Date   : Thu, 14 Oct 1999 21:58:21 +0100
From   : Graham Bisset <graham@...>
Subject: Re: Protection schemes

At 23:01 13/10/99 -0600, you wrote:
>Sometimes people come across copy protection, and I wanted to share a simple
>method of keeping the disk catalogue non-viewable on dfs disks. It
involved using in
>the title block of the catalogue sectors characters which were out of the
viewable 
>range, specifically ASCII zero. I once copied the catalog block to another
location,
>re-wrote the block, and put it back.  Then the catalog was visible.
>
>What other protection schemes were in use?

I recall some that had files that didn't have any catalogue entry
but a "header" programme would load them direct from disc using
a &FFF7 call.  This was a popular one.

I wrote quite a few protection schemes over the years (still have
them somewhere), these were quite complex and I was proud of them :-)  

I recall a programme called DDD-Suite which had an interesting
scheme.  It always tried to write to the catalogue section of the
disc.  Since the discs were write protected, it failed, but remove
the write protection and it would clear the first two sectors (where
the catalogue is stored) with 2 dummy files - BLANK and DISC !!

There are others that I recall, email if you want further details.

Cheers
Graham