A method for developing integrated circuits includes generating a core (logic core) in an HDL format readable by a logic synthesis tool, from an ASIC core (logic core) made of ports of blocks and port connection information, creating a temporary chip design from chip terminal information to generate a terminal in the temporary chip design, generating a design identical to that created, as a cell within the design created, connecting a design port with a cell port, wherein a name of the design port is identical to a name of the cell port, inserting an I/O buffer, depending on the device technology, into a net between the ports connected, replacing the cell by the core (logic core) created to gerate a netlist, and expanding a hierarchy of the design, being the top hierarchy.