Cisco WS-X4515 Hardware Maintenance Manual - Page 22
Memory Systems, Cisco Internetwork Operating System Cisco IOS software executes from main memory.
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Memory Systems Memory Systems The Cisco 4000 series memory systems (see Figure 1-2) have the following functions: • Main memory-Stores the running configuration and routing tables. The Cisco Internetwork Operating System (Cisco IOS) software executes from main memory. • Shared memory-Used for packet buffering by the router's network interfaces. • Nonvolatile memory-Stores the system configuration file and the virtual configuration register. • Flash memory-Stores the operating system software image. In the Cisco 4500-M, the Flash memory also stores the boot helper software. • EPROM-based memory-In the Cisco 4000-M, EPROM-based memory stores the boot helper-a subset of the Cisco IOS software-and the ROM monitor. In the Cisco 4500-M and Cisco 4700, only the ROM monitor is EPROM-based. The boot helper image allows you to boot the router when Flash memory does not contain a valid system image. In the Cisco 4500-M, the ROM monitor allows you to boot a system image from Flash memory if a boot helper image is not present in boot Flash memory. The boot helper prompt is as follows: router(boot)> The ROM monitor prompt for the Cisco 4000-M is the greater than sign: > The Cisco 4500-M and Cisco 4700 ROM monitor prompt is as follows: rommon 1 > (See the appendix "Cisco 4000 Series Virtual Configuration Register," the appendix "Cisco 4000-M ROM Monitor," and the appendix "Cisco 4500-M and Cisco 4700 ROM Monitor.") Figure 1-2 Cisco 4000 Series Memory Systems and Software Images Cisco 4000 and Cisco 4000-M EPROM-based Flash-memory based Boot helper (xboot) Cisco IOS ROM monitor Cisco 4500, Cisco 4500-M, Cisco 4700, and Cisco 4700-M EPROM-based Flash-memory based ROM monitor Boot helper (xboot) Cisco IOS H3537 1-4 Cisco 4000 Series Hardware Installation and Maintenance