This project contains the (unofficial) disassembly of both the ZX Spectrum and the PC DOS version of The Lords of Midnight (LOM), the 1984 video game designed and developed by Mike Singleton.
My motivation for doing two disassembly at the same time came about after I found that Chris Wild had released a large chunk of the source code to his PC version, and that his port was an also almost byte-for-byte conversion of the ZX Spectrum game (due to the similarities between the Z80 and 8086 microprocessors). This piqued my interest and I wondered exactly how close the two versions of the game really are.
Although I've disassembled a couple of ZX Spectrum games before I've never tackled a DOS game, but with Chris' source code in hand I was feeling confident.
The Ghidra reverse engineering tool was used to disassemble the PC version. I then applied all the labels and comments from the DOS source code to the Ghidra disassembly. Chris' release doesn't contain the whole game so I had to disassemble the remaining code myself. Further labels and annotations were added where things seemed obvious or didn't take too long to figure out.
After the DOS version was complete I then booted up Skoolkit and started disassembling the Spectrum game. Although time consuming, this was relatively straight forward at this point.
The Icemark website contains a great deal of useful information on the game data formats along with information on what many of the associated data values mean, including:
- location coordinates for items and places in the world
- character stats (coords, race, life, energy, strength, etc.)
- citadels/keeps location, unit count and type
- strategic places data
- recruitment information
- doomdark's regiment stats (coords, soldier count, type, and orders)
This information is found under the Guidance from the Wise section.
I used various parts of this additional information to flesh out the two disassembly's with more labels and annotations. The resulting source codes are still relatively sparse, but you can certainly see how close the two versions of the game are.
Download and extract .z80 binary with the following command:
tap2sna.py -f @lom.t2s
The .skool can be generated using the provided .ctl file:
sna2skool.py -I LineWidth=96 -c lom.ctl -H lom.z80 > lom.skool
When editing the .skool file directly, the .ctl file should be re-generated:
skool2ctl.py -h lom.skool > lom.ctl
Disassembly, comments, and notes, 2023, Michael R. Cook.
Designed and developed by Mike Singleton.
Copyright (c) 1984 Beyond Software.
PC Version and DOS source code, Copyright Chris Wild. https://www.icemark.com