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4-4
© Copyright ARM Limited 1999. All rights reserved.
ARM DUI 0125A
4.1.3 SDRAM accesses
The Integrator memory map provides a 256MB address space for SDRAM. When a
smaller sized SDRAM DIMM is fitted, it is mapped repeatedly to fill the 256MB space.
For example, a 64MB DIMM appears four times, as shown in Figure 4-2.
Figure 4-2 SDRAM repeat mapping for a 64MB DIMM
Local SDRAM
The local processor can access the local SDRAM (that is, the SDRAM on the same core
module) at 0x00000000 to 0x0FFFFFFF in the core module address space. However,
the lowest 256KB (0x00000000 to 0x0003FFFF) is hidden by the SSRAM or boot
ROM, depending upon whether the core module is attached to a motherboard and upon
the state of the REMAP bit.
The SDRAM cannot be accessed within this address space, although it can be accessed
at one of its repeat images or at its alias location. In the case of a 256MB DIMM which
fills the local SDRAM space, the first 256KB can only be accessed at the alias location
(see System bus accesses to SDRAM below).
SSRAM
0x0FFFFFFF
0x0003FFFF
256KB
64MB
64MB
64MB
64MB
Local SDRAM
Local SDRAM
(repeat image)
Local SDRAM
(repeat image)
Local SDRAM
(repeat image)