RAM The 2500 series uses a single 72pin FPM (70ns) SIMM with parity, and can take a maximum of 16 MB. System boards with a revision 'A' through 'G', have an additional 2 MB of RAM soldered to the system card. Revisions 'I' through 'N' do not have any RAM soldered to the system card. This means total RAM can be 18 MB on routers having the additional 2 MB on board. On system boards with on board RAM, the SIMM socket may be left unpopulated.
FLASH There are 2 Flash Memory sockets available (80pin, 120ns), with the maximum flash memory supported being 16 MB. Standard flash memory was 8 MB on most routers and 4 mb on 'Mission Specific' models. A boot
ROM upgrade may be needed to use 16 MB of flash. The 2500 ran its IOS directly from flash memory. An erasable, programmable read-only memory (EPROM) of 2 MB in size was used to permanently store the startup diagnostic code (ROM Monitor), and RxBoot. This ROM was held in 2x PLCC sockets and was user upgradeable. Each unit had 32k of NVRAM, used for storage of the startup configuration. Some 2500 models (e.g. 2511) had a
PCMCIA slot installed on the board. It was intended that Cisco would send IOS updates on PCMCIA, which would then update the router. Support for this was very limited, and the device was read only. == Software ==