An anonymous reader writes "id Software has a history of releasing the source code for their older games under the GPL. Coder Fabien Sanglard has been taking it upon himself to go through each of these releases, analyze the source code, and post a detailed write-up about it. He's now completed a review of the Quake 3 source code, diving into the details of idTech3. It's an interesting read — he says he was impressed in particular by the 'virtual machines system and the associated toolchain that altogether account for 30% of the code released. Under this perspective idTech3 is a mini operating system providing system calls to three processes.'"