[755-1] Point-to-point routing

[Konstantinos Dovrolis <dovrolis@cs.wisc.edu>]

At some point we mentioned the use of point-to-point routing
at a discussion session, without giving details on how
you can use it though. First, select the menu "Place and Route".
Then, select the "Pt-To-Pt" autorouting operation. This operation
allows you to "draw" a path just by specifying manually
a route with the mouse. The tool uses metal-1 for horizontal
lines, and metal-2 for vertical lines, and it automatically
places the vias whenever you switch from one metal layer to another.

If you want to use only metal-2, for example, select the "options"
menu, and in the "routing levels" specify only "2" (delete the "1"
routing level).

Point-to-point routing can save you a lot of time when you 
draw the final 19-bit adder interconnections.

C.