Where does at&t assembly syntax come from?

Intel makes microprocessor, so he could define the instruction format and its corresponse assembly of its processors,so why AT&T could also create开发者_如何学C its syntax of assembly language?

thanks.

This google book link (Assembly Language Step-by-Step: Programming with Linux By Jeff Duntemann p. 444) matches what I would have guessed: that AT&T developed the syntax for use on a number of different platforms.

AT&T played a major role in the history of computers. AT&T (Bell Labs) was the source of Unix, the C programming language, and many other fundamental tools that we continue to use today.