Eight-Way System Interleave Of Four 128-Mbyte Memory Modules - DEC AlphaServer 8200 Technical Manual

module can result in reduced system throughput due to common data path
contention between the two banks.
At the module level, the DRAM arrays can be interleaved on 64-byte block
boundaries. The DRAM array in a 2-string MS7CC memory module is al-
ways interleaved.
In multimodule memory subsystems, three modes of interleave are possi-
ble at the system level: default, explicit, and none. The interleave mode
selection parameters are stored in the console FEPROM and can be modi-
fied through the console program. Initialization software uses registers in
TLSB commanders and each memory module to configure the memory in-
terleave as specified by the FEPROM parameters. A memory configura-
tion consisting of four memory modules supports a maximum of 8-way in-
terleaving when each of the four modules is 2-way interleaved. The three
additional modules (modules 5 to 7), if present, can be configured into the
system as two modules 4-way interleaved and 1 module 2-way interleaved.
Figure 4-7 shows four memory modules in an 8-way interleaved organiza-
tion.
Figure 4-7

Eight-Way System Interleave of Four 128-Mbyte Memory Modules

2-Way Module Interleave; No System Interleave
Bank 0
0000 0000 0000 0040
0000 0080 0000 00C0
07FF FF80 07FF FFC0
2-Way Module Interleave; 8-Way System Interleave
Bank 0 1
0000 0000 0000 0100
0000 0200 0000 02FF
1FFF FE00 1FFF FF00
Block size = 64 Bytes
DRAM size =
Memory Capacity = 512 Mbytes
If the FEPROM specifies default interleave, the console attempts to form
interleave sets so that the largest interleave factor is obtained for each
1 2 3
0800 0000 0800 0040
0800 0080 0800 00C0
0FFF FF80 0FFF FFC0
2 3
0000 0040 0000 0140
0000 0240 0000 033F
1FFF FE40 1FFF FF40
4 Mbits
4 5
1000 0000 1000 0040 1800 0000 1800 0040
1000 0080 1000 00C0 1800 0080 1800 00C0
17FF FF80 17FF FFCO IFFF FF80 IFFF FFC0
4 5
0000 0080 0000 0180 0000 00C0 0000 01C0
0000 0280 0000 037F 0000 02C0 0000 03BF
1FFF FE80 1FFF FF80 1FFF FEC0 1FFF FFC0
Memory Subsystem 4-15
6 7
6 7
BXB-0307-92