Abstract: A logic circuit generating method and apparatus generating logic circuits of a circuit system by minimizing the fan-out count of cells or cell macros constituting information specific to the circuit system. According to the method, a Boolean expression and the polarities of its input/output variables are input from a design master file of the apparatus. The Boolean expression is then transformed into a two-branch tree composed of nodes represented by the logical operators of that expression. In the two-branch tree, the nodes representing a parent and a child logical operator are converted into a single node, whereby a multiple-branch tree is generated. That is, a plurality of gates are connected to a single net, or signal line. A cell library is referenced so that cells are assigned initially to the multiple-branch tree thus obtained. The initial cell assignment is performed preferentially starting from the cell whose fan-out count is the largest.

Abstract: A logical operation method for evaluating a train of output data to be obtained when a plurality of input patterns are successively applied to a memory element whose output value depends upon a sequence of input values. For each of the plurality of patterns in time series, the method decides whether or not the pertinent pattern is a holding pattern which means that the output value of the memory element depends upon a preceding pattern. Subsequently, the method evaluates a first train of data which consists of flags each indicating whether or not the respective pattern is the holding pattern, and a second train of data which consist of a predetermined logical values for the holding patterns and output logical values of the memory element for the non-holding patterns. Finally, the method subjects the first and second trains of data to operations in parallel by the use of a parallel arithmetic unit, thereby obtaining the train of output data of the memory element in parallel.

Abstract: A logic circuit to be an object for fault simulation is logically modified into a logic circuit configuration using logic gates of a predetermined basic gate form. Pin management data indicative of a correspondence of pins of the logic gates to a position of fault assumption of each of the pins prior to logic modification is formed. Logic simulation is then performed by injecting a fault logic value into the position of fault assumption of each of the pins of the gate of the logic circuit subsequent to the logic modification corresponding to each of the pins prior to the logic modification with reference to the pin management data, thereby implementing a fault simulation for detecting the fault of the logic circuit.