mirror of https://github.com/mre/mos6502.git
376 lines
8.6 KiB
HTML
376 lines
8.6 KiB
HTML
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
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"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
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<head>
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<title>6502Arch</title>
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<meta http-equiv="Content-Type" content="text/html;charset=utf-8"/>
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<meta name="title" content="6502Arch"/>
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<meta name="generator" content="Org-mode"/>
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<meta name="generated" content="2014-09-25T21:09-0400"/>
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<meta name="author" content="Alex Weisberger"/>
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<meta name="description" content=""/>
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<meta name="keywords" content=""/>
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<style type="text/css">
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<script type="text/javascript">
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/*
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@licstart The following is the entire license notice for the
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JavaScript code in this tag.
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Copyright (C) 2012-2013 Free Software Foundation, Inc.
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The JavaScript code in this tag is free software: you can
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redistribute it and/or modify it under the terms of the GNU
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General Public License (GNU GPL) as published by the Free Software
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Foundation, either version 3 of the License, or (at your option)
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any later version. The code is distributed WITHOUT ANY WARRANTY;
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without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU GPL for more details.
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As additional permission under GNU GPL version 3 section 7, you
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may distribute non-source (e.g., minimized or compacted) forms of
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that code without the copy of the GNU GPL normally required by
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section 4, provided you include this license notice and a URL
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through which recipients can access the Corresponding Source.
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@licend The above is the entire license notice
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for the JavaScript code in this tag.
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/*]]>*///-->
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</script>
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</head>
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<body>
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<div id="preamble">
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</div>
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<div id="content">
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<h1 class="title">6502Arch</h1>
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<div id="table-of-contents">
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<h2>Table of Contents</h2>
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<div id="text-table-of-contents">
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<ul>
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<li><a href="#sec-1">1 Addressing modes</a>
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<ul>
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<li><a href="#sec-1-1">1.1 Absolute</a></li>
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<li><a href="#sec-1-2">1.2 Zero-page</a></li>
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<li><a href="#sec-1-3">1.3 Zero-page, X</a></li>
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<li><a href="#sec-1-4">1.4 Zero-page, Y</a></li>
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<li><a href="#sec-1-5">1.5 Immediate</a></li>
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<li><a href="#sec-1-6">1.6 Relative</a></li>
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<li><a href="#sec-1-7">1.7 Implicit</a></li>
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<li><a href="#sec-1-8">1.8 Indirect</a></li>
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<li><a href="#sec-1-9">1.9 Indexed Indirect</a></li>
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<li><a href="#sec-1-10">1.10 Indirect Indexed</a></li>
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</ul>
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</li>
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<li><a href="#sec-2">2 Stack</a></li>
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<li><a href="#sec-3">3 Jumping</a></li>
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</ul>
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</div>
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</div>
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<div id="outline-container-1" class="outline-2">
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<h2 id="sec-1"><span class="section-number-2">1</span> Addressing modes</h2>
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<div class="outline-text-2" id="text-1">
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<p>
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has a 16-byte address bus.
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</p>
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</div>
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<div id="outline-container-1-1" class="outline-3">
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<h3 id="sec-1-1"><span class="section-number-3">1.1</span> Absolute</h3>
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<div class="outline-text-3" id="text-1-1">
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<ul>
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<li>Full memory location specified, i.e. $c000
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</li>
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<li>65536 bytes of addressable memory (2<sup>16</sup> duyyy)
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</li>
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</ul>
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</div>
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</div>
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<div id="outline-container-1-2" class="outline-3">
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<h3 id="sec-1-2"><span class="section-number-3">1.2</span> Zero-page</h3>
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<div class="outline-text-3" id="text-1-2">
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<ul>
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<li>1 byte adress, i.e. $c0, 256 bytes adressable
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</li>
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<li>faster, takes less program space
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</li>
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</ul>
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</div>
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</div>
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<div id="outline-container-1-3" class="outline-3">
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<h3 id="sec-1-3"><span class="section-number-3">1.3</span> Zero-page, X</h3>
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<div class="outline-text-3" id="text-1-3">
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<ul>
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<li>Relative adressing <span style="text-decoration:underline;">within</span> the zero page.
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</li>
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<li>Adds the value in reg. x with a 1-byte adress
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</li>
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<li>i.e. STA $a0, X
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</li>
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<li>Address wraps around if the addition is larger than 1 byte
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</li>
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</ul>
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</div>
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</div>
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<div id="outline-container-1-4" class="outline-3">
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<h3 id="sec-1-4"><span class="section-number-3">1.4</span> Zero-page, Y</h3>
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<div class="outline-text-3" id="text-1-4">
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<ul>
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<li>equiv to zero-page, X but can only be used with LDX and STX
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</li>
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</ul>
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</div>
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</div>
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<div id="outline-container-1-5" class="outline-3">
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<h3 id="sec-1-5"><span class="section-number-3">1.5</span> Immediate</h3>
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<div class="outline-text-3" id="text-1-5">
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<ul>
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<li>i.e. #$c0
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</li>
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<li>loads immedate number into register
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</li>
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</ul>
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</div>
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</div>
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<div id="outline-container-1-6" class="outline-3">
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<h3 id="sec-1-6"><span class="section-number-3">1.6</span> Relative</h3>
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<div class="outline-text-3" id="text-1-6">
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<ul>
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<li>i.e. $c0, or label
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</li>
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</ul>
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</div>
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</div>
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<div id="outline-container-1-7" class="outline-3">
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<h3 id="sec-1-7"><span class="section-number-3">1.7</span> Implicit</h3>
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<div class="outline-text-3" id="text-1-7">
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<ul>
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<li>when operation doesn't deal with memory
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</li>
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</ul>
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</div>
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</div>
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<div id="outline-container-1-8" class="outline-3">
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<h3 id="sec-1-8"><span class="section-number-3">1.8</span> Indirect</h3>
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<div class="outline-text-3" id="text-1-8">
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<ul>
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<li>Uses absolute address to get another address
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</li>
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<li>first address is LSB of address, following byte is MSB
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</li>
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</ul>
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</div>
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</div>
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<div id="outline-container-1-9" class="outline-3">
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<h3 id="sec-1-9"><span class="section-number-3">1.9</span> Indexed Indirect</h3>
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<div class="outline-text-3" id="text-1-9">
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<ul>
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<li>i.e. LDA ($c0, X)
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</li>
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<li>Take a zero page adress and add the value in reg. x to it, look up 2 byte address
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</li>
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</ul>
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</div>
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</div>
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<div id="outline-container-1-10" class="outline-3">
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<h3 id="sec-1-10"><span class="section-number-3">1.10</span> Indirect Indexed</h3>
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<div class="outline-text-3" id="text-1-10">
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<ul>
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<li>zero page address dereferenced then Y is added to it
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</li>
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</ul>
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</div>
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</div>
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</div>
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<div id="outline-container-2" class="outline-2">
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<h2 id="sec-2"><span class="section-number-2">2</span> Stack</h2>
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<div class="outline-text-2" id="text-2">
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<ul>
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<li>lives in memory between $0100 and $01ff
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</li>
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</ul>
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</div>
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</div>
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<div id="outline-container-3" class="outline-2">
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<h2 id="sec-3"><span class="section-number-2">3</span> Jumping</h2>
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<div class="outline-text-2" id="text-3">
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<ul>
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<li>JSR/RTS: Jump to subroutine and return from subroutine
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</li>
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</ul>
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</div>
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</div>
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</div>
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<div id="postamble">
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<p class="date">Date: 2014-09-25T21:09-0400</p>
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<p class="author">Author: Alex Weisberger</p>
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<p class="creator"><a href="http://orgmode.org">Org</a> version 7.9.3f with <a href="http://www.gnu.org/software/emacs/">Emacs</a> version 24</p>
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<a href="http://validator.w3.org/check?uri=referer">Validate XHTML 1.0</a>
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</div>
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</body>
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</html>
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