The DS33Z44 extends four 10/100 Ethernet LAN segments by encapsulating MAC frames in HDLC or X.86 (LAPS) for transmission over four PDH/TDM data streams. The serial links support bidirectional synchronous interconnect up to 52Mbps over xDSL, T1/E1/J1, T3/E3, V.35/Optical, OC-1/EC-1, or SONET/SDH Tributary. The device performs store-and-forward of packets with full wire-speed transport capability. The built-in Committed Information Rate (CIR) controllers provide fractional bandwidth allocation up to the line rate in increments of 512kbps. The DS33Z44 can operate with an inexpensive external processor, EEPROM or in a stand-alone hardware mode. Applications * Ethernet Delivery Over T1/E1/J1, T3/E3, OC-1/EC-1, G.SHDSL, or HDSL2/4 * LAN Extension * Transparent LAN Service * Four 10/100 IEEE 802.3 Ethernet MACs (MII and RMII) Half/Full-Duplex with Automatic Flow Control * Four 52Mbps Synchronous TDM Serial Ports with Independent Transmit and Receive Timing * HDLC/LAPS Encapsulation with Programmable FCS and Interframe Fill * Committed Information Rate Controllers Provide Fractional Allocations in 512kbps Increments * Programmable BERT for Serial (TDM) Interfaces * External 16MB, 100MHz SDRAM Buffering * Parallel Microprocessor Interface * SPI Interface and Hardware Mode for Operation Without a Host Processor * 1.8V Operation with 3.3V Tolerant I/O * IEEE 1149.1 JTAG Support