Abstract: An integrated circuit (10) comprises a functional circuit (12a-c) that contain information that must be secured against unauthorized access. The integrated circuit comprises a test access circuit (14, 16) coupled to the functional circuit (12a-c), and a plurality of fuse elements (18) coupled to the test access circuit (14, 16). The fuse elements (18) are connected in a circuit configuration that makes the functional circuit (12a-c) consistently accessible via the test access circuit (14, 16) only when first fuse elements (18) of the plurality are in a blown state and second fuse elements (18) of the plurality are in a not-blown state. As a result the integrated circuit can be tested after selectively blowing all of the first fuse elements (18). After testing at least part of the second fuse elements (18) is blown.

Abstract: An integrated circuit comprises a scan chain with parallel inputs and outputs coupled to a functional circuit. A scan chain modifying circuit is provided coupled to the scan chain. When testing is authorized the scan chain modifying circuit operates in a mode wherein a normal shift path is provided through the scan chain. When testing is not authorized the scan chain modifying circuit operates to effect spontaneous dynamic changes in the shift path, which dynamically vary the length of the shift path between external terminals of the integrated circuit while shifting takes place. In an embodiment the dynamical variations are controlled by a running key comparison. In other embodiments running key comparison is used to disable transfer through the scan chain or operation of functional circuits.

Abstract: An electronic circuit has a data producing circuit (12), such as a matrix of memory cells. A capture circuit (14) has e an input coupled to the data producing circuit (10) for capturing the data signals after allowing a selected part of the data producing circuit to drive the input of the capture circuit. An error detection circuit (15) detects errors in the captured data signals. In response to detection of an error in particular data signals, the error detection circuit causes recapture of the particular data signals, allowing the data producing circuit (10) to drive the data signals at the input of the capture circuit (14) during a second time interval until recapture, the second time interval having a longer duration than the first time interval. This makes it possible to select the duration of the first time interval allowing for average driving speed of circuit parts (e.g. memory cells), without using a duration designed to account for worst case driving speed that may occur due to spread.

Abstract: With respect to a particular facility semaphore-based synchronizing is executed among a first station and one or more second stations. For each station a single bivalent semaphore is provided. The first station checks all second station semaphores as having a second state relative to its own semaphore's first state. It then executes a first accessing operation and flips the first state. Otherwise it foregoes the first accessing operation. Any second station checks the first station semaphore as having the second state relative to its own semaphore's second state. It then executes a second accessing operation an d flips the latter state. Otherwise it foregoes the second accessing operation.

Abstract: Method and System For Synchronizing Block-Organized Data Transfer Amongst a Plurality of Producer and Consumer Stations. With respect to a particular facility semaphore-based synchronizing is executed among a first station and one or more second stations. For each station a single bivalent semaphore is provided. The first station checks all second station semaphores as having a second state relative to its own semaphore's first state. It then executes a first accessing operation and flips the first state. Otherwise it foregoes the first accessing operation. Any second station checks the first station semaphore as having the second state relative to its own semaphore's second state. It then executes a second accessing operation and flips the latter state. Otherwise it foregoes the second accessing operation.