Describe the Internal Components of a Router Exercise

Knowing the functions of the main internal components of a router is more important than knowing the locations of the physical components inside a particular model. Therefore, in your own words, provide a sufficiently detailed description of each component.
Component Description
CPU The central processing unit (CPU) executes the instructions of the operating system. Among these functions are system initialization, routing functions, and network interface control.
RAM RAM is used for storing the IOS and for the working memory needed by the IOS. This includes the routing table, running configurations, and packet queues, which hold packets until the interface can be used to forward the packet. The contents of RAM are lost when the router loses power.
Flash Flash memory is used for storage of a full Cisco IOS Software image. In most routers, a copy of the IOS is transferred to RAM from flash during the bootup process. Physically, flash memory consists of single in-line memory modules (SIMM) or PCMCIA cards, which can be upgraded to increase the amount of flash. Flash memory does not lose its contents when the router loses power.
NVRAM NVRAM is used to store the startup configuration. As described in Chapter 2, “Static Routing,” a router will copy the startup configuration from NVRAM into RAM when the router is initialized, and use the running configuration in RAM for normal router operation. NVRAM retains its contents when the router loses power.
Buses Buses provide a physical means for the router to move bits between the different components of the router. Most routers contain a system bus and a CPU bus. The system bus is used to communicate between the CPU and the interfaces. For example, this bus transfers the packets to and from the interfaces. The CPU bus is used by the CPU for accessing router storage devices, like NVRAM and flash memory.
ROM ROM holds the bootstrap program, the ROM Monitor software, and optionally a scaled-down version of the IOS. (Chapter 2 covers these types of software.) ROMs are not erasable and can only be upgraded by replacing the ROM chips, but ROM does retain its contents when the router loses power.
Power supply The power supply converts the voltage and current of a standard power source to the voltage and current required by the devices in the router. The power supplies can be internal or external to the router chassis (the chassis is the metal box that holds the components of the router), and some routers have multiple power supplies for redundancy.