as, the GNU Assembler
=====================

   GNU `as' is really a family of assemblers.  If you use (or have
used) the GNU assembler on one architecture, you should find a fairly
similar environment when you use it on another architecture.  Each
version has much in common with the others, including object file
formats, most assembler directives (often called "pseudo-ops)" and
assembler syntax.

   `as' is primarily intended to assemble the output of the GNU C
compiler `gcc' for use by the linker `ld'.  Nevertheless, we've tried
to make `as' assemble correctly everything that the native assembler
would.  Any exceptions are documented explicitly (*note Machine
Dependent::.).  This doesn't mean `as' always uses the same syntax as
another assembler for the same architecture; for example, we know of
several incompatible versions of 680x0 assembly language syntax.

   Unlike older assemblers, `as' is designed to assemble a source
program in one pass of the source file.  This has a subtle impact on the
`.org' directive (see `.org': Org.).