The DS26401 is an octal, software-selectable T1, E1 or J1 framer. It is composed of eight framer/formatters and a system (backplane) interface. Each framer has an HDLC controller that can be mapped to any DS0 or FDL (T1)/Sa (E1) bit. The DS26401 also includes a full-feature BERT device, which can be used with any of the eight T1/E1 ports, and an internal clock adapter useful for creating synchronous, high frequency backplane timing. The DS26401 is controlled through an 8-bit parallel port that can be configured for nonmultiplexed Intel or Motorola operation.