Service manual

System Overview 1-47
• Memory interleaving is used to improve memory bandwidth by “staggering”
transactions on the memory arbitration bus. See memory interleaving guidelines in
the AlphaServer GS80/160/320 User’s Guide.
• Read data wrapping is used to reduce apparent memory latency by allowing
quadword (8 bytes) access in a prescribed order.
• A microcontroller initiates memory built-in self-test and communicates DIMM
EEPROM data to the PSM.
• Short-circuit protection.
Table 1– 10 Memory Configurations
DIMM
Module
Min. Max.
QBB
Max.
GS80
Max.
GS320
Max. SDRAM
256 MB 1 GB 2 GB 8 GB 16 GB 64 GB 64-Mbit
512 MB 2 GB 4 GB 16 GB 32 GB 128 GB 64/256-Mbit
1 GB 4 GB 8 GB 32 GB 64 GB 256 GB 256-Mbit
Configuration Guidelines
• Minimum configuration: 1 Gbyte.
• Memory arrays on a memory module may be of different sizes but no mixed DIMM
sizes are allowed in a memory array.
• If your system has two memory arrays, for better bandwidth, have two single arrays
(4 DIMMs) on two memory modules rather than two memory arrays on a single
memory module.
For more information, see the AlphaServer GS80/160/320 User’s Guide.