# Ultima IV: near-matching reconstruction of its DOS executables

> Ultima IV decompiled reconstructs the PC game's AVATAR.EXE and TITLE.EXE as C and assembly source. The author reports that compiling and linking the recovered files with Microsoft C Compiler 4.00 produces executables about ten bytes different from each original.

- Type: Case study
- Targets: Binary · 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/ergonomy-joe/u4-decompiled>
- Primary source: <https://github.com/ergonomy-joe/u4-decompiled/blob/2185af4414ddc13ebb0fb9ab84526b28f9158a81/README.md>
- Catalog page: <https://awesomerea.org/resources/ultima-iv-decompiled-case/>
- Record JSON: <https://awesomerea.org/resources/ultima-iv-decompiled-case/record.json>
- Chinese version: [简体中文](https://awesomerea.org/zh/resources/ultima-iv-decompiled-case/index.md)

## Requirements & limits

- **Prerequisites:** Rebuilding uses Microsoft C Compiler 4.00.
- **Testing evidence:** The author reports roughly ten bytes of difference per rebuilt executable.
- **Limits:** Only CGA.DRV was reversed among the separate graphics drivers.
- **License:** No licence file in the repository.

## Primary sources

1. <https://github.com/ergonomy-joe/u4-decompiled/blob/2185af4414ddc13ebb0fb9ab84526b28f9158a81/README.md>

## More in Games

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- [UNO!: a Game Boy Color disassembly](https://awesomerea.org/resources/uno-game-boy-color-disassembly-case/index.md) · Case study
- [Valkyrie Profile: a partial matching PlayStation decompilation](https://awesomerea.org/resources/valkyrie-profile-decomp-case/index.md) · Case study
- [Warblade Service Release: decompiling Warblade 1.34 and replacing PTK with SDL](https://awesomerea.org/resources/warblade-service-release-case/index.md) · Case study
- [Wario Land 4: a matching US/EU and Japanese GBA decompilation](https://awesomerea.org/resources/tsilaallaoui-warioland4-case/index.md) · Case study
- [Wario Land 4: rebuilding US/EU and Japanese GBA ROMs](https://awesomerea.org/resources/wario-land-4-decomp-case/index.md) · Case study

## 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.