The Prolok Saga (Was: Applesauce FDC

Fred Cisin cisin at
Tue Nov 2 15:35:10 CDT 2021

On Tue, 2 Nov 2021, dwight via cctalk wrote:
> The trickiest protection I've seen is where there is a hole punched 
> through the disk on one track. The idea is that the protected program 
> writes to that track and expects to see a failure to read that track.
It doesn'tneed to be a hole all the way through, merely any physical 
defect that renders that spot unusable.

The "Physical Defect" protection.

Copy protected disks had already been made with flawed content to produce 
an error on READ, and were easily circumvented by the "duplicate" copy 
having flawed content. The next step was to have a physical defect, so 
that the protection software would WRITE to the bad track, and confirm 
that the track really was damaged.
So, they would scratch the disk.
In the case of Prolok, the check to confirm a physical defect consisted of 
writing all zeroes to that area; verifying all zeroes; writing all ones; 
and verifying all ones.

Vault Corporation produced "Prolok" with a physical defect.  To make it 
MUCH MORE IMPRESSIVE to investors and clients, instead of a roomful of 
people scratching disks with paperclips, they used a "laser fingerprint" 
(use a laser, instead of a paperclip).

Since they gave the same or similar subroutines, that checked for the 
defect, to every client, it was cracked with software that would locate 
that subroutine, and replace the subroutine call with NOPs or gut the 
innards of the subroutine.  The cracks were often posted on Compuserve. 
(Vault sued Quaid software for "CopyWrite"/"RAMKEY") )

For "cloning" (pirating copies, often with the Central Point Option 
board (flux hardware)), software was developed that would 
identify the location of the defect, the cloner would then attempt to 
scratch the disk at that location, and then the software would locate the 
defect and juggle stuff around to put the content in the right place(s) 
relative to the defect.

But, Vault Corporation wasn't satisfied until they shot themselves in the 
foot with very high caliber rounds.
They announced "Prlok PLUS".  W. Krag Brotby (chairman of Vault) said that 
it would, if it detected a "fake" copy, wipe out the user's hard disk!
Even at the announcement of Prolok PLUS, the computer marketing 
community was aghast and enraged.  It doesn't take much to realize the PR 
nightmare, and the legal liabilities for damaging a customer computer, 
even if it was NOT a false positive!

Ashton-Tate, the largest Prolok client for dBase III, and part 
owner of Vault, immediately cancelled their contracts.  And announced 
that they had done so, that they had never used Prolok Plus, never would, 
and no longer used Vault Corporation products.
Almost all of Vault's other clients follwed suit.

Prolok Plus never made it to market!
'Course the "word was out".  Few people realize that it was NEVER 
actually put to use.  In fact some of the more idiotic newspaper "solve 
your computer problems" columnists, when stumped, would actually speculate 
"maybe your computer was attacked by an out of control copy-protection 

So, we ended up with a mythical monster, and the creator of that mythical 
monster was vanquished.

If anybody can document an actual existence of Prolok Plus, I would like 
to hear about it.

There is little mention of it on the web, but:
"Re:Ahhh, holes burned in disks (Score:5, Informative)"
Kryoflux display of Prolok

Grumpy Ol' Fred

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