A package (1) comprising a first semiconductor chip (100) with pads for wire bonding and contacts for chip-to-chip interconnection, and a second semiconductor chip (200) also with contacts for chip-to-chip interconnection is mounted on a substrate (4) with a printed circuit (6). The first and second chips are coupled together via respective contacts. Chip-to-chip interconnections can be made by heat hardened silver pastel by anisotropic conductive material (9) or by a tape carrier having printed wires (9') supported by flexible film (8a). The two chips together are tightly-coupled pair having low interconnect capacitances and resistances. The first chip comprises an arithmetic logic unit (ALU), at least one register, a stack pointer, a program counter, and an index register.; The second chip comprises a command register, a command decoder, and a timing generator, the command decoder in communication with the first semiconductor chip, the command register responsive to a program memory located outside the device.