ASZ is a file extension that was used by a tool called LoseThos. It is an operating system designed to run on x86 and x64 hardware platforms. Its author is Terry A. Davis. The main assumption of this project was experimenting with the system by the programmers as they had the power to modify the system kernel.

ASZ are files that were used to store source code written in a low-level programming language called assembler. It is often said to be machine code because the instructions of this language refer directly to the registers of the processor. ASZ is a text file.