Abstract: A circuit architecture for driving a tri-state bus in a logic circuit that uses a built-in self-test (BIST) mechanism. The architecture includes tri-state drivers which have circuitry to inhibit other drivers from driving the bus when another driver is driving the bus. The architecture includes circuitry to pullup the bus or to allow the bus to retain the last state it was driven to when none of the drivers is driving the bus. This circuitry also drives the bus to a known state during testing of the logic circuit.

Abstract: A process for implementing logic units using base cells and implementing an electrical connection between the logic units in a gate array. The process includes determining a connection path between the base cells and connecting the base cells at the second metalization layer using a portion of the first metalization layer. This is possible due to the gate array having vertical first metalization layer segments of the first metalization layer positioned vertically in the channel between the rows of base cells, wherein each of the vertical segments has vias in the insulation layer between the first metalization layer and the second metalization layer at its endpoints for connecting the metalization layers. Similarly, the individual transistors which comprise the base cell are coupled using the second metalization layer to implement a specific logic unit.