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<title>Using as: PDP-11-Syntax</title>
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<a name="PDP_002d11_002dSyntax"></a>
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Next: <a href="PDP_002d11_002dMnemonics.html#PDP_002d11_002dMnemonics" accesskey="n" rel="next">PDP-11-Mnemonics</a>, Previous: <a href="PDP_002d11_002dPseudos.html#PDP_002d11_002dPseudos" accesskey="p" rel="prev">PDP-11-Pseudos</a>, Up: <a href="PDP_002d11_002dDependent.html#PDP_002d11_002dDependent" accesskey="u" rel="up">PDP-11-Dependent</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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<a name="PDP_002d11-Assembly-Language-Syntax"></a>
<h4 class="subsection">9.32.3 PDP-11 Assembly Language Syntax</h4>
<a name="index-PDP_002d11-syntax"></a>
<a name="index-DEC-syntax"></a>
<a name="index-BSD-syntax"></a>
<p><code>as</code> supports both DEC syntax and BSD syntax. The only
difference is that in DEC syntax, a <code>#</code> character is used to denote
an immediate constants, while in BSD syntax the character for this
purpose is <code>$</code>.
</p>
<a name="index-PDP_002d11-general_002dpurpose-register-syntax"></a>
<p>general-purpose registers are named <code>r0</code> through <code>r7</code>.
Mnemonic alternatives for <code>r6</code> and <code>r7</code> are <code>sp</code> and
<code>pc</code>, respectively.
</p>
<a name="index-PDP_002d11-floating_002dpoint-register-syntax"></a>
<p>Floating-point registers are named <code>ac0</code> through <code>ac3</code>, or
alternatively <code>fr0</code> through <code>fr3</code>.
</p>
<a name="index-PDP_002d11-comments"></a>
<p>Comments are started with a <code>#</code> or a <code>/</code> character, and extend
to the end of the line. (FIXME: clash with immediates?)
</p>
<a name="index-PDP_002d11-line-separator"></a>
<p>Multiple statements on the same line can be separated by the &lsquo;<samp>;</samp>&rsquo; character.
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