The DS26101 maps ATM cells to T1/E1 TDM frames as specified in ATM Forum Specifications af-phy0016.000 and af-phy-0064.000. In the receive direction, the cell delineation mechanism used for finding ATM cell boundary within T1/E1 frame is performed as per ITU I.432. The DS26101 provides a mapping solution for up to 8 T1/E1 TDM ports. The terms physical layer (PHY) and line side are used synonymously in this document and refer to the device interfacing with the line side of the DS26101. The terms ATM layer and system side are used synonymously and refer to the DS26101's UTOPIA II interface.