be very helpful. Often these can be purchased in a package, like the NORTON UTILITIES or Quest's combination of SUPER RX and SUPER UNERASE, with clear cost benefits. For the more accomplished user, a data-manipulation program is invaluable, and a novice will certainly be able to use some of its features immediately and grow into the others.

Whatever the choices, it's clear that the only reasons datum is lost are because of some outrageous calamity or because someone didn't care enough to explore the numerous programs that can prevent it!