I recently installed a second Flash chips in a 2500. When look in It shows the two chips as separate memory banks. One is read only and the other as read and write. What is going on with this?? Do I need to change anything in the router or the chips??
Cisco FLASH coms in 3 main "types for various Cisco devices, and the very earliest type (Type 1), is what the 2500 uses. Its been a while since I played with a 2500, but from distant memory a "Type 1 FLASH" only holds ONE File per PARTITION in the flash. The "trick" being that you need to PARTITION or divide up the FLASH to handle more than 1 file, and in your case adding the extra memory chip just adds a new (unused) PARTITION. Normaly you define the size of each PARTITION by a statement in the config, but I am not sure if this is created automatically if FLASH is added or not.
An existing FILE stored in a FLASH PARTITION will take up an entire PARTITION, which is why that partition is marked as Read-Only (its already got something stored in it). To combine ALL FLASH into ONE PARTITION, you need to ERASE any existing files and then PARTITION the FLASH to whatever format you want. Have a look at the PARTITION command for the 2500 FLASH File System on the Cisco Web site, and all will be revealed.
The 2500 actually runs the code from the flash. For the flash bank holding the CURRENLY RUNNING code, it must be read only (can't rewrite the code you are running).
If you boot to an image in the other bank, that bank will become read only and the other will become read write.
Exepcted behavior for added flash - it is treated as a new bank.
If you want to set the pair of flash SIMMs to be a single large partition, you will need to boot to the ROM image and repartition the flash to one large bank. The only way to rewrite the flash is to boot to the ROM version of the IOS. IOS has a feature called "Flash Boot Helper" that does all of the magic dance to fix that all up.