GCIXP1240AB 837151 Intel, GCIXP1240AB 837151 Datasheet - Page 15

• Manufacturer Part Number: GCIXP1240AB 837151
• Manufacturer: Intel

Specifications of GCIXP1240AB 837151

• Lead Free Status / Rohs Status: Not Compliant

2.5
2.5.1
Datasheet
SDRAM and SRAM Units
The IXP1240 supports two high performance memory units. The SRAM Unit provides fast
memory that can be used to store look-up tables. The SDRAM Unit provides lower cost memory
for forwarding information and transmit queues. Both units contain features that improve memory
bandwidth utilization.
SDRAM Unit
The IXP1240 provides an SDRAM Unit to access low cost, high bandwidth memory for mass data
storage. The StrongARM* core address space allows up to 256 Mbytes of SDRAM to be
addressed. The SDRAM interface operates at half the core frequency (0.5*F
bandwidth of 928 Mbytes per second at 232 MHz.
Bus cycles are generated by requests from the PCI Unit including PCI DMA cycles, the
StrongARM* core, and the Microengines.
The SDRAM is operated by commands that are loaded into command queues within the unit. The
SDRAM Unit decodes the command, reads or writes the data, then deletes the command from the
head of the queue. The read and write sources may be SDRAM memory locations, transfer
registers, or the Transmit and Receive FIFOs in the FBI Unit. Refer to the IXP1200 Network
Processor Family Hardware Reference Manual for details on how these requests are queued,
prioritized, and serviced by the SDRAM Unit.
SDRAM should have an access time (t
ac
) of 6 ns or less (CAS latency = 2), PC100 compatible.
Intel
®
IXP1240 Network Processor
core
), providing a peak
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