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<h3 class="section">1.2 The GNU Assembler</h3>
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<p><span class="sc">gnu</span> <samp><span class="command">as</span></samp> is really a family of assemblers.
If you use (or have used) the <span class="sc">gnu</span> 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
<dfn>pseudo-ops</dfn>) and assembler syntax.
<p><a name="index-purpose-of-_0040sc_007bgnu_007d-assembler-23"></a><samp><span class="command">as</span></samp> is primarily intended to assemble the output of the
<span class="sc">gnu</span> C compiler <code>gcc</code> for use by the linker
<code>ld</code>. Nevertheless, we've tried to make <samp><span class="command">as</span></samp>
assemble correctly everything that other assemblers for the same
machine would assemble.
Any exceptions are documented explicitly (see <a href="Machine-Dependencies.html#Machine-Dependencies">Machine Dependencies</a>).
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This doesn't mean <samp><span class="command">as</span></samp> 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.
<!-- man end -->
<p>Unlike older assemblers, <samp><span class="command">as</span></samp> is designed to assemble a source
program in one pass of the source file. This has a subtle impact on the
<kbd>.org</kbd> directive (see <a href="Org.html#Org"><code>.org</code></a>).
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