When would you need this: When you want to upgrade the IOS file and you do not have TFTP of FTP servers around, so you turn to the good old console for the upgrade.
Special Requirements: The router flash size should be adequate for the new IOS image, and you should have enough RAM in the router for the operation and temporary storage of the new IOS file.
It is recommended that you backup the old IOS file before the upgrade using this procedure, and backup the configuration too using this procedure. And keep in mind that this procedure is not recommended. It is recommended that you upgrade using a TFTP or FTP server. This is because it takes a long time and you do not see an error when it occurs until the copying is finished.
1. Create a console connection with the default settings (9600 baud, 8 databits, 0 parity bits, 1 stop bit, no flow control).
2. Change the baud rate of the console port to its maximum 115,200
Router#set baud = 115200
3. Reset the console port
Now you will not get anymore output on the screen until you finish step 3.
4. Change the connection speed of the HyperTerminal. Disconnect and reconnect with the baud rate of 115200 with all the rest of the settings mentioned in step 1.
Read the rest of the article in the Router Geek Book: Guide to Cisco Routers Configuration