The DS26401 is an octal, software-selectable T1, E1,
or J1 framer. It is composed of 8 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 8 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.