# Ultima IV: a matching Master System rebuild and PC port

> Rebuilds the Sega Master System version of Ultima IV: Quest of the Avatar from a disassembly and ports its routines to native C for PC. The ROM build is checked byte for byte against a user-supplied release, while shadow execution compares C rewrites with the original code's state and can also compare timing.

- Type: Case study
- Targets: Game
- Category: Independent reconstruction cases
- Relationship: Independent reconstruction project
- Sources reviewed: 2026-11-06
- Added to the catalog: 2026-11-09
- Original resource: <https://github.com/alexdia25/u4-sms-recompiled>
- Primary source: <https://github.com/alexdia25/u4-sms-recompiled/blob/38374090ab30305e14dfabc03991e3c3f0c98a76/README.md>
- Catalog page: <https://awesomerea.org/resources/ultima-iv-sms-recompiled-case/>
- Record JSON: <https://awesomerea.org/resources/ultima-iv-sms-recompiled-case/record.json>
- Chinese version: [简体中文](https://awesomerea.org/zh/resources/ultima-iv-sms-recompiled-case/index.md)

## Requirements & limits

- **Prerequisites:** A user-supplied 512 KB Europe/USA ROM with SHA1 a90e21e5961bcf2e10b715a009c04e7c2017a3b1.
- **Prerequisites:** Python 3, a POSIX shell and WLA-DX for the ROM build; Zig and SDL2 for the PC port.
- **Scope:** The PC build script targets 64-bit Windows.
- **License:** No licence file in the repository.

## Primary sources

1. <https://github.com/alexdia25/u4-sms-recompiled/blob/38374090ab30305e14dfabc03991e3c3f0c98a76/README.md>
2. <https://github.com/alexdia25/u4-sms-recompiled/blob/38374090ab30305e14dfabc03991e3c3f0c98a76/docs/architecture.md>

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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.