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Cisco 2900 Series and 3900 Series Hardware Installation Guide
OL-18712-02
Chapter 1      Overview of the Routers
  Hardware Features
Ta b l e  1-7 EHWIC Support for SPE 200 and SPE 250
Integrated Service Modules
Internal Services Modules (ISM) supersede advanced integration modules (AIM) on Cisco 2900 series 
and Cisco
 3900 series ISRs. The ISM is larger in size than the AIM. Due to these physical differences, 
the AIM does not fit into the ISM slot and is no longer supported on Cisco
 2900 series and 
Cisco
 3900 series ISRs.
Packet Voice Data Modules
The Packet Voice Data Modules (PVDM3s) are the latest generation of PVDMs. First-generation 
PVDM-I cards are not supported in the PVDM3 slots. Due to physical differences, PVDM2s require an 
adapter for installation in the PVDM3 slot. See the  for installation instructions.
Note
PVDM2 cards cannot be mixed with PVDM3s.
Memory
Cisco 2900 series and Cisco 3900 series routers contain the following types of memory:
  •
DRAM—Stores the running configuration and routing tables and is used for packet buffering by the 
network interfaces. Cisco
 IOS software executes from DRAM memory. Supported module types are 
Unregistered Dual In-Line Memory Module (UDIMM) and very low profile registered DIMM (VLP 
RDIMM). 
Note
UDIMMs and VLP RDIMMs are not interchangeable.
  •
Boot/NVRAM—256K of internal non-volatile memory. Stores the bootstrap program (ROM 
monitor), the configuration register, and the startup configuration.
  •
Flash memory—External flash memory. Stores the operating system software image. Each model 
supports 2 external CompactFlash 4-GB memory cards provide a maximum 8-GB of CompactFlash.
Note
You must use Cisco-qualified CompactFlash cards supporting True IDE PIO Mode 6 and 
True IDE Multiword DMA Mode 4 as defined in CompactFlash Specification Revision 4.1 
of the CompactFlash Association. Use of any other cards during normal network operation 
can affect system performance.
Table 1-8 summarizes the memory options for Cisco 2900 series and Cisco 3900 series routers. Default 
memory represents the minimum usable RAM. You can install additional RAM up to the maximum 
amount. 
Expansion memory modules are UDIMMs or VLP RDIMMs with error correction code (ECC). All 
onboard RAM uses ECC.
Slot 0 Slot 1  Slot 2
WIC/VIC and HWIC WIC/VIC, HWIC, 
EHWIC, DHWIC, and 
EDHWIC
WIC/VIC and HWIC