Abstract: The present invention is directed to methods and circuits for testing open collector or open drain output pads. In a preferred embodiment, the open collector or open drain outputs are hard driven to both their normal low and high level logic states during a test mode of operation. By actively driving open collector or open drain output pads to both their active and their inactive states, the existence of a stable output at any given sample time is guaranteed during a functionality test. The need to accurately estimate time delays associated with RC loads of external circuitry and the need to precisely strobe an open collector or open drain output following transition to an inactive, disabled state are therefore eliminated. Further, control signal inputs associated with a high impedance condition of open collector or open drain output pads can be directly examined at the circuit output using appropriate test logic.

Abstract: The present invention is directed to providing a level of security on a chip which makes accessing stored data so burdensome that it is outweighed by the cost of merely purchasing the chip through conventional, legal avenues. In accordance with the present invention, secure data stored in a circuit cannot be accessed without destroying circuit operation, nor can the circuit be reverse engineered without significant time, cost and expense. For example, where the secure data stored on an ASIC includes a data encryption key, the key cannot be accessed or be modified to create a new key without destroying circuit operation.

Abstract: A video image is extracted and stored as a geometric figure by generating a binary pixel map of the image. The binary pixel map contains one bit for each pixel in the image, representative of the value of a characteristic feature of that pixel relative to a threshold range. A crack following algorithm locates the border of a group of contiguous pixels all having the same binary value. This border defines the boundaries of the scanned image. It is smoothed by a recursive adaption technique to generate one or more polygons related to the shape of the image.