DP83932C-33

The SONIC (Systems-Oriented Network Interface Controller) is a second-generation Ethernet Controller designed to meet the demands of today's high-speed 32- and 16-bit systems. Its system interface operates with a high speed DMA that typically consumes less than 3% of the bus bandwidth (25 MHz bus clock). Selectable bus modes provide both big and little endian byte ordering and a clean interface to standard microprocessors. The linked-list buffer management system of SONIC offers maximum flexibility in a variety of environments from PC-oriented adapters to high-speed motherboard designs. Furthermore, the SONIC integrates a fully-compatible IEEE 802.3 Encoder/Decoder (ENDEC) allowing for a simple 2-chip solution for Ethernet when the SONIC is paired with the DP8392 Coaxial Transceiver Interface or a 10BASE-T transceiver.

For increased performance, the SONIC implements a unique buffer management scheme to efficiently process, receive and transmit packets in system memory. No intermediate packet copy is necessary. The receive buffer management uses three areas in memory for (1) allocating additional resources, (2) indicating status information, and (3) buffering packet data. During reception, the SONIC stores packets in the buffer area, then indicates receive status and  control information in the descriptor area. The system allocates more memory resources to the SONIC by adding descriptors to the memory resource area. The transmit buffer management uses two areas in memory: one for indicating status and control information and the other for fetching packet data. The system can create a transmit queue allowing multiple packets to be transmitted from a single transmit command. The packet data can reside on any arbitrary byte boundary and can exist in several non-contiguous locations.