+
+{\tt Alu1} is a ``one-input'' arithmetic logic unit. It includes
+logic for performing arithmetic operations on a single argument.
+Currently this includes
+negate ({\sc neg}),
+increment ({\sc inc}),
+decrement ({\sc dec}), and
+absolute value ({\sc abs}).
+
+\subsection*{Semantics}
+
+When a value is present at each of {\tt in} and {\tt inOp}, these two
+values are consumed. Based on the value consumed at {\tt inOp}, the
+requested operation is performed on the value consumed from {\tt in}.
+The result of this operation is then made available at {\tt out}.
+