Abstract: An algorithm is disclosed to partition input variables between a feeder logic block and a receiver logic block. For a given input variable partition, the algorithm assigns both a cost to the number of product terms cascaded from the feeder logic block to the receiver logic block as well as a cost that increases as the number of input variables assigned to the receiver logic block approaches its maximum input width. The costs for a variety of input variable partitions are tested to determine an optimal input variable partition.

Abstract: A security tag includes a tag body and an attaching pin for attaching the tag body to a protected article. The security tag further includes a locking mechanism for releasably preventing the attaching pin from being removed from the protected article. The locking mechanism is provided for mechanically or magnetically released the attaching pin for detaching the tag body from the article. In a preferred embodiment, the locking mechanism further includes a plurality of balls for tightly holding to the attaching pin for releasably preventing the attaching means from being removed from the article. In a preferred embodiment, the locking mechanism further includes a mechanical unlocking probe finger for applying a mechanical force to release the balls from the attaching pin whereby the attaching pin may be released and detached from the tag body.

Abstract: A system and method for routing signals to function blocks of a programmable logic device (PLD) via an interconnect multiplexer (XMUX). All available paths from an interconnect multiplexer input resource to an interconnect multiplexer output resource are first identified. Signals are assigned to XMUX paths in order of number of fanouts to function blocks. The signal required by the most function blocks is assigned first. The costs of the XMUX paths relative to the signal to be assigned are determined, and the signal is assigned to the path having the least cost. The process is repeated until all the signals are assigned. A recovery method uses augmenting paths to assign signals if all the signals could not be assigned using least cost paths assignment.

Abstract: A method for programming complex programmable logic devices (CPLDs) to implement a logic function, whereby user-designated locked equations of the logic function are mapped into the macrocells of a function block, and then undesignated (non-locked) equations are mapped into the remaining macrocells. The method shifts product terms between the macrocells to adjust the placement arrangement of the mapped equations, thereby obtaining a placement arrangement which is both valid and meets user-defined timing constraints.

Abstract: An EPLD having improved routing and arithmetic function implementation characteristics. Cascade and carry logic in macrocells allows for simultaneous product term exporting to both previous and subsequent macrocells.

Abstract: A method for placing a logic function into the function blocks of a complex programmable logic device (CPLD) to maintain the same input/output pin locations after the logic function is subsequently modified by a user. The method utilizes a weighting function to assign portions of the logic function to the function blocks such that sufficient resources are available in each function block to implement subsequent modifications to the logic function without changing the originally-assigned input and output pin locations. For each portion of the logic function, the weighting function is employed to identify the function block which implements the portion while maximizing the available resources in all of the function blocks. If a particular equation cannot be placed, the method utilizes a corrective measure such as fitting refinement, buffering and logic reformation to place the equation.