Uh, microcode has been around since the 1960&#x27;s!<p>Any aspect of the machine which is data-driven is <i>de facto</i> hardware if that data is fixed in read-only memory.<p>Consider than an AND gate can just be memory. The two inputs can be treated as a two bit address: 00, 01, 10, or 11.  If we stuff in the values 0, 0, 0, 1 into the 1-bit content cells at these addresses, we have an AND gate.<p>If this memory is ROM, then the overall circuit is not distinguishable from a conventional AND gate where a few transistors do the signaling directly.