Cisco GSR12/60 - 12012 Router -AnyLAN, SONET/SDH Installation And Configuration Manual page 37

DRAM
The extended data output (EDO) dynamic random-access memory (DRAM) on the GRP
stores routing tables, protocols, and network accounting applications, and runs the
Cisco IOS software. The standard (default) GRP DRAM configuration is 64 megabytes
(MB) of EDO DRAM, which you can increase up to 256 MB through DRAM upgrades.
The Cisco IOS software runs from within GRP DRAM. Table 1-2 lists the DRAM
configurations and upgrades.
Table 1-2 DRAM Configurations
Total DRAM Product Numbers
1
64 MB MEM-GRP/LC-64(=)
128 MB MEM-GRP/LC-64(=)
128 MB MEM-GRP/LC-128(=)
256 MB MEM-GRP/LC-256(=)
1. 64-MB is the standard (default) DRAM configuration for the GRP.
To prevent memory problems, DRAM DIMMs must be 3.3-volt (V),
Caution
60-nanosecond (ns) devices. Do not attempt to install other devices in the DIMM sockets.
SRAM
SRAM provides secondary CPU cache memory. The standard GRP configuration is
512 KB. Its principle function is to act as a staging area for routing tables update
information to and from the line cards. SRAM is not user configurable or field-upgradeable.
Physical and Functional Overviews
DRAM Sockets Number of DIMMs
U39 (bank 1) 1 64-MB DIMM
U39 (bank 1) and
U42 (bank 2) 2 64-MB DIMMs
U39 (bank 1) 1 128-MB DIMM
U39 (bank 1) and
U42 (bank 2) 2 128-MB DIMMs
Product Overview 1-9