This is a set of tools for reverse engineering C64 demos.
This tool allows extracting files and trackmo chains from disk images created using ByteBoozer 1.1 and 2.0 crunching algorithms and the BoozeLoader trackmo loader and corresponding Disk creation utility by HCL/Booze Design.
This came out of my experience partially disassembling Uncensored by Booze Design. This involved a lot of manual work, so I wrote this tool to fully automate extraction and decrunching of the files and trackmo chains from the D64 image.
To extract a Booze Design demo disk, type debooze DiskName.d64. This will create a directory structure like this:
DiskName.dumpdir.txt: Unicode approximation of the PETSCII directory listingfiles: All normal files on the disk with Unicode translation of the PETSCII filename.decrunched: decrunched version of the extracted files
trackmo- e.g.
00-01-14.prg: decrunched trackmo chains named as index-track-sector.prg
- e.g.
The tool automatically figures out which sector contains the trackmo index by looking for a sector with a bunch of valid track/sector pairs padded at the end with zeros. Usually this is on track 18 sector 9, but some older demos use different sectors (e.g., sector 6 for Edge of Disgrace). It will also automatically detect the version of ByteBoozer used based on the signature of the decrunching code in the bootloader and then try to use the same version to decrunch all the trackmo files as well. If the tool incorrectly detects something, it is possible to manually override it by passing parameters to the appropriate functions, but currently I haven't made commandline switches for this, so it would require editing the code.
I have extensively verified the results for Uncensored, and less extensively verified that the results for Remains, confirming that the decrunched files match the decrunched data dumped from the VICE monitor, so I think I got both algorithms right. It appears to successfully extract and decrunch 1991, Edge of Disgrace, and The Elder Scrollers, but I haven't done any verification yet. It doesn't find any crunched files or trackmo indexes on some other demos like Mekanix or Royal Arte and I haven't investigated why yet.
program.py contains the beginnings of a disassembler I'm currently trying to build. It is inspired by features from Regenerator by Nostalgia and Ghidra by the Naughty Spying Agency. I like both of these tools but they both do things that annoy me, so I'm writing my own and hopefully I'll learn a lot in the process.
Currently this is very much a work in progress. It can correctly parse BASIC tokens and do simple tracing disassembly from a starting address. Right now it is just a set of functions and classes that can be called from an Jupyter notebook or IPython shell. Interactive features are still to come. I will probably prototype the UI using the Python curses library and I may consider doing a graphical or web-based version later. I am planning to use sqlite to store the code blocks, labels, comments, etc.
Copyright (c) 2021 J.B. Langston
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