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71 lines
3.4 KiB
HTML
71 lines
3.4 KiB
HTML
4 years ago
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<title>PDP-11-Syntax - Using as</title>
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<meta name="description" content="Using as">
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<link title="Top" rel="start" href="index.html#Top">
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<link rel="up" href="PDP_002d11_002dDependent.html#PDP_002d11_002dDependent" title="PDP-11-Dependent">
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<link rel="prev" href="PDP_002d11_002dPseudos.html#PDP_002d11_002dPseudos" title="PDP-11-Pseudos">
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<link rel="next" href="PDP_002d11_002dMnemonics.html#PDP_002d11_002dMnemonics" title="PDP-11-Mnemonics">
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<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
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<!--
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This file documents the GNU Assembler "as".
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Copyright (C) 1991-2015 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3
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or any later version published by the Free Software Foundation;
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with no Invariant Sections, with no Front-Cover Texts, and with no
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Back-Cover Texts. A copy of the license is included in the
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section entitled ``GNU Free Documentation License''.
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</head>
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<body>
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<div class="node">
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<a name="PDP-11-Syntax"></a>
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<a name="PDP_002d11_002dSyntax"></a>
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<p>
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Next: <a rel="next" accesskey="n" href="PDP_002d11_002dMnemonics.html#PDP_002d11_002dMnemonics">PDP-11-Mnemonics</a>,
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Previous: <a rel="previous" accesskey="p" href="PDP_002d11_002dPseudos.html#PDP_002d11_002dPseudos">PDP-11-Pseudos</a>,
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Up: <a rel="up" accesskey="u" href="PDP_002d11_002dDependent.html#PDP_002d11_002dDependent">PDP-11-Dependent</a>
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<hr>
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</div>
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<h4 class="subsection">9.33.3 PDP-11 Assembly Language Syntax</h4>
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<p><a name="index-PDP_002d11-syntax-1797"></a>
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<a name="index-DEC-syntax-1798"></a><a name="index-BSD-syntax-1799"></a><code>as</code> supports both DEC syntax and BSD syntax. The only
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difference is that in DEC syntax, a <code>#</code> character is used to denote
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an immediate constants, while in BSD syntax the character for this
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purpose is <code>$</code>.
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<p><a name="index-PDP_002d11-general_002dpurpose-register-syntax-1800"></a>general-purpose registers are named <code>r0</code> through <code>r7</code>.
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Mnemonic alternatives for <code>r6</code> and <code>r7</code> are <code>sp</code> and
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<code>pc</code>, respectively.
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<p><a name="index-PDP_002d11-floating_002dpoint-register-syntax-1801"></a>Floating-point registers are named <code>ac0</code> through <code>ac3</code>, or
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alternatively <code>fr0</code> through <code>fr3</code>.
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<p><a name="index-PDP_002d11-comments-1802"></a>Comments are started with a <code>#</code> or a <code>/</code> character, and extend
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to the end of the line. (FIXME: clash with immediates?)
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<p><a name="index-PDP_002d11-line-separator-1803"></a>Multiple statements on the same line can be separated by the ‘<samp><span class="samp">;</span></samp>’ character.
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</body></html>
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