| 摘要 |
PURPOSE:To form test data which takes a high impedance state into consideration by making prescribed operation by using the hexadecimal logical value expressed in the combination of normal circuits and fault circuits by introducing the high impedance state Z in addition to logical values 0, 1, X. CONSTITUTION:The element model of tri-state elements and truth table used in the D operation for the hexadecimal value (the operation to propagate fault information up to external output), C operation for the hexadecimal value (the operation to determine the logical value of the external input in order to obtain the logical values of the respective elements determined by the D operation) and X operation (the operation to make one of input lines X and all the remaining lines X in order to assure the averting of collision for all bus elements for which the output values of the normal circuits or fault circuits remain X) are constituted as shown in the figure. The test data for function tests in which the high impedance conditions in logical circuits is taken into consideration are obtd. in accordance with the providing truth table.
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