This is a method devised by Fiveways Software. It is found on several Heineman titles, for example.

The catalogue cannot be viewed due to VDU21 and VDU23 characters in the disk title. When *CAT is used the string (c)FWS appears and the computer appears to hang.

There is only one file in the catalogue, !BOOT. This is a machine code file resident at &7000 to &7FFF.

The !BOOT file handles a lot of the protection mechanisms. Amongst other things !BOOT does;

  • calls various OSBYTE routines to disable possible interruption of its working,
  • resets FILEV and BREAKV to point to its own code in page &700,
  • Disables all ROMs except DFS and BASIC,
  • Copies part of itself down to &700 to &7FF,
  • Checks for memory size and working tube presence and exits if these are incorrect,
  • Checks for OS1.0 or above.

The code at &700 is responsible for loading files from the disc surface and decrypting them by adding &41 and EORing with &97. The new FILEV points to this code.

The RAM-based disk catalogue at &E00 to &FFF is modified to include an entry for a BASIC file called A. This is CHAINed and uses the code at &700 to *LOAD the needed files and decrypt them on the fly. These files are then moved down in memory and RUN.

In addition tracks 1 and 2 are specially formatted. Track 2 is formatted with 1 sector of 128 or 256 bytes and numbered 147. Track 1 is formatted as 8 sectors of 256 bytes if Track 2 is formatted with one sector of 256 bytes or one sector of 2048 bytes if Track two is formatted with one sector of 128 bytes. Track 1 is deleted data.

Most of the other tracks are deleted data but even amongst those there is the odd track that is normal data.

Tracks 24 onwards are not formatted.

Thanks to billcarr2005 from the StarDot forum for cracking this protection and providing the working SSD files in the downloads.


2018 - 2021 flaxcottage.com