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<title>Using as: Z80 Opcodes</title>

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<a name="Z80-Opcodes"></a>
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<p>
Previous: <a href="Z80-Directives.html#Z80-Directives" accesskey="p" rel="prev">Z80 Directives</a>, Up: <a href="Z80_002dDependent.html#Z80_002dDependent" accesskey="u" rel="up">Z80-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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<hr>
<a name="Opcodes-21"></a>
<h4 class="subsection">9.54.5 Opcodes</h4>
<p>In line with common practice, Z80 mnemonics are used for both the Z80 and
the R800.
</p>
<p>In many instructions it is possible to use one of the half index
registers (&lsquo;<samp>ixl</samp>&rsquo;,&lsquo;<samp>ixh</samp>&rsquo;,&lsquo;<samp>iyl</samp>&rsquo;,&lsquo;<samp>iyh</samp>&rsquo;) in stead of an
8-bit general purpose register. This yields instructions that are
documented on the R800 and undocumented on the Z80.
Similarly <code>in f,(c)</code> is documented on the R800 and undocumented on
the Z80.
</p>
<p>The assembler also supports the following undocumented Z80-instructions,
that have not been adopted in the R800 instruction set:
</p><dl compact="compact">
<dt><code>out (c),0</code></dt>
<dd><p>Sends zero to the port pointed to by register c.
</p>
</dd>
<dt><code>sli <var>m</var></code></dt>
<dd><p>Equivalent to <code><var>m</var> = (<var>m</var>&lt;&lt;1)+1</code>, the operand <var>m</var> can
be any operand that is valid for &lsquo;<samp>sla</samp>&rsquo;. One can use &lsquo;<samp>sll</samp>&rsquo; as a
synonym for &lsquo;<samp>sli</samp>&rsquo;.
</p>
</dd>
<dt><code><var>op</var> (ix+<var>d</var>), <var>r</var></code></dt>
<dd><p>This is equivalent to
</p>
<div class="example">
<pre class="example">ld <var>r</var>, (ix+<var>d</var>)
<var>opc</var> <var>r</var>
ld (ix+<var>d</var>), <var>r</var>
</pre></div>

<p>The operation &lsquo;<samp><var>opc</var></samp>&rsquo; may be any of &lsquo;<samp>res <var>b</var>,</samp>&rsquo;,
&lsquo;<samp>set <var>b</var>,</samp>&rsquo;, &lsquo;<samp>rl</samp>&rsquo;, &lsquo;<samp>rlc</samp>&rsquo;, &lsquo;<samp>rr</samp>&rsquo;, &lsquo;<samp>rrc</samp>&rsquo;,
&lsquo;<samp>sla</samp>&rsquo;, &lsquo;<samp>sli</samp>&rsquo;, &lsquo;<samp>sra</samp>&rsquo; and &lsquo;<samp>srl</samp>&rsquo;, and the register
&lsquo;<samp><var>r</var></samp>&rsquo; may be any of &lsquo;<samp>a</samp>&rsquo;, &lsquo;<samp>b</samp>&rsquo;, &lsquo;<samp>c</samp>&rsquo;, &lsquo;<samp>d</samp>&rsquo;,
&lsquo;<samp>e</samp>&rsquo;, &lsquo;<samp>h</samp>&rsquo; and &lsquo;<samp>l</samp>&rsquo;.
</p>
</dd>
<dt><code><var>opc</var> (iy+<var>d</var>), <var>r</var></code></dt>
<dd><p>As above, but with &lsquo;<samp>iy</samp>&rsquo; instead of &lsquo;<samp>ix</samp>&rsquo;.
</p></dd>
</dl>

<p>The web site at <a href="http://www.z80.info">http://www.z80.info</a> is a good starting place to
find more information on programming the Z80.
</p>


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