The IOS is not the same as the router's config.  The IOS is the underlying operating system of the router, and includes numerous low-level software routines to keep the router functioning.  This is similar to Windows on a PC.  The operating system is Windows, while the Desktop with all it's icons and shortcuts is analogous to the "config".


How to Copy the IOS


NOTE:  you must reboot afterwards


copy IOS from TFTP to flash:   copy tftp flash

copy IOS from flash to tftp:                   copy flash tftp

copy IOS from flash to DRAM:            boot system tftp

copy IOS from ROM to DRAM:          boot system bootflash