Cisco 12404 Installation And Configuration Manual page 33

Chapter 1 Product Overview
NVRAM
Caution
Flash Memory or SIMM
Read Only Memory
OL-11636-01
Non-Volatile Random Access Memory (NVRAM) cannot be upgraded or
configured. The system configuration, software configuration register settings,
and environmental monitoring logs are contained in the 512-KB NVRAM, which
is backed up with built-in lithium batteries that retain the contents for a minimum
of five years.
Before you replace the RP in the system, back up the running configuration to a
Trivial File Transfer Protocol (TFTP) file server or an installed Flash memory
card so you can retrieve it later.
A single inline memory module (SIMM) is a Flash memory card that allows you
to remotely load and store multiple Cisco IOS software and microcode images.
You can download a new image over the network or from a local server and then
add the new image to Flash memory or replace the existing files. You can then
boot the routers either manually or automatically from any of the stored images.
Flash memory also functions as a trivial file transfer protocol (TFTP) server to
allow other servers to boot remotely from stored images or to copy them into their
own Flash memory.
Read-only memory (ROM), computer memory on which data has been
prerecorded. Once data has been written onto a ROM chip, it cannot be removed
and can only be read.
Unlike main memory (RAM), ROM retains its contents even when the computer
is turned off. ROM is referred to as being nonvolatile, whereas RAM is volatile.
The GRP provides two dedicated PCMCIA card slots. Either slot can support a
Flash memory card or an input/output (I/O) device, as long as the device requires
only +5 VDC. The GRP supports Type 1 and Type 2 devices. Each PCMCIA slot
has an ejector button for ejecting the card from its slot.
Cisco 12404 Internet Router Installation and Configuration Guide
Route Processors
1-9