Cisco 1720 flash filesystem erased

Since your router is in ROMON mode its better to use XMODEM command to upload a new IOS here are the steps to do this job,

From the ROMmon prompt, issue the xmodem command. However, before you issue the xmodem command, ensure that you have the new Cisco IOS software image on your PC.

In this example, all Flash memory is erased before downloading using the f option (only on the Cisco 1600 Series ). Perform a CRC-16 checksum using the c option and using a download speed of 115200 bps (only on the Cisco 1600 Series ) by specifying -s115200:

rommon 12 >xmodem -cfs115200 c1600-sy-mz.121-16.bin
Do not start the sending program yet...Note: If the console port is attached to a modem, both the console port and the modem must be operating at the same baud rate.

Use console speed 115200 bps for download [confirm]
File size Checksum File name
1957444 bytes (0x1dde44) 0xe345 c1600-y-mz.113-9.TErasing flash at 0x83f0000 no partition 2 on device: PCMCIA slot 1

Ready to receive file c1600-sy-mz.121-16.bin ...
Download will be performed at 115200.
make sure your terminal emulator is set to
this speed before sending file. Warning:  

All existing files in the partition displayed and files in any
other partitions on this device will be lost! Continue ? press 'y'
for yes, 'n' for no:yConfigure the terminal emulator program for a data rate of 115200 bps to match the xmodem speed specified above. This is done by closing the previous terminal session of 9600 bps and opening a new one at 115200 with 8-N-1. The trick here is that the Cisco 1603 only supports a maximum baud rate of 9600 bps. Therefore, when connecting at 115200 bps, you cannot see the router prompt. This is an important point to remember. Once connected to the router at 115200 bps, select Transfer and Send File from the HyperTerminal menu bar.

 

Specify the image file name and location and enter xmodem as the protocol.

 

Click on Send to start the transfer.

 

This message is received when the transfer is complete:

Download Complete!

Returning console speed to 9600

Please reset your terminal emulator to this speed...Per the message above, you need to exit your 115200 bps HyperTerminal session and restart a new one at 9600 bps. Once connected, the router's ROMmon prompt appears. Verify that the download was successful by issuing a dir flash:.

rommon 9 >dir flash:
File size Checksum File name
3686656 bytes (0x384100) 0x1a5e c1600-sy-mz.121-16.bin
Change the config register back to 0x2102 and reset or power cycle the router so that the new Cisco IOS software image gets loaded.

rommon 10 >confreg 0x2102

You must reset or power cycle for new config to take effect.

rommon 11 >reset
System Bootstrap, Version 12.0(19981130:173850) [rameshs-120t_lava 114],
DEVELOPMENT SOFTWARE Copyright (c) 1994-1998 by cisco Systems, Inc.
Simm with parity detected, ignoring onboard DRAM
C1600 platform with 16384 Kbytes of main memory
program load complete, entry point: 0x4020060, size: 0x15568c
%SYS-6-BOOT_MESSAGES: Messages above this line are from the boot loader.
program load complete, entry point: 0x2005000, size: 0x3840e0

Self decompressing the image : ########################################
################


........
             
Cisco Internetwork Operating System Software
IOS (tm) 1600 Software (C1600-SY-M), Version 12.1(16),
RELEASE SOFTWARE (fc1)
Copyright (c) 1986-2002 by cisco Systems, Inc.
Compiled Mon 08-Jul-02 17:09 by kellythw
Image text-base: 0x02005000, data-base: 0x0275BD48
.......

http://www.cisco.com/en/US/products/hw/routers/ps259/products_tech_note09186a008015bfac.shtml

cheers

Yasir

For rommon operations, please see the link posted above. It has detaile description and step-by-step instruction

When your router will give you initial prompt for initial config, follow basic management config branch. Or just interrupt it and configure it manually. You will need to configure ethernnet interface first

>en
#conf t
(config)#interface fa0
(config)#ip address <LAN IP> <LAN mask>
(config)#no shu
(config)#end

! then erase flash just in case
#erase flash:
! then copy a copy from tftp
#copy tftp: flash:
[IP]<enter IP of tftp server>
[source-filename]<IOS image file>
[destination-filename]<Enter key, will use the same as source>
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!![OK]

#wr mem
#reload

If you need TFTP server for Windows, you can use this one
http://www.solarwinds.com/products/freetools/index.aspx