Case study

Cosmic Ark: a commented Atari 2600 disassembly with PAL conversion

Cosmic Ark for the Atari 2600 (Imagic, 1982) is reconstructed as an analyzed, labeled and commented 6502 assembly listing with NTSC and PAL builds. The PAL conversion rescales nearly all game speeds through the game's fractional addition so both versions play at the same pace, and optional switches enable size optimizations. The notes point out the leftover code for a non-cooperative two-player mode and the game's heavy use of status flags.

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

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Requirements & limits

Prerequisites: A 6502 assembler and the vcs.h header that the listing includes; the listing itself defines TIMINT = $285, which older versions of vcs.h lack.
Limits: Version 0.9. The author states that PAL meteor speeds do not match NTSC exactly and that some status flags may be misidentified.
License: No licence stated on the project page.

Cite

BibTeX

@misc{cosmic-ark-atari-2600-disassembly-case,
  title = {{Cosmic Ark: a commented Atari 2600 disassembly with PAL conversion}},
  howpublished = {\url{https://www.qotile.net/minidig/disassembly/CosmicArk.asm}},
  url = {https://www.qotile.net/minidig/disassembly/CosmicArk.asm},
  urldate = {2026-11-09},
  note = {Awesome REA entry: \url{https://awesomerea.org/resources/cosmic-ark-atari-2600-disassembly-case/}}
}

Plain text

Cosmic Ark: a commented Atari 2600 disassembly with PAL conversion. https://www.qotile.net/minidig/disassembly/CosmicArk.asm (accessed 2026-11-09). Awesome REA entry: https://awesomerea.org/resources/cosmic-ark-atari-2600-disassembly-case/

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The description was reviewed against primary sources.

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