The network processing engine maintains and executes the system management functions for the Cisco 7200 series routers. The network processing engine also shares the system memory and environmental monitoring functions with the I/O controller.The NPE-100 has an R4700 microprocessor that operates at an internal clock speed of 150 MHz. The NPE-100 has a system controller that uses direct memory access (DMA) to transfer data between DRAM and packet SRAM on the network-processing engine. The NPE-100 uses DRAM for storing routing tables, network accounting applications, packets of information in preparation for process switching. The NPE-100 has unified cache SRAM that functions as the secondary cache for the microprocessor. (The primary cache is within the microprocessor).