Intel NETWORK PROCESSOR IXP2800 - Manual (Page 188)

188 Hardware Reference Manual
Intel
®
IXP2800 Network Processor
DRAM
5.2 Size Configuration
Each channel can be populated with 1 – 4 RDRAMs (Short Channel Mode). For supported loading
configurations, refer to Table 61 . The RAM technology used determines the increment size and
maximum memory per channel as shown in Table 62 .
Note: One or two channels can be left unpopulated if desired.
RDRAMs with 1 x 16 dependent banks, 2 x 16 dependent banks, and four independent banks are
supported.
Table 61. RDRAM Loading
Bus Interface Maximum Number of Loads Trace Length (inches)
Short Channel: 400 and 533 MHz 4 devices per channel. 20 1
1. For termination, the DRAMs should be located as close as possible to the IXP2800 Network Processor.
Long Channel: 400 MHz
2 RIMMs per channel – a maximum of
32 devices in both RIMMs.
20 1
Long Channel: 533 MHz
1 RIMM and 1 C-RIMM per channel –
a maximum of 16 devices.
20 1
Table 62. RDRAM Sizes
RDRAM Technology 1 Increment Size Maximum per Channel
64/72 MB 8 MBs 256 MB
128/144 MB 16 MB 512 MB
256/288 MB 32 MB 1 GB 2
512/576 MB 64 MB 2 GB 2
NOTES:
1. The two numbers shown for each technology indicate x16 parts and x18 parts.
2. The maximum memory that can be addressed across all channels is 2 Gbytes. This limitation is based on
the partitioning of the 4-Gbyte address space (32-bit addresses). Therefore, if all three channels are used,
each can be populated up to a maximum of 768 Mbytes. Two channels can be populated to a maximum of
1 Gbyte each. A single channel could be populated to a maximum of 1 Gbyte.