# GEOS 2.0: source that rebuilds the cbmfiles KERNAL binaries

> Reorganized cc65 source for GEOS 2.0 on the Commodore 64 and 128. The README says a standard compile generates binaries identical to the GEOS 64 2.0 and GEOS 128 2.0 distribution binaries, and make regress compares the bsw and wheels builds with the reference tree.

- Type: Case study
- Targets: Binary
- Category: Independent reconstruction cases
- Relationship: Independent reconstruction project
- Sources reviewed: 2026-11-04
- Added to the catalog: 2026-11-09
- Original resource: <https://github.com/mist64/geos>
- Primary source: <https://github.com/mist64/geos/blob/617efdc7191eda14eaf699d317e66d5bda68c039/README.md>
- Catalog page: <https://awesomerea.org/resources/geos-20-kernal-case/>
- Record JSON: <https://awesomerea.org/resources/geos-20-kernal-case/record.json>
- Chinese version: [简体中文](https://awesomerea.org/zh/resources/geos-20-kernal-case/index.md)

## Requirements & limits

- **Prerequisites:** The README builds with make. reference/ holds the original binaries from the cbmfiles.com version. make regress builds the bsw and wheels variants and compares them with those references.
- **Scope:** The README says this tree does not use the original encrypted loader and that the kernel is plaintext, matching the cbmfiles.com version it describes. It says the serial number 0x58B5 is pre-filled to match that version.
- **Testing evidence:** make regress is the comparison named in the README.
- **License:** The repository root has no LICENSE file. The README says the intellectual property added by the reverse-engineering and the subsequent improvements is in the public domain, asks to be credited, and says to respect the license of the underlying GEOS work.

## Primary sources

1. <https://github.com/mist64/geos/blob/617efdc7191eda14eaf699d317e66d5bda68c039/README.md>
2. <https://github.com/mist64/geos/blob/617efdc7191eda14eaf699d317e66d5bda68c039/regress.sh>
3. <https://github.com/mist64/geos/tree/617efdc7191eda14eaf699d317e66d5bda68c039/reference>

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## About this entry

The description was reviewed against primary sources.
Original editorial content: MIT. Linked projects, papers and assets retain their own rights and licenses.