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# Discrete Wire Routing Method

IP.com Disclosure Number: IPCOM000081864D
Original Publication Date: 1974-Aug-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 17K

IBM

## Related People

Sanborn, MA: AUTHOR

## Abstract

This method considers the congestion resulting from discrete wiring installed on computer packages caused by engineering changes, repairs of printed circuitry, etc. Specifically, it considers the case where the wires are forced to lie in orthogonal channels rather than point-to-point. To some extent, the routing of wires can be chosen to avoid areas congested with wires already placed on the package.

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Discrete Wire Routing Method

This method considers the congestion resulting from discrete wiring installed on computer packages caused by engineering changes, repairs of printed circuitry, etc. Specifically, it considers the case where the wires are forced to lie in orthogonal channels rather than point-to-point. To some extent, the routing of wires can be chosen to avoid areas congested with wires already placed on the package.

The routing of a wire is a sequence of streets and avenues. The list of wires is presorted according to some desirable criteria and then routed one at a time.

It has been found that an effective way of reducing congestion is to presort the list of wires according to the number of ways in which a wire can be routed. Thus, the wires with the most freedom of path are placed last. Considering that the two end points of a wire are fixed and that between these two points there are l channels in the x direction and m channels in the y direction, then the number of ways w in which this wire can be routed is:.

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The number w thus calculated is the criteria used in presorting the list before placement. Only the shortest-path routing is considered in this formula.

In one application of the method, as each wire was routed, a running list was kept of all of the possible routings for that wire which were acceptable from a congestion standpoint. As additional wires were placed, the routing of all previous wires were re-examined, to elimina...