\ncline[linestyle=dotted]{res}{idle}
-\ncarc[arcangle=20]{idle}{add}\ncput*[npos=.50]{\shortstack{do\_calc$\uparrow$\\opc == ADD}}
+\ncarc[arcangle=20]{idle}{add}\ncput*[npos=.50]{\shortstack{do\_calc$\uparrow$ \emph{\textbf{and}}\\opc = ADD}}
\ncarc[arcangle=20]{add}{idle}
-\ncarc[arcangle=20]{idle}{sub}\ncput*[npos=.50]{\shortstack{do\_calc$\uparrow$\\opc == SUB}}
+\ncarc[arcangle=20]{idle}{sub}\ncput*[npos=.50]{\shortstack{do\_calc$\uparrow$ \emph{\textbf{and}}\\opc = SUB}}
\ncarc[arcangle=20]{sub}{idle}
-\ncarc[arcangle=20]{idle}{mul}\ncput*[npos=.50]{\shortstack{do\_calc$\uparrow$\\opc == MUL}}
+\ncarc[arcangle=20]{idle}{mul}\ncput*[npos=.50]{\shortstack{do\_calc$\uparrow$ \emph{\textbf{and}}\\opc = MUL}}
\ncarc[arcangle=20]{mul}{idle}
-\ncarc[arcangle=20]{idle}{div}\ncput*[npos=.50]{\shortstack{do\_calc$\uparrow$\\opc == DIV}}
+\ncarc[arcangle=20]{idle}{div}\ncput*[npos=.50]{\shortstack{do\_calc$\uparrow$ \emph{\textbf{and}}\\opc = DIV}}
\ncarc[arcangle=20]{div}{idle}
\end{document}