Dungeon Master + Analyser Optimisation

1 March 2002

We have a damaged Amiga copy of this game. Since it has an AmigaDOS file system we thought we would try to copy all the files under workbench (see below for why), and they do indeed copy (we are not talking about the protection track here). We also checked the contents of the bad tracks, and they contain data that may be just left over, or could be real data accessed directly through trackdisk by the program.

We have looked at various cracks, but they are all from different Dungeon Master versions, so we can’t tell if the data on the cracked versions is correct or not.

The point of copying files in AmigaDOS is that data blocks get an AmigaDOS checksum, which usually fails with bad data. This is probably the reason why Commodore went for the simple low-level parity system (apart from being cheap) for disk format integrity, since the OS layer had a different kind (and better) checksum. Unfortunately this level of security is gone if a program does not use the file system provided by the OS. This is the case for at least half of the games that have an AmigaDOS low level disk format.

A big optimisation was made to the analyser. It now marks possibly similar data, which takes the processing time for whole disk from 4 mins down to about 1.5 mins on a 450Mhz P3 system.