The Fast Serial Interface Processor (FSIP) provides four (FSIP4) or eight (FSIP8) channel-independent, synchronous serial ports that support full-duplex operation at T1 (1.544 Mbps) and E1 (2.048 Mbps) speeds. The ports are divided into two 4-port modules, each of them is controlled by a dedicated Motorola MC68040 processor and contains 128 KB of static random-access memory (SRAM). Each module can support up to four T1 or three E1 interfaces, and an aggregate bandwidth of up to 6.132 Mbps at full-duplex operation.The FSIP4 has one module for ports 0-3, and the FSIP8 has two modules, one for ports 0-3 and the other for ports 4-7. To provide a high density of ports, the FSIP uses special port adapters and adapter cables. A port adapter is a daughter board that provides the physical interface for two FSIP serial ports. Each FSIP comprises an FSIP board with two or four port adapters. (One module is equivalent to two port adapters.) Additional port adapters are available as spares so that you can replace one that fails; however, you cannot upgrade a 4-port FSIP to an 8-port FSIP by adding port adapters. Each serial port on the FSIP4 or FSIP8 can transmit and receive data at the rate of 6.132 Mbps.