Cisco Memory comes in four different types: DRAM, EPROM, NVRAM, and Flash. Dynamic Random-Access Memory (DRAM) contains two types, one of which is reserved for the CPU to execute Cisco IOS software and hold running configurations and routing tables. The other buffers data transmitted or received by the router’s network interfaces. Erasable Programmable Read-Only Memory (EPROM) contains ROM monitor software and the boot loader/helper software. Non-Volatile Random-Access-Memory (NVRAM) stores the startup configuration file for every platform except Class A Flash, and the software configuration register. Flash memory stores the Cisco IOS software image, and on most platforms it can store boot-images and configuration files. Depending on the device, Flash is available as either internal Flash (usually containing the system image), Bootflash (usually containing the boot image and sometimes the ROM Monitor), and PCMCIA cards (can be used to store system images, boot images, and configuration files). All of these types are available as Approved or Third Party. Approved memory is manufactured by companies on Cisco’s approved vendor list. Third Party are manufactured by companies that do not appear on Cisco’s approved vendor list and do not bear the Cisco label, but is also 100% compatible and guaranteed to work in the Cisco device for which it’s sold. Installing a Third Party memory into a Cisco chassis and components DOES NOT void your Cisco Factory Warranty or any Cisco SMARTnets you may have purchased for the equipment.