The Input/Output controller, shares the system memory functions and the environmental monitoring functions for the Cisco routers with the network processing engine.The I/O controller consists of the following components: dual EIA/TIA-232 channels for local console and auxiliary ports (the console port has full data communications equipment (DCE) functionality and a DB-25 receptacle; the auxiliary port has full data terminal equipment (DTE) functionality and a DB-25 plug); an optional Fast Ethernet port with a single female MII receptacle that is configurable for use at 100 megabits per second (Mbps): two Personal Computer Memory Card International Association (PCMCIA) slots for Type II Flash memory cards; Flash memory SIMM and Flash memory cards for storing the boot helper image and the default Cisco IOS software image; erasable programmable read-only memory (EPROM) for storing sufficient code for booting the Cisco IOS software; two environmental sensors for monitoring the cooling air as it enters and leaves the Cisco router chassis; nonvolatile random-access memory (NVRAM) for storing the system configuration and environmental monitoring logs.