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<a name="AMD64-ISA-vs_002e-Intel64-ISA"></a>
<h4 class="subsection">9.16.16 AMD64 ISA vs. Intel64 ISA</h4>

<p>There are some discrepancies between AMD64 and Intel64 ISAs.
</p>
<ul>
<li> For &lsquo;<samp>movsxd</samp>&rsquo; with 16-bit destination register, AMD64
supports 32-bit source operand and Intel64 supports 16-bit source
operand.

</li><li> For far branches (with explicit memory operand), both ISAs support
32- and 16-bit operand size.  Intel64 additionally supports 64-bit
operand size, encoded as &lsquo;<samp>ljmpq</samp>&rsquo; and &lsquo;<samp>lcallq</samp>&rsquo; in AT&amp;T syntax
and with an explicit &lsquo;<samp>tbyte ptr</samp>&rsquo; operand size specifier in Intel
syntax.

</li><li> &lsquo;<samp>lfs</samp>&rsquo;, &lsquo;<samp>lgs</samp>&rsquo;, and &lsquo;<samp>lss</samp>&rsquo; similarly allow for 16-
and 32-bit operand size (32- and 48-bit memory operand) in both ISAs,
while Intel64 additionally supports 64-bit operand sise (80-bit memory
operands).

</li></ul>


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