The BSA file format stands for Bethesda Software Archive. It has was originally used by Bethesda for Morrowind and was first used in in the Fallout series for Fallout 3. It is a binary file which contains textures, meshes, and other resources the game depends on. Preliminary work indicates that they have been bumped up to version 68 over Bethesda's previous game The Elder Scrolls IV: Oblivion, which used version 67.
To open them with BSA Commander (Also see below) you have to do the following:
- Backup the original .bsa file
- Open the file in a hex editor
- Change byte 5 from 68 to 67
- Open in BSA Commander and extract the files
Another way is to use BSAUnpack, telling it to go on when it warns you about archive incompatibility
Fallout BSA Unpacker
A fallout specific unpacker has been released on www.fallout3nexus.com
- The packer requires Java and is multiplatform.
- Get the program here: FO3 Archive Utility