The TC9021/TC9020 is part of a new generation of high performance, host-optimized network interface cards designed for mission critical systems such as servers and high-end workstations. Offering two gigabits per second of aggregate bandwidth, the TC9021/TC9020 optimizes performance while minimizing network overhead on the host system. Compared to leading Fast Ethernet solutions, the TC9021/TC9020 transfers data at less than one tenth of the host CPU utilization rate. IEEE 802.3z Gigabit Ethernet MAC The TC9021/TC9020 implements IEEE 802.3z half duplex functions such as Carrier Extension and Packet Bursting. In full duplex mode, the TC9021/TC9020 implements both symmetrical and asymmetrical flow control via IEEE 802.3x PAUSE MAC Control frames. PAUSE frames can be automatically generated by the TC9021/TC9020 according to programmable flow control thresholds within the on-chip receive FIFO. The TC9021/TC9020 MAC has been carefully implemented to ensure full wire speed at 1Gbps with 96-bit transmit and 64-bit receive inter-frame spacing.