The routing tool contains a number of different subsystems for creating wires. Two stitching routers can be used in array-based design to connect adjoining cells. A maze-router runs individual wires. A river-router is available for running multiple parallel wires. Finally, the sea-of-gates router handles many wires in arbitrary connection situations.

All of the non-stitching routers make use of the "Unrouted Arc", a thin-line arc that can connect any two components. Creating "rats nests" of these arcs forms a graphical specification that the router can use. The unrouted arc is from the Generic Technology (see Section 7-6-3). To create one, use the Get Unrouted Wire command (in menu Tools / Routing). Then use standard wiring commands to run the unrouted arc. Another way to get unrouted wires is to select all or part of an existing route (made with any arc) and use the Unroute command.
Figure 9.63

Another way to get Unrouted arcs for router input is to use the Copy Routing Topology and Paste Routing Topology commands. These copy the network topology from one cell (the "copied" cell) to another cell (the "pasted" cell). The copied cell should be properly routed. The Paste Routing Topology command uses node and arc names to associate the two cells.

The Routing Preferences (in menu File / Preferences..., "Tools" section, "Routing" tab) controls all of the different routers. The section in the upper-left applies to the two stitching routers (Mimic and Auto). Specific sections apply to specific routers (see Section 9-6-3 for the Mimic Stitcher, Section 9-6-2 for the Auto Stitcher, and Section 9-6-6 for the Sea-of-Gates router).

Figure 9.5