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