Specifications

4-14 Memory Subsystem
Figure 4-5 Two-Way Interleave of a 128-Mbyte DRAM Array
Memory modules of different capacities can be interleaved as a set with
modules of another capacity. For example, two 128-Mbyte modules can be
interleaved with a single 256-Mbyte module as one set that is 4-way inter-
leaved. This type of configuration yields 2-way module interleaving and 4-
way system-level interleaving as shown in Figure 4-6. This same set can
also be interleaved into a "pseudo 8-way" interleave set that will further
boost system performance.
NOTE: For such a memory module set, the console configures memory to the
"pseudo 8-way" interleave.
Figure 4-6 Interleaving Different Size Memory Modules
Interleaving of memory modules is set up by initialization software
through mapping registers in TLSB commanders and in each memory
module.
When memory modules are interleaved, each interleaved set is addressed
on a 64-byte block boundary. In multiple interleaved modules, each con-
secutive 64-byte address targets the next memory module in the inter-
leaved set. This is done because accessing multiple banks in one memory
Bank 0 Bank 1 

0000 0000 0000 0040
0000 0080 0000 00C0





07FF FF80 07FF FFC0
BXB-0307A-92
Block size = 64 Bytes
DRAM size = 4 Mbits
Memory Capacity = 128 Mbytes
64 Mbytes64 Mbytes
BXB-0389A-92
256
Mbytes
128
Mbytes
128
Mbytes
256
Mbytes
128
Mbytes
128
Mbytes
Noninterleaved Interleaved