rommon 1 > dev
Devices in device table:
id name
flash: flash

rommon 2 > meminfo
Main memory size: 32 MB.
Available main memory starts at 0x10000, size 32704KB
IO (packet) memory size: 15 percent of main memory.
NVRAM size: 32KB

rommon 3 > IP_ADDRESS=192.168.20.100 (The Address of the Router you're working on)

rommon 4 > IP_SUBNET_MASK=255.255.255.0 (The Subnet of the Router)

rommon 5 > DEFAULT_GATEWAY=192.168.20.1 (The Default Gateway)

rommon 6 > TFTP_SERVER=192.168.20.180 (The Address of the TFTP Server)

rommon 7 > TFTP_FILE=c2600-i-mz.122-12.bin (The IOS image file name)

rommon 8 > tftpdnld (Download IOS through TFTP)

IP_ADDRESS: 192.168.20.100
IP_SUBNET_MASK: 255.255.255.0
DEFAULT_GATEWAY: 192.168.20.1
TFTP_SERVER: 192.168.20.180
TFTP_FILE: c2600-i-mz.122-12.bin

Invoke this command for disaster recovery only.
WARNING: all existing data in all partitions on flash will be lost!
Do you wish to continue? y/n: [n]: y
Copying file c2600-i-mz.122-12.bin to flash.
Erasing flash at 0x60fc0000
program flash location 0x60520000

rommon 9 > dir flash: (Confirm IOS image file is now in flash - don't forget the colon!)
File size Checksum File name
5424680 bytes (0x52c628) 0x4158 c2600-i-mz.122-12.bin

rommon 10 > reset (Reset Router)

When restarted, 'sh ver' to ensure it's written correctly.