Abstract: The Arbitrated Bus Interface (ABI) is a set of custom LSI circuits which sends and receives minipackets of binary information to and from a data bus. The ABI performs arbitration, address recognition, and buffering required for transmitting and receiving mini-packets of information between the local packet bus and a microprocessor.

Abstract: The Mini Packet Receiver Transmitter Circuit (MPRT) provides an interface between one or two eight bit microprocessors and a digital subscriber loop interface circuit. The bi-directional communication on a single wire pair is accomplished by alternating the subscriber loop receive and transmit frames controlled by a "Ping-Pong Protocol" using fixed frame format and bipolar alternate mark inversion (AMI) line encoding. There are two microprocessor ports within the MPRT, a transparent port for voice transmission and a non-transparent port for data trasmission. The MPRT implements the Mini Packet Protocol frame format as a mini packet (MP) of information, for both transparent and non-transparent data.