Gas: The Gnu as Assembler

Gas (actually, "as") is Gnu's portable assembler. Although this assembler was written specifically to process GCC output, many programmers use Gas as an assembly language development (on the x86, the ability to use Gas was greatly enhanced by the addition of the ".intel_syntax" directive). Though Gas tends to use a very different syntax than most people are used to, if you've done assembly programming using "AT&T" syntax on a different assembler, you'll feel right at home with Gas.

You may download Gas from any large number of sites worldwide. It is part of the GNU "binutils" package. Those wanting to use the ".intel_syntax" directive will need to download version 2.10 or later.

GNU
Official Download Site
http://www.fsf.org
GNU Documentation
Documentation for Gas
GNU Profiler documentation gprof_toc.html
Jonathon Bartlett's "Programming From the Ground Up", featuring Gas PgmGndUp