Cisco 1600 - Manual (Page 6)

MB. If SIMM is with parity, total DRAM can be up to 16 MB (on−board 2 MB will be disabled).
Note: The Cisco 1605−R Series Router has 8 MB on−board. Therefore, total DRAM can be up to 24 MB on
that router. For more information, see Comparison of Cisco 1601, Cisco 1604, and Cisco 1605−R Memory
Architectures.
Note: To install or replace the DRAM, see Installing or Replacing the DRAM SIMM in Cisco 1600 Series
Routers.
PCMCIA Flash
PCMCIA Flash is the only way to permanently store and move a complete Cisco IOS software image,
backup configurations, or any other files.
PCMCIA Flash on the Cisco 1600 Series Router is implemented using one slot for Fast PC cards (up to
16MB).
The PCMCIA Flash card on the Cisco 1600 Series Router uses the Filesystem Class "B". This is the same
type used for the Cisco 1000 Series Router and Cisco 3600 Series Router. For PCMCIA format compatibility
information, see PCMCIA Filesystem Compatibility Matrix.
NVRAM
NVRAM is used for permanent storage of the startup configuration that is writeable. It is also used for
permanent storage of hardware revision and identification information, and also Media Access Control
(MAC) addresses for LAN interfaces. It is a battery−backed Static RAM (SRAM). The life−span of NVRAM
is specified in the maximum number of writes and a maximum time limit. NVRAM size is 8 KB.
BOOT ROM
BOOT ROM is an Erasable programmable read−only memory (EPROM) used to permanently store startup
diagnostic code (ROM Monitor), and RxBoot. Boot ROM size is 2 MB. The Cisco 1600 Series Router runs
RxBoot from Boot ROM.
For information on how to upgrade the Boot ROM, see Upgrading the Boot ROMs in Cisco 1600 Series
Routers.
Registers
Registers are small, fast memory units used to store special purpose information, such as interrupt status,
instruction currently in execution, and so on. The location of registers depends upon their use. For example,
the main processor contains the instruction register and other control registers. UART contains its own status
register such as other I/O devices and data read/write registers on various components. The main processor
also contains general purpose registers for integer and floating point data used in an instruction execution.
Sample Output
The different types of memory can be seen in the output of the show version command:
Router−1600#show version
Cisco Internetwork Operating System Software
IOS (tm) 1600 Software (C1600−Y−L), Version 12.2(10b), RELEASE SOFTWARE (fc1)
Cisco − Cisco 1600 Series Router Architecture