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AVSIG Discussion Sections >> Hardware/Software

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Ward Miller POU-NY
Top Gun


Reged: 05/05/04
Posts: 10508
Loc: New York
CHKDSK & Scandisk
      #140447 - 01/15/07 02:08 AM

I did a defrag on one of my computers and when it finished it gave a list of
7 files it could not defrag. So I ran CHKDSK and it said it "found problems
with the file system." It further said I should run CHKDSK /F to correct
them.

Three of the files are Netscape files and I'm afraid the old DOS program
CHKDSK might screw them up if it tried to correct them. I remember in OS
past (Win 98?) when you ran CHKDSK it recommended you run Scandisk, but I
can't find such a program in my Win XP.

Any suggestions of a better program to analyze my harddisk for corrupt or
otherwise bad files and correct them without crashing some of my
applications?


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sreyoB yrraL
AVSIG Member


Reged: 05/16/04
Posts: 9442
Re: CHKDSK & Scandisk [Re: Ward Miller POU-NY]
      #140464 - 01/15/07 08:07 AM

The best, without a doubt, is Spinrite from www.grc.com.

Watch the video clip of Spinrite creator Steve Gibson explaining Spinrite to Leo Laporte on Call for Help.


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Geoff Sjostrom - Chicago
Top Gun


Reged: 04/29/04
Posts: 4312
CHKDSK & Scandisk [Re: Ward Miller POU-NY]
      #140479 - 01/15/07 09:43 AM

The CHKDSK program that comes with Windows XP is intended to be used with
that operating system. I use it frequently. Just click "Start" , then
"Run", and enter "CHKDSK /F".

In all probability the program will say that it can't run on your C: drive
and will ask if it should run next time you reboot. That's OK.

This isn't a thing to worry about.

Geoff


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Ward Miller POU-NY
Top Gun


Reged: 05/05/04
Posts: 10508
Loc: New York
CHKDSK & Scandisk [Re: Geoff Sjostrom - Chicago]
      #140489 - 01/15/07 11:16 AM

Thanks for that info, Geoff.

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Ward Miller POU-NY
Top Gun


Reged: 05/05/04
Posts: 10508
Loc: New York
CHKDSK & Scandisk [Re: sreyoB yrraL]
      #140490 - 01/15/07 11:16 AM

Thanks, Larry. I'll look into it.

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Ward Miller POU-NY
Top Gun


Reged: 05/05/04
Posts: 10508
Loc: New York
CHKDSK & Scandisk [Re: sreyoB yrraL]
      #140544 - 01/16/07 04:08 AM

Larry, with $89 and 9+ hours of harddisk exercise later, they seem to have
produced a "repaired" disk. It encounter two flaky sectors. One was
previously known to Win XP, but apparently it isolated another area that had
been causing occasional problems. Time will tell....

It was interesting the program kept showing the temperature of the drive --
about 107 degrees F. Perhaps it stops if it gets too hot?

It was refreshing to use a DOS-level program that didn't need no stinkin'
operating system to function. Got right down to the nuts & bolts of the
hardware. Its simple/complex features (and egos of the development team)
reminded me of a somewhat similar program (and development team) from the
early 1980s. (Was it really just 25 years ago the IBM PC eventually spawned
millions of copies and hundreds of thousands of programs?)

Early on program developers learned they were losing a ton of revenue because
customers were easily copying their products and giving copies away free. So
copy protection schemes soon were commonplace...and then quickly followed by
copy protection override utilities. Again, nuts & bolts (perhaps, bits and
bytes) programming accomplished only by the most nerdy of the breed.

Lotus 1-2-3 was one of the early copy protected products (with an attitude
that caused a later erosion of their enviable market share), and very soon
thereafter a team of bright kids (I think they were from MIT) produced a
utility that would copy the Lotus 1-2-3 program disks flawlessly. That team
was much like the SpinRite team, in both hardware skills and modest egos.

Perhaps the most creative copy protection scheme intentionally zapped their
5.25" disk with a tiny laser beam during manufacture. When running, the
program expected to find a certain damaged sector and thus knew it was an
original disk and proceeded to run properly. But if someone copied the disk
the copy program would just skip the damaged sector and go on. When the
copied program did not encounter the expected bad sector, it knew it was a
bootleg copy and terminated its run. Of course, some bright guys soon
figured out how to overcome that scheme as well. And so it goes.


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Ralph Jones
Top Gun


Reged: 08/31/01
Posts: 21214
Loc: 4CO2
Re: CHKDSK & Scandisk [Re: Ward Miller POU-NY]
      #140557 - 01/16/07 06:20 AM

Quote:

Perhaps the most creative copy protection scheme intentionally zapped their 5.25" disk with a tiny laser beam during manufacture. When running, the program expected to find a certain damaged sector and thus knew it was an original disk and proceeded to run properly. But if someone copied the disk the copy program would just skip the damaged sector and go on. When the copied program did not encounter the expected bad sector, it knew it was a bootleg copy and terminated its run. Of course, some bright guys soon figured out how to overcome that scheme as well. And so it goes.




That was the ProLok disk, used by Ashton-Tate on their database product dBase III. The effect of the laser burn (melt, actually) was to create a sector that could be read but not altered. The protection routine would write all zeroes to the sector, test for all zeroes, write all ones, and test for all ones; the melted sector would always produce at least one read error.

And that's where it got interesting. In order to do the special read/write operations, the program had to make a slight modification to the BIOS. Now today that would be easy, because modern PCs copy the BIOS out into RAM on bootup and execute it from there for more speed. Back in the 32K RAM days, they had to execute it directly from the BIOS ROM, and there was no direct way to hook into it. So the disk had to have its own complete disk BIOS aboard. And they created it by...

...copying IBM's.

They lifted some 800 bytes directly from the IBM Fixed Disk BIOS, inserted the necessary hooks, and incorporated it into the disk. In effect, the ProLok disk was a pirate product. And it was clear that they knew this, because they went out of their way to disguise it: they went through the code and interchanged logical-shift-left and arithmetic-shift-left instructions in every case where the MSB was guaranteed to be zero (meaning both instructions would produce the same result). It was quite easy to observe this, because the original PC-XT hardware manual contained the BIOS source code.

Then they added a crude encryption routine that simply ran over and over again, 30-odd times, to expose the underlying code for the protection routine -- and left a back door a mile wide. It could be shorted out with a two-byte change to the disk.

The center for copy-breaking information in those days was an online service called...ummm, what was that...oh yes, Compuserve. Every software-related forum had a data library called "Patches & Unprotects", and the crack for the ProLok disk appeared there within a couple of days, along with the revelation of the copied content. One of the major computer magazines reported the copying, though of course not the crack.

The vendor that provided the disks, Vault Corp, was run by a former detective who fancied himself the nemesis of computer crime...he was very proud of the product. Before long he announced ProLok Plus: it would not only be uncrackable, but if it detected a cracking attempt it would wreck the computer. Corporate orders for dBase evaporated overnight, and Ashton-Tate cancelled the contract -- not an easy move, because they owned about a third of Vault. Vault was toast within a few months.

The "Patches & Unprotects" files later disappeared from Compuserve, quite literally overnight.

--------------------
Ralph Jones
LS-4a N49LS 6R


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sreyoB yrraL
AVSIG Member


Reged: 05/16/04
Posts: 9442
Re: CHKDSK & Scandisk [Re: Ward Miller POU-NY]
      #140564 - 01/16/07 08:14 AM

There is no Spinrite team, Just Steve Gibson. :) His site also has an interesting collection of small, free utilities and web applications most of which are related to security. He is also co-host of the excellent Security Now weekly Podcast.. Every fourth episode is a listener Q&A session and are the episodes that I like best.

You are right about Spinrite getting right down to the nuts and bolts. It gets right down to the hardware level and works with each bit on the HD's platter. When it finds a bit, or bits, that it can't read it is much more persistent than the operating systems would be. It tries all sorts of combinations of head movements in order to get a good read of the data and will work for extended periods of time trying to recover any specific data that is otherwise unreadable. In fact, if you have serious damage on a disk Spinrite may run for days working to recover your data.

Spinrite is also intended to be run periodically on working disks as it tests every single spot on the disk and will detect areas that are failing on the platter and will move your data and mark those failing areas as bad even before the operating system has lost the ability to read it. During this process it's also refreshing each bit on the disk so files which may not have been access in years are read, tested and rewritten fresh.

Spinrite does monitor the drive's temperature, assuming that the drive reports it, and will pause to allow a drive to cool down if necessary.

Steve even encourages the loaning of your Spinrite disk to others who are having disk trouble. He says he picks up a lot of customers this way when Spinrite saves someone's data that they thought was lost and they then buy Spinrite after the fact for future use.


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Russell Holton
AVSIG Member


Reged: 07/07/05
Posts: 14136
Re: CHKDSK & Scandisk [Re: sreyoB yrraL]
      #140603 - 01/16/07 01:44 PM

Quote:

Steve even encourages the loaning of your Spinrite disk to others who are having disk trouble. He says he picks up a lot of customers this way when Spinrite saves someone's data that they thought was lost and they then buy Spinrite after the fact for future use.




Ah! I always liked Steve Gibson. Now I like him even more. He can see beyond bean counting to the real bottom line. I think if one were to look up "hacking" in a dictionary, in the section that talks about old-school hacking (tinkering) I think you'd find photos of Steve Gibson and Don Lancaster.


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Joe Budge (W29)
Top Gun


Reged: 04/30/04
Posts: 7423
Re: CHKDSK & Scandisk [Re: Russell Holton]
      #140635 - 01/16/07 05:41 PM

Quote:

Ah! I always liked Steve Gibson. Now I like him even more. He can see beyond bean counting to the real bottom line. I think if one were to look up "hacking" in a dictionary, in the section that talks about old-school hacking (tinkering) I think you'd find photos of Steve Gibson and Don Lancaster.




Me too! I met Steve when he was making light pens for Apple ]['s. They didn't really catch on. But now, here I am scribbling on AvSig with a touchpen on a tablet which is reading my handwriting (more or less). Before his time. Sigh. I'm glad to see Steve still seems to be doing well. It could be worse. Anyone else see the article about John Draper in Saturday's WSJ?

And Don Lancaster? Damn! I learned more about how digital circuits ticked from "TTL Cookbook" than anywhere else.

Regards,
Joe


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Joe Budge (W29)
Top Gun


Reged: 04/30/04
Posts: 7423
Re: CHKDSK & Scandisk [Re: Ralph Jones]
      #140638 - 01/16/07 05:51 PM

Ralph,

MANY thanks for that post. I arrived at Ashton-Tate two weeks before they took the copy protection off of dBase III Plus. It was a super hush-hush project and nobody was telling me anything. Silly me, I thought they were doing it because it was a good idea. Subsequent events proved that they weren't that bright, but I never really thought about it till now.

Regards,
Joe


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Russell Holton
AVSIG Member


Reged: 07/07/05
Posts: 14136
Re: CHKDSK & Scandisk [Re: Joe Budge (W29)]
      #140770 - 01/17/07 05:04 PM

Quote:

And Don Lancaster? Damn! I learned more about how digital circuits ticked from "TTL Cookbook" than anywhere else.




You and me both. I think it was Popular Electronics's "beginning of the end" when they dropped his column.


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Ron Koyich
Top Gun


Reged: 04/28/04
Posts: 1469
Loc: YWVA
CHKDSK & Scandisk [Re: Joe Budge (W29)]
      #142212 - 01/30/07 10:14 PM

Another Cookbook learner here, Joe...

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