Abstract: In one embodiment, a method for specifying addressability in a memory-mapped device is disclosed. A data access primitive is used to model addressablity for the memory-mapped device. Addressability comprises an address matching function, a lane matching function and one or more bus connections. A first starting address for the memory-mapped device is specified. A first set of addressing matching function, lane matching function and one or more bus connections for the memory-mapped device is generated using the data access primitive and the first starting address.

Abstract: The I/O circuit of the present invention provides optimal flexibility and performance using a number of different structures and methods. The present invention provides a signal follower circuit for an input pad. In one embodiment, the output buffer is capable of injecting a constant onto a pad during reconfiguration of a configurable system logic circuit. The present invention also provides a circuit for generating a programmable data propagation delay, thereby guaranteeing zero hold time for an arbitrary input register. Zero hold time is accomplished by allowing the user to optimally characterize clock delay to a given input/output circuit. The present invention also provides fast switching between input pads, thereby minimizing data propagation delay between the input pads. Additionally, the present invention reduces time spent in production product test by facilitating the testing of multiple routes with one test configuration.