Build, investigate and preserve C64 software

C64 RE Tools connects AI coding agents to a running VICE emulator and established tools including ACME, DXA and Ghidra. It supports new 6510 programs as well as the investigation of existing binaries: assemble, run, inspect, revise and test.

Live memory, CPU and hardware state inform the next step. Labels, comments and memory regions remain in version-controlled text files. A reconstructed program can be rebuilt and compared with a reference capture, then exercised through repeatable emulator scenarios.

Example prompts

Build and test: “Write a small ACME program where a sprite moves with the joystick. Build it, run it in VICE and add a scenario that checks its position after recorded input.”

Investigate a binary: “Analyse original/game.d64. Find how the program starts, capture it after unpacking if needed, and identify its main routines. Generate assembly that rebuilds the captured program byte for byte and compare its behavior in VICE.”

Evidence from a complete game

The reconstruction of Datasoft’s 1984 C64 game Bruce Lee demonstrates this workflow on a commercial program. Its documented source covers startup, interrupts, actors, combat, graphics, sound, protection and all 20 rooms.

Release-specific builds reproduce the captured game portions of the SAEGER, TBC and DC distributions byte for byte. Behavioral scenarios compare memory, screens and VIC-II state at defined checkpoints. These are checks against surviving cracked releases; an uncracked original master was not recovered, and remaining test coverage gaps are documented.

Recovering development history

The same investigation exposed material outside the active game. Decoding a 165-byte assembler-text fragment and comparing its graphics bytes with the reconstructed character set linked surviving source text to finished room tiles. A surviving 896-byte symbol-table fragment preserves 88 complete entries. Address comparisons connect original names to later code and sprite layouts. Other remnants include earlier routines and graphics, MicroPearl music-editor data, a bitmap utility and Atari keyboard tables.

Together these findings show how unused bytes can preserve parts of a development history. The research separates observations, code-level facts and interpretations. Apple II-style source conventions do not establish the exact assembler or development machine.

Source and reproducibility

The toolkit is MIT licensed. Setup instructions, reconstructed source, release comparisons and scenario definitions are public. The historical game and artwork remain credited to Datasoft and their original creators.

Toolkit: https://github.com/henols/c64-re-tools

Reconstruction and tests: https://github.com/henols/c64_games/tree/main/bruce_lee

Historical evidence: https://github.com/henols/c64_games/blob/main/bruce_lee/docs/development.md

Companion research project: https://hackaday.io/project/207112-bruce-lee-1984-development-archaeology