This is a 4MB DIMM memory module designed for CISCO 2600 routers.The Cisco 2600 series routers contain two 100-pin single DIMM sockets (or banks) for DRAM, numbered 0 and 1.Each socket can be filled with a dual, 100-pin DRAM DIMM. You can use the �memory-size iomem� software command to configure DRAM as a mixture of shared memory, which is used for data transmitted or received by network modules and WAN interface cards, and primary or main memory, which is reserved for the CPU.