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66Next: <a href="Object-Formats.html#Object-Formats" accesskey="n" rel="next">Object Formats</a>, Previous: <a href="Manual.html#Manual" accesskey="p" rel="previous">Manual</a>, Up: <a href="Overview.html#Overview" accesskey="u" rel="up">Overview</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p>
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69<a name="The-GNU-Assembler"></a>
70<h3 class="section">1.2 The GNU Assembler</h3>
71
72
73<p><small>GNU</small> <code>as</code> is really a family of assemblers.
74If you use (or have used) the <small>GNU</small> assembler on one architecture, you
75should find a fairly similar environment when you use it on another
76architecture.  Each version has much in common with the others,
77including object file formats, most assembler directives (often called
78<em>pseudo-ops</em>) and assembler syntax.
79</p>
80<a name="index-purpose-of-GNU-assembler"></a>
81<p><code>as</code> is primarily intended to assemble the output of the
82<small>GNU</small> C compiler <code>gcc</code> for use by the linker
83<code>ld</code>.  Nevertheless, we&rsquo;ve tried to make <code>as</code>
84assemble correctly everything that other assemblers for the same
85machine would assemble.
86Any exceptions are documented explicitly (see <a href="Machine-Dependencies.html#Machine-Dependencies">Machine Dependencies</a>).
87This doesn&rsquo;t mean <code>as</code> always uses the same syntax as another
88assembler for the same architecture; for example, we know of several
89incompatible versions of 680x0 assembly language syntax.
90</p>
91
92<p>Unlike older assemblers, <code>as</code> is designed to assemble a source
93program in one pass of the source file.  This has a subtle impact on the
94<kbd>.org</kbd> directive (see <a href="Org.html#Org"><code>.org</code></a>).
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