Case study

Jawbreaker: an annotated Atari VCS disassembly that compiles to the exact ROM

Tiger Electronic Toys' 1982 Atari VCS game Jawbreaker is disassembled into labeled and commented 6502 assembly that compiles to the exact ROM image. Notes explain how sprite positions are kept as combined fine-motion and coarse values and how an inverted playfield masks the maze, and record that joystick input is read from $0288 instead of SWCHA; assembler switches select an NTSC or PAL build and an optional no-defeat mode.

Targets: Game
Category: Independent reconstruction cases
Relationship: Independent reconstruction project
Sources reviewed: 2026-11-09

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Requirements & limits

Prerequisites: Assembling needs a 6502 assembler and vcs.h version 105 or later.
Limits: The author notes that the PAL version keeps the NTSC game speeds.
License: No licence stated on the project page.

Cite

BibTeX

@misc{jawbreaker-atari-vcs-disassembly-case,
  title = {{Jawbreaker: an annotated Atari VCS disassembly that compiles to the exact ROM}},
  howpublished = {\url{https://www.qotile.net/minidig/disassembly/jaw_breaker.asm}},
  url = {https://www.qotile.net/minidig/disassembly/jaw_breaker.asm},
  urldate = {2026-11-09},
  note = {Awesome REA entry: \url{https://awesomerea.org/resources/jawbreaker-atari-vcs-disassembly-case/}}
}

Plain text

Jawbreaker: an annotated Atari VCS disassembly that compiles to the exact ROM. https://www.qotile.net/minidig/disassembly/jaw_breaker.asm (accessed 2026-11-09). Awesome REA entry: https://awesomerea.org/resources/jawbreaker-atari-vcs-disassembly-case/

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About this entry

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Primary sources

https://web.archive.org/web/20260222165051/https://www.qotile.net/minidig/disassembly/jaw_breaker.asm