< < < BERKELEY SOFTNORKS : GEOS 2.0 > > >
      
      Warning: Trying to understand this chapter may be hazardous to
      your mental health. If you haven't read "Inside Commodore DOS",
      "CSM's Program Protection Manual Vol. 2", and "The Official GEOS
      Programmer's Reference Guide" at least twice, cover-to-cover, then
      turn the page ....
      
      The copy protection routine in GEOS has been a thorn in the
      side of everyone who ever needed a working backup of their
      original. A backup copy of GEOS only boots and loads properly when
      all of the several layers of protection checks have been satisfied
      perfectly. We found this out the hard way with our first GEOS 1.3
      parameter. What appeared to be an ideal way around the protection
      check turned into a nightmare. Customers complained that file
      selection dialogue boxes acted strangely; that the dreaded "SYSTEM
      ERROR NEAR $XXXX" appeared at odd times; and that; sometimes, the
      GEOS System files would inexplicably disappear.

      That we had failed was obvious. What was not obvious was the
      subtle complexity of the protection scheme. It took almost a week
      of sleepless nights to come up with a satisfactory solution to the
      problem. If you're still game, let's analyze exactly what GEOS BOOT
      does and how it does it.
      
      Prepare a fast copy of your ORIGINAL GEOS 2.0. It should
      contain little or no modifications to the disk structure and
      directory, especially the System Boot Files "GEOS", "GEOS BOOT",
      and "KERNAL". Make sure you have a work disk ready so you can save
      code to it. You will also need a reset button and the "GMON" drive
      monitor on the Revealed III utility disk to conveniently follow the
      boot routine from its humble beginning to the bitter end. "GMON" is
      a modified "Kracker Mon" and is NOT relocatable. It was assembled
      to occupy C-64 memory from $2000 - $3FFF, which GEOS ignores until
      the inevitable entrance of "DESK TOP". It may be activated from
      BASIC with the command "SYS 8192".
      
      If you use the included Disk Logger, you will find that "GEOS"
      and "GEOS BOOT" (GB) load respectively from $0110 - $0206 and $6000
      - $64A9. Using "GMON", load and examine "GEOS" in memory. No funny
      stuff here. Its only purpose is loading and executing GB. You may
      safely ignore this file and directly load GB with "GMON".
      
      The next step is to browse through the program code. You'll
      find a lot of areas that don't disassemble properly because the
      code is encrypted. The decryption routine is actually fairly
      simple. It may be seen near the bottom of the GB file at $6483 in

            K.J. REVEALED TRILOGY    PAGE [106]    (C)1990 K.J.P.B.