For example, power sources (such as a battery or solar panel), displays (such as LEDs), antennas, speakers, sensors, or other parts may be incorporated within or on the subassembly. [0043] The embodiment illustrated in FIG. 1 has four attachment sites 113 for four microelectronic elements: element 101 a, element 101 b, element 101 c, and element 101 d.