METHOD FOR DESIGNING APPLICATION SPECIFIC INTEGRATED CIRCUITS

An ASIC design methodology in which portions of the ASIC are implemented in silicon or other suitable semiconductor technology at an early stage in the design flow through the use of a series of interim devices. The invention provides a method in which additional portions or subsystems of the integrated circuit are incorporated into successive versions of the interim device. In this manner, the invention provides for the gradual incorporation of a plurality of architectural subsystems into the integrated device such that the synthesis and verification of each iteration is broken into manageable pieces. In the preferred embodiment, this design method is facilitated by incorporating a programmable portion into the design flow of each interim device such that each interim device includes a custom portion into which the subsystems that have been implemented in silicon are fabricated and a programmable portion. The programmable portion is useful in permitting the designer to make modifications to the subsystems implemented in the custom portion or to simulate the subsystems of the target device that have yet to be implemented in the custom portion.