Editing Spec.isa (section)

=== endianness ===
Defines the byte order of the instructions.
<pre>
endianness = big
endianness = little
</pre>
The default is big endian.

For example, if we have an instruction defined as <code>11110000 00001111</code> then:
* <code>big</code> endian will encode the instruction as <code>240 15</code>.
* <code>little</code> endian will encode the same instruction as <code>15 240</code>.
(as shown in, for example, the {{Component|ROM||alpha}} component)

{{note|type=info|The ROM component has it's own endianness flag, which can reverse the byte order again.  This is straightforward if your instruction width happens to match the ROM's bit width, but can be confusing if the widths differ.}}