Hitachi, Ltd.

Hitachi Computer Engineering Co., Ltd.

Mitsuru Morikuni

Kenji Matsumoto

Tomoatsu Yanagita

Masahiko Nagai

Yoshinori Nishiyama

A signal line terminal allocation method includes an electronic device which is hierarchically designed to obtain terminal allocations which satisfy electrical restrictive conditions. The electronic device includes high hierarchial components and low hierarchial components; the high hierarchial components are connected to the low hierarchical components by a plurality of signal lines through a plurality of signal line terminals. The method including the steps of: 1) obtaining all the different combinations of an allocation of the signal lines to the signal line terminals; 2) calculating a plurality of signal line lengths for all the different combinations, each of the plurality of signal line lengths corresponding to a sum of the line lengths of each of the signal lines in the allocation; and 3) selecting the combinations of allocation of signal lines in which electrical restrictions corresponding to each of the plurality of signal lines are satisfied, the electrical restrictions including the maximum line length. The above method includes groups of plural signal lines of both high and low hierarchial components.

Signal line terminal allocation method

A load distribution method in which loads are divided into groups and each of a plurality of input pins of integrated circuits of a load is wired continuously with one stroke of a signal transmission line in a sequence from a driving output pin in each group when the wiring for distributing the drive signal from the driving output pin of an integrated circuit to plural input pins of integrated circuits, functioning as a load, is such that a plurality of intergrated circuits are mounted at given positions on a printed circuit board. In the load distribution method, the load is divided into groups by equally distributing a number of the loads so as to allow load capacities to be equal to each other on each of a plurality of signal transmission lines, and there is computed a signal propagation delay time of the signal transmission line wired equally in a distance to a load which is equal in a wiring sequence from the driving output pin in each group. Also, the loads are grouped by determining a combination of loads in which the signal propagation delay time of the signal transmission line becomes the shortest.

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Ebina, Japan

Mitsuru Morikuni