Cisco Systems 4000 manual Memory Systems, DRAM = dynamic random-access memory

			Memory Systems
Table 1-3	Cisco 4000 Series Processor and Memory Specifications
Description	Cisco 4000-M	Cisco 4500-M	Cisco 4700-M
Processor	40-MHz Motorola	100-MHz IDT Orion	133-MHz IDT Orion
	68EC030	RISC1	RISC
Main memory	4, 8, 16, or 32 MB	8, 16, or 32 MB	16, 32, or 64 MB
(DRAM)2
Secondary cache	None	None	512 KB
memory
Shared memory	4 or 16 MB	4, 8, or 16 MB	4, 8, or 16 MB
(DRAM)
Flash memory	4 or 8 MB	4, 8, 16, 32, or 64 MB	4, 8, 16, 32, or 64 MB
NVRAM3	128 KB	128 KB	128 KB
Boot ROM	128 KB–8 MB	128–512 KB	128–512 KB
Boot Flash	Not available	4–16 MB	4–16 MB

1.The Orion microprocessor is based on the MIPS R4400 and is pin-compatible.

2.DRAM = dynamic random-access memory.

3.NVRAM = nonvolatile random-access memory.

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 IOS software executes from main memory.

•Shared memory—Used for packet buffering by the router’s network interfaces.

•Flash memory—Stores the operating system software image. In the Cisco 4500-M and 4700-M, the Flash memory also stores the boot helper software.

•NVRAM—Stores the system configuration file and the virtual configuration register.

•Boot EPROM—In the Cisco 4000-M, erasable programmable read-only memory (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-M, only the ROM monitor is EPROM based. The boot helper image allows you to boot the router

Overview of the Cisco 4000 Series Routers 1-9