The invention relates to an assembly comprising a series of unitary support modules that arc assembled to one another to form a lower flat support that can be inserted vertically between the floor and a modular upper cover comprising a series of cover elements which are affixed to the upper surfaces of the unitary support modules. According to an example embodiment of the present invention, the filled trench is formed in a substrate adjacent to at least one thyristor body region. The digital signal processor receives pulse-code modulated voice data, compresses the pulse-code modulated voice data, and generates data packets that correspond to the compressed pulse-code modulated voice data. 20 and Mn is manganese in a form that is present from about 0.